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Effects of primary productivity and ecosystem size on food-chain length in Raohe River, China

Acta Ecologica Sinica 2015年第3期35卷 29-34页

作者： Xiewen Xiao Yuyu Wang Huan Zhang Xiubo Yu Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research CAS Beijing 100101 China University of Chinese Academy of Sciences Beijing 100039 China School of Nature Conservation Beijing Forestry University Beijing 100083 China

Food chains illustrate the fundamental relationship among different producers and consumers in the natural world. The length of a food chain describes the relationship from primary producers to top predators, and has long been a central concept in community ecology. Many different drivers, including productivity and ecosystem size, explain natural variations in the lengths of food chains. A significant amount of knowledge remains to be obtained about the roles of these various drivers in determining the lengths of food chains and the mechanisms by which they operate in river ecosystems. Raohe River in China is one of main rivers that flow into Lake Poyang. We examined the main channel and tributaries of Raohe River and collected the most common species in them. We found a total of 336 species belonging to 12 orders, 26 families, and 43 genera. We also collected 10 water samples. We conducted stable nitrogen isotope analysis of the consumers and used calculated nitrogen ratios (δ 15 N) to determine the lengths of the food chains at various sites in Raohe River. Subsequently, we examined the effects of primary productivity and ecosystem size on food-chain length. We used chlorophyll- a concentration obtained by analyzing filtered water samples to calculate the primary productivity of the river. The lengths of food chains in Raohe River ranged from 1.86 to 3.71. The longest food chains were at the Lake Poyang and Lianhu sample sites, and the shortest food chain (<2.0) was at Xiagang sample site. Results indicated that food chains in these rivers lengthened from the upper reaches to the lower reaches, reflecting an increased number of consumer species in the lower reaches. Significant positive correlations were observed between the lengths of the food chains in Raohe River and primary productivity (y = 0.41x + 2.13, R 2 = 0.58, p < 0.01) as well as ecosystem size (river width: y = 0.61x + 1.28, R 2 = 0.43, p < 0.05; catchment area: y = 0.32x + 1.48, R 2 = 0.42, p

关键词： Food chain length Stable isotope analysis Primary productivity ecosystem size Raohe River

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Temperature sensitivity quandary of soil microbial community structure in Tibetan alpine grasslands: A meta-analysis and field experiment

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Science of the Total Environment 2024年 955卷 176961页

作者： Fu, Gang Li, Tianyu Zha, Xinjie Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China Xi'an University of Finance and Economics Xi'an China University of Chinese Academy of Sciences Beijing100049 China

Soil microorganisms act as the primary decomposers in global terrestrial ecosystems. Whether climate warming will lead to the convergence of the temperature sensitivity of soil microbial community structure and the convergence of the responses of soil microbial community structure to warming remains controversial. This study explored how warming amplitude affected the temperature sensitivity of soil bacteria and fungi community structures, and how it influenced the responses of soil bacteria and fungi community structures to warming on the Qinghai-Tibet Plateau based on meta-analysis and a single-site warming experiment. The temperature sensitivity of soil microbial community structure did not consistently decline with increasing warming magnitude;instead, it even rose, which might be associated with the nonlinear relationships of the warming magnitude with the temperature sensitivity of ecological processes of soil microbial community assembly or the topological parameters of species co-occurrence network. Meta-analysis indicated that responses of soil microbial community to warming were independent of warming amplitude. However, the single-site warming experiment demonstrated that responses of soil microbial community to warming varied with warming amplitude. These inconsistent results might be attributed to distinct spatial scales, grassland types, climatic conditions and warming magnitudes between the single-site experiment and the meta-analysis. Therefore, the temperature sensitivity of soil microbial community and its response to climate warming cannot be simply characterized as monotonically decreasing or increasing in relation to increasing warming magnitude. © 2024 Elsevier B.V.

关键词： Abiotic

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modeling soil salinization at the downstream of a lowland reservoir

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Hydrology Research 2019年第5期50卷 1202-1215页

作者： Wu, Xia Xia, Jun Zhan, Chesheng Jia, Ruiliang Li, Yang Qiao, Yunfeng Zou, Lei Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China University of Chinese Academy of Sciences Beijing100049 China State Key Laboratory of Water Resources and Hydropower Engineering Sciences Wuhan University Wuhan430000 China College of Water Conservancy and Civil Engineering Xinjiang Agricultural University Urumqi830052 China Agriculture and Forestry Animal Husbandry Bureau Karamay834000 China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China

Soil salinization is a crucial issue in arid and semi-arid regions, especially for reservoir-based irrigation systems. In this study, the HYDRUS-1D model was used to investigate soil salinity resulting from seepage from a lowland reservoir in Xinjiang province, China. After successfully developing a model to simulate field observations, it was used to evaluate four hypothetical scenarios with different groundwater (GW) salinities and depths to GW. The model was calibrated, validated, and run for scenarios with periods of 367, 363, and 436 days. Root mean square error values of soil water and soil salinity ranged from 0.000 to 0.053 cm3/cm3 and 0.56 to 5.66 g/L, respectively, during calibration, and from 0.009 to 0.039 cm3/cm3 and 1.86 to 7.52 g/L, respectively, during validation. The results indicate that soil salinity downstream of the reservoir depends strongly on the depth to the GW level, while GW salinity has a much smaller impact. Controlling leakage from lowland reservoirs to avoid rising GW levels is therefore important to minimize soil salinization. These findings are generally useful for lowland reservoir design and construction, and for irrigation management in arid regions. © IWA Publishing 2019

关键词： Groundwater

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The use of stable isotopes to partition evapotranspiration fluxes into evaporation and transpiration

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Acta Ecologica Sinica 2010年第4期30卷 201-209页

作者： Shichun Zhang Xuefa Wen Jianlin Wang Guirui Yu Xiaomin Sun Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China Qingdao Agricutural University Qingdao 266109 China

It is crucial to partition evapotranspiration ( ET ) into evaporation ( E ) and transpiration ( T ) components for better understanding eco-hydrological processes and their underlying mechanisms, and improving the establishment and validation of hydrological models at the ecosystem scale. Traditional eddy covariance technique serves as a useful tool to estimate ET , but it encounters difficulties in quantifying the relative contribution of E and T to ET . Combining with eddy covariance technique, it is possible to partition ET based on the measurements of stable oxygen and hydrogen isotopes in liquid and vapor phases of water in the Soil–Plant–Atmosphere Continuum (SPAC) system. The key challenge is to precisely determine the oxygen-18 and deuterium isotopic compositions of ET ( δ ET ), E ( δ E ) and T ( δ T ). δ E can be estimated based on the Craig–Gordon model. δ T is usually approximated by the δ 18 O and δ D of water in xylem or twig ( δ x ), assuming δ T equals δ x under isotopic steady state (SSA). However, the SSA is only likely satisfied during midday in field conditions. The diurnal variations of δ T is affected by isotopic composition of atmospheric water vapor ( δ v ) and leaf water at the evaporating sites ( δ L , e ), and relative humidity, resulting in the non-steady-state behavior of δ T at the sub-daily cycles. δ ET can be estimated using the flux-gradient approach or the Keeling plot by measuring the vapor mixing ratio and δ v at different heights in the surface layer. However, δ v observations by the traditional cold trap/mass spectrometer method are limited to a coarse time resolution, leading to discrete time series of δ ET . It is now possible to make in situ and high time resolution measurements of δ v and to analyze a large number of plant and soil samples due to technical and instrumental advances in recent years. It provides an opportunity to improve the model prediction of δ L , e , and more importantly, to calculate δ T from δ L , e witho

关键词： Stable isotope Evapotranspiration Transpiration Evaporation In situ measurement Isotopic steady state Keeling plot

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Stable isotopic observation of water use sources of Pinus sylvestris var. mongolica in Horqin Sandy Land, China

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TREES-STRUCTURE AND FUNCTION 2013年第5期27卷 1249-1260页

作者： Wei, Y. F. Fang, J. Liu, S. Zhao, X. Y. Li, S. G. Chinese Acad Sci Key Lab Ecosystem Network Observat & Modeling Inst Geog Sci & Nat Resources Res Beijing 100101 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Chinas Minist Agr Grassland Monitoring & Supervis Ctr Beijing 100125 Peoples R China Chinese Acad Sci Cold & Arid Reg Environm & Engn Res Inst Lanzhou 730000 Peoples R China

Since the late 1950s, Mongolian pine (Pinus sylvestris var. mongolica) has been widely planted for vegetation restoration in arid and semi-arid areas in North China. We used stable isotope signals from precipitation, soil water, and xylem water of Mongolian pine trees, which were planted in early 1980s on sand dunes in the east-southern margin of Horqin Sandy Land, to identify water uptake sources of this tree. (1) Stable O-18 isotope composition of the xylem water exhibited little seasonality, suggesting that the trees use a relatively stable water source;(2) the water source of the pine trees primarily came from a soil depth of 20-60 cm (sampling depth up to 60 cm in this study) and the trees might use groundwater when soil moisture became extremely low;and (3) there was not much difference in water sources used by the pine trees grown at the top of the fixed dune and in the inter dune lowland, although these two sites had 3-8 m elevation difference. This study suggests that it is critical for Mongolian pine trees to access relatively reliable and stable water sources to grow in sandy land habitats, and timely recharging of rainwater to the trees' rooting depth is requisite for avoiding and/or reducing their degradation caused by water shortage.

关键词： Mongolian pine plantation Stable isotope composition Tree water uptake sources

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Effect of Functional Microorganisms and Environmental Factors on Co2 and Ch4 Emissions in a Typical Floodplain Lake System

SSRN

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SSRN 2024年

作者： Wu, Fan Gao, Yang Li, Jiajia Ha, Xianrui Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China University of Chinese Academy of Sciences Beijing100049 China

Lakes are known as potential carbon dioxide (CO2) and methane (CH4) emission hotspots, whose associated flux is spatially variable. However, the microbial processes and the environmental controls that influence CO2 and CH4 emission heterogeneity remain poorly understood. Accordingly, this study investigates CO2 and CH4 emission heterogeneity in a large floodplain lake system and distribution characteristics of associated functional microorganisms. Findings show that mean CO2 and CH4 flux values in the sub lake area were 62.03 ± 24.21 mg m-2 d-1 and 5.97 ± 3.2 μg m-2 d-1, which were greater by factors of 1.78 and 2.96 compared to the water channel and the main lake area, respectively. The Shannon index of methanogens in the sub lake area was lower than that in the main lake and water channel *** abundance of methanogens in bottom water layer was higher compared with the middle and surface layers. Conversely, the abundance of methane (CH4)-oxidizing bacteria in the surface layer was higher than that in the bottom layer. Additionally, the composition of methanogen and CH4-oxidizing bacterial community, chlorophyll a (Chl-a), pH, total phosphorus (TP) and dissolved organic carbon (DOC) content constituted the dominate driving factors affecting lake carbon (C) emissions. Results from this study can be used to improve our understanding of lake CO2 and CH4 emission driving mechanisms in floodplain lakes under the coupling effects of functional C microorganisms and environmental factors. © 2024, The Authors. All rights reserved.

关键词： Lakes

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modeling Aboveground Biomass Using MODIS Images and Climatic Data in Grasslands on the Tibetan Plateau

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Journal of Resources and Ecology 2017年第1期8卷 42-49页

作者： FU Gang SUN Wei LI Shaowei ZHANG Jing YU Chengqun SHEN Zhenxi Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China School of geography Beijing Normal University Beijing 100875 China

Accurate quantification of aboveground biomass of grasslands in alpine regions plays an important role in accurate quantification of global carbon *** monthly normalized difference vegetation index（NDVI）,enhanced vegetation index（EVI）,mean air temperature（Ta）,≥5℃ accumulated air temperature（AccT）,total precipitation（TP）,and the ratio of TP to AccT（TP/AccT） were used to model aboveground biomass（AGB） in grasslands on the Tibetan *** stepwise multiple regression methods,including stepwise multiple regression of AGB with NDVI and EVI,stepwise multiple regression of AGB with Ta,AccT,TP and TP/AccT,and stepwise multiple regression of AGB with NDVI,EVI,Ta,AccT,TP and TP/Acc T were *** mean absolute error（MAE） and root mean squared error（RMSE） values between estimated AGB by the NDVI and measured AGB were 31.05 g m^（-2） and 44.12 g m^（-2）,and 95.43 g m^（-2） and 131.58 g m^（-2） in the meadow and steppe,*** MAE and RMSE values between estimated AGB by the AccT and measured AGB were 33.61 g m^（-2） and 48.04 g m^（-2） in the steppe,*** MAE and RMSE values between estimated AGB by the vegetation index and climatic data and measured AGB were 28.09 g m^（-2） and 42.71 g m^（-2）,and 35.86 g m^（-2） and 47.94 g m^（-2）,in the meadow and steppe,*** study finds that a combination of vegetation index and climatic data can improve the accuracy of estimates of AGB that are arrived at using the vegetation index or climatic *** accuracy of estimates varied depending on the type of grassland.

关键词： enhanced vegetation index normalized difference vegetation index air temperature precipitation alpine grassland

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Effects of nitrogen addition on soil inorganic N content and soil N mineralization of a cold-temperate coniferous forest in Great Xing'an Mountains

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Acta Ecologica Sinica 2015年第5期35卷 130-136页

作者： Wenlong Gao Wei Zhao Hao Yang Haijun Yang Gaoqi Chen Yachen Luo Huajun Fang Shenggong Li Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China School of Geographical Sciences Southwest University Chongqing 400715 China

Nitrogen (N) plays an important role in carbon and nutrient cycling in forest ecosystems. Previous studies have shown that increased atmospheric N deposition has led to changes in forest soil N transfomations and soil N availability. However, knowledge gap exists about the impacts of N deposition on soil N dynamics of forest, especially for the boreal forests in China. In order to explore such impacts, a low-dose (Control, 0 kgN hm − 2 years − 1 , Low N—10 kgN hm − 2 years − 1 and High N, 40 kgN hm − 2 years − 1 ) and multiple forms (NH 4 Cl, KNO 3 and NH 4 NO 3 ) of simulated atmospheric N deposition experiment was conducted from 2010–2012 in a cold-temperate coniferous forest in the Great Xing'an Mountains. This paper reports inorganic N (NH 4 + -N and NO 3 − -N) content, net ammonification rate, net nitrification rate and net N mineralization rate in the 0–10 cm mineral soil during the growing season from May to September in 2012, the third year after N addition. Results that during the growing season, soil inorganic N was dominated by NH 4 + -N, showing a significant seasonal variation. Soil NH 4 + -N and NO 3 − -N responded differently to exogenous N addition. Soil NH 4 + -N content was more affected by the forms of N addition, while soil NO 3 − -N content was more affected by the doses of N addition. Relative to control, NH 4 + -N content of 0–10 cm mineral soil increased greatly with NH 4 + -N addition, which was completely different from the results observed in the first growing season of N addition in that no obvious effects of N addition on NH 4 + -N content of 0–10 cm mineral soil was observed. In agreement with results observed in the growing season, NO 3 − -N content of 0–10 cm mineral soil still showed a trend of enrichment with low dose N addition. For the N-limited forest ecosystem, soil net ammonification with a significant seasonal variation contributed most to soil net N mineralization, and soil net ammonifica

关键词： N deposition Net N mineralization Net nitrification Net ammonification Cold-temperate coniferous forest

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人为管理措施诱导土壤微生物磷与土壤微生物碳氮内稳态解耦的代谢证据

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Journal of Plant Ecology 2023年第6期16卷 185-196页

作者： Lihua Zhang Lizhi Jia Liyuan He David A.Lipson Yihui Wang Shunzhong Wang Xiaofeng Xu College of Life and Environmental Sciences Minzu University of ChinaBeijing 100081China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Biology Department San Diego State UniversitySan DiegoCA 92182USA

微生物化学计量学理论能够预测微生物对碳(C)、氮(N)、磷(P)的同化作用具有比例耦合性。这种耦合性被量化为稳态值,用于计算内稳性系数(H)。C、N、P的H值协变量表明,微生物对C、N、P的同化作用是耦合的。因此,在本文中我们利用全球数据... 详细信息

微生物化学计量学理论能够预测微生物对碳(C)、氮(N)、磷(P)的同化作用具有比例耦合性。这种耦合性被量化为稳态值,用于计算内稳性系数(H)。C、N、P的H值协变量表明,微生物对C、N、P的同化作用是耦合的。因此,在本文中我们利用全球数据集研究微生物C、N、P的H值在不同生物群落中的时空动态变化。研究结果表明,土地利用和人为管理措施导致P与C、N的代谢在时间和空间上解耦,并且我们利用结构方程模型(SEM)分析结果表明,土壤因子主导P的微生物动态平衡,而土壤元素含量则主导C和N的微生物动态平衡。利用机器学习算法得出的微生物P与微生物C和N的对比因子也证实了这一结果。总的来说,我们的研究强调了在营养循环中人为管理措施对微生物角色转变具有重要的影响。

关键词：碳氮磷微生物的内稳性管理措施

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IMPACTS OF EXTREME PRECIPITATION ON TREE PLANTATION CARBON CYCLE

IMPACTS OF EXTREME PRECIPITATION ON TREE PLANTATION CARBON C...

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2010年亚洲通量网会议(Asiaflux workshop2010)

作者： Mei Huang Jinjun Ji Feng Deng Hongsheng Liu Institute of Atmospheric Physics CASBeijing100029China Department of GeographyUniversity of TorontoTorontoOntarioM5S 3G3Canada Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographical Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing100101China Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographical Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing100101China

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