摘要:选取三峡库区典型马尾松杉木混交林和马尾松杉木栎类混交林为研究对象，对其表层土壤（0-10 cm）3种团聚体等级（大团聚体（ > 2 mm），中团聚体（0.25-2 mm），微团聚体（ < 0.25 mm））分布特征，团聚体5种水解酶活性（β-葡糖苷酶，酸性磷酸酶，N-乙酰-葡糖苷酶，纤维二糖水解酶，亮氨基酸氨基肽酶）和2种氧化还原酶活性（多酚氧化酶和过氧化物酶），以及团聚体酶活性与团聚体有机碳、全氮、全磷、碳氮比的关系进行了分析，旨在理解不同马尾松混交林类型下土壤团聚体及其酶活性的分布特征，为科学制定营林措施提供基础数据。结果表明：（1）各等级土壤团聚体分布随着粒径的增加而呈现显著增加的趋势，其中大团聚体所占比例最高，为60%左右；马尾松杉木混交林的中团聚体分布比例（39.53%±1.65%）显著高于马尾松杉木栎类混交林（32.24%±2.51%）；（2）微团聚体5种水解酶活性、有机碳含量以及全氮含量最高，而大团聚体中2种氧化还原酶活性最高；（3）马尾松杉木栎类混交林大团聚体和微团聚体纤维二糖水解酶、亮氨基酸氨基肽酶、土壤酶活性几何平均数、土壤碳氮比均显著高于马尾松杉木混交林；团聚体全氮含量的差异是造成上述酶活性差异的主要原因。马尾松杉木栎类混交林中栎类阔叶树种的增加显著提高了土壤团聚体酶活性，有利于土壤养分质量的提高。



Abstract:Soil enzymes, which were secreted by soil microorganisms, play important role in soil nutrients cycles through mediating the degradation, transformation and mineralization of soil organic matter. And soil aggregate structure can affect the soil enzyme activities by influencing microbial activities and accessibility of soil organic matter. Thus, study of soil enzyme activities on an aggregate level could provide insight into nutrient cycling and could also be used as sensitive indicators for soil fertility. Pinus massoniana Lamb., as the top 5 plantation species in China, is also the main vegetation type with key ecological and economic importance in the Three Gorges Reservoir Area, China, but the productivity of P. massoniana forests is low due to extensive management. Quantifying the enzymatic activities within soil aggregates in P. massoniana forests could provide basic data for forest managements in this area. Hence, in this study, we chose two typical mixed P. massoniana plantations in the Three Gorges Reservoir area, P. massoniana and Cunninghamia lanceolata mixed plantations (MS) and P. massoniana, C. lanceolate and Quercus mixed plantations (MH), as the objects. The soil samples in top 10 cm were collected from six 20 m×20 m plots (three plots in each mixed plantation) to test distribution of soil aggregate (i.e. large macroaggregates (> 2 mm), small macroaggregates (0.25-2 mm), and microaggregates (< 0.25 mm)) through modified dry-sieving method, and to analyze the activities of 5 hydrolases (i.e. soil β-glucosidase, cellobiohydrolase, N-acetyl-glucosaminidase, acid phosphatase and leucine aminopeptidase) and 2 oxidase (phenoloxidase and peroxidase) within soil aggregates. The relationships between soil enzymes activities, soil nitrogen, soil organic carbon, soil total phosphorus and soil carbon to nitrogen ratio within aggregate were also observed. The results showed that: 1) the distribution of soil aggregates significantly increased as the aggregate size increased in both two mixed plantations, and the proportion of large macroaggregates was the highest, which accounting for 60% in the soil. The distribution of small macroaggregates was significantly higher in MS (39.53%±1.65%) than that in MH (32.24%±2.51%) but no significant differences were found in other two aggregate sizes. 2) The activities of 5 hydrolases, soil organic carbon and soil total nitrogen were higher in microaggregates than those in other two aggregates, while the activities of 2 oxidase were highest in large macroaggregates in both two mixed plantations. 3) The activities of cellobiohydrolase and leucine aminopeptidase, geometric mean of soil enzymes activities and soil carbon to nitrogen ratio in large macroaggregates and microaggregates were significantly higher in MH than those in MS, and variation of soil nitrogen within soil aggregates attributed to the significant differences of soil enzymes discussed above. Our results indicated that Quercus in MH improved the enzymatic activities within soil aggregates and was beneficial to improvement of soil fertilities in the study area.





PDF全文下载地址:

https://www.ecologica.cn/stxb/article/pdf/stxb201912252783