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Incorporating Spatial Variations in Parameters for Improvements of an Evapotranspiration Model

JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 2020年第11期125卷 1-21页

作者： Wu, Genan Hu, Zhongmin Keenan, Trevor F. Li, Shenggong Zhao, Wei Cao, Ruo Chen Li, Yuzhe Guo, Qun Sun, Xiaomin Chinese Acad Sci Synth Res Ctr Chinese Ecosystem Res Network Key Lab Ecosyst Network Observat & Modeling Inst Geog Sci & Nat Resources Res Beijing Peoples R China Univ Chinese Acad Sci Coll Resources & Environm Beijing Peoples R China Lawrence Berkeley Natl Lab Berkeley CA USA Univ Calif Berkeley Dept Environm Sci Policy & Management Berkeley CA 94720 USA South China Normal Univ Sch Geog Guangzhou Peoples R China

ecosystem models are important tools for exploring the temporal and spatial patterns of ecosystem processes and their responses to climate change. However, the implications of uncertainty in model parameters are often overlooked, especially in regional ecosystem model simulations. Here, we use eddy-covariance observations to estimate parameters in an ecosystem model, which was developed from Shuttleworth-Wallace model, and examine the effect on estimates of evapotranspiration (ET). Using a simple ecosystem model as an example, we use Monte Carlo techniques to optimize key model parameters using eddy covariance (EC) data from 163 FLUXNET sites. The optimization process revealed a strong spatial correlation between key parameters and environmental variables, particularly leaf area index (LAI) and soil characteristics (e.g., clay fraction). The optimization of parameters related to canopy conductance and soil surface resistance greatly improved model performance, particularly when incorporating the identified spatial variation of parameters. The improved model agreed well with the measurements with an increase in the coefficient of determination (R-2) from 73% to 80% in the 8-day averaged ET estimation and a decrease in the root mean square error (RMSE) from 130.2 to 104.3 mm year(-1) compared with the original model. The results suggest the potential of eddy-covariance flux observations to identify predictable spatial variations of key parameters, which can be used to better constrain ecosystem models. And in this case, a universal and efficient method for reducing the uncertainties in key parameters across different PFTs and ecosystem applications is suggested.

关键词： evapotranspiration models ecosystem models parameter optimization FLUXNET

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Dominant roles but distinct effects of groundwater depth on regulating leaf and fine-root N,P and N:P ratios of plant communities

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Journal of Plant Ecology 2021年第6期14卷 1158-1174页

作者： Yin Wang Jianming Wang Xiaolin Wang Yicheng He Guanjun Li Jingwen Li School of Ecology and Nature Conservation Beijing Forestry UniversityBeijing 100083China Ejina Institute of Populus euphratica Beijing Forestry UniversityInner Mongolia 735400China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Aims As the determinant of water availability in drylands,groundwater plays a fundamental role in regulating vegetation distribution and ecosystem *** considerable progress has been made over the past years in the relationship between environment stress and plant community-level traits,the potential influence of water stress induced by groundwater changes on plant community-level stoichiometry remains largely ***,we examined whether belowground and aboveground community-level stoichiometry responded differently to groundwater *** We measured nitrogen(N)and phosphorus(P)concentrations in plant leaves and fine-roots of 110 plots under a broad range of groundwater depths in a typical arid inland river *** examined the spatial patterns and drivers of community-level N:P stoichiometry in leaves and *** Findings Community-level leaf and fine-root N,P and N:P ratios were mainly determined by groundwater,vegetation types and species composition,among which groundwater played a dominant *** indirectly regulated community-level N:P stoichiometry through affecting vegetation types and species *** types and species composition had significant direct influences on communitylevel N:P ***,groundwater depth had opposite influences on community-level leaf and fine-root N:P *** depth regulated vegetation types and further decreased leaf N,P but increased leaf N:P ratios and fine-root *** depth had a positive indirect impact on fine-root P but a negative indirect impact on fine-root N:P ratios primarily by affecting species *** findings indicate that groundwater rather than climate conditions effectively regulates community-level N:P stoichiometry,and below-and aboveground N:P stoichiometry has opposite responses to groundwater.

关键词： ecological stoichiometry groundwater depth N:P ratio fine-root leaf arid inland river basin

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The Bowen Ratio of an Alpine Grassland in Three-River Headwaters, Qinghai-Tibet Plateau, from 2001 to 2018

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Journal of Resources and Ecology 2021年第3期12卷 305-318页

作者： ZHAO Xuanlan WANG Junbang YE Hui MUHAMMAD Amir WANG Shaoqiang National Ecosystem Science Data Center Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China College of Tourism and Geography JiuJiang UniversityJiujiangJiangxi 332005China

The Bowen ratio(β) is used to quantify heat transfer from the land surface into the air, which is becoming a hot topic in research on the biogeophysical effects of land use and cover changes. The Three-River Headwaters(TRH), as a sensitive and fragile region, was selected as the study area. The β for 2001–2018 was estimated from the evapotranspiration product(ETMOD16) of MODIS and the net radiation of the land surface through the albedo from GLASS. The ETMOD16 data were evaluated against the observation data(ETOBS) at two alpine grassland flux towers obtained from ChinaFLUX. The interannual trend of the β was analyzed by multiple linear regression(MLR) and structure model(SEM) with the multiple factors of precipitation, temperature, humidity, albedo, and normalized difference vegetation index(NDVI, MOD09 Q1). The results show that the ETMOD16 values were significantly correlated with ETOBS, with a correlation coefficient above 0.70(P < 0.01) for the two sites. In 2001–2018, the regional mean β was 2.52 ± 0.77 for the whole grassland, and its spatial distribution gradually increased from the eastern to western region. The interannual β showed a downward trend with a slope of-0.025 and a multiple regression coefficient(R^(2)) of 0.21(P = 0.056). Most of the variability(51%) in the interannual β can be explained by the linear regression of the above multiple factors, and the temperature plays a dominant role for the whole region. The SEM analysis further shows that an increasing NDVI results in a decreasing albedo with a path coefficient of-0.57, because the albedo was negatively correlated with NDVI(R^(2) = 0.52, P < 0.01), which indicates a negative and indirect effect on β from vegetation restoration. An obvious warming climate was found to prompt more evapotranspiration, and restoring vegetation makes the land surface receive more radiation, which both resulted in a decreasing trend in the annual β. This study revealed the biogeophysical mechanisms of vegetation re

关键词： alpine grassland Bowen ratio Three-River Headwaters MODIS evapotranspiration

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Land-use impact on soil carbon and nitrogen sequestration in typical steppe ecosystems, Inner Mongolia

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Journal of Geographical Sciences 2012年第5期22卷 859-873页

作者： HE Nianpeng ZHANG Yunhai DAI Jingzhong HAN Xingguo BAOYIN Taogetao YU Guirui Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic: Sciences and Natural Resources Research CAS Beijing 100101 China State Key Laboratory of Vegetation and Environmental Change Institute of Botany CASBeijing 100093 China Inner Mongolia Agricultural University Hohhot 010018 China Institute of Natural Resources Inner Mongolia University Huhhot 010021 China

To explore the optimal land-use for soil carbon （C） sequestration in Inner Mongolian grasslands, we investigated C and nitrogen （N） storage in soil and soil fractions in 8 floristi- cally and topographically similar sites which subjected to different lancl-use types （free-grazing, grazing exclusion, mowing, winter grazing, and reclamation）. Compared with free-grazing grasslands, C and N storage in the 0-50 cm layer increased by 18.3% （15.5 Mg C ha-1） and 9.3% （0.8 Mg N ha-1） after 10-yr of grazing exclusion, respectively, and 21.9% （18.5 Mg C ha-1） and 11.5% （0.9 Mg N ha-1） after 30-yr grazing exclusion, respectively. Similarly, soil C and N storage increased by 15.3% （12.9 Mg C ha-1） and 10.2% （0.8 Mg N ha-1） after 10-yr mowing, respectively, and 19.2% （16.2 Mg C ha-1） and 7.1% （0.6 Mg N ha-1） after 26-yr mowing, respectively. In contrast, soil C and N storage declined by 10.6% （9.0 Mg C ha-1） and 11.4% （0.9 Mg N ha-1） after 49-yr reclamation, respectively. Moreover, increases in C and N storage mainly occurred in sand and silt fractions in the 0-10 cm soil layer with grazing exclusion and mowing. Our findings provided evidence that Inner Mongolian grassslands have the capacity to sequester C and N in soil with improved management practices, which were in the order： grazing exclusion 〉 mowing 〉 winter grazing 〉 reclamation.

关键词： carbon grazing land-use nitrogen reclamation soil fractions

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A Meta-analysis of the Effects of Organic and Inorganic Fertilizers on the Soil Microbial Community

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Journal of Resources and Ecology 2020年第3期11卷 298-303页

作者： WANG Jiangwei ZHANG Guangyu YU Chengqun Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

In order to investigate the general tendency of soil microbial community responses to fertilizers, a meta-analysis approach was used to synthesise observations on the effects of inorganic and organic fertilizer addition(N: nitrogen;P: phosphorus;NP: nitrogen and phosphorus;PK: phosphorus and potassium;NPK: nitrogen, phosphorus and potassium;OF: organic fertilizer;OF+NPK: organic fertilizer plus NPK) on soil microbial communities. Among the various studies, PK, NPK, OF and OF+NPK addition increased total phospholipid fatty acid(PLFA) by 52.0%, 19.5%, 334.3% and 58.3%, respectively;while NP, OF and OF+NPK addition increased fungi by 5.6%, 21.0% and 8.2%, respectively. NP, NPK and OF addition increased bacteria by 6.4%, 9.8% and 13.3%, respectively;while NP and NPK addition increased actinomycetes by 7.0% and 14.8%, respectively. Addition of ammonium nitrate rather than urea decreased gram-negative bacteria(G–). N addition increased total PLFA、bacteria and actinomycetes in croplands, but decreased fungi and bacteria in forests, and the F/B ratio in grasslands. NPK addition increased total PLFA in forests but not in croplands. The N addition rate was positively correlated with the effects of N addition on gram-positive bacteria(G+) and G–. Therefore, different fertilizers appear to have different effects on the soil microbial community. Organic fertilizers can have a greater positive effect on the soil microbial community than inorganic fertilizers. The effects of fertilizers on the soil microbial community varied with ecosystem types. The effect of N addition on the soil microbial community was related to both the forms of nitrogen that were added and the nitrogen addition rate.

关键词： ecosystem types nitrogen addition rate response ratio soil PLFA

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Soil Total Organic Carbon, δ 13 C Values and Their Responses to the Soil Core Transferring Experiment from High- to Low-elevation Forest along Natural Altitudinal Transect of Old Temperate Volcanic Forest Soils

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Procedia Environmental Sciences 2011年 5卷 139-144页

作者： Xinyu Zhang Xianjing Meng Jinjuan Fan Lupeng Gao Xiaomin Sun Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 Shenyang Agricultural University Shenyang 110161 China National Science and Technology Infrastructure Center Beijing 100862 China

In this study, the responses of soil organic carbon and δ 13 C values to soil warming were conducted by relocating intact soil cores from high- to lowelevation forests for one year along a natural altitudinal transect in the northern slope of Changbai Mountain. As expected, the soil-core relocation caused significant increase in soil temperature but made no significant effect on soil moisture. The results showed that after one year incubation, soil relocation significantly decreased TOC contents, and δ 13 C decreased. Pearson correlation analysis demonstrates that TOC content was negatively related to soil temperature but positively related to soil moisture. After one-year simulated warming experiment, δ 13 C values in bulk soils reduced by 0.45 ‰. Furthermore, the decreases in the size fractions <63 μm were larger than those in the size fractions 63-1000 μm.

关键词： Soil-core relocation experiment Old temperate volcanic forest soils Soil organic carbon species δ 13 C Soil particle-size fractions

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Vegetation controls over grassland ecosystem water use efficiency within and among four grassland ecosystems over 3-year growing season

Vegetation controls over grassland ecosystem water use effic...

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第三届世界生态高峰会(Eco Summit 2007)

作者： Hu Z.M. Yu G.R. Fu Y.L. Ren C.Y. Li Z.Q. Li Y.N. Shi P.L. Wang Y.F. Key Laboratory of Ecosystem Network Observation and Modeling The Center for Synthesis ResearchChinese Ecosystem Research NetworkInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Graduate University of Chinese Academy of Sciences Beijing 100039China Key Laboratory of Ecosystem Network Observation and ModelingThe Center for Synthesis ResearchChinese Ecosystem Research NetworkInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Northwest institute of Plateau BiologyChinese Academy of SciencesXining810001China Graduate University of Chinese Academy of Sciences.Beijing 100039China

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ASSESSMENT OF THE DAMAGE CAUSED BY THE 2008 ICE STORM ON SUBTROPICAL FOREST IN JIANGXI,CHINA

ASSESSMENT OF THE DAMAGE CAUSED BY THE 2008 ICE STORM ON SUB...

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2010年亚洲通量网会议(Asiaflux workshop2010)

作者： Leilei Shi Huimin Wang Qianyanzhou Ecological Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing lO0101China Graduate University of Chinese Academy of Sciences Beijing 100049China Qianyanzhou Ecological StationKey Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing lO0101China

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Interdependent Dynamics of LAI-ET across Roofing Landscapes:the Mongolian and Tibetan Plateaus

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Journal of Resources and Ecology 2019年第3期10卷 296-306页

作者： TIAN Li Qianyanzhou Ecological 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 Zhongke-Ji'an Institute of Eco-Environmental Sciences Ji'an Jiangxi 343000 China

The Mongolian and Tibetan Plateaus have experieneed warming higher than the global average in recent decades, resulting in many significant changes to ecosystem structures and functions. Among items that show change are the leaf area in dex (LAI) and evapotranspirati on (ET), both of which play a fun dame ntal role in shapi ng many causes and conseque nces of la nd surface processes and climate. This study examines the spatiotemporal changes of the LAI and ET and their relationships on these two roofing Iandscapes. Based on the MODIS products from 2000 through 2014, we found that there existed a gen era I positive relationship betwee n LAI and ET on the Mongolia Plateau (MP), while synergy did not exist on the Tibetan Plateau (TP). Overall, 49.38%(50.62%) of land areas on the TP experieneed significant increases (decreases) in LAI, while on the MP the percentages of increase and decrease were 94.92%(5.09%). For ET, the increased land area was 21.70%(124100 km^2) on the TP and 88.01%(341600 km^2) on the MP. More importantly, the relationships varied substantially across space and over time, with mismatches found in some parts of the Iandscapes. Additional observational investigations and/or experime ntal research are n eeded to explore the relati on ships, including the in flue nces of vegetation characteristics and disturbances.

关键词： ET LAI alpine Eurasian continent altitude and latitude land surface process

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

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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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