中亚热带3种典型森林土壤碳氮含量和酶活性的关系

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鲍勇, 高颖, 曾晓敏, 袁萍, 司友涛^,^*, 陈岳民, 陈滢伊福建师范大学湿润亚热带山地生态国家重点实验室培育基地, 福州 350007

Relationships between carbon and nitrogen contents and enzyme activities in soil of three typical subtropical forests in China

BAO Yong, GAO Ying, ZENG Xiao-Min, YUAN Ping, SI You-Tao^,^*, CHEN Yue-Min, CHEN Ying-YiSchool of Geography Sciences, Fujian Normal University, Fuzhou 350007, China; and State Key Laboratory of Sub-tropical Mountain Ecology (Founded by Ministry of Science and Technology and Fujian Province), Fujian Normal University, Fuzhou 350007, China

通讯作者: *(yt.si@fjnu.edu.cn)

编委: 李意德
责任编辑: 王葳

基金资助:

国家自然科学基金(31570606)和福建省自然科学基金(2015J01120).
Supported by the National Natural Science Foundation of China (31570606), and the Natural Science Foundation of Fujian Province (2015J01120)..

Online:2018-04-20

Fund supported:

摘要
森林类型更替是影响生态系统有机质循环的重要因素, 它对森林生态系统的生产力、碳吸存和养分保持功能有影响。然而关于中亚热带不同森林类型对土壤碳氮含量和酶活性的影响及土壤碳氮含量和酶活性之间的关系鲜有报道。该文研究了福建省三明市3种典型亚热带森林——米槠(Castanopsis carlesii)天然次生林(SF)、米槠人工促进天然更新林(AR)、马尾松(Pinus massoniana)人工林(PM)的淋溶层(A层)土壤碳氮含量和土壤微生物酶活性的关系。结果表明: 在3种森林类型表层土壤中, 可溶性有机质中可溶性有机碳、可溶性有机氮(DON)、荧光发射光谱腐殖化指数的趋势均为SF > AR > PM, 芳香化指数大小为PM > AR > SF; SF和AR的NH₄ ⁺-N显著高于PM, NO₃ ^--N在3种林分中的含量低且差异不明显, 造成这种差异的原因是树种差异和人为干扰程度不同。PM的β-葡萄糖苷酶活性显著低于SF和AR; 纤维素水解酶活性大小为AR > SF > PM; PM多酚氧化酶显著高于SF和AR, 3种林分过氧化物酶无显著差异。AR的β-N-乙酰氨基葡萄糖苷酶(NAG)显著高于其他两种林分。冗余分析显示土壤总氮和DON是驱动淋溶层土壤酶活性的主要环境因子。总之, 土壤总氮含量与NAG活性呈正相关关系, 并且可溶性有机氮可能是氮循环中的重要一环; 土壤微生物优先利用易分解碳; 且碳氮养分循环之间存在一定的耦合关系。氮提高了与土壤碳相关的水解酶活性, 从而可促进碳周转。
关键词： 森林类型;可溶性有机质;碳氮养分;酶活性;土壤碳氮循环

Abstract
Aims Forest conversion is an important factor affecting the ecosystem organic matter cycle, and has an impact on the productivity of forest ecosystems, carbon sequestration and nutrient conservation. This study aims to provide more scientific evidence for better understanding the mechanism of different forest types regulating forest soil carbon and nitrogen cycling in the context of forest conversion. Methods The study site is located in Sanming City, Fujian Province, in subtropical China. Soil samples in the A horizon from an artificial-assisted natural regeneration forest of Castanopsis carlesii (AR), a natural secondary forest of C. carlesii (SF) and a plantation of Pinus massoniana (PM) sites were collected in November, 2016. We investigated the contents of soil organic carbon, soil organic nitrogen, soil dissolved organic matter (DOM), NH₄ ⁺-N and NO₃ ^--N. The spectroscopic characteristics of soil DOM were also measured by means of ultraviolet absorbance and fluorescence emission spectroscopic techniques. The activity of five kinds of enzymes related to carbon and nitrogen cycle were determined to decipher their relationships with soil properties. Important findings The results showed that, due to different tree species and man-made disturbance, the contents of dissolved organic carbon (DOC), DON, humification index of fluorescence emission spectrum were all in the order SF > AR > PM, whereas the aromatization index was in the order PM > AR > SF. NH₄ ⁺-N were significantly richer for SF and AR than for PM, while NO₃ ^--N content was low and similar across the three stands. The β-glucosidase activity of PM was significantly lower than that of SF and AR. The activities of cellulolytic enzyme were in sequence of AR > SF > PM. The activities of polyphenol oxidase enzyme in PM was significantly higher than in SF and AR. There was no significant difference in the type of forest peroxidase. The activity of β-N-acetylglucosaminidase of AR was significantly higher than those of the other two kinds of stands. The redundancy analysis indicates that total nitrogen (TN) and DON are the major environmental factors driving soil enzyme activity. Soil total nitrogen content and NAG activity were positively correlated, and DON may be an important component of the N cycle. Soil microorganisms prefer to use readily decomposable carbon; and there is a certain coupling relationship between carbon and nitrogen cycles. Higher soil N contents would increase the C-related hydrolytic enzyme activity, thereby promoting carbon turnover.
Keywords：forest type;dissolved organic matter;carbon and nitrogen nutrients;enzyme activity;soil carbon and nitrogen cycle

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本文引用格式
鲍勇, 高颖, 曾晓敏, 袁萍, 司友涛, 陈岳民, 陈滢伊. 中亚热带3种典型森林土壤碳氮含量和酶活性的关系. 植物生态学报[J], 2018, 42(4): 508-516 DOI:10.17521/cjpe.2017.0311
BAO Yong, GAO Ying, ZENG Xiao-Min, YUAN Ping, SI You-Tao, CHEN Yue-Min, CHEN Ying-Yi. Relationships between carbon and nitrogen contents and enzyme activities in soil of three typical subtropical forests in China. Chinese Journal of Plant Ecology[J], 2018, 42(4): 508-516 DOI:10.17521/cjpe.2017.0311

森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000)。森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化。土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境。土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中。土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节。酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983)。研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005)。

酶活性的大小可以指示微生物养分需求和土壤养分供给之间的关系。大多数研究表明, 土壤养分含量和酶活性之间呈负相关关系, 即随着无机或有机形式的营养物质的增加, 微生物获取该营养物质的难度降低, 所需的相关催化酶的活性也相应降低(Allison & Vitousek, 2005; Burns et al., 2013)。然而, Debosz等(1999)的研究表明输入有机物使纤维素酶活性增强; Taylor等(2002)的研究结果也显示, 酶活性与土壤有机质之间存在显著的正相关关系。因此生态系统养分含量与酶活性之间的明确关系目前还没有定论。同时, 由于土壤中各元素之间存在耦合关系, 养分有效性和酶活性之间还依赖于其他元素含量的高低, 含量相对高的元素可能会促进胞外酶对另一种元素的分解利用, 例如氮的有效性将会影响碳分解酶的活性, 进而改变凋落物及土壤有机质的分解速率(Sinsabaugh, 2010)。

目前, 关于森林土壤酶的研究主要集中在欧洲和北美洲的北方森林或温带森林, 以外源养分添加对酶的影响居多, 对亚热带不同森林类型中内源养分与酶的关系研究较少(莫江明等, 2004)。我国中亚热带地区, 由于雨水充沛, 森林群落种类丰富, 土壤可溶性养分多, 森林在生态过程中的作用比温带更大, 是全球同纬度地带上的“绿洲”, 有着旺盛的能量转化和物质循环的能力, 以及极强的生物生产力与生态效应, 是全球碳氮循环的重要组成部分(吴波波等, 2014)。在过去几十年中, 我国中亚热带地区发生着剧烈的森林类型更替, 大面积的天然常绿阔叶林经过强烈人为干扰后, 转变为次生林和人工林, 但这种人为干扰对森林生态系统的生产力、碳吸存和养分保持功能所产生的影响至今并不清楚, 森林类型更替后各林分类型中土壤碳氮养分和酶活性之间有何关系和变化也不清楚。本文选取典型的米槠(Castanopsis carlesii)天然次生林、米槠人工促进天然更新林、马尾松(Pinus massoniana)人工林为研究对象, 探索不同森林类型土壤碳氮含量和土壤酶活性之间的关系, 为中亚热带陆地土壤碳、氮等物质循环提供科学依据, 为森林经营方式的合理调整及未来森林更新方式的选择提供科学参考。

1 材料和方法

1.1 研究样地概况

研究地区位于福建三明森林生态系统与全球变化野外观测研究站陈大观测点(26.32° N, 117.60° E), 地处武夷山东南, 戴云山脉西北。地貌以低山丘陵为主, 山地平均坡度25°-35o, 属中亚热带海洋季风气候, 年平均气温19.1 ℃, 年降水量1β749 mm, 年蒸发量1β585 mm, 相对湿度81%, 全年无霜期达300 天。区域内地带性植被为常绿阔叶林, 亦分布有一定面积的针阔混交林和针叶林(胥超等, 2017)。

该试验样地主要包括3种典型的亚热带森林类型——米槠天然次生林(SF)、米槠人工促进天然更新林(AR)和马尾松人工林(PM), 即为试验的3个处理, 每个处理设3个重复。3种森林类型的林龄相近, 且具有相同的立地条件, 在转换之前均为米槠天然林(200年左右未受干扰)。其中, SF由米槠天然林经过择伐后封山育林再经过自然次生演替形成, 海拔330 m, 坡度40o, 形成时间40年, 林分密度为3β788株·hm^-2, 平均树高10.8 m, 平均胸径12.2 cm, 土壤容重1.16 g·cm^-3。主要树种有米槠、闽粤栲(Castanopsis fissa)等。AR为采伐时保留林下幼树, 采伐后保留剩余物, 并沿水平带平铺堆积残留的枝桠、树梢等以促其腐烂形成的人工促进更新林, 海拔335 m, 坡度38o, 形成时间40年, 林分密度为?2158株·hm^-2, 平均树高13.7 m, 平均胸径16.8 cm, 土壤容重1.21 g·cm^-3。其主要树种有米槠、东南野桐(Malloyus lianus)等。PM为皆伐后, 经火烧、挖穴造林和幼林抚育营造的人工纯林, 林冠单层, 海拔313 m, 坡度38o, 形成时间41年, 林分密度为1β500株·hm^-2, 平均树高18.3 m, 平均胸径18.3 cm, 土壤容重1.33 g·cm^-3。林下植被覆盖度约为90%, 灌木较少, 以芒萁(Dicranopteris pedata)、芒(Miscanthus sinensis)和蕨(Pteridium aquilinum)等草本植物为主。

1.2 土壤样品采集和处理

2016年11月进行采样。每块样地按照“S”形随机设定5个取样点, 去除表面凋落物后采集淋溶层(A层), 将土样混合均匀。土样低温保鲜运回实验室进行分析, 一部分去除石砾、植物根系过2 mm筛后4 ℃储存, 用于土壤养分(DOM)、铵态氮(NH₄⁺-N)和硝态氮(NO₃^--N)和土壤理化性质(pH值、含水率、土壤总有机碳(SOC)和土壤总氮(TN))的测定; 另一部分保存在-20 ℃冷藏, 用于后续的微生物酶活性试验。

1.3 土壤基本理化性质的测定

土壤有机碳及全氮用碳氮元素分析仪(Elementar Vario EL III, Elementar, German)测定, pH值用CHN868型pH计测定, 水土体积质量比为2.5:1。采用烘干法测定质量含水率。

1.4 土壤铵态氮和硝态氮浓度测定

采用KCl溶液浸提法(苏涛等, 2005), 取5 g过 2 mm筛的鲜土于离心管中, 加入20 mL 2.0 mol·L^-1 KCl溶液, 振荡30 min后离心30 min (4 000 r·min^-1), 用0.45 μm滤膜过滤, 使用连续流动分析仪(San++, Skalar, Breda, the Netherlands)测定滤液中的土壤NH₄⁺-N和NO₃^--N浓度。

1.5 DOM提取与可溶性有机碳(DOC)、可溶性有机氮(DON)浓度测定

样品DOM采用水浸提法(Wu et al., 2010), 取 15 g过2 mm筛的鲜土于离心管中, 加入去离子水(水土体积质量比2:1), 振荡30 min后离心10 min (4β000 r·min^-1), 用0.45 μm滤膜过滤, 滤液中的有机物即为DOM。采用有机碳分析仪(TOC-VCPH, Shimadzu, Kyoto, Japan)测定样品DOC浓度, 使用连续流动分析仪测定DON浓度。

1.6 光谱分析测定

用紫外-可见光分光度计(UV-2450, Shimadzu, Kyoto, Japan)测定254 nm的吸光度值。利用待测液254 nm处吸收值(SUVA)分析其芳香化程度和疏水特性(Akagi et al., 2007), 计算芳香化指数(AI)(Saadi et al., 2006): AI = (UV₂₅₄/C) × 100

式中: UV₂₅₄为254 nm的吸光度值(cm^-1); C为DOC浓度(mg·L^-1)。

用F-7000荧光分光光度计(Hitachi, Tokyo, Japan)测定样品的荧光发射光谱, 测定方法及参数设定参照文献(刘翥等, 2014)。荧光发射光谱腐殖化指数(HIX_em)为荧光发射光谱中波长435-480 nm与波长300-345 nm的面积比(Kalbitz et al., 1999; Zsolnay et al., 1999)。为提高灵敏度, 荧光光谱测定前使用2 mol·L^-1 HCl将所有待测液的pH值调成2 (Akagi et al., 2007)。HIX_em可用来表征DOM的腐殖化程度, HIX_em越大, 说明DOM中分子构成越复杂, π-π共轭体系越大, 腐殖类物质如缩合芳环和大分子化合物的含量越高(Bu et al., 2010)。

1.7 酶活性的测定

参照Saiya-Cork (2002)的方法, 提取和培养土壤中5种与碳、氮循环相关的水解酶和氧化酶。方法如下: 取1 g新鲜土壤, 用125 mL 50 mmol·L^-1的醋酸盐缓冲液(pH = 5)提取, 用磁力搅拌器搅拌5 min使其均质化, 用移液器取200 μL移于96孔微孔板。用伞形酮(MUB)作为底物标示水解酶活性, 用L-二羟苯丙氨酸(DOPA)为底物标示氧化酶活性。微平板置于暗环境下经过20 ℃恒温培养后, 用多功能酶标仪(SpectraMax M5, Molecular Devices, Sunnyvale, USA)测定其荧光度(水解酶)或吸光度(氧化酶)。底物以碳为主的多糖(纤维素)、芳香族化合物(木质素)和脂肪族化合物, 其分解酶主要为纤维素水解酶类(β-葡萄糖苷酶(βG)和纤维素水解酶(CBH)和木质素分解酶类多酚氧化酶(PHO)和过氧化物酶(PEO))。底物为以氮为主的氨基化合物、缩氨酸和非缩氨基化合物, 其分解酶为β-N-乙酰氨基葡萄糖苷酶(NAG) (Knicker et al., 1981)。5种土壤酶的名称、缩写、功能及所用标定底物见表1。各种酶都通过预实验确定获得最大酶活性所需要的底物浓度和培养时间。

Table 1
表1
表1土壤酶的名称、缩写、功能及底物
Table 1The abbreviations, function and substrates of soil enzyme

酶 Enzyme	缩写 Abbreviation	功能 Function	底物 Substrate
β-葡萄糖苷酶 β-glucosidase	βG	分解易降解碳 Decomposition of labile carbon	4-甲基伞形酮-β-D-葡萄糖苷 4-methylumbelliferyl-β-D-glucoside
纤维素水解酶 Cellulose hydrolysis	CBH	分解易降解碳 Decomposition of labile carbon	4-甲基伞形酮-β-D-纤维素二糖苷 4-methylumbelliferyl-β-D-cellobioside
β-N-乙酰氨基葡萄糖苷酶 β-N-acetylglucosaminidase	NAG	分解氮 Hydrolyze nitrogen	4-甲基伞形酮-2-乙酰氨基-2-脱氧-β-D-吡喃葡萄糖苷 4-methylumbelliferyl-N-acetyl-β-D-glucosaminide
多酚氧化酶 Phenol oxidase	PHO	分解难降解碳 Decomposition of recalcitrant carbon	二羟基苯 L-dihydroxyphenylalanine
过氧化物酶 Peroxidase	PEO	分解难降解碳 Decomposition of recalcitrant carbon	二羟基苯 L-dihydroxyphenylalanine

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1.8 数据分析

用Excel 2013和SPSS 21.0软件对数据进行处理。采用单因素方差分析和最小显著差异法(LSD)检验不同林型土壤理化性质、碳氮养分含量和酶活性的差异显著性, 显著性水平设定为p = 0.05; 采用CanocoβSoftwareβ5.0软件, 以土壤酶活性为响应变量, 同时以土壤养分以及土壤基本理化性质为解释变量做冗余分析(RDA)。用Originβ9.0软件绘图。

2 结果

2.1 各林分类型土壤基本理化性质和有效养分

由表2可知, 土壤pH值在4.55-4.79之间, 不同林分类型间差异均不显著。AR含水率显著高于其他两种林分。PM土壤有机碳含量显著低于其他两种林分类型。3种林分类型全氮含量差异显著, 表现为AR > SF > PM; SF和AR的土壤C/N显著高于PM (p < 0.05)。

Table 2
表2
表2不同林分类型的主要土壤理化性质和有效养分(平均值±标准偏差, n = 3)
Table 2Main soil physical and chemical properties and soil available nutrients in different forest types (mean ± SD, n = 3)

林分类型 Forest type	pH	含水率 Moisture (%)	土壤总有机碳 Total soil organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	C:N	NH₄⁺-N (mg·kg^-1)	NO₃^--N (mg·kg^-1)	可溶性有机碳 Dissolved organic carbon (mg·kg^-1)	可溶性有机氮 Dissolved organic nitrogen (mg·kg^-1)
SF	4.72 ± 0.18^a	27.24 ± 1.42^b	41.69 ± 1.46^a	2.43 ± 0.11^b	17.20 ± 0.50^a	80.17 ± 5.10^a	7.67 ± 1.93^a	87.47 ± 29.59^a	8.80 ± 2.28^a
AR	4.79 ± 0.10^a	35.02 ± 0.56^a	45.82 ± 5.64^a	2.89 ± 0.16^a	15.80 ± 1.03^a	92.40 ± 3.76^a	4.83 ± 2.80^a	76.98 ± 12.55^a	6.68 ± 2.28^a
PM	4.63 ± 0.06^a	28.79 ± 2.49^b	25.16 ± 0.52^b	1.83 ± 0.04^c	13.73 ± 0.59^b	54.47 ± 11.28^b	6.50 ± 0.24^a	26.55 ± 6.44^b	5.84 ± 1.46^a

SF, natural secondary forest of Castanopsis carlesii; AR, artificial-assisted natural regeneration forest of Castanopsis carlesii; PM, plantation of Pinus massoniana. Different lowercase letters indicate significant difference among different stands (p < 0.05).
SF, 米槠天然次生林; AR, 米槠人工促进天然更新林; PM, 马尾松人工林。不同小写字母表示不同林分间差异显著(p < 0.05)。

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SF和AR的NH₄⁺-N含量显著高于PM, 且AR最高; 3种林分中NO₃^--N无显著差异。SF和AR土壤DOC浓度分别是PM的3.3和2.9倍, 差异达到显著水平(p < 0.05); SF土壤DON浓度最高, 为8.80β mg·kg^-1, 但与其他两种林分差异不显著。

2.2 各林分土壤DOM芳香化和腐殖化指标

如图1所示, SF的AI显著低于AR和PM (p < 0.05)。AR和PM分别是SF的1.87和2.19倍。SF的HIX_em显著高于AR和PM (p < 0.05), 分别是AR和PM的1.30和1.49倍。AR与PM的HIX_em无显著差异。

图1

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图1不同林分土壤的芳香化指数(AI)和荧光发射光谱腐殖化指数(HIX_em)(平均值±标准偏差, n = 3)。SF, 米槠天然次生林; AR, 米槠人工促进天然更新林; PM, 马尾松人工林。不同小写字母表示不同林分间差异显著(p < 0.05)。

Fig. 1Aromatic index (AI) and humification index emission mode (HIX_em) in different forests (mean ± SD, n = 3). SF, natural secondary forest of Castanopsis carlesii; AR, artificial-assisted natural regeneration forest of Castanopsis carlesii; PM, plantation of Pinus massoniana. Different lowercase letters indicate significant difference among different stands (p < 0.05).

2.3 不同林分的土壤酶活性

PM的βG活性显著低于SF和AR (p < 0.05); 3种林分CBH活性差异显著, 表现为AR > SF > PM; PM的PHO活性显著高于SF和AR (p < 0.05), 3种林分PEO活性无显著差异(表3)。AR的NAG活性显著高于其他两种林分(p < 0.05)。

Table 3
表3
表3不同林分类型的土壤酶活性(平均值±标准偏差, n = 3)
Table 3Soil enzyme activities in different forest types (mean ± SD, n = 3)

林分类型 Forest type	βG (nmol·g^-1·h^-1)	CBH (nmol·g^-1·h^-1)	NAG (nmol·g^-1·h^-1)	PHO (μmol·g^-1·h^-1)	PEO (μmol·g^-1·h^-1)
SF	38.93 ± 7.44^a	1.41 ± 0.29^b	36.42 ± 7.68^b	0.53 ± 0.37^b	14.61 ± 3.86^a
AR	36.93 ± 6.72^a	3.49 ± 0.59^a	76.98 ± 20.43^a	0.25 ± 0.11^b	13.48 ± 3.74^a
PM	23.86 ± 5.12^b	0.48 ± 0.16^c	38.94 ± 8.09^b	3.92 ± 0.52^a	20.70 ± 3.83^a

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2.4 土壤酶活性变化的RDA分析

以5种土壤酶活性为响应变量, 以土壤理化性质和有效养分为解释变量, 对3种森林类型A层土壤酶活性进行冗余分析, 从而探究土壤理化性质、有效养分和微生物胞外酶活性之间的相关关系。我们只选择了贡献率达到显著水平的两个解释变量。如图2所示, 3种林分土壤酶活性在第一轴上可以较明显地区分开来, 第一轴主要由βG、CBH和PHO 3种酶控制, 第一轴可以解释酶活性总变异的74.63%, 影响这3种酶的主要因素是TN。第二轴主要由NAG酶控制, 解释了其酶活性总变异的9.74%。TN和DON分别解释了土壤酶活性变化的71.2% (p = 0.002)和13.2% (p = 0.012)。TN与βG、CBH、NAG呈正相关关系; DON与βG呈正相关关系, 且βG与PEO, 以及CBH与PHO之间都是显著负相关关系。

图2

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图2不同林分土壤环境因子对土壤酶活性影响的冗余分析(RDA)。SF1、SF2、SF3表示米槠次生林样地的3个平行重复; AR1、AR2、AR3表示米槠人工促进天然更新林样地的3个平行重复; PM1、PM2、PM3表示马尾松人工林样地的3个平行重复; DON,可溶性有机氮; DOC,可溶性有机碳; SOC, 土壤有机碳; TN, 总氮。图右下角变量注释表示对土壤酶变化有显著影响作用的环境因子的相应解释比例。

Fig. 2Redundancy analysis (RDA) of the effect of soil environmental factors on soil enzyme activity in different forest types. SF1, SF2, SF3 represent three parallel replicates of the secondary broadleaved forests of Castanopsis carlesii plot; AR1, AR2, AR3 represent three parallel replicates of the Human-assisted naturally regenerated forests of Castanopsis carlesii plot; PM1, PM2, PM3 represent three parallel replicates representing the Human-assisted naturally regenerated forests of Pinus massoniana plots of Pinus massoniana plantation. DON, dissolved organic nitrogen; DOC, dissolved organic carbon; SOC, soil organic carbon; TN, total nitrogen. The notes of variables in lower right corner of the plot represents the corresponding proportion of environmental factors that have a significant effect on soil enzyme changes.

3 讨论

3.1 不同森林类型对土壤碳氮含量的影响

植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者。本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复。氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001)。本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化。NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低。同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004)。

DOM主要来源于新近凋落物、土壤腐殖质及根系分泌物(Camino-Serrano et al., 2014), 所以树种对DOM具有显著影响(万菁娟等, 2016)。在本研究中, DOC、DON的变化趋势均为SF > AR > PM, 其中PM的DOC含量显著低于SF和AR (表3), 这是由于PM属于针叶林, 而SF和AR属于阔叶林。康根丽等(2014b)研究发现, 阔叶树叶片凋落物产生的DOC、DON浓度高于针叶树叶。AI可以指示DOM中芳香类化合物的多少, 而HIX_em可以用来表征DOM的腐殖化程度; 本研究中3种林分土壤DOM的AI和HIX_em的趋势相反。作者所在的森林土壤有机质课题组以前的研究发现马尾松凋落物中含有相对较多难以分解的、疏水性芳香族化合物, 而米槠凋落物中含有较多易分解的、亲水性低分子量化合物(万晓华等, 2014), 所以SF和AR土壤为微生物提供了更多的可利用能量和养分, HIX_em也高。SF和AR的建群树种虽然都是米槠, 但前者的林下植被较多, 而林下植被如芒萁往往会释放AI较低的DOM (康根丽等, 2014a), 所以SF土壤DOM的AI最低, 更有利于微生物的分解。

3.2 不同森林类型对酶活性的影响及关键驱动因子

作为催化土壤中众多生化反应的主要承载体, 土壤酶活性会受到一系列理化因子及生物因子的影响。凋落物和根系的改变会引起土壤养分的变化(Bending et al., 2002; 王春阳等, 2011), 所以森林类型对酶的活性有着重要的影响。

在本研究涉及的5种酶之中, 活性最高的是NAG, 说明了N转化在亚热带森林土壤中的重要性。AR土壤NAG活性显著高于SF和PM (p < 0.05), NAG活性顺序与土壤TN和NH₄⁺-N的趋势一致, 这很可能说明了NAG是催化TN矿化为NH₄⁺-N的关键酶。同时NAG活性与土壤含水率显著正相关(p < 0.05), 这与大多研究结果(Sardans & Pe?uelas, 2005; A’Bear et al., 2014)类似。

研究中SF和AR土壤中βG和CBH两种酶活性较PM高, 而PM土壤中PEO和PHO活性高于SF和AR。这是因为阔叶树土壤中易分解碳多, 促进了微生物对易分解碳的利用; 这体现了底物与酶活性之间的正相关关系。针叶树种凋落物中木质素、粗纤维、多酚类等难溶性物质含量较高, 导致凋落物难以分解, 对土壤有机碳的影响较弱(Zhao et al., 2003)。PM土壤易分解的有机碳较少, 难分解的碳相对较多, 所以PEO和PHO的活性就高; 这与PM中AI高于SF和AR, DOC含量和HIX_em低于SF和AR的结果吻合。这与前人研究结果一致: 从天然阔叶林到人工林的转化增加了土壤中PHO的活性, 但降低了CBH的活性(Sardans & Pe?uelas, 2005)。通过相关性分析, C/N与PHO呈正相关关系, 与其他酶没有显著关系, 而微生物中真菌在偏酸性和高C/N的土壤中比例较大(Hogberg et al., 2007), 真菌可利用较难分解的碳源。另外, 本研究发现βG和PEO, 以及CBH和PHO之间都是显著负相关关系, 且PHO和PEO活性小于βG和CBH, 这说明微生物利用有机碳往往有一定的选择性, 更倾向于利用易分解的有机质。

RDA显示TN和DON是3种森林类型表层土壤酶活性的主要影响因子, 并且TN与NAG呈显著正相关关系(图2), 这再次反映了底物与酶活性之间的正相关关系。中亚热带是N饱和区, 森林土壤的N相对富集(Lu et al., 2013), N在本地区发挥着养分利用的引领作用。有研究结果证实土壤DOM周转是元素循环的主要途径(Currie et al., 1996), DON是微生物最易利用的有机氮源, 从而刺激相关酶的活性, 所以DON对森林表层土壤酶的影响很大。在N循环过程中土壤固态氮可能要先转变为DON后才能被微生物利用分解成NH₄⁺-N和NO₃^--N。同时3种林分DON没有显著差异, 但是NH₄⁺-N有显著差异, 这很可能说明了DON到NH₄⁺-N的矿化速率较快, 这与NAG活性最高相一致。虽然是氮饱和区, 但土壤氮转化酶活性仍然较高, 说明土壤可利用性氮不足。土壤氮转化酶活性越高土壤中可利用性氮越缺乏。有可能是微生物自身对氮的需求较大; 也有可能是微生物为了得到更多的碳或其他营养元素, 而通过分解土壤有机氮, 为植物提供更多氮素, 促进植物的生长, 从而固定更多的碳输入土壤, 导致土壤中的易分解有机碳也增多, 最终满足微生物的需求(Kuzyakov & Xu, 2013), TN与βG、CBH之间也是显著正相关关系, 说明N也提高了与土壤C循环相关的酶活性, 这与Jian等(2016)的研究结果一致。有研究表明碳循环酶潜在活性随着无机氮可用性增加而增加, 而氮循环酶的活性随着碳可用性的增加而增加(Allison et al., 2007)。氮是微生物新陈代谢的重要养分, 当氮含量升高时, 微生物也需要同化吸收更多的碳, 使微生物C/N保持相对稳定。

4 结论

在本研究涉及的3种森林土壤中, 氮是影响A层土壤酶活性的主要因子, TN、NAG和NH₄⁺-N三者趋势一致, 反映了底物对酶活性的促进作用; DON可能是微生物矿化分解土壤氮的重要一环。同时微生物对碳的利用有一定的选择性, 更倾向于利用易分解的有机碳; 阔叶林土壤易分解碳多, 所以βG和CBH活性较高, 相反, 针叶林土壤PHO和PEO活性较高。在氮的引领下, 3种林分碳循环相关的水解酶活性也提高, 说明碳氮养分循环之间存在一定的耦合关系。在不同森林类型下, 季节差异和微生物群落变化也会影响土壤碳氮含量和酶活性(刘捷豹等, 2017), 因此, 在本研究样地还需对季节动态和微生物做进一步研究, 以便更好地探究土壤碳氮含量、酶活性和微生物群落之间的联系, 从而为揭示森林类型更替后不同林分对土壤碳氮吸存的影响机制提供基础科学依据。

致谢感谢福建师范大学地理科学学院彭园珍、林燕语、刘兰英及杨柳明老师在实验过程中提供帮助。

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参考文献原文顺序
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[1]

A’Bear

, Jones

, Kandeler

( 2014). Interactive effects of temperature and soil moisture on fungal-mediated wood decomposition and extracellular enzyme activity.
Soil Biology and Biochemistry, 70, 151- 158.

DOI URL [本文引用: 1]

61Temperature and soil moisture control wood decay and enzyme production by fungi.61Warming increased wood decay and compensated for the negative effect of drying.61Soil enzyme activities were greater with wetting than drying at ambient temperature.61Warming moderated the effect of soil moisture on soil enzyme activity.61Interactions between abiotic factors are not predicted by individual effects.

[2]

Akagi

, ádám

, Bastida

( 2007). Quantity and spectroscopic properties of soil dissolved organic matter (DOM) as a function of soil sample treatments: Air-drying and pre-incubation.
Chemosphere, 69, 1040- 1046.

DOI URL PMID [本文引用: 2]

The dissolved organic matter (DOM) in soils is essentially defined by the way in which it is obtained. Therefore, we need to understand as to how pre-treatment of a soil will affect the characteristics of DOM, since this fraction may be strongly influenced by a soil water content. The effect of two different pre-treatments on DOM from the A-horizons of a large variety of ecosystems and regions were compared. In both cases the soils were allowed to air-dry. In one case the air-dried soil was directly extracted (AD), while in the other case it was pre-incubated for 1/week at 50% of its water holding capacity (INCU). AD is simpler, but INCU brings the soil, and especially its microbial population, back to a standardised state, which is more representative of the usual state in the field. Both methods are used whenever an adjustment of the soil water content is essential to compare different regions or to eliminate short term weather effects. A significant regression indicated that the dissolved organic carbon (DOC) extracted from INCU samples was only 20% of AD DOC. Both the absorptivity (UV absorption divided by DOC) of 86% of the samples, and a fluorescence emission spectrum based Humification Index in all cases increased as a result of pre-incubation. This would indicate that labile compounds released during drying were metabolised during the incubation. However, the magnitude of this increase varied, and no correlation with soil organic and microbial carbon, pH, or texture could be detected. The results show that DOM extracted from AD and INCU soils is not comparable and that the differences are mainly due to the impact of air-drying on the microbial activity.

[3]

Allison

, Vitousek

( 2005). Responses of extracellular enzymes to simple and complex nutrient inputs.
Soil Biology and Biochemistry, 37, 937- 944.

DOI URL [本文引用: 1]

Soil microbes produce extracellular enzymes that mineralize organic matter and release carbon and nutrients in forms that can be assimilated. Economic theories of microbial metabolism predict that enzyme production should increase when simple nutrients are scarce and complex nutrients are abundant; however, resource limitation could also constrain enzyme production. We tested these hypotheses by monitoring enzyme activities and nutrient pools in soil incubations with added simple and complex nutrient compounds. Over 28 days of incubation, we found that an enzyme's activity increased when its target nutrient was present in complex but not simple form, and carbon and nitrogen were available. β-Glucosidase and acid phosphatase activities also increased in treatments where only carbon and nitrogen were added. Glycine aminopeptidase and acid phosphatase activities declined in response to ammonium and phosphate additions, respectively. In some cases, mineralization responses paralleled changes in enzyme activity—for example, β-glucosidase activity increased and respiration was 5-fold greater in soil incubations with added cellulose, ammonium, and phosphate. However, a doubling of acid phosphatase activity in response to collagen addition was not associated with any changes in phosphorus mineralization. Our results indicate that microbes produce enzymes according to ‘economic rules’, but a substantial pool of mineral stabilized or constitutive enzymes mediates this response. Enzyme allocation patterns reflect microbial nutrient demands and may allow microbes to acquire limiting nutrients from complex substrates available in the soil.

[4]

Allison

, Condron

, Peltzer

( 2007). Changes in enzyme activities and soil microbial community composition along carbon and nutrient gradients at the Franz Josef chronosequence, New Zealand.
Soil Biology and Biochemistry, 39, 1770- 1781.

DOI URL [本文引用: 1]

During primary succession, the abundance of carbon (C) and nitrogen (N) in soil increases, while phosphorus (P) declines. These changes in nutrient concentrations in organic matter are likely to play an important role in controlling enzyme-mediated nutrient mineralization. We examined how enzyme activity and efficiency changed with successional time in organic and mineral soils taken from the 120 000-year-old Franz Josef soil development sequence, New Zealand, and the relationship between enzyme activity and efficiency and soil nutrient concentrations. We found that the activity of enzymes involved in P mineralization increased with site age across the Franz Josef chronosequence, while the activity of enzymes regulating C and N mineralization declined in organic but not mineral soil. Sulfatase activity peaked at an intermediate-aged site, possibly indicating a transient period of S limitation. The activity of phosphatase enzymes was negatively correlated with the concentration of P in the soil, whereas activity of C-, N- and S-hydrolyzing enzymes was not strongly dependent on nutrient concentrations. When assessed as efficiency (activity per unit microbial biomass), there were strong patterns of increasing efficiency of P-, and decreasing efficiency of C- and N-hydrolyzing enzymes with site age. We suggest that activity patterns for C-, N- and S-hydrolyzing enzymes were obscured by simultaneous and opposing changes in enzyme efficiency and microbial biomass. In mineral soil, efficiency of enzymes was negatively correlated with soil nutrient availability. In contrast, in organic soil, efficiency of C-, N- and S-hydrolyzing enzymes was positively correlated with soil P, while efficiency of P-hydrolyzing enzymes was negatively correlated with soil P. The increase in efficiency of P-hydrolyzing enzymes, and decrease in efficiency of C-, N- and S-hydrolyzing enzymes with site age was accompanied by a shift in microbial community composition towards higher relative abundances of fungi. Changes in enzyme efficiency with site age are likely to be due to both constitutive differences in enzyme production, and down-regulation of enzyme expression.

[5]

Bending

, Turner

, Jones

( 2002). Interactions between crop residue and soil organic matter quality and the functional diversity of soil microbial communities.
Soil Biology and Biochemistry, 34, 1073- 1082.

DOI URL [本文引用: 1]

The effect of crop residue and soil organic matter (SOM) quality on the functional characteristics of soil microbial communities was investigated. Five shoot and root materials with contrasting biochemical qualities were incorporated into soil taken from a cultivated field (FC) and a field edge (FE). These soils had contrasting native SOM qualities, with organic C contents of 0.9 and 2.5%, respectively. The amended soils were incubated under controlled environment conditions before the metabolic characteristics of the soil microbial community were determined by analysis of the activities of 19 hydrolytic enzymes, by substrate utilization within Biolog GN microplates, and C and N mineralization dynamics. For enzyme and Biolog data, metabolic diversity and community level physiological profiles (CLPP) were determined by calculating Shannon's diversity index and performing canonical variate analysis, respectively. Soil type significantly affected mineralization of N from the residues, although the size and direction of the effect varied according to the crop residue material added. Both enzyme and Biolog metabolic diversity were affected by the type of crop residue incorporated. Enzyme diversity was higher in FE relative to FC soil, but soil type had no effect on metabolic diversity recorded in Biolog microplates. There were significant interactions between soil type and crop residue material for respiration, N mineralization and enzyme diversity. During the early stages of decomposition, there were similarities in the response of enzyme and Biolog CLPP to crop residue quality and soil type. In the high OM soil, there was evidence for convergence of CLPP in treatments receiving low and high quality crop residue types. However, in the low SOM soil, CLPP of low and high quality crop residue treatments were clearly different. The length of time required for the CLPP of residue amended soil to converge with that of unamended control soil depended on both residue and soil type. We conclude that both crop residue and SOM quality can affect the functional diversity of the soil microbial community, and that enzyme and Biolog analyses reflect complementary, but not inter-changeable, analyses.

[6]

, Wang

, Ma

( 2010). Spectroscopic characterization of hot-water extractable organic matter from soils under four different vegetation types along an elevation gradient in the Wuyi Mountains.
Geoderma, 159, 139- 146.

DOI URL [本文引用: 1]

78Water extractable organic carbon (WEOC) is the most active component in global carbon cycle and its chemical and structural characteristics most likely influence its biodegradation. 78 To obtain deeper insights into the dynamics of carbon in soils under different vegetation types in the Wuyi Mountains in southeastern China, we have studied the structural characteristics of hot-water extractable organic matter. And at the same time, we related its structural characteristics to soil properties and biological properties.

[7]

Burns

( 1982). Enzyme activity in soil-location and a possible role in microbial ecology.
Soil Biology and Biochemistry, 14, 423- 427.

DOI URL [本文引用: 1]

The activity of any particular enzyme in soil is a composite of activities associated with various biotic and abiotic components, e.g. proliferating cells, latent cells, cell debris, clay minerals, humic colloids and the soil aqueous phase. The location of the enzyme is at least partially determined by such factors as the size and solubility of its substrate, the species of microorganism, and the physical and chemical nature of the soil colloids. However, enzymes may change location with time, for example, many hydrolases are intracellular sensu stricto but are also found associated with cell debris and clay and organic colloids. There are difficulties in quantifying the various activities, but this may be possible by employing different types of assays, the prudent use of controls and the study of crude enzyme extracts from soil. Enzymes bound to clay and humic colloids (the immobilized or accumulated enzyme fraction) have a residual activity not found in enzymes free in the soil aqueous phase. However, the mere adsorption of enzymes to soil surfaces does not guarantee subsequent activity, and it appears that some mechanism of association with the humic polymer offers the best form of protection, yet permits the retention of enzyme activity. The catalytic activity of extracellular enzymes is discussed and a possible relationship between soil microorganisms, exogenous substrates and immobilized enzymes is suggested.

[8]

Burns

, Deforest

, Marxsen

( 2013). Soil enzymes in a changing environment: Current knowledge and future directions.
Soil Biology and Biochemistry, 58, 216- 234.

DOI URL [本文引用: 1]

This review focuses on some important and challenging aspects of soil extracellular enzyme research. We report on recent discoveries, identify key research needs and highlight the many opportunities offered by interactions with other microbial enzymologists. The biggest challenges are to understand how the chemical, physical and biological properties of soil affect enzyme production, diffusion, substrate turnover and the proportion of the product that is made available to the producer cells. Thus, the factors that regulate the synthesis and secretion of extracellular enzymes and their distribution after they are externalized are important topics, not only for soil enzymologists, but also in the broader context of microbial ecology. In addition, there are many uncertainties about the ways in which microbes and their extracellular enzymes overcome the generally destructive, inhibitory and competitive properties of the soil matrix, and the various strategies they adopt for effective substrate detection and utilization. The complexity of extracellular enzyme activities in depolymerising macromolecular organics is exemplified by lignocellulose degradation and how the many enzymes involved respond to structural diversity and changing nutrient availabilities. The impacts of climate change on microbes and their extracellular enzymes, although of profound importance, are not well understood but we suggest how they may be predicted, assessed and managed. We describe recent advances that allow for the manipulation of extracellular enzyme activities to facilitate bioremediation, carbon sequestration and plant growth promotion. We also contribute to the ongoing debate as to how to assay enzyme activities in soil and what the measurements tell us, in the context of both traditional methods and the newer techniques that are being developed and adopted. Finally, we offer our collective vision of the future of extracellular enzyme research: one that will depend on imaginative thinking as well as technological advances, and be built upon synergies between diverse disciplines.

[9]

Camino-Serrano

, Gielen

, Luyssaert

( 2014). Linking variability in soil solution dissolved organic carbon to climate, soil type, and vegetation type.
Global Biogeochemical Cycles, 28, 497- 509.

DOI URL [本文引用: 1]

Lateral transport of carbon plays an important role in linking the carbon cycles of terrestrial and aquatic ecosystems. There is, however, a lack of information on the factors controlling one of the main C sources of this lateral flux i.e. the concentration of dissolved organic carbon (DOC) in soil solution across large spatial scales and under different soil, vegetation and climate conditions. We compiled a database on DOC in soil solution down to 80 cm and analyzed it with the aim, firstly, to quantify the differences in DOC concentrations among terrestrial ecosystems, climate zones, soil and vegetation types at global scale and, secondly, to identify potential determinants of the site-to-site variability of DOC concentration in soil solution across European broadleaved and coniferous forests. We found that DOC concentrations were 75 % lower in mineral than in organic soil and temperate sites showed higher DOC concentrations than boreal and tropical sites. The majority of the variation (R2=0.67-0.99) in DOC in mineral European forest soils correlates with NH4+, C/N, Al and Fe as the most important predictors. Overall, our results show that the magnitude (23% lower in broadleaved than in coniferous) and the controlling factors of DOC in soil solution differ between forest types, with site productivity being more important in broadleaved forests and water balance in coniferous stands.

[10]

Condron

, Tiessen

, Turner

( 2005). Interactions of organic phosphorus in terrestrial ecosystems.
Uspekhi Mat Nauk, 38, 205- 206.

DOI URL [本文引用: 1]

This paper discusses the nature of organic carbon-phosphorus interactions in soil based on the changes in the intensity of input, output, transfer and transformation processes in various managed agricultural and forest ecosystems including the effects of cultivation and afforestation of grasslands.

[11]

Currie

, Aber

, Mcdowell

, Boone

, Magill

( 1996). Vertical transport of dissolved organic C and N under long-term N amendments in pine and hardwood forests.
Biogeochemistry, 35, 471- 505.

DOI URL [本文引用: 1]

At the Harvard Forest, Massachusetts, a long-term effort is under way to study responses in ecosystem biogeochemistry to chronic inputs of N in atmospheric deposition in the region. Since 1988, experimental additions of NH4NO3 (0,5 and 15 g N m-2 yr-1) have been made in two forest stands: Pinus resinosa (red pine) and mixed hardwood. In the seventh year of the study, we measured solute concentrations and estimated solute fluxes in throughfall and at two soil depths, beneath the forest floors (Oa) and beneath the B horizons. Beneath the Oa, concentrations and fluxes of dissolved organic C and N (DOC and DON) were higher in the coniferous stand than in the hardwood stand. The mineral soil exerted a strong homogenizing effect on concentrations beneath the B horizons. In reference plots (no N additions), DON composed 56% (pine) and 67% (hardwood) of the total dissolved nitrogen (TDN) transported downward from the forest floor to the mineral soil, and 98% of the TDN exported from the solums. Under N amendments, fluxes of DON from the forest floor correlated positively with rates of N addition, but fluxes of inorganic N from the Oa exceeded those of DON. Export of DON from the solums appeared unaffected by 7 years of N amendments, but as in the Oa, DON composed smaller fractions of TDN exports under N amendments. DOC fluxes were not strongly related to N amendment rates, but ratios of DOC:DON often decreased. The hardwood forest floor exhibited a much stronger sink for inorganic N than did the pine forest floor, making the inputs of dissolved N to mineral soil much greater in the pine stand. Under the high-N treatment, exports of inorganic N from the solum of the pine stand were increased >500-fold over reference (5.2 vs. 0.01 g N m-2 yr-1), consistent with other manifestations of nitrogen saturation. Exports of N from the solum in the pine forest decreased in the order $\text{NO}_{3}\text{-N}>\text{NH}_{4}\text{-N}>\text{DON}$, with exports of inorganic N 14-fold higher than exports of DON. In the hardwood forest, in contrast, increased sinks for inorganic N under N amendments resulted in exports of inorganic N that remained lower than DON exports in N-amended plots as well as the reference plot.

[12]

Debosz

, Rasmussen

, Pedersen

( 1999). Temporal variations in microbial biomass C and cellulolytic enzyme activity in arable soils: Effects of organic matter input.
Applied Soil Ecology, 13, 209- 218.

DOI URL

Temporal variations in soil microbial biomass C concentration and in activity of extracellular enzymes of the cellulolytic complex were investigated in a field experiment after eight years of cultivation with either low organic matter input (low-OM) or high organic matter input (high-OM). The cultivation systems differed in whether their source of fertiliser was mainly mineral or organic, in whether a winter cover crop was grown, and whether straw was mulched or removed. Sampling occurred at approximately monthly intervals, over a period of two years. Distinct temporal variations in microbial biomass C concentration and activity of extracellular enzymes of the cellulolytic complex were observed. The temporal pattern was generally similar in the low-OM and high-OM cultivation systems. Temporal variations may have been driven by environmental factors (e.g., temperature and moisture) and crop growth, i.e. by factors common to both systems but not differences in organic matter input. Pronounced and constant increases in -glucosidase activity (40%) and endocellulase activity (30%) in high-OM were detected across all sampling periods. The increases in microbial biomass C concentration and cellobiohydrolase activity varied over the sampling periods (0-60% and 24-92%, respectively). Over the experimental period a mean of 148+/-6.0g biomass Cg, a -glucosidase activity of 123+/-3.3nmolgh, a cellobiohydrolase activity of 122+/-2.4nmolghand an endocellulase activity of 33.8+/-0.9nmolghwere recorded in the low-OM soil (0-20cm). The corresponding means in the high-OM treatment were 189+/-6.6g biomass Cg, a -glucosidase activity of 174+/-4.1nmolgh, a cellobiohydrolase activity of 173+/-3.4nmolghand an endocellulase activity of 44.2+/-1.1nmolgh.

[13]

Frankenberger

, Dick

( 1983). Relationships between enzyme activities and microbial growth and activity indices in soil.
Soil Science Society of America Journal, 47, 945- 951.

DOI URL [本文引用: 1]

Abstract Relationships between the activities of 11 soil enzymes and microbial respiration, biomass, viable plate counts, and soil properties were determined in surface samples of 10 diverse soils. Alkaline phosphatase, amidase, alpha -glucosidase, and dehydrogenase activities were significantly related to microbial respiration. Alkaline phosphatase, amidase, and catalase were the most satisfactory choices in determining the relative activity and mass of the microbial population in soils. The activities of these enzymes were highly correlated with both microbial respiration and total biomass in soils. -from Authors

[14]

, Xiao

, Zeng

( 2012). Relationships between soil nutrient contents and soil enzyme activities in Pinus massoniana stands with different ages in Three Gorges Reservoir Area.
Chinese Journal of Applied Ecology, 23, 445- 451.

[本文引用: 1]

[ 葛晓改, 肖文发, 曾立雄 ( 2012). 三峡库区不同林龄马尾松土壤养分与酶活性的关系
应用生态学报, 23, 445- 451.]

[本文引用: 1]

[15]

Hogberg

, Hogberg

, Myrold

( 2007). Is microbial community composition in boreal forest soils determined by pH, C-to-N ratio, the trees, or all three?
Oecologia, 150, 590- 601.

[本文引用: 1]

[16]

Houghton

( 2007). Balancing the global carbon budget.
Annual Review of Earth & Planetary Sciences, 35, 313- 347.

[本文引用: 1]

[17]

Jian

, Li

, Chen

( 2016). Soil extracellular enzyme activities, soil carbon and nitrogen storage under nitrogen fertilization: A meta-analysis.
Soil Biology and Biochemistry, 101, 32- 43.

DOI URL

61A meta-analysis was conducted based on 65 published nitrogen fertilization experiments.61Nitrogen fertilization stimulated hydrolases associate with C and P but depressed oxidases..61Nitrogen fertilization has no significant effect on hydrolases associated with N.61A significantly positive relationship was found between response ratios of hydrolases associate with C and microbial biomass.61Future model projections could consider the above relationship for different ecosystems.

[18]

Jobbágy

, Jackson

( 2000). The vertical distribution of soil organic carbon and its relation to climate and vegetation.
Ecological Applications, 10, 423- 436.

DOI URL [本文引用: 1]

[19]

Kalbitz

, Geyer

( 1999). Spectroscopic properties of dissolved humic substances—A reflection of land use history in a fen area.
Biogeochemistry, 47, 219- 238.

DOI URL [本文引用: 1]

The elemental composition and spectroscopic properties of dissolved fulvic acids isolated from different sampling media (topsoil, ground and surface water) of a natural fen area (high portion of organic soils) were examined to reveal the effects of land use history. These effects need to be known if dissolved humic substances are to be a major factor in identifying the impact of present and future changes in land use. Dissolved fulvic acids (topsoil, groundwater) from highly degraded peatlands (due to a long-term agricultural use) exhibit lower C/N ratios, higher absorption in the UV spectra, and higher absorption at 1,620 cm-1 in the FTIR spectra compared with fulvic acids from relatively intact peatlands. These properties illustrate that long-term agricultural use with high inputs results in increased aromatic structures and a further humification of dissolved fulvic acids due to very strong peat decomposition compared with relatively intact peatlands. Synchronous fluorescence spectra also indicate the higher level of aromatic structures within fulvic acids isolated from sites with long-term agricultural use (high peat decomposition) compared with a land use history resulting in a lower peat decomposition. The different sources of fulvic acids in surface water (precipitation, runoff, interflow, groundwater) are the main reason for these effects not being detected in fulvic acids isolated from surface water. Short-term changes in land use characterized by a transition from crop farming to an unimproved grassland were found not to affect the spectroscopic properties of dissolved fulvic acids. A humification index deduced from the synchronous fluorescence spectra is proposed. We have strong evidence that dissolved humic substances indicate changes in the environmental conditions (both anthropogenic and natural) of wetlands with a high proportion of organic soils.

[20]

Kang

, Yang

, Si

( 2014a). Soluble and spectral characteristics of DOM in leaching solution from leaves and litter-fall of Pinus massoniana and Dicranopteris dichotoma.
Journal of Tropical and Subtropical Botany, 22, 357- 366.

DOI URL [本文引用: 1]

为探讨福建省三明市马尾松人工林淋溶液中水溶性有机物（DOM）的溶解特征和光谱学特征，以马尾松（Pinus massoniana）和芒萁（Dicranopteris dichotoma）鲜叶、未分解层（L层）和半分解层（F层）凋落物为研究对象进行室内淋溶，对淋溶液中的水溶性有机碳（DOC）、水溶性有机氮（DON）与水溶性有机磷（DOP）含量和紫外光谱（SUVA）、荧光光谱指标和红外光谱（FTIR）等特征进行研究。结果表明，在24 h内，随着淋溶时间的延长，DOM含量呈现有波动的上升趋势；芒萁除鲜叶的DOC含量显著高于马尾松外（P〈0.01），其余DOM含量均小于马尾松。两植物F层DOM的SUVA值和腐殖化指标（HIX）都显著高于鲜叶和L层（P〈0.05），表明F层的芳香性化合物含量和腐殖化程度越来越高。DOM的同步荧光峰值显示淋溶液中含有类蛋白和类富里酸荧光团。两植物的红外光谱显示有5个相似的吸收谱带，强度最大的吸收来自于H键键合的-OH的伸缩振动，同一植物3种样品之间红外吸收的差异证明从鲜叶-L层-F层凋落物的共轭体系逐渐增大，结构更复杂。因此，随分解进程两植被DOM的化学结构越来越复杂；马尾松较芒萁含有更多的DON和DOP，这一方面为微生物提供了更多的养分，另一方面又增加了底物分解的难度。

[ 康根丽, 杨玉盛, 司友涛 ( 2014a). 马尾松与芒萁鲜叶及凋落物水溶性有机物的溶解特征和光谱学特征
热带亚热带植物学报, 22, 357- 366.]

DOI URL [本文引用: 1]

Kang

, Yang

, Si

( 2014b). Quantities and spectral characteristics of DOM released from leaf and litterfall in Castanopsis carlesii forest and Cunninghamia lanceolata plantation.
Acta Ecologica Sinica, 34, 1946- 1955.

[ 康根丽, 杨玉盛, 司友涛 ( 2014b). 米槠人促更新林与杉木人工林叶片及凋落物溶解性有机物的数量和光谱学特征
生态学报, 34, 1946- 1955.]

[22]

Keeney

( 1980). Prediction of soil nitrogen availability in forest ecosystems: A literature review.
Forest Science, 26, 159- 171.

DOI URL [本文引用: 1]

The increasing interest in the use of N fertilizers to stimulate forest growth is prompting consideration of laboratory soil testing methods to predict the probability of N response. However, even in tilled agricultural systems, laboratory tests for N availability are not widely accepted. To be successful in predicting N response in the forest ecosystem, many additional factors than those used in agriculture must be considered. These include the sources and sinks of N and the internal redistribution of N in the trees, as well as intensity of management. Problems also exist with selection of the sample, since the forest floor litter oftentimes constitutes a major reservoir of N. Availability of this N will be difficult to estimate. Spatial variability also presents formidable obstacles in obtaining a valid sample. However, some success with N availability tests has been reported in the Douglas-fir ecosystems of western United States, particularly with the anaerobic incubation method. Further progress will require considerable research effort and careful attention to the N cycle. Forest Sci. 26:159-171.

[23]

Knicker

, Lüdemann

, Haider

( 1981). Incorporation studies of NH₄ + during incubation of organic residues by ^l5N-CPMAS-NMR-spectroscopy.
European Journal of Soil Science, 48, 431- 441.

DOI URL [本文引用: 1]

This study focuses on the processes occurring during incorporation of inorganic nitrogen into humic substances. Therefore rye grass, wheat straw, beech saw dust, sulphonated lignin and organosolve lignin were incubated together with highly 15 N-enriched ammonium sulphate in the laboratory for 600 days. Samples from the incubates were periodically analysed for weight loss, and carbon and nitrogen contents. The samples were also analysed by solid-state 13 C- and 15 N-CPMAS-NMR-spectroscopy to follow the turnover of the materials during incubation. Most of the detectable N-signals was assigned to amide - peptide structures. The remaining intensities could be ascribed to free and alkylated amino groups, and those on the low field side of the broad amide-peptide signal to indole, pyrrole and nucleotide derivatives. Abiotic reactions of ammonia with suitable precursors and the formation of pyridine, pyrazine or phenyloxazone derivatives were not observed. Signals from ammonia and nitrate occurred only at the end of the incubation.

[24]

Kuzyakov

, Xu

( 2013). Competition between roots and microorganisms for nitrogen: Mechanisms and ecological relevance.
New Phytologist, 198, 656- 669.

DOI URL PMID [本文引用: 1]

Contents I.II.III.IV.V.VI.VII.VIII. SummaryDemand of all living organisms on the same nutrients forms the basis for interspecific competition between plants and microorganisms in soils. This competition is especially strong in the rhizosphere. To evaluate competitive and mutualistic interactions between plants and microorganisms and to analyse ecological consequences of these interactions, we analysed 424 data pairs from 41 15N-labelling studies that investigated 15N redistribution between roots and microorganisms. Calculated Michaelis Menten kinetics based on Km (Michaelis constant) and Vmax (maximum uptake capacity) values from 77 studies on the uptake of nitrate, ammonia, and amino acids by roots and microorganisms clearly showed that, shortly after nitrogen (N) mobilization from soil organic matter and litter, microorganisms take up most N. Lower Km values of microorganisms suggest that they are especially efficient at low N concentrations, but can also acquire more N at higher N concentrations (Vmax) compared with roots. Because of the unidirectional flow of nutrients from soil to roots, plants are the winners for N acquisition in the long run. Therefore, despite strong competition between roots and microorganisms for N, a temporal niche differentiation reflecting their generation times leads to mutualistic relationships in the rhizosphere. This temporal niche differentiation is highly relevant ecologically because it: protects ecosystems from N losses by leaching during periods of slow or no root uptake; continuously provides roots with available N according to plant demand; and contributes to the evolutionary development of mutualistic interactions between roots and microorganisms.

[25]

Liu

, Chen

, Guo

, Yang

, Li

, Lin

, Yang

( 2017). Advances in research on the responses of forest soil enzymes to environmental change.
Acta Ecologica Sinica, 37, 110- 117.

DOI URL [本文引用: 1]

全球气候变化已是不争的事实,对陆地生态系统特别是森林生态系统物质循环将产生显著的影响.土壤酶是森林土壤物质循环的主要限制因素之一,对气候变化的响应近年来受到广泛关注.由于森林土壤酶对全球气候变化的响应研究是预测未来环境变化对森林生态系统过程影响的关键,因此,着重综述了森林土壤酶对环境变化尤其是全球变暖和氮沉降响应方面的研究,并分析了未来研究的主要方向.环境变化会引起土壤pH、水分及其营养成分的变化,而这些变化会反作用于土壤酶的活性和稳定性.森林土壤酶对增温的响应,不仅与酶的种类以及增温的温度范围和持续时间有关,还与土壤类型有关,是多种因子综合作用的结果.森林土壤酶对氮添加的响应与林分类型和土层类型有关,受复合氮的影响更大.建议未来的研究应加强酶的基本性质对环境变化的响应研究,注重林分类型、土层类型导致的差异,强化多因素的交互作用,并进行长期、综合的观测.

[ 刘捷豹, 陈光水, 郭剑芬, 杨智杰, 李一清, 林成芳, 杨玉盛 ( 2017). 森林土壤酶对环境变化的响应研究进展
生态学报, 37, 110- 117.]

DOI URL [本文引用: 1]

, Gilliam

, Yu

, Li

( 2013). Long-term nitrogen addition decreases carbon leaching in nitrogen-rich forest ecosystems.
Biogeosciences Discussions, 10, 3931- 3941.

DOI URL [本文引用: 1]

Dissolved organic carbon (DOC) plays a critical role in the carbon (C) cycle of forest soils, and has been recently connected with global increases in nitrogen (N) deposition. Most studies on effects of elevated N deposition on DOC have been carried out in N-limited temperate regions, with far fewer data available from N-rich ecosystems, especially in the context of chronically elevated N deposition. Furthermore, mechanisms for excess N-induced changes of DOC dynamics have been suggested to be different between the two kinds of ecosystems, because of the different ecosystem N status. The purpose of this study was to experimentally examine how long-term N addition affects DOC dynamics below the primary rooting zones (the upper 20 cm soils) in typically N-rich lowland tropical forests. We have a primary assumption that long-term continuous N addition minimally affects DOC concentrations and effluxes in N-rich tropical forests. Experimental N addition was administered at the following levels: 0, 50, 100 and 150 kg N halt;supgt;amp;minus;1lt;/supgt; yrlt;supgt;amp;minus;1lt;/supgt;, respectively. Results showed that seven years of N addition significantly decreased DOC concentrations in soil solution, and chemo-physical controls (solution acidity change and soil sorption) rather than biological controls may mainly account for the decreases, in contrast to other forests. We further found that N addition greatly decreased annual DOC effluxes from the primary rooting zone and increased water-extractable DOC in soils. Our results suggest that long-term N deposition could increase soil C sequestration in the upper soils by decreasing DOC efflux from that layer in N-rich ecosystems, a novel mechanism for continued accumulation of soil C in old-growth forests.

[27]

Liu

, Yang

, Zhu

, Si

, Xie

, Yang

( 2014). Comparative study on quantities and spectroscopic characteristics of soil dissolved organic matter between two economic forests in subtropical China.
Journal of Soil & Water Conservation, 28( 5), 170- 175.

[本文引用: 1]

[ 刘翥, 杨玉盛, 朱锦懋, 司友涛, 谢锦升, 杨智杰 ( 2014). 中亚热带2种经济林土壤可溶性有机质数量与光谱学特征比较
水土保持学报, 28( 5), 170- 175.]

[本文引用: 1]

[28]

Meng

, Xue

, Sha

, Tang

( 2001). Variations of soil NH₄ +-N, NO₃ --N and N mineralization under different forests in Xishuangbanna, Southwest China.
Acta Phytoecologica Sinica, 25, 99- 104.

DOI URL [本文引用: 1]

用顶盖埋管法（Ｃlose-Top Incubations)就西双版纳３种热带森林（热带季节雨林、版断热雨林、橡胶林）研究了土壤铵态氮（ＮＨ４－Ｎ）和硝态氮（ＮＯ３－Ｎ）以及土壤氮素矿化速率的季节动态情况。结果表明：西双版纳３种不同林型土壤ＮＨ４－Ｎ、ＮＯ３－Ｎ和氮素矿化速率均具有明显的季节性变化。ＮＨ４－Ｎ以干热季（４月末）最高（平均为２６．９２mg.kg^-1)和干季（２月末）最低（平均为１２．０１mg.kg^-1);NO3-3则以雨季中期（７月中旬）最高（平均为８．９mg.kg^-1）和干季（２月末）最低（平均为４．０４mg.kg^-1）；矿化速率则以干热季（２月末－４月末）最高（平均国０．４９６mg.kg^-1.d^-1），以雨季（７月中旬－１１月初）最低（平均０．００３７mg.kg^-1.d^-1）。就不同林型而言，季节雨林年均氮矿化速率（０．３１９mg.kg^-1.d^-1）＞片断热带雨林（０．２５mg.kg^-1.d^-1)>橡胶林（０．０７４mg.kg^-1.d^－１）。

[ 孟盈, 薛敬意, 沙丽清, 唐建维 ( 2001). 西双版纳不同热带森林下土壤铵态氮和硝态氮动态研究
植物生态学报, 25, 99- 104.]

DOI URL [本文引用: 1]

, Xue

, Fang

( 2004). Litter decomposition and its responses to simulated N deposition for the major plants of Dinghushan forests in subtropical China.
Acta Ecologica Sinica, 24, 1413- 1420.

[本文引用: 2]

[ 莫江明, 薛璟花, 方运霆 ( 2004). 鼎湖山主要森林植物凋落物分解及其对N沉降的响应
生态学报, 24, 1413- 1420.]

[本文引用: 2]

[30]

Parfitt

, Ross

, Coomes

( 2005). N and P in New Zealand soil chronosequences and relationships with foliar N and P.
Biogeochemistry, 75, 305- 328.

DOI URL [本文引用: 1]

The growth of forest species in soil development chronosequences becomes increasingly phosphorus (P)-limited with time, as P is weathered, eroded and leached from soil. Foliar nitrogen (N) concentrations also tend to decrease with soil age when vegetation may be limited in both N and P. Here we report on soil development in temperate rain forests along three New Zealand chronosequences that have minimal pollution and disturbance from human activities, at Franz Josef, Waitutu and Central Volcanic Plateau, and on factors influencing soil net N mineralization (aerobic; 56 days) and foliar N and P concentrations. Except in very young soils (&lt 500 years), at least 85% of total-P in mineral soil (0-10 cm) was transformed to organic-P. In each chronosequence, total-P declined with time, and foliar N:P ratios (mass) generally increased from 8 to 15-18, suggesting P was more limiting than N in the oldest soils of the chronosequence. There was a negative relationship between net N mineralization and C:N ratio for mineral soil. For the FH (organic) layer, net N mineralization had the strongest relationships with total-N concentration (positively) and C:organic-P ratio (negatively); however, relationships varied with forest group, suggesting that other factors were also important. Foliar P of kamahi (Weinmannia racemosa Linn. f.), a dominant canopy species, was related to soil organic-P, suggesting mineralization was an important process for tree nutrition. Foliar N was positively related to N concentration in the FH layer, but was not significantly related to any measured property in mineral soil, possibly because of the wide range of soils. The consistent declines in both soil and foliar P across the contrasting chronosequences strongly suggest that vegetation becomes progressively P-limited during long-term ecosystem development.

[31]

Saadi

, Borisover

, Armon

, Laor

( 2006). Monitoring of effluent DOM biodegradation using fluorescence, UV and DOC measurements.
Chemosphere, 63, 530- 539.

DOI URL PMID [本文引用: 1]

The potential of effluent DOM to undergo microbial degradation was assessed in batch experiments. Effluent samples from Haifa wastewater treatment plant and Qishon reservoir (Greater Haifa wastewater reclamation complex, Israel) were incubated either with effluent or soil microorganisms for a period of 2–4 months and were characterized by dissolved organic carbon contents (DOC), UV 254 absorbance and by fluorescence excitation–emission matrices. Three main fluorescence peaks were identified that can be attributed to humic/fulvic components and “protein-like” structures. During biodegradation, specific fluorescences (F/DOC) of the three peaks were increased at various extents, suggesting selective degradation of non-fluorescing constituents. In some cases increase in the effluent fluorescence (F) was observed thus proposing (i) the formation of new fluorescing material associated with DOM biodegradation and/or (ii) degradation of certain organic components capable of quenching DOM fluorescence. Based on the ratio between fluorescence intensity and UV 254, different biodegradation dynamics for fluorescent DOM constituents as compared with other UV-absorbing molecules was delineated. Overall, about 50% of the total DOM was found to be readily degradable such that residual resistant DOC levels were between 8 and 10 mg l 611. Enhanced levels of residual DOM in effluent-irrigated soils may contribute to the DOM pool capable of carrying pollutants to groundwater.

[32]

Saiya-Cork

, Sinsabaugh

, Zak

( 2002). The effects of long term nitrogen deposition on extracellular enzyme activity in an Acer saccharum forest soil.
Soil Biology and Biochemistry, 34, 1309- 1315.

DOI URL

Anthropogenic N deposition affects litter decomposition and soil organic matter (SOM) storage through multiple mechanisms. Microbial community responses to long-term N deposition were investigated in a sugar maple-dominated forest in northern Michigan during the 1998–2000 growing seasons. Litter and soil were collected from three fertilized plots (30 kg N ha 611 y 611) and three control plots. The activities of 10 extracellular enzymes (EEA) were assayed. ANOVA and meta-analysis techniques were used to compare treatment responses. EEA responses to N amendment were greater in litter than in soil (litter mean effect size [ d]=0.534 std. dev.; soil d=0.308). Urease, acid phosphatase and glycosidase (β-glucosidase, α-glucosidase, cellobiohydrolase, β-xylosidase) activities increased in both soil and litter; mean responses ranged from 7 to 56%. N-Acetylglucosaminidase activity increased 14% in soil but decreased 4% in litter. Phenol oxidase activity dropped 40% in soil, but increased 63% in litter. These responses suggest that N deposition has increased litter decomposition rate and depressed SOM decomposition. In previous studies, loss of phenol oxidase activity in response to N deposition has been attributed to suppression of lignin-degrading basidiomycetes. However, the decline of this activity in bacterially-dominated soil suggest that N inhibition of recalcitrant organic matter decomposition may be a more general phenomenon.

[33]

Sardans

, Pe?uelas

( 2005). Drought decreases soil enzyme activity in a Mediterranean Quercus ilex L. forest.
Soil Biology and Biochemistry, 37, 455- 461.

DOI URL [本文引用: 2]

Longer and more severe drought periods are expected in the near future for Mediterranean ecosystems. Soil enzymes play an essential role in the nutrient mineralization and their activity is an exceptional sensor in predicting the capacity of nutrient supply to plants. We conducted an experiment of water availability manipulation in evergreen oak mountain stands with the aim to study the effects of enhanced drought on the activity of five soil enzymes. The drought treatment consisted of runoff exclusion by a ditch along the entire top edge of the upper part of treatment plots and partial rain exclusion by suspending PVC strips and funnels. The reduction of 10% of soil moisture produced by runoff exclusion decreased urease activity by 10–67%, protease activity by 15–66% and β-glucosidase activity by 10–80%, depending on annual period and soil depth. The reduction of 21% of soil moisture produced by runoff and rainfall exclusion together reduced urease activity by 42–60%, protease activity by 35–45%, β-glucosidase activity by 35–83% and acid phosphatase activity by 31–40%. No significant effects were observed on alkaline phosphatase activity. The activities of the enzymes involved in the nitrogen cycle, protease and urease, were the most affected by drought. In all cases, the activities of these enzymes strongly decreased with soil depth and they were greater in spring than in autumn. These results show the link between drought and a slower nutrient turn-over, which decreases the nutrient supply to plants.

[34]

Sedjo

( 1992). Temperate forest ecosystems in the global carbon cycle.
AMBIO, 21( 4), 274- 277.

DOI URL [本文引用: 1]

Abstract The estimates of the temperate forest as being roughly in carbon balance in recent decades are at variance with the well-documented rise in northern forest timber volumes that has been occurring throughout much of the temperate Northern Hemisphere for the past several decades. Newly available data for all the forests of North America, Europe, and the former USSR allow a reexamination of the overall northern forest carbon balance. The findings of that re-examination suggest northern forest ecosystems as a missing carbon sink. These forests are estimated to be sequestering carbon at a rate of about 0.7 Gigatons (Gt) annually. -from Author

[35]

Sinsabaugh

( 2010). Phenol oxidase, peroxidase and organic matter dynamics of soil.
Soil Biology and Biochemistry, 42, 391- 404.

DOI URL [本文引用: 1]

Extracellular enzymes mediate the degradation, transformation and mineralization of soil organic matter. The activity of cellulases, phosphatases and other hydrolases has received extensive study and in many cases stoichiometric relationships and responses to disturbances are well established. In contrast, phenol oxidase and peroxidase activities, which are often uncorrelated with hydrolase activities, have been measured in only a small subset of soil enzyme studies. These enzymes are expressed for a variety of purposes including ontogeny, defense and the acquisition of carbon and nitrogen. Through excretion or lysis, these enzymes enter the environment where their aggegrate activity mediates key ecosystem functions of lignin degradation, humification, carbon mineralization and dissolved organic carbon export. Phenol oxidases and peroxidases are less stable in the environment than extracellular hydrolases, especially when associated with organic particles. Activities are also affected, positively and negatively, by interaction with mineral surfaces. High spatiotemporal variation obscures their relationships with environmental variables and ecological process. Across ecosystems, phenol oxidase and peroxidase activities generally increase with soil pH, a finding not predicted from the pH optima of purified enzymes. Activities associated with plant litter and particulate organic matter often correlate with decomposition rates and potential activities generally increase with the lignin and secondary compound content of the material. At the ecosystem scale, nitrogen amendment alters the expression of phenol oxidase and peroxidase enzymes more broadly than culture studies imply and these responses correlate with positive and negative changes in litter decomposition rates and soil organic matter content. At the global scale, N amendment of basidiomycete-dominated soils of temperate and boreal forest ecoystems often leads to losses of oxidative enzyme activity, while activities in grassland soils dominated by glomeromycota and ascomycetes show little net response. Land use that leads to loss of soil organic matter tends to increase oxidative activities. Across ecosystems, soil organic matter content is not correlated with mean potential phenol oxidase and peroxidase activities. A multiple regression model that includes soil pH, mean annual temperature, mean annual precipitation and potential phenol oxidase activity accounts for 37% of the variation in soil organic matter (SOM) content across ecosystems ( n=63); a similar model for peroxidase activity describes 32% of SOM variance ( n=43). Analysis of residual variation suggest that suites of interacting factors create both positive and negative feedbacks on soil organic matter storage. Soils with high oxygen availability, pH and mineral activity tend to be substrate limited: high in situ oxidative activities limit soil organic matter accumulation. Soils with opposing characteristics are activity limited: low in situ oxidative activities promote soil organic matter storage.

[36]

, Si

, Wang

( 2005). Effects of pretreatment, shaking and conserving method and extracting solution on results for soil mineral nitrogen. Journal of
Agro-Environment Science, 24, 1238- 1242.

DOI URL [本文引用: 1]

为探明土壤矿质氮分析方法的影响因素，应用采白果园、菜园、麦田、麦田休闲地和草地的5种土样，研究了土样预处理方式、KCl浸提液的保存方式对用连续流动分析仪测定土壤矿质氮具体测定方法的影响。结果表明，土样预处理方式和浸提液保存方式都不同程度地影响土壤中矿质氮的测定结果。方差分析结果进一步表明各种影响因子对土壤硝态氮含量测定值的影响较铵态氮大。采用鲜土直接测定、KCl浸提液不保存直接用连续流动分析仪测定能更准确地反映出土壤矿质氮的实际含量。

[ 苏涛, 司美茹, 王朝辉 ( 2005). 土壤矿质氮分析方法的影响因素研究
农业环境科学学报, 24, 1238- 1242.]

DOI URL [本文引用: 1]

Taylor

, Wilson

, Mills

( 2002). Comparison of microbial numbers and enzymatic activities in surface soils and subsoils using various techniques.
Soil Biology and Biochemistry, 34, 387- 401.

DOI URL

Knowledge of microbial numbers and activity in subsoils is essential for understanding the transformation and downward movement of natural and synthetic organics. Soil cores were taken from two soil profiles (surface textures: silty clay loam and loamy sand), and samples extracted from the 0–30 cm (surface), 1.0–1.3 m (mid) and 2.7–3.0 m (deep; clay) and 3.9–4.2 m (deep; sand) layers. A variety of soil biotic (microbial numbers, microbial biomass, enzyme activities) and abiotic properties (pH, organic C, texture, CEC) were measured. Bacterial numbers decreased with depth as indicated by viable counts and by calculations based upon biomass carbon and extracted DNA. Direct microscopic counts were the most sensitive method of enumeration and gave bacterial numbers between 37 and 442× greater than colony forming units and those calculated from DNA extracted from soil. DNA extracted from soil ranged from 1.23 (sand surface) and 1.34 (clay surface) μg g 611 d wt soil to 0.02 (sand deep) and 0.01 (clay deep) μg g 611 d wt soil. Bacterial numbers, estimated from biomass-C measurements, were comparable to direct counts. Large numbers of bacteria were recorded in the subsoils (direct counts: 5.6×10 8 sand, 4.5×10 8 clay) even though this was equivalent to only 4.7 and 1.7% of those in the surface soils. Fungi were isolated from surface and mid-depth layers of both soils but were absent from the deep soil samples. Enzymatic activities (arylsulphatase, β-glucosidase, phosphomonoesterases, urease, dehydrogenase, FDA hydrolysis), assayed with or without buffers, also decreased with depth. The exception was urease activity in the clay soil where no difference was seen between mid and deep in non-buffered assays but a 2.9-fold greater activity was exhibited in the mid than in the surface soil when buffered. Strong positive correlations ( R>0.95) were observed between all enzyme activities (except with urease activity in clay soil and non-buffered phosphatase activity in sand soil) and between all methods of estimating bacterial abundance. Strong positive correlations ( R>0.90) were also found between bacterial abundance and enzyme activities and between enzyme activities and organic matter content.

[38]

Waldrop

, Firestone

( 2004). Microbial community utilization of recalcitrant and simple carbon compounds: Impact of oak-woodland plant communities.
Oecologia, 138, 275- 284.

DOI URL PMID [本文引用: 1]

Little is known about how the structure of microbial communities impacts carbon cycling or how soil microbial community composition mediates plant effects on C-decomposition processes. We examined the degradation of four$^{13} {\rm{C}}$-labeled compounds (starch, xylose, vanillin, and pine litter), quantified rates of associated enzyme activities, and identified microbial groups utilizing the$^{13} {\rm{C}}$-labeled substrates in soils under oaks and in adjacent open grasslands. By quantifying increases in non-$^{13} {\rm{C}}$-labeled carbon in microbial biomarkers, we were also able to identify functional groups responsible for the metabolism of indigenous soil organic matter. Although microbial community composition differed between oak and grassland soils, the microbial groups responsible for starch, xylose, and vanillin degradation, as defined by$^{13} {\rm{C}}$-PLFA, did not differ significantly between oak and grassland soils. Microbial groups responsible for pine litter and SOM-C degradation did differ between the two soils. Enhanced degradation of SOM resulting from substrate addition (priming) was greater in grassland soils, particularly in response to pine litter addition; under these conditions, fungal and Gram + biomarkers showed more incorporation of SOM-C than did Gram - biomarkers. In contrast, the oak soil microbial community primarily incorporated C from the added substrates. More$^{13} {\rm{C}}$(from both simple and recalcitrant sources) was incorporated into the Gram - biomarkers than Gram + biomarkers despite the fact that the Gram + group generally comprised a greater portion of the bacterial biomass than did markers for the Gram - group. These experiments begin to identify components of the soil microbial community responsible for decomposition of different types of C-substrates. The results demonstrate that the presence of distinctly different plant communities did not alter the microbial community profile responsible for decomposition of relatively labile C-substrates but did alter the profiles of microbial communities responsible for decomposition of the more recalcitrant substrates, pine litter and indigenous soil organic matter.

[39]

Wan

, Guo

, Ji

( 2016). Effects of dissolved organic matter input on soil CO₂ emission and microbial community composition in a subtropical forest.
Scientia Silvae Sinicae, 52( 2), 106- 113.

DOI URL Magsci [本文引用: 1]

[目的] 研究可溶性有机物(DOM)输入对森林土壤CO2排放及微生物群落的影响,为探讨DOM在森林生态系统碳循环中的作用提供依据。[方法] 设置添加米槠凋落叶DOM、杉木凋落叶DOM、米槠枯死根DOM、杉木枯死根DOM及添加去离子水(对照)处理,通过36 h短期室内培养,研究添加米槠及杉木凋落叶和枯死根DOM后土壤CO2排放速率最大值出现的时间及对土壤微生物群落的影响。[结果] 无论米槠还是杉木,其凋落叶DOC含量均显著高于枯死根DOC含量,而凋落叶DOM的腐殖化指数(HIX)则显著低于枯死根DOM的HIX,添加米槠枯死根DOM和杉木枯死根DOM的土壤CO2排放速率在第2 h达到最大值,分别是对照的7.3和8.3倍,在24 h时则降低至最大值的78.9%和66.3%;而添加米槠凋落叶DOM和杉木凋落叶DOM的土壤CO2排放速率在12 h时达到最大值,分别是对照的20.6和13.2倍,在24 h时则分别降低至最大值的84.0%和53.1%;磷脂脂肪酸(PLFA)分析结果显示,土壤添加米槠凋落叶DOM后革兰氏阳性细菌、革兰氏阴性细菌、放线菌和真菌的PLFAs含量显著低于土壤添加杉木凋落叶DOM的27%,38%,46%和41% (P<0.05);土壤添加米槠枯死根DOM后革兰氏阳性细菌、革兰氏阴性细菌和真菌PLFAs含量显著低于添加杉木枯死根DOM的21%,21%和22% (P<0.05);培养36 h时,添加米槠凋落叶DOM的土壤和对照土壤中G+:G-(革兰氏阳性细菌:革兰氏阴性细菌)高于培养前,但添加米槠凋落叶DOM的土壤中真菌:细菌低于培养前,这与其他处理的结果相反,表明添加不同来源DOM对土壤微生物群落的影响不一致。[结论] 外源添加DOM后土壤CO2排放速率最大值的出现时间由外源添加DOM的组成和化学性质决定,而且外源添加DOM显著影响土壤微生物的群落组成。

[ 万菁娟, 郭剑芬, 纪淑蓉 ( 2016). 可溶性有机物输入对亚热带森林土壤CO₂排放及微生物群落的影响
林业科学, 52( 2), 106- 113.]

DOI URL Magsci [本文引用: 1]

Wan

, Huang

, He

( 2014). Effects of tree species transfer on soil dissolved organic matter pools in a reforested Chinese fir (Cunninghamia lanceolata) woodland.
Chinese Journal of Applied Ecology, 25, 12- 18.

URL [本文引用: 2]

以二代杉木林采伐迹地上营造的19年生米老排与杉木人工林为对象,采用冷水、热水和2 mol·L-1 KCl溶液提取0～5、5～10和10 ～ 20 cm层土壤中的可溶性有机碳(DOC)和有机氮(DON),研究造林树种转变对土壤可溶性有机质的影响.结果表明:造林树种转变对林地土壤DOC和DON 库有显著影响.米老排人工林土壤中用冷水、热水和KCl溶液浸提的DOC含量均显著高于杉木人工林,0～5和5～10 cm层土壤中用冷水和热水浸提的DON含量显著高于杉木林,不同方法浸提的DOC和DON含量大小顺序均为KCl＞热水＞冷水.在0～5 cm土层,米老排人工林土壤微生物生物量碳(MBC)含量比杉木林高76.3％.相关分析结果显示,热水浸提的DOC和DON与土壤MBC之间均呈显著正相关,不同树种人工林间土壤可溶性有机质的差异主要与凋落物输入的数量和质量有关.在杉木采伐迹地上营造米老排,能够明显改善土壤肥力.

[ 万晓华, 黄志群, 何宗明 ( 2014). 杉木采伐迹地造林树种转变对土壤可溶性有机质的影响
应用生态学报, 25, 12- 18.]

URL [本文引用: 2]

Wang

, Zhou

, Xia

( 2011). Effects of mixed plant residues from the loess plateau on microbial biomass carbon and nitrogen in soil.
Acta Ecologica Sinica, 31, 2139- 2147.

[本文引用: 1]

[ 王春阳, 周建斌, 夏志敏 ( 2011). 黄土高原区不同植物凋落物搭配对土壤微生物量碳、氮的影响
生态学报, 31, 2139- 2147.]

[本文引用: 1]

[42]

, Guo

, Wu

( 2014). Effects of logging residues on surface soil biochemical properties and enzymatic activity.
Acta Ecologica Sinica, 34, 1645- 1653.

[本文引用: 1]

[ 吴波波, 郭剑芬, 吴君君 ( 2014). 采伐剩余物对林地表层土壤生化特性和酶活性的影响
生态学报, 34, 1645- 1653.]

[本文引用: 1]

[43]

, Jiang

, Chang

( 2010). Dissolved soil organic carbon and nitrogen were affected by conversion of native forests to plantations in subtropical China.
Canadian Journal of Soil Science, 90, 27- 36.

DOI URL [本文引用: 1]

To better understand the impact of converting native forests to intensively managed plantations on soil carbon (C) and nitrogen (N) dynamics in subtropical China, we examined the seasonal patterns of water-soluble organic C (WSOC) and N (WSON) concentrations in soils in Chinese chestnut (Castanea mollissima Blume) (CF) and bamboo (Phyllostachys praecox C.D. Chu & C.S. Chou) plantation forests (...

[44]

, Lin

, Liu

, Xiong

, Lin

, Chen

, Xie

, Yang

( 2017). Effects of forest conversion on concentrations and fluxes of dissolved organic carbon in runoff.
Acta Ecologica Sinica, 37, 84- 92.

DOI URL [本文引用: 1]

米槠次生林转换成米槠人工幼林和米槠人工促进天然更新幼林(以下简称"人促幼林")后,以这三种森林类型为研究对象,连续监测每次降雨后地表径流量及径流水中可溶性有机碳(DOC)的含量及通量,比较不同森林类型观测结果的差异,并分析降雨对实验结果的影响。结果表明:米槠人工幼林单次产流量是米槠次生林的1.5—19.0倍,观测期间总径流量为5.9倍;米槠人促幼林单次径流量和总径流量均与米槠次生林无显著差异(P0.05)。观测期间米槠次生林、人工幼林、人促幼林径流水DOC浓度值范围为5.9—18.4 mg/L,4.3—13.5 mg/L和3.2—9.9 mg/L,米槠次生林径流水浓度均值(12.6 mg/L)分别是米槠人促幼林(7.6 mg/L)和米槠人工幼林(5.3 mg/L)的1.6和2.4倍。回归分析表明,径流水中DOC浓度与降雨前土壤含水率呈显著相关;降雨前土壤含水率20.8%是一个临界值,含水率低于20.8%时,径流水DOC浓度与降雨前含水率呈显著正相关(P0.05);高于20.8%时,径流水DOC浓度与降雨前土壤含水率呈显著负相关(P0.05)。米槠人工幼林地表径流DOC输出通量是米槠次生林的0.7—5.4倍,观测期间总输出通量为2.1倍;米槠人促林DOC单次通量和观测期间总通量均与米槠次生林差异不显著(P0.05)。三种森林类型DOC输出通量均与降雨量呈显著相关(P0.05)。可见,米槠次生林转变成米槠人工幼林后DOC输出浓度降低,但径流量显著增加,导致DOC输出通量增加;而转变成米槠人促幼林后DOC输出浓度也降低,但径流量并未增加,因而并未增加DOC输出通量。

[ 胥超, 林成芳, 刘小飞, 熊德成, 林伟盛, 陈仕东, 谢锦升, 杨玉盛 ( 2017). 森林类型更替对地表径流可溶性有机碳输出浓度和通量的影响
生态学报, 37, 84- 92.]

DOI URL [本文引用: 1]

Yang

, Wang

( 2004). Advances in forest soil enzymology.
Scientia Silvae Sinicae, 40( 2), 152- 159.

DOI Magsci [本文引用: 1]

土壤酶在土壤生态系统的物质循环和能量流动方面扮演重要的角色。目前,在几乎所有的森林生态系统研究中,土壤酶活性的监测似乎成为必不可少的研究内容。森林凋落物分解过程中的酶活性动态,植被特征与土壤酶活性的关系,土壤微生物与土壤酶的关系,植物-土壤界面的土壤酶,森林土壤质量评价指标的土壤酶及人类活动干扰对森林土壤酶活性的影响等是当前森林土壤酶学的研究重点。由于土壤酶的功能和生态重要性,森林土壤酶研究可能包括:(1 )土壤酶系统分异;(2 )作为森林土壤质量综合评价指标的土壤酶活性;(3)植被动态与土壤酶的关系;(4 )退化森林生态系统的土壤酶活性特征;(5 )人工林土壤酶活性特征;(6 )人类活动对森林土壤酶系统的影响。本文从土壤酶系统分异和生态系统的角度对土壤酶在森林生态系统中的作用和地位进行了综述,这对于加深理解森林生态系统中的物质循环、土壤酶的生态重要性以及森林生态系统退化机理有重要作用

[ 杨万勤, 王开运 ( 2004). 森林土壤酶的研究进展
林业科学, 40( 2), 152- 159.]

DOI Magsci [本文引用: 1]

Zhang

, Si

, Wang

, Gao

, Xu

( 2016). Effects of short-term nitrogen and silicon addition on above-?ground biomass and biodiversity of alpine meadow of the Qinghai-Tibetan Plateau, China.
Pratacultural Science, 33, 38- 45.

DOI URL [本文引用: 1]

草地施肥多集中于添加氮肥与磷肥,很少涉及硅肥.硅作为对植物有益的一种元素,能提高植物对环境的抗性,促进植物的生长.本研究以青藏高原高寒草甸为研究对象,通过添加不同组合的氮肥和硅肥,研究群落地上生物量和生物多样性的变化.结果表明,氮肥和硅肥的添加均能提高群落的地上生物量,然而硅肥提高群落地上生物量的幅度远低于氮肥;在添加氮肥导致群落物种多样性下降的同时,添加硅肥可以缓解群落多样性下降的趋势;硅肥的生物学功能在群落水平上存在着最佳浓度效应.同时,我们推测硅肥在维持群落中杂草的存活率上发挥着积极的作用,并通过比较不同硅肥处理时,杂草生物量所占群落生物量比重的变化,支持了上述推测.

[ 张文鹏, 司晓林, 王文银, 高天鹏, 徐当会 ( 2016). 氮硅添加对高寒草甸生物量和多样性的影响——以青藏高原为例
草业科学, 33, 38- 45.]

DOI URL [本文引用: 1]

Zhao

, Ma

, Zhang

, Lei

, Yao

, Zhou

( 2016). The reproductive allocation of Avena sativa under different planting densities and nitrogen addition treatments.
Pratacultural Science, 33, 249- 258.

DOI URL [本文引用: 1]

本研究基于在中国科学院海北高寒草甸生态系统定位站进行的盆栽试验,分析了不同种植密度和施氮水平对燕麦(Avena sativa)(巴燕3号)的生长特性、生物量积累及生物量分配格局的影响。结果表明,不同密度处理下,燕麦的植株高度、叶的长度、穗的长度、分蘖个数、繁殖生物量(穗)、茎叶生物量及地下生物量(根)等各性状参数均呈现极显著差异(P0.01);繁殖器官生物量分配比例随密度的增加呈上升趋势,根生物量分配随密度的增加逐渐减少;随种植密度增大,燕麦茎叶生物量分配呈现先减少后增加的趋势。氮素的施用有利于燕麦营养生长和繁殖生长生物量的积累。施氮肥对燕麦茎叶器官的生物量累积作用明显大于地下根器官。对照(F1)和低氮肥(0.6 g·盆-1,F2)大致相等,中氮肥(1 g·盆-1,F3)和高氮肥(2 g·盆-1,F4)大致相等,且前两者大于后两者,即在不施氮肥条件下,燕麦增加了对茎叶、根器官生物量的分配比例。在不同处理下,燕麦地下生物量分配、茎叶生物量分配及繁殖生物量分配三者间存在权衡。总体来看,不同处理下,燕麦选择最佳资源配置策略,即增大与获取限制资源相关器官的资源分配,而减少与获取非限制资源相关器官的资源分配,以适应生物环境(例如密度)和非生物环境(例如氮素添加)的变化。

[ 赵宏魁, 马真, 张春辉, 雷占兰, 姚步青, 周华坤 ( 2016). 种植密度和施氮水平对燕麦生物量分配的影响
草业科学, 33, 249- 258.]

DOI URL [本文引用: 1]

Zhao

, Zhang

, Yuan

( 2003). Characteristics and environmental significance of soil dissolved organic matter.
Chinese Journal of Applied Ecology, 14, 126- 130.

URL PMID [本文引用: 2]

Soil is a complex ecosystem with multi-interface. A numerous studies on soil dissolved organic matter (DOM) were carried out, and proved that DOM was one of the most active chemical components in the environment. Increasing attention has been paid on the study of soil DOM, especially in recent years, and the study has become an interdisciplinary focus in the fields of soil science, ecology, and environmental science due to the important roles of DOM in the biogeochemical cycles of carbon, nitrogen, phosphorus, sulfur, etc. In addition, DOM has significant effects on pedogenesis, growth and metabolism of soil microorganisms, decomposition and transformation of soil organic matter, and transport of pollutants in soils. The recent literatures about extraction methods, origin, composition, contents and controlling factors, bioavailability,and environmental significance of DOM were therefore reviewed, and future research aspects on this topic were also proposed.

[49]

Zsolnay

, Baigar

, Jimenez

( 1999). Differentiating with fluorescence spectroscopy the sources of dissolved organic matter in soils subjected to drying.
Chemosphere, 38, 45- 50.

DOI URL PMID [本文引用: 1]

Abstract The relative fluorescence, normalised on dissolved organic carbon (DOC), and a humification index, based on the location of the fluorescence emission spectra, were used to investigate the possible sources of the increase in dissolved organic matter (DOM) when a soil is dried. From these 2 parameters it could be seen that air drying resulted in a minor increase of more humified material in DOM while the effect of oven drying was mainly due to cell lysis.
Interactive effects of temperature and soil moisture on fungal-mediated wood decomposition and extracellular enzyme activity.
1
2014

... 在本研究涉及的5种酶之中, 活性最高的是NAG, 说明了N转化在亚热带森林土壤中的重要性.AR土壤NAG活性显著高于SF和PM (p < 0.05), NAG活性顺序与土壤TN和NH₄⁺-N的趋势一致, 这很可能说明了NAG是催化TN矿化为NH₄⁺-N的关键酶.同时NAG活性与土壤含水率显著正相关(p < 0.05), 这与大多研究结果(Sardans & Pe?uelas, 2005; A’Bear et al., 2014)类似. ...

Quantity and spectroscopic properties of soil dissolved organic matter (DOM) as a function of soil sample treatments: Air-drying and pre-incubation.
2
2007

... 用紫外-可见光分光度计(UV-2450, Shimadzu, Kyoto, Japan)测定254 nm的吸光度值.利用待测液254 nm处吸收值(SUVA)分析其芳香化程度和疏水特性(Akagi et al., 2007), 计算芳香化指数(AI)(Saadi et al., 2006): AI = (UV₂₅₄/C) × 100 ...

... 用F-7000荧光分光光度计(Hitachi, Tokyo, Japan)测定样品的荧光发射光谱, 测定方法及参数设定参照文献(刘翥等, 2014).荧光发射光谱腐殖化指数(HIX_em)为荧光发射光谱中波长435-480 nm与波长300-345 nm的面积比(Kalbitz et al., 1999; Zsolnay et al., 1999).为提高灵敏度, 荧光光谱测定前使用2 mol·L^-1 HCl将所有待测液的pH值调成2 (Akagi et al., 2007).HIX_em可用来表征DOM的腐殖化程度, HIX_em越大, 说明DOM中分子构成越复杂, π-π共轭体系越大, 腐殖类物质如缩合芳环和大分子化合物的含量越高(Bu et al., 2010). ...

Responses of extracellular enzymes to simple and complex nutrient inputs.
1
2005

... 酶活性的大小可以指示微生物养分需求和土壤养分供给之间的关系.大多数研究表明, 土壤养分含量和酶活性之间呈负相关关系, 即随着无机或有机形式的营养物质的增加, 微生物获取该营养物质的难度降低, 所需的相关催化酶的活性也相应降低(Allison & Vitousek, 2005; Burns et al., 2013).然而, Debosz等(1999)的研究表明输入有机物使纤维素酶活性增强; Taylor等(2002)的研究结果也显示, 酶活性与土壤有机质之间存在显著的正相关关系.因此生态系统养分含量与酶活性之间的明确关系目前还没有定论.同时, 由于土壤中各元素之间存在耦合关系, 养分有效性和酶活性之间还依赖于其他元素含量的高低, 含量相对高的元素可能会促进胞外酶对另一种元素的分解利用, 例如氮的有效性将会影响碳分解酶的活性, 进而改变凋落物及土壤有机质的分解速率(Sinsabaugh, 2010). ...

Changes in enzyme activities and soil microbial community composition along carbon and nutrient gradients at the Franz Josef chronosequence, New Zealand.
1
2007

... RDA显示TN和DON是3种森林类型表层土壤酶活性的主要影响因子, 并且TN与NAG呈显著正相关关系(图2), 这再次反映了底物与酶活性之间的正相关关系.中亚热带是N饱和区, 森林土壤的N相对富集(Lu et al., 2013), N在本地区发挥着养分利用的引领作用.有研究结果证实土壤DOM周转是元素循环的主要途径(Currie et al., 1996), DON是微生物最易利用的有机氮源, 从而刺激相关酶的活性, 所以DON对森林表层土壤酶的影响很大.在N循环过程中土壤固态氮可能要先转变为DON后才能被微生物利用分解成NH₄⁺-N和NO₃^--N.同时3种林分DON没有显著差异, 但是NH₄⁺-N有显著差异, 这很可能说明了DON到NH₄⁺-N的矿化速率较快, 这与NAG活性最高相一致.虽然是氮饱和区, 但土壤氮转化酶活性仍然较高, 说明土壤可利用性氮不足.土壤氮转化酶活性越高土壤中可利用性氮越缺乏.有可能是微生物自身对氮的需求较大; 也有可能是微生物为了得到更多的碳或其他营养元素, 而通过分解土壤有机氮, 为植物提供更多氮素, 促进植物的生长, 从而固定更多的碳输入土壤, 导致土壤中的易分解有机碳也增多, 最终满足微生物的需求(Kuzyakov & Xu, 2013), TN与βG、CBH之间也是显著正相关关系, 说明N也提高了与土壤C循环相关的酶活性, 这与Jian等(2016)的研究结果一致.有研究表明碳循环酶潜在活性随着无机氮可用性增加而增加, 而氮循环酶的活性随着碳可用性的增加而增加(Allison et al., 2007).氮是微生物新陈代谢的重要养分, 当氮含量升高时, 微生物也需要同化吸收更多的碳, 使微生物C/N保持相对稳定. ...

Interactions between crop residue and soil organic matter quality and the functional diversity of soil microbial communities.
1
2002

... 作为催化土壤中众多生化反应的主要承载体, 土壤酶活性会受到一系列理化因子及生物因子的影响.凋落物和根系的改变会引起土壤养分的变化(Bending et al., 2002; 王春阳等, 2011), 所以森林类型对酶的活性有着重要的影响. ...

Spectroscopic characterization of hot-water extractable organic matter from soils under four different vegetation types along an elevation gradient in the Wuyi Mountains.
1
2010

... 用F-7000荧光分光光度计(Hitachi, Tokyo, Japan)测定样品的荧光发射光谱, 测定方法及参数设定参照文献(刘翥等, 2014).荧光发射光谱腐殖化指数(HIX_em)为荧光发射光谱中波长435-480 nm与波长300-345 nm的面积比(Kalbitz et al., 1999; Zsolnay et al., 1999).为提高灵敏度, 荧光光谱测定前使用2 mol·L^-1 HCl将所有待测液的pH值调成2 (Akagi et al., 2007).HIX_em可用来表征DOM的腐殖化程度, HIX_em越大, 说明DOM中分子构成越复杂, π-π共轭体系越大, 腐殖类物质如缩合芳环和大分子化合物的含量越高(Bu et al., 2010). ...

Enzyme activity in soil-location and a possible role in microbial ecology.
1
1982

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

Soil enzymes in a changing environment: Current knowledge and future directions.
1
2013

... 酶活性的大小可以指示微生物养分需求和土壤养分供给之间的关系.大多数研究表明, 土壤养分含量和酶活性之间呈负相关关系, 即随着无机或有机形式的营养物质的增加, 微生物获取该营养物质的难度降低, 所需的相关催化酶的活性也相应降低(Allison & Vitousek, 2005; Burns et al., 2013).然而, Debosz等(1999)的研究表明输入有机物使纤维素酶活性增强; Taylor等(2002)的研究结果也显示, 酶活性与土壤有机质之间存在显著的正相关关系.因此生态系统养分含量与酶活性之间的明确关系目前还没有定论.同时, 由于土壤中各元素之间存在耦合关系, 养分有效性和酶活性之间还依赖于其他元素含量的高低, 含量相对高的元素可能会促进胞外酶对另一种元素的分解利用, 例如氮的有效性将会影响碳分解酶的活性, 进而改变凋落物及土壤有机质的分解速率(Sinsabaugh, 2010). ...

Linking variability in soil solution dissolved organic carbon to climate, soil type, and vegetation type.
1
2014

... DOM主要来源于新近凋落物、土壤腐殖质及根系分泌物(Camino-Serrano et al., 2014), 所以树种对DOM具有显著影响(万菁娟等, 2016).在本研究中, DOC、DON的变化趋势均为SF > AR > PM, 其中PM的DOC含量显著低于SF和AR (表3), 这是由于PM属于针叶林, 而SF和AR属于阔叶林.康根丽等(2014b)研究发现, 阔叶树叶片凋落物产生的DOC、DON浓度高于针叶树叶.AI可以指示DOM中芳香类化合物的多少, 而HIX_em可以用来表征DOM的腐殖化程度; 本研究中3种林分土壤DOM的AI和HIX_em的趋势相反.作者所在的森林土壤有机质课题组以前的研究发现马尾松凋落物中含有相对较多难以分解的、疏水性芳香族化合物, 而米槠凋落物中含有较多易分解的、亲水性低分子量化合物(万晓华等, 2014), 所以SF和AR土壤为微生物提供了更多的可利用能量和养分, HIX_em也高.SF和AR的建群树种虽然都是米槠, 但前者的林下植被较多, 而林下植被如芒萁往往会释放AI较低的DOM (康根丽等, 2014a), 所以SF土壤DOM的AI最低, 更有利于微生物的分解. ...

Interactions of organic phosphorus in terrestrial ecosystems.
1
2005

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

Vertical transport of dissolved organic C and N under long-term N amendments in pine and hardwood forests.
1
1996

... RDA显示TN和DON是3种森林类型表层土壤酶活性的主要影响因子, 并且TN与NAG呈显著正相关关系(图2), 这再次反映了底物与酶活性之间的正相关关系.中亚热带是N饱和区, 森林土壤的N相对富集(Lu et al., 2013), N在本地区发挥着养分利用的引领作用.有研究结果证实土壤DOM周转是元素循环的主要途径(Currie et al., 1996), DON是微生物最易利用的有机氮源, 从而刺激相关酶的活性, 所以DON对森林表层土壤酶的影响很大.在N循环过程中土壤固态氮可能要先转变为DON后才能被微生物利用分解成NH₄⁺-N和NO₃^--N.同时3种林分DON没有显著差异, 但是NH₄⁺-N有显著差异, 这很可能说明了DON到NH₄⁺-N的矿化速率较快, 这与NAG活性最高相一致.虽然是氮饱和区, 但土壤氮转化酶活性仍然较高, 说明土壤可利用性氮不足.土壤氮转化酶活性越高土壤中可利用性氮越缺乏.有可能是微生物自身对氮的需求较大; 也有可能是微生物为了得到更多的碳或其他营养元素, 而通过分解土壤有机氮, 为植物提供更多氮素, 促进植物的生长, 从而固定更多的碳输入土壤, 导致土壤中的易分解有机碳也增多, 最终满足微生物的需求(Kuzyakov & Xu, 2013), TN与βG、CBH之间也是显著正相关关系, 说明N也提高了与土壤C循环相关的酶活性, 这与Jian等(2016)的研究结果一致.有研究表明碳循环酶潜在活性随着无机氮可用性增加而增加, 而氮循环酶的活性随着碳可用性的增加而增加(Allison et al., 2007).氮是微生物新陈代谢的重要养分, 当氮含量升高时, 微生物也需要同化吸收更多的碳, 使微生物C/N保持相对稳定. ...

Temporal variations in microbial biomass C and cellulolytic enzyme activity in arable soils: Effects of organic matter input.
1999

Relationships between enzyme activities and microbial growth and activity indices in soil.
1
1983

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

三峡库区不同林龄马尾松土壤养分与酶活性的关系
1
2012

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

三峡库区不同林龄马尾松土壤养分与酶活性的关系
1
2012

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

Is microbial community composition in boreal forest soils determined by pH, C-to-N ratio, the trees, or all three?
1
2007

... 研究中SF和AR土壤中βG和CBH两种酶活性较PM高, 而PM土壤中PEO和PHO活性高于SF和AR.这是因为阔叶树土壤中易分解碳多, 促进了微生物对易分解碳的利用; 这体现了底物与酶活性之间的正相关关系.针叶树种凋落物中木质素、粗纤维、多酚类等难溶性物质含量较高, 导致凋落物难以分解, 对土壤有机碳的影响较弱(Zhao et al., 2003).PM土壤易分解的有机碳较少, 难分解的碳相对较多, 所以PEO和PHO的活性就高; 这与PM中AI高于SF和AR, DOC含量和HIX_em低于SF和AR的结果吻合.这与前人研究结果一致: 从天然阔叶林到人工林的转化增加了土壤中PHO的活性, 但降低了CBH的活性(Sardans & Pe?uelas, 2005).通过相关性分析, C/N与PHO呈正相关关系, 与其他酶没有显著关系, 而微生物中真菌在偏酸性和高C/N的土壤中比例较大(Hogberg et al., 2007), 真菌可利用较难分解的碳源.另外, 本研究发现βG和PEO, 以及CBH和PHO之间都是显著负相关关系, 且PHO和PEO活性小于βG和CBH, 这说明微生物利用有机碳往往有一定的选择性, 更倾向于利用易分解的有机质. ...

Balancing the global carbon budget.
1
2007

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

Soil extracellular enzyme activities, soil carbon and nitrogen storage under nitrogen fertilization: A meta-analysis.
2016

The vertical distribution of soil organic carbon and its relation to climate and vegetation.
1
2000

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

Spectroscopic properties of dissolved humic substances—A reflection of land use history in a fen area.
1
1999

... 用F-7000荧光分光光度计(Hitachi, Tokyo, Japan)测定样品的荧光发射光谱, 测定方法及参数设定参照文献(刘翥等, 2014).荧光发射光谱腐殖化指数(HIX_em)为荧光发射光谱中波长435-480 nm与波长300-345 nm的面积比(Kalbitz et al., 1999; Zsolnay et al., 1999).为提高灵敏度, 荧光光谱测定前使用2 mol·L^-1 HCl将所有待测液的pH值调成2 (Akagi et al., 2007).HIX_em可用来表征DOM的腐殖化程度, HIX_em越大, 说明DOM中分子构成越复杂, π-π共轭体系越大, 腐殖类物质如缩合芳环和大分子化合物的含量越高(Bu et al., 2010). ...

马尾松与芒萁鲜叶及凋落物水溶性有机物的溶解特征和光谱学特征
1
2014a

... DOM主要来源于新近凋落物、土壤腐殖质及根系分泌物(Camino-Serrano et al., 2014), 所以树种对DOM具有显著影响(万菁娟等, 2016).在本研究中, DOC、DON的变化趋势均为SF > AR > PM, 其中PM的DOC含量显著低于SF和AR (表3), 这是由于PM属于针叶林, 而SF和AR属于阔叶林.康根丽等(2014b)研究发现, 阔叶树叶片凋落物产生的DOC、DON浓度高于针叶树叶.AI可以指示DOM中芳香类化合物的多少, 而HIX_em可以用来表征DOM的腐殖化程度; 本研究中3种林分土壤DOM的AI和HIX_em的趋势相反.作者所在的森林土壤有机质课题组以前的研究发现马尾松凋落物中含有相对较多难以分解的、疏水性芳香族化合物, 而米槠凋落物中含有较多易分解的、亲水性低分子量化合物(万晓华等, 2014), 所以SF和AR土壤为微生物提供了更多的可利用能量和养分, HIX_em也高.SF和AR的建群树种虽然都是米槠, 但前者的林下植被较多, 而林下植被如芒萁往往会释放AI较低的DOM (康根丽等, 2014a), 所以SF土壤DOM的AI最低, 更有利于微生物的分解. ...

马尾松与芒萁鲜叶及凋落物水溶性有机物的溶解特征和光谱学特征
1
2014a

... DOM主要来源于新近凋落物、土壤腐殖质及根系分泌物(Camino-Serrano et al., 2014), 所以树种对DOM具有显著影响(万菁娟等, 2016).在本研究中, DOC、DON的变化趋势均为SF > AR > PM, 其中PM的DOC含量显著低于SF和AR (表3), 这是由于PM属于针叶林, 而SF和AR属于阔叶林.康根丽等(2014b)研究发现, 阔叶树叶片凋落物产生的DOC、DON浓度高于针叶树叶.AI可以指示DOM中芳香类化合物的多少, 而HIX_em可以用来表征DOM的腐殖化程度; 本研究中3种林分土壤DOM的AI和HIX_em的趋势相反.作者所在的森林土壤有机质课题组以前的研究发现马尾松凋落物中含有相对较多难以分解的、疏水性芳香族化合物, 而米槠凋落物中含有较多易分解的、亲水性低分子量化合物(万晓华等, 2014), 所以SF和AR土壤为微生物提供了更多的可利用能量和养分, HIX_em也高.SF和AR的建群树种虽然都是米槠, 但前者的林下植被较多, 而林下植被如芒萁往往会释放AI较低的DOM (康根丽等, 2014a), 所以SF土壤DOM的AI最低, 更有利于微生物的分解. ...

米槠人促更新林与杉木人工林叶片及凋落物溶解性有机物的数量和光谱学特征
2014b

米槠人促更新林与杉木人工林叶片及凋落物溶解性有机物的数量和光谱学特征
2014b

Prediction of soil nitrogen availability in forest ecosystems: A literature review.
1
1980

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

Incorporation studies of NH₄ + during incubation of organic residues by ^l5N-CPMAS-NMR-spectroscopy.
1
1981

... 参照Saiya-Cork (2002)的方法, 提取和培养土壤中5种与碳、氮循环相关的水解酶和氧化酶.方法如下: 取1 g新鲜土壤, 用125 mL 50 mmol·L^-1的醋酸盐缓冲液(pH = 5)提取, 用磁力搅拌器搅拌5 min使其均质化, 用移液器取200 μL移于96孔微孔板.用伞形酮(MUB)作为底物标示水解酶活性, 用L-二羟苯丙氨酸(DOPA)为底物标示氧化酶活性.微平板置于暗环境下经过20 ℃恒温培养后, 用多功能酶标仪(SpectraMax M5, Molecular Devices, Sunnyvale, USA)测定其荧光度(水解酶)或吸光度(氧化酶).底物以碳为主的多糖(纤维素)、芳香族化合物(木质素)和脂肪族化合物, 其分解酶主要为纤维素水解酶类(β-葡萄糖苷酶(βG)和纤维素水解酶(CBH)和木质素分解酶类多酚氧化酶(PHO)和过氧化物酶(PEO)).底物为以氮为主的氨基化合物、缩氨酸和非缩氨基化合物, 其分解酶为β-N-乙酰氨基葡萄糖苷酶(NAG) (Knicker et al., 1981).5种土壤酶的名称、缩写、功能及所用标定底物见表1.各种酶都通过预实验确定获得最大酶活性所需要的底物浓度和培养时间. ...

Competition between roots and microorganisms for nitrogen: Mechanisms and ecological relevance.
1
2013

... RDA显示TN和DON是3种森林类型表层土壤酶活性的主要影响因子, 并且TN与NAG呈显著正相关关系(图2), 这再次反映了底物与酶活性之间的正相关关系.中亚热带是N饱和区, 森林土壤的N相对富集(Lu et al., 2013), N在本地区发挥着养分利用的引领作用.有研究结果证实土壤DOM周转是元素循环的主要途径(Currie et al., 1996), DON是微生物最易利用的有机氮源, 从而刺激相关酶的活性, 所以DON对森林表层土壤酶的影响很大.在N循环过程中土壤固态氮可能要先转变为DON后才能被微生物利用分解成NH₄⁺-N和NO₃^--N.同时3种林分DON没有显著差异, 但是NH₄⁺-N有显著差异, 这很可能说明了DON到NH₄⁺-N的矿化速率较快, 这与NAG活性最高相一致.虽然是氮饱和区, 但土壤氮转化酶活性仍然较高, 说明土壤可利用性氮不足.土壤氮转化酶活性越高土壤中可利用性氮越缺乏.有可能是微生物自身对氮的需求较大; 也有可能是微生物为了得到更多的碳或其他营养元素, 而通过分解土壤有机氮, 为植物提供更多氮素, 促进植物的生长, 从而固定更多的碳输入土壤, 导致土壤中的易分解有机碳也增多, 最终满足微生物的需求(Kuzyakov & Xu, 2013), TN与βG、CBH之间也是显著正相关关系, 说明N也提高了与土壤C循环相关的酶活性, 这与Jian等(2016)的研究结果一致.有研究表明碳循环酶潜在活性随着无机氮可用性增加而增加, 而氮循环酶的活性随着碳可用性的增加而增加(Allison et al., 2007).氮是微生物新陈代谢的重要养分, 当氮含量升高时, 微生物也需要同化吸收更多的碳, 使微生物C/N保持相对稳定. ...

森林土壤酶对环境变化的响应研究进展
1
2017

... 在本研究涉及的3种森林土壤中, 氮是影响A层土壤酶活性的主要因子, TN、NAG和NH₄⁺-N三者趋势一致, 反映了底物对酶活性的促进作用; DON可能是微生物矿化分解土壤氮的重要一环.同时微生物对碳的利用有一定的选择性, 更倾向于利用易分解的有机碳; 阔叶林土壤易分解碳多, 所以βG和CBH活性较高, 相反, 针叶林土壤PHO和PEO活性较高.在氮的引领下, 3种林分碳循环相关的水解酶活性也提高, 说明碳氮养分循环之间存在一定的耦合关系.在不同森林类型下, 季节差异和微生物群落变化也会影响土壤碳氮含量和酶活性(刘捷豹等, 2017), 因此, 在本研究样地还需对季节动态和微生物做进一步研究, 以便更好地探究土壤碳氮含量、酶活性和微生物群落之间的联系, 从而为揭示森林类型更替后不同林分对土壤碳氮吸存的影响机制提供基础科学依据. ...

森林土壤酶对环境变化的响应研究进展
1
2017

... 在本研究涉及的3种森林土壤中, 氮是影响A层土壤酶活性的主要因子, TN、NAG和NH₄⁺-N三者趋势一致, 反映了底物对酶活性的促进作用; DON可能是微生物矿化分解土壤氮的重要一环.同时微生物对碳的利用有一定的选择性, 更倾向于利用易分解的有机碳; 阔叶林土壤易分解碳多, 所以βG和CBH活性较高, 相反, 针叶林土壤PHO和PEO活性较高.在氮的引领下, 3种林分碳循环相关的水解酶活性也提高, 说明碳氮养分循环之间存在一定的耦合关系.在不同森林类型下, 季节差异和微生物群落变化也会影响土壤碳氮含量和酶活性(刘捷豹等, 2017), 因此, 在本研究样地还需对季节动态和微生物做进一步研究, 以便更好地探究土壤碳氮含量、酶活性和微生物群落之间的联系, 从而为揭示森林类型更替后不同林分对土壤碳氮吸存的影响机制提供基础科学依据. ...

Long-term nitrogen addition decreases carbon leaching in nitrogen-rich forest ecosystems.
1
2013

... RDA显示TN和DON是3种森林类型表层土壤酶活性的主要影响因子, 并且TN与NAG呈显著正相关关系(图2), 这再次反映了底物与酶活性之间的正相关关系.中亚热带是N饱和区, 森林土壤的N相对富集(Lu et al., 2013), N在本地区发挥着养分利用的引领作用.有研究结果证实土壤DOM周转是元素循环的主要途径(Currie et al., 1996), DON是微生物最易利用的有机氮源, 从而刺激相关酶的活性, 所以DON对森林表层土壤酶的影响很大.在N循环过程中土壤固态氮可能要先转变为DON后才能被微生物利用分解成NH₄⁺-N和NO₃^--N.同时3种林分DON没有显著差异, 但是NH₄⁺-N有显著差异, 这很可能说明了DON到NH₄⁺-N的矿化速率较快, 这与NAG活性最高相一致.虽然是氮饱和区, 但土壤氮转化酶活性仍然较高, 说明土壤可利用性氮不足.土壤氮转化酶活性越高土壤中可利用性氮越缺乏.有可能是微生物自身对氮的需求较大; 也有可能是微生物为了得到更多的碳或其他营养元素, 而通过分解土壤有机氮, 为植物提供更多氮素, 促进植物的生长, 从而固定更多的碳输入土壤, 导致土壤中的易分解有机碳也增多, 最终满足微生物的需求(Kuzyakov & Xu, 2013), TN与βG、CBH之间也是显著正相关关系, 说明N也提高了与土壤C循环相关的酶活性, 这与Jian等(2016)的研究结果一致.有研究表明碳循环酶潜在活性随着无机氮可用性增加而增加, 而氮循环酶的活性随着碳可用性的增加而增加(Allison et al., 2007).氮是微生物新陈代谢的重要养分, 当氮含量升高时, 微生物也需要同化吸收更多的碳, 使微生物C/N保持相对稳定. ...

中亚热带2种经济林土壤可溶性有机质数量与光谱学特征比较
1
2014

... 用F-7000荧光分光光度计(Hitachi, Tokyo, Japan)测定样品的荧光发射光谱, 测定方法及参数设定参照文献(刘翥等, 2014).荧光发射光谱腐殖化指数(HIX_em)为荧光发射光谱中波长435-480 nm与波长300-345 nm的面积比(Kalbitz et al., 1999; Zsolnay et al., 1999).为提高灵敏度, 荧光光谱测定前使用2 mol·L^-1 HCl将所有待测液的pH值调成2 (Akagi et al., 2007).HIX_em可用来表征DOM的腐殖化程度, HIX_em越大, 说明DOM中分子构成越复杂, π-π共轭体系越大, 腐殖类物质如缩合芳环和大分子化合物的含量越高(Bu et al., 2010). ...

中亚热带2种经济林土壤可溶性有机质数量与光谱学特征比较
1
2014

... 用F-7000荧光分光光度计(Hitachi, Tokyo, Japan)测定样品的荧光发射光谱, 测定方法及参数设定参照文献(刘翥等, 2014).荧光发射光谱腐殖化指数(HIX_em)为荧光发射光谱中波长435-480 nm与波长300-345 nm的面积比(Kalbitz et al., 1999; Zsolnay et al., 1999).为提高灵敏度, 荧光光谱测定前使用2 mol·L^-1 HCl将所有待测液的pH值调成2 (Akagi et al., 2007).HIX_em可用来表征DOM的腐殖化程度, HIX_em越大, 说明DOM中分子构成越复杂, π-π共轭体系越大, 腐殖类物质如缩合芳环和大分子化合物的含量越高(Bu et al., 2010). ...

西双版纳不同热带森林下土壤铵态氮和硝态氮动态研究
1
2001

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

西双版纳不同热带森林下土壤铵态氮和硝态氮动态研究
1
2001

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

鼎湖山主要森林植物凋落物分解及其对N沉降的响应
2
2004

... 目前, 关于森林土壤酶的研究主要集中在欧洲和北美洲的北方森林或温带森林, 以外源养分添加对酶的影响居多, 对亚热带不同森林类型中内源养分与酶的关系研究较少(莫江明等, 2004).我国中亚热带地区, 由于雨水充沛, 森林群落种类丰富, 土壤可溶性养分多, 森林在生态过程中的作用比温带更大, 是全球同纬度地带上的“绿洲”, 有着旺盛的能量转化和物质循环的能力, 以及极强的生物生产力与生态效应, 是全球碳氮循环的重要组成部分(吴波波等, 2014).在过去几十年中, 我国中亚热带地区发生着剧烈的森林类型更替, 大面积的天然常绿阔叶林经过强烈人为干扰后, 转变为次生林和人工林, 但这种人为干扰对森林生态系统的生产力、碳吸存和养分保持功能所产生的影响至今并不清楚, 森林类型更替后各林分类型中土壤碳氮养分和酶活性之间有何关系和变化也不清楚.本文选取典型的米槠(Castanopsis carlesii)天然次生林、米槠人工促进天然更新林、马尾松(Pinus massoniana)人工林为研究对象, 探索不同森林类型土壤碳氮含量和土壤酶活性之间的关系, 为中亚热带陆地土壤碳、氮等物质循环提供科学依据, 为森林经营方式的合理调整及未来森林更新方式的选择提供科学参考. ...

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

鼎湖山主要森林植物凋落物分解及其对N沉降的响应
2
2004

... 目前, 关于森林土壤酶的研究主要集中在欧洲和北美洲的北方森林或温带森林, 以外源养分添加对酶的影响居多, 对亚热带不同森林类型中内源养分与酶的关系研究较少(莫江明等, 2004).我国中亚热带地区, 由于雨水充沛, 森林群落种类丰富, 土壤可溶性养分多, 森林在生态过程中的作用比温带更大, 是全球同纬度地带上的“绿洲”, 有着旺盛的能量转化和物质循环的能力, 以及极强的生物生产力与生态效应, 是全球碳氮循环的重要组成部分(吴波波等, 2014).在过去几十年中, 我国中亚热带地区发生着剧烈的森林类型更替, 大面积的天然常绿阔叶林经过强烈人为干扰后, 转变为次生林和人工林, 但这种人为干扰对森林生态系统的生产力、碳吸存和养分保持功能所产生的影响至今并不清楚, 森林类型更替后各林分类型中土壤碳氮养分和酶活性之间有何关系和变化也不清楚.本文选取典型的米槠(Castanopsis carlesii)天然次生林、米槠人工促进天然更新林、马尾松(Pinus massoniana)人工林为研究对象, 探索不同森林类型土壤碳氮含量和土壤酶活性之间的关系, 为中亚热带陆地土壤碳、氮等物质循环提供科学依据, 为森林经营方式的合理调整及未来森林更新方式的选择提供科学参考. ...

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

N and P in New Zealand soil chronosequences and relationships with foliar N and P.
1
2005

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

Monitoring of effluent DOM biodegradation using fluorescence, UV and DOC measurements.
1
2006

... 用紫外-可见光分光度计(UV-2450, Shimadzu, Kyoto, Japan)测定254 nm的吸光度值.利用待测液254 nm处吸收值(SUVA)分析其芳香化程度和疏水特性(Akagi et al., 2007), 计算芳香化指数(AI)(Saadi et al., 2006): AI = (UV₂₅₄/C) × 100 ...

The effects of long term nitrogen deposition on extracellular enzyme activity in an Acer saccharum forest soil.
2002

Drought decreases soil enzyme activity in a Mediterranean Quercus ilex L. forest.
2
2005

... 在本研究涉及的5种酶之中, 活性最高的是NAG, 说明了N转化在亚热带森林土壤中的重要性.AR土壤NAG活性显著高于SF和PM (p < 0.05), NAG活性顺序与土壤TN和NH₄⁺-N的趋势一致, 这很可能说明了NAG是催化TN矿化为NH₄⁺-N的关键酶.同时NAG活性与土壤含水率显著正相关(p < 0.05), 这与大多研究结果(Sardans & Pe?uelas, 2005; A’Bear et al., 2014)类似. ...

... 研究中SF和AR土壤中βG和CBH两种酶活性较PM高, 而PM土壤中PEO和PHO活性高于SF和AR.这是因为阔叶树土壤中易分解碳多, 促进了微生物对易分解碳的利用; 这体现了底物与酶活性之间的正相关关系.针叶树种凋落物中木质素、粗纤维、多酚类等难溶性物质含量较高, 导致凋落物难以分解, 对土壤有机碳的影响较弱(Zhao et al., 2003).PM土壤易分解的有机碳较少, 难分解的碳相对较多, 所以PEO和PHO的活性就高; 这与PM中AI高于SF和AR, DOC含量和HIX_em低于SF和AR的结果吻合.这与前人研究结果一致: 从天然阔叶林到人工林的转化增加了土壤中PHO的活性, 但降低了CBH的活性(Sardans & Pe?uelas, 2005).通过相关性分析, C/N与PHO呈正相关关系, 与其他酶没有显著关系, 而微生物中真菌在偏酸性和高C/N的土壤中比例较大(Hogberg et al., 2007), 真菌可利用较难分解的碳源.另外, 本研究发现βG和PEO, 以及CBH和PHO之间都是显著负相关关系, 且PHO和PEO活性小于βG和CBH, 这说明微生物利用有机碳往往有一定的选择性, 更倾向于利用易分解的有机质. ...

Temperate forest ecosystems in the global carbon cycle.
1
1992

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

Phenol oxidase, peroxidase and organic matter dynamics of soil.
1
2010

... 酶活性的大小可以指示微生物养分需求和土壤养分供给之间的关系.大多数研究表明, 土壤养分含量和酶活性之间呈负相关关系, 即随着无机或有机形式的营养物质的增加, 微生物获取该营养物质的难度降低, 所需的相关催化酶的活性也相应降低(Allison & Vitousek, 2005; Burns et al., 2013).然而, Debosz等(1999)的研究表明输入有机物使纤维素酶活性增强; Taylor等(2002)的研究结果也显示, 酶活性与土壤有机质之间存在显著的正相关关系.因此生态系统养分含量与酶活性之间的明确关系目前还没有定论.同时, 由于土壤中各元素之间存在耦合关系, 养分有效性和酶活性之间还依赖于其他元素含量的高低, 含量相对高的元素可能会促进胞外酶对另一种元素的分解利用, 例如氮的有效性将会影响碳分解酶的活性, 进而改变凋落物及土壤有机质的分解速率(Sinsabaugh, 2010). ...

土壤矿质氮分析方法的影响因素研究
1
2005

... 采用KCl溶液浸提法(苏涛等, 2005), 取5 g过 2 mm筛的鲜土于离心管中, 加入20 mL 2.0 mol·L^-1 KCl溶液, 振荡30 min后离心30 min (4 000 r·min^-1), 用0.45 μm滤膜过滤, 使用连续流动分析仪(San++, Skalar, Breda, the Netherlands)测定滤液中的土壤NH₄⁺-N和NO₃^--N浓度. ...

土壤矿质氮分析方法的影响因素研究
1
2005

... 采用KCl溶液浸提法(苏涛等, 2005), 取5 g过 2 mm筛的鲜土于离心管中, 加入20 mL 2.0 mol·L^-1 KCl溶液, 振荡30 min后离心30 min (4 000 r·min^-1), 用0.45 μm滤膜过滤, 使用连续流动分析仪(San++, Skalar, Breda, the Netherlands)测定滤液中的土壤NH₄⁺-N和NO₃^--N浓度. ...

Comparison of microbial numbers and enzymatic activities in surface soils and subsoils using various techniques.
2002

Microbial community utilization of recalcitrant and simple carbon compounds: Impact of oak-woodland plant communities.
1
2004

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

可溶性有机物输入对亚热带森林土壤CO₂排放及微生物群落的影响
1
2016

... DOM主要来源于新近凋落物、土壤腐殖质及根系分泌物(Camino-Serrano et al., 2014), 所以树种对DOM具有显著影响(万菁娟等, 2016).在本研究中, DOC、DON的变化趋势均为SF > AR > PM, 其中PM的DOC含量显著低于SF和AR (表3), 这是由于PM属于针叶林, 而SF和AR属于阔叶林.康根丽等(2014b)研究发现, 阔叶树叶片凋落物产生的DOC、DON浓度高于针叶树叶.AI可以指示DOM中芳香类化合物的多少, 而HIX_em可以用来表征DOM的腐殖化程度; 本研究中3种林分土壤DOM的AI和HIX_em的趋势相反.作者所在的森林土壤有机质课题组以前的研究发现马尾松凋落物中含有相对较多难以分解的、疏水性芳香族化合物, 而米槠凋落物中含有较多易分解的、亲水性低分子量化合物(万晓华等, 2014), 所以SF和AR土壤为微生物提供了更多的可利用能量和养分, HIX_em也高.SF和AR的建群树种虽然都是米槠, 但前者的林下植被较多, 而林下植被如芒萁往往会释放AI较低的DOM (康根丽等, 2014a), 所以SF土壤DOM的AI最低, 更有利于微生物的分解. ...

可溶性有机物输入对亚热带森林土壤CO₂排放及微生物群落的影响
1
2016

... DOM主要来源于新近凋落物、土壤腐殖质及根系分泌物(Camino-Serrano et al., 2014), 所以树种对DOM具有显著影响(万菁娟等, 2016).在本研究中, DOC、DON的变化趋势均为SF > AR > PM, 其中PM的DOC含量显著低于SF和AR (表3), 这是由于PM属于针叶林, 而SF和AR属于阔叶林.康根丽等(2014b)研究发现, 阔叶树叶片凋落物产生的DOC、DON浓度高于针叶树叶.AI可以指示DOM中芳香类化合物的多少, 而HIX_em可以用来表征DOM的腐殖化程度; 本研究中3种林分土壤DOM的AI和HIX_em的趋势相反.作者所在的森林土壤有机质课题组以前的研究发现马尾松凋落物中含有相对较多难以分解的、疏水性芳香族化合物, 而米槠凋落物中含有较多易分解的、亲水性低分子量化合物(万晓华等, 2014), 所以SF和AR土壤为微生物提供了更多的可利用能量和养分, HIX_em也高.SF和AR的建群树种虽然都是米槠, 但前者的林下植被较多, 而林下植被如芒萁往往会释放AI较低的DOM (康根丽等, 2014a), 所以SF土壤DOM的AI最低, 更有利于微生物的分解. ...

杉木采伐迹地造林树种转变对土壤可溶性有机质的影响
2
2014

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

... DOM主要来源于新近凋落物、土壤腐殖质及根系分泌物(Camino-Serrano et al., 2014), 所以树种对DOM具有显著影响(万菁娟等, 2016).在本研究中, DOC、DON的变化趋势均为SF > AR > PM, 其中PM的DOC含量显著低于SF和AR (表3), 这是由于PM属于针叶林, 而SF和AR属于阔叶林.康根丽等(2014b)研究发现, 阔叶树叶片凋落物产生的DOC、DON浓度高于针叶树叶.AI可以指示DOM中芳香类化合物的多少, 而HIX_em可以用来表征DOM的腐殖化程度; 本研究中3种林分土壤DOM的AI和HIX_em的趋势相反.作者所在的森林土壤有机质课题组以前的研究发现马尾松凋落物中含有相对较多难以分解的、疏水性芳香族化合物, 而米槠凋落物中含有较多易分解的、亲水性低分子量化合物(万晓华等, 2014), 所以SF和AR土壤为微生物提供了更多的可利用能量和养分, HIX_em也高.SF和AR的建群树种虽然都是米槠, 但前者的林下植被较多, 而林下植被如芒萁往往会释放AI较低的DOM (康根丽等, 2014a), 所以SF土壤DOM的AI最低, 更有利于微生物的分解. ...

杉木采伐迹地造林树种转变对土壤可溶性有机质的影响
2
2014

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

... DOM主要来源于新近凋落物、土壤腐殖质及根系分泌物(Camino-Serrano et al., 2014), 所以树种对DOM具有显著影响(万菁娟等, 2016).在本研究中, DOC、DON的变化趋势均为SF > AR > PM, 其中PM的DOC含量显著低于SF和AR (表3), 这是由于PM属于针叶林, 而SF和AR属于阔叶林.康根丽等(2014b)研究发现, 阔叶树叶片凋落物产生的DOC、DON浓度高于针叶树叶.AI可以指示DOM中芳香类化合物的多少, 而HIX_em可以用来表征DOM的腐殖化程度; 本研究中3种林分土壤DOM的AI和HIX_em的趋势相反.作者所在的森林土壤有机质课题组以前的研究发现马尾松凋落物中含有相对较多难以分解的、疏水性芳香族化合物, 而米槠凋落物中含有较多易分解的、亲水性低分子量化合物(万晓华等, 2014), 所以SF和AR土壤为微生物提供了更多的可利用能量和养分, HIX_em也高.SF和AR的建群树种虽然都是米槠, 但前者的林下植被较多, 而林下植被如芒萁往往会释放AI较低的DOM (康根丽等, 2014a), 所以SF土壤DOM的AI最低, 更有利于微生物的分解. ...

黄土高原区不同植物凋落物搭配对土壤微生物量碳、氮的影响
1
2011

... 作为催化土壤中众多生化反应的主要承载体, 土壤酶活性会受到一系列理化因子及生物因子的影响.凋落物和根系的改变会引起土壤养分的变化(Bending et al., 2002; 王春阳等, 2011), 所以森林类型对酶的活性有着重要的影响. ...

黄土高原区不同植物凋落物搭配对土壤微生物量碳、氮的影响
1
2011

... 作为催化土壤中众多生化反应的主要承载体, 土壤酶活性会受到一系列理化因子及生物因子的影响.凋落物和根系的改变会引起土壤养分的变化(Bending et al., 2002; 王春阳等, 2011), 所以森林类型对酶的活性有着重要的影响. ...

采伐剩余物对林地表层土壤生化特性和酶活性的影响
1
2014

... 目前, 关于森林土壤酶的研究主要集中在欧洲和北美洲的北方森林或温带森林, 以外源养分添加对酶的影响居多, 对亚热带不同森林类型中内源养分与酶的关系研究较少(莫江明等, 2004).我国中亚热带地区, 由于雨水充沛, 森林群落种类丰富, 土壤可溶性养分多, 森林在生态过程中的作用比温带更大, 是全球同纬度地带上的“绿洲”, 有着旺盛的能量转化和物质循环的能力, 以及极强的生物生产力与生态效应, 是全球碳氮循环的重要组成部分(吴波波等, 2014).在过去几十年中, 我国中亚热带地区发生着剧烈的森林类型更替, 大面积的天然常绿阔叶林经过强烈人为干扰后, 转变为次生林和人工林, 但这种人为干扰对森林生态系统的生产力、碳吸存和养分保持功能所产生的影响至今并不清楚, 森林类型更替后各林分类型中土壤碳氮养分和酶活性之间有何关系和变化也不清楚.本文选取典型的米槠(Castanopsis carlesii)天然次生林、米槠人工促进天然更新林、马尾松(Pinus massoniana)人工林为研究对象, 探索不同森林类型土壤碳氮含量和土壤酶活性之间的关系, 为中亚热带陆地土壤碳、氮等物质循环提供科学依据, 为森林经营方式的合理调整及未来森林更新方式的选择提供科学参考. ...

采伐剩余物对林地表层土壤生化特性和酶活性的影响
1
2014

... 目前, 关于森林土壤酶的研究主要集中在欧洲和北美洲的北方森林或温带森林, 以外源养分添加对酶的影响居多, 对亚热带不同森林类型中内源养分与酶的关系研究较少(莫江明等, 2004).我国中亚热带地区, 由于雨水充沛, 森林群落种类丰富, 土壤可溶性养分多, 森林在生态过程中的作用比温带更大, 是全球同纬度地带上的“绿洲”, 有着旺盛的能量转化和物质循环的能力, 以及极强的生物生产力与生态效应, 是全球碳氮循环的重要组成部分(吴波波等, 2014).在过去几十年中, 我国中亚热带地区发生着剧烈的森林类型更替, 大面积的天然常绿阔叶林经过强烈人为干扰后, 转变为次生林和人工林, 但这种人为干扰对森林生态系统的生产力、碳吸存和养分保持功能所产生的影响至今并不清楚, 森林类型更替后各林分类型中土壤碳氮养分和酶活性之间有何关系和变化也不清楚.本文选取典型的米槠(Castanopsis carlesii)天然次生林、米槠人工促进天然更新林、马尾松(Pinus massoniana)人工林为研究对象, 探索不同森林类型土壤碳氮含量和土壤酶活性之间的关系, 为中亚热带陆地土壤碳、氮等物质循环提供科学依据, 为森林经营方式的合理调整及未来森林更新方式的选择提供科学参考. ...

Dissolved soil organic carbon and nitrogen were affected by conversion of native forests to plantations in subtropical China.
1
2010

... 样品DOM采用水浸提法(Wu et al., 2010), 取 15 g过2 mm筛的鲜土于离心管中, 加入去离子水(水土体积质量比2:1), 振荡30 min后离心10 min (4β000 r·min^-1), 用0.45 μm滤膜过滤, 滤液中的有机物即为DOM.采用有机碳分析仪(TOC-VCPH, Shimadzu, Kyoto, Japan)测定样品DOC浓度, 使用连续流动分析仪测定DON浓度. ...

森林类型更替对地表径流可溶性有机碳输出浓度和通量的影响
1
2017

... 研究地区位于福建三明森林生态系统与全球变化野外观测研究站陈大观测点(26.32° N, 117.60° E), 地处武夷山东南, 戴云山脉西北.地貌以低山丘陵为主, 山地平均坡度25°-35o, 属中亚热带海洋季风气候, 年平均气温19.1 ℃, 年降水量1β749 mm, 年蒸发量1β585 mm, 相对湿度81%, 全年无霜期达300 天.区域内地带性植被为常绿阔叶林, 亦分布有一定面积的针阔混交林和针叶林(胥超等, 2017). ...

森林类型更替对地表径流可溶性有机碳输出浓度和通量的影响
1
2017

... 研究地区位于福建三明森林生态系统与全球变化野外观测研究站陈大观测点(26.32° N, 117.60° E), 地处武夷山东南, 戴云山脉西北.地貌以低山丘陵为主, 山地平均坡度25°-35o, 属中亚热带海洋季风气候, 年平均气温19.1 ℃, 年降水量1β749 mm, 年蒸发量1β585 mm, 相对湿度81%, 全年无霜期达300 天.区域内地带性植被为常绿阔叶林, 亦分布有一定面积的针阔混交林和针叶林(胥超等, 2017). ...

森林土壤酶的研究进展
1
2004

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

森林土壤酶的研究进展
1
2004

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

氮硅添加对高寒草甸生物量和多样性的影响——以青藏高原为例
1
2016

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

氮硅添加对高寒草甸生物量和多样性的影响——以青藏高原为例
1
2016

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

种植密度和施氮水平对燕麦生物量分配的影响
1
2016

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

种植密度和施氮水平对燕麦生物量分配的影响
1
2016

... 植被对土壤物理、化学和生物学过程有重要影响(杨万勤和王开运, 2004), 地上凋落物和植物根系是土壤主要的有机养分供应者和养分归还者.本研究中SOC、TN含量大小顺序为AR > SF > PM, 这一方面是由于阔叶林凋落物量高于针叶林, 针叶林马尾松凋落物中含有相对较多难以分解的化合物, 而米槠凋落物中含有较多易分解的化合物(万晓华等, 2014), 另一方面是因为造林初期炼山等因素使马尾松人工林有机质流失较多; 3种林分中PM的SOC、TN、NH₄⁺-N、DOC、DON浓度低于SF和AR, 在相同立地条件下森林类型更替后的针叶人工林土壤肥力很难恢复.氮是植物重要的营养元素(张文鹏等, 2016; 赵宏魁等, 2016), NH₄⁺-N和NO₃^--N均为水溶性, 可被植物直接吸收利用(孟盈等, 2001).本研究中3种林分土壤NH₄⁺-N的含量与土壤TN的含量趋势一致, SF和AR的显著高于PM, 且AR最高; 这很可能说明了NH₄⁺-N主要来自于土壤TN的矿化.NO₃^--N在3种林分中含量无显著差异且都较低, 一是因为植物偏向吸收NH₄⁺-N, 土壤对NO₃^--N几乎不吸附(葛晓改等, 2012), 易于从土壤尤其是阴离子交换能力差的土壤淋溶流失; 二是因为低的土壤pH值对硝化细菌的生长具有抑制作用(Keeney, 1980), 使硝化作用减弱从而使NO₃^--N含量降低.同时硝态氮也会通过反硝化作用变为易挥发的气体而减少(莫江明等, 2004). ...

Characteristics and environmental significance of soil dissolved organic matter.
2
2003

... 森林生态系统是陆地生态系统最主要的碳库(Houghton, 2007), 作为全球碳循环的重要组成部分, 在全球碳循环中扮演着重要角色(Sedjo, 1992; Jobbágy & Jackson, 2000).森林类型更替会改变地上植被群落组成, 以及细根和凋落物向土壤的有机质输入, 使输入土壤的可溶性有机质(DOM)数量和质量发生变化.土壤DOM作为土壤养分中十分活跃的组分, 虽只占土壤养分库的一小部分, 却极容易被微生物利用, 影响微生物的生长代谢(Zhao et al., 2003), 从而改变土壤的养分环境.土壤微生物需要从土壤中获取能量和养分来满足自身的生长代谢, 从而参与到土壤碳氮的生物化学循环过程中.土壤环境一旦改变, 微生物活性也会随之改变, 其活性主要体现在胞外酶上, 它对土壤有机质进行矿化分解被认为是养分循环的关键环节.酶是有机质分解、周转和矿化的主要生物催化剂(Burns, 1982; Frankenberger & Dick, 1983).研究发现随着土壤有机质的积累, 生态系统的生产力越来越依赖于胞外酶的矿化分解作用(Waldrop & Firestone, 2004; Condron et al., 2005; Parfitt et al., 2005). ...

... 研究中SF和AR土壤中βG和CBH两种酶活性较PM高, 而PM土壤中PEO和PHO活性高于SF和AR.这是因为阔叶树土壤中易分解碳多, 促进了微生物对易分解碳的利用; 这体现了底物与酶活性之间的正相关关系.针叶树种凋落物中木质素、粗纤维、多酚类等难溶性物质含量较高, 导致凋落物难以分解, 对土壤有机碳的影响较弱(Zhao et al., 2003).PM土壤易分解的有机碳较少, 难分解的碳相对较多, 所以PEO和PHO的活性就高; 这与PM中AI高于SF和AR, DOC含量和HIX_em低于SF和AR的结果吻合.这与前人研究结果一致: 从天然阔叶林到人工林的转化增加了土壤中PHO的活性, 但降低了CBH的活性(Sardans & Pe?uelas, 2005).通过相关性分析, C/N与PHO呈正相关关系, 与其他酶没有显著关系, 而微生物中真菌在偏酸性和高C/N的土壤中比例较大(Hogberg et al., 2007), 真菌可利用较难分解的碳源.另外, 本研究发现βG和PEO, 以及CBH和PHO之间都是显著负相关关系, 且PHO和PEO活性小于βG和CBH, 这说明微生物利用有机碳往往有一定的选择性, 更倾向于利用易分解的有机质. ...

Differentiating with fluorescence spectroscopy the sources of dissolved organic matter in soils subjected to drying.
1
1999

... 用F-7000荧光分光光度计(Hitachi, Tokyo, Japan)测定样品的荧光发射光谱, 测定方法及参数设定参照文献(刘翥等, 2014).荧光发射光谱腐殖化指数(HIX_em)为荧光发射光谱中波长435-480 nm与波长300-345 nm的面积比(Kalbitz et al., 1999; Zsolnay et al., 1999).为提高灵敏度, 荧光光谱测定前使用2 mol·L^-1 HCl将所有待测液的pH值调成2 (Akagi et al., 2007).HIX_em可用来表征DOM的腐殖化程度, HIX_em越大, 说明DOM中分子构成越复杂, π-π共轭体系越大, 腐殖类物质如缩合芳环和大分子化合物的含量越高(Bu et al., 2010). ...