孔令阳^1,,
羊向东^2,,,
王倩²,
胡竹君³
1. 云南师范大学旅游与地理科学学院, 高原地理过程与环境变化云南省重点实验室, 云南 昆明 650500
2. 中国科学院南京地理 与湖泊研究所, 湖泊与环境国家重点实验室, 江苏 南京 210008
3. 南京师范大学地理科学学院, 江苏 南京 210023

基金项目: 国家重点研究发展计划项目"全球变化及应对"重点专项项目（批准号：2017YFA0605203）、国家自然科学基金项目（批准号：41302277）和云南师范大学博士启动基金项目（批准号：2017ZB024）共同资助


详细信息

作者简介: 孔令阳, 男, 33岁, 博士/讲师, 自然地理学专业, E-mail:konglingyang20504@163.com

通讯作者: 羊向东, E-mail:xdyang@niglas.ac.cn

中图分类号: Q958.15⁺4;Q948.15⁺4;P941.78

收稿日期:2018-03-09
修回日期:2018-05-08
刊出日期:2018-07-30

Environmental change and biological response during the past 200 years from two alpine lakes below and above modern treeline in Southwest China

Kong Lingyang^1,,
Yang Xiangdong^2,,,
Wang Qian²,
Hu Zhujun³
1. Yunnan Provincial Key Laboratory of Plateau Geographical Processes and Environmental Change, School of Tourism and Geography, Yunnan Normal University, Kunming 650500, Yunnan
2. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, Jiangsu
3. School of Geography Science, Nanjing Normal University, Nanjing 210023, Jiangsu


More Information

Corresponding author: Yang Xiangdong,E-mail:xdyang@niglas.ac.cn

MSC: Q958.15⁺4;Q948.15⁺4;P941.78

--> Received Date: 09 March 2018
Revised Date: 08 May 2018
Publish Date: 30 July 2018


摘要
摘要:根据西南地区树线附近的错恰湖和吉仁错这两个高山湖泊沉积钻孔中生物化石指标（枝角类、硅藻）及多环境代用指标分析，重建了两个湖泊近200年来生物群落组合和环境变化的过程，在此基础上对比分析了区域高山湖泊生物群落组合并探讨了其对环境变化的响应模式。两个贫营养湖泊中枝角类群落组成有明显差异，位于较高海拔的吉仁错以沿岸种尖额溞属（Alona）和兼浮游种圆形盘肠溞（Chydorus sphaericus）为主，而位于树线以下的错恰湖则以浮游种长刺溞（Daphnia longispina）为单一优势种。过去两百年来，吉仁错中枝角类和硅藻群落均有相对明显的变化，枝角类群落变化以Alona rustica和矮小锐额溞（Alonella nana）相对丰度较明显下降为主要特征，硅藻群落变化表现为眼斑小环藻（Cyclotella ocellata）与脆杆藻属（Fragilaria）的含量互为消长；而错恰湖中硅藻群落没有明显变化，枝角类组合以D.longispina和虱形大眼溞（Polyphemus pediculus）相对丰度互有增减为主要特征，其他属种枝角类变化不明显。分析发现，海拔梯度和湖泊流域差异对生物群落组合和长期变化影响明显，从流域森林带输入的溶解性有机质（DOM）和溶解性有机碳（DOC）含量的差异可能是两个湖泊优势种组成和浮游种相对丰度差别明显的主要原因；在过去200年中，更高海拔、位于0℃等温线附近的吉仁错流域受冰雪融水的影响，温度变化要更为明显，气候变暖通过间接途径影响水体碱度，从而引起生物群落发生较明显变化，而错恰湖海拔较低，且流域森林覆盖对温度的变化有一定的缓冲作用，因而生物群落结构相对较为稳定。
关键词: 树线/
高山湖泊/
沉积枝角类/
古生态/
气候变化

Abstract:Southwest China, which includes the eastern margin of Tibet, is a hotspot of global biodiversity research. Previous studies showed rapid ecological change in this region, due to global environmental forcing, most notably landcover change and Nr deposition. In this study, two alpine glacier lakes, one is Jiren Lake(29°43'19″N, 100°48'56″E), located above the modern treeline(altitude ca. 4480 m a.s.l.), from Yajiang County, Garze tibetan autonomous prefecture, in Western Sichuan Plateau, and the other Lake Cuoqia(27°24'13″N, 99°46'18″E), lies below the modern treeline(altitude ca. 3980 m a.s.l.), from Shangri-La City, Diqing Tibetan Autonomous prefecture, in northwest Yunnan Province, are selected. All lakes are deep(of maximum water depth about 27 m), small and oligotrophic.
A 48 cm long sediment core was taken from the center of Cuoqia Lake using UWITEC sediment corer(diameter is 60 mm) in 2012, and divided by 1 cm in the field, and a 38 cm long sediment core was taken from the center of Jiren Lake using Hon-Kajak sediment corer(diameter is 90 mm) in 2014, and 0.5 cm divided in the field. Multi-proxies(i.e., cladoceran, diatom, geochemical) from two lakes sediment cores over the past 200 years, 0~28.5 cm of Jiren Lake and 0~31 cm depth of Cuoqia Lake, were analysed, to reconstruct the environment change history of two Lakes, and to understand how physicochemical characteristics and catchment characteristics of lakes above and below treeline affect the composition of aquatic organisms(i.e., cladocera and diatom) and their response to environmental change.
Based on the ²¹⁰Pb/¹³⁷Cs dating, the chronology of two cores were established. The composition of cladocera are different in two oligotrophic lakes, littoral species(Alona spp., Pleuroxus spp. etc) and ubiquitous species Chydorus sphaericus are dominated in Jiren Lake, while the Cuoqia Lake was predominated by planktonic cladocera Daphnia longispina with rare littoral species. The diatom assemblages at Jiren Lake was predominated by small Fragilaria and Cyclotella. Aulacoseira spp. and benthic species were dominated at Cuoqia Lake. During the last 200 years, all cladocera and diatom composition showed obvious changes in Jiren Lake, while, there are subtle changes of diatom composition and only obsolete fluctuation between the dominate cladcera species D. longispina and predatory species Polyphemus pediculus at Cuoqia Lake.
Our results indicates that, the composition of aquatic organisms(cladoceran and diatom) and their response to regional environmental change were mediated by lake altitude, lake physicochemical characteristics and catchment characteristics. Lower altitude and higher water temperature in Cuoqia Lake promote the growth of planktonic cladocera, besides, high DOM and DOC taken from the catchment not only provide more available food for cladocera, but also reduce the water transparent and UV radiation, and then benefit the survive of planktonic species in the open water zone. For the case of Jiren Lake, lower water temperature, shorter growth period and higher UV radiation intensity should restrained the growth of planktonic cladocera. Although there is no evidence of climate warming affect the composition changes of cladocera and diatom in two lakes, climate warming may contribute to the noticeable change of organisms in Jiren Lake indirectly. Higher altitude of Jiren Lake makes it more sensitive to climate change, and the degradation of increase temperature during the past 200 years should be higher than that in Cuoqia Lake, climate warming result in more glacial water inputs and reduced the pH of water body, ultimately changed the composition of cladocera and diatom. For the Cuoqia Lake, lower altitude and forest cover around the catchment buffer the increasing temperature, thus, no obvious change of aquatic organism in this lake.
Key words:treeline/
alpine lake/
cladoceran remains/
paleoecology/
climate change



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