globalchange  > 气候变化事实与影响
DOI: 10.1002/2016GB005392
Scopus记录号: 2-s2.0-84977569285
论文题名:
Convergent approaches to determine an ecosystem's transpiration fraction
作者: Berkelhammer M; , Noone D; C; , Wong T; E; , Burns S; P; , Knowles J; F; , Kaushik A; , Blanken P; D; , Williams M; W
刊名: Global Biogeochemical Cycles
ISSN: 8866236
出版年: 2016
卷: 30, 期:6
起始页码: 933
结束页码: 951
语种: 英语
英文关键词: ecohydrology ; eddy covariance ; evergreen ; stable isotopes ; transpiration ; trees
Scopus关键词: covariance analysis ; ecohydrology ; eddy covariance ; evapotranspiration ; heterogeneity ; humidity ; leaf area index ; primary production ; seasonal variation ; stable isotope ; stomatal conductance ; time series analysis ; vapor pressure ; Colorado ; Front Range ; Niwot Ridge ; Rocky Mountains
英文摘要: The transpiration (T) fraction of total terrestrial evapotranspiration (ET), T/ET, can vary across ecosystems between 20–95% with a global average of ∼60%. The wide range may either reflect true heterogeneity between ecosystems and/or uncertainties in the techniques used to derive this property. Here we compared independent approaches to estimate T/ET at two needleleaf forested sites with a factor of 3 difference in leaf area index (LAI). The first method utilized water vapor isotope profiles and the second derived transpiration through its functional relationship with gross primary production. We found strong agreement between T/ET values from these two independent approaches although we noted a discrepancy at low vapor pressure deficits (VPD). We hypothesize that this divergence arises because stomatal conductance is independent of humidity at low VPD. Overall, we document significant synoptic-scale T/ET variability but minimal growing season-scale variability. This result indicates a high sensitivity of T/ET to passing weather but convergence toward a stable mean state, which is set by LAI. While changes in T/ET could emerge from a myriad of processes, including aboveground (LAI) or belowground (rooting depth) changes, there was only minimal interannual variability and no secular trend in our analysis of T/ET from the 15 year eddy covariance time series at Niwot Ridge. If the lack of trend observed here is apparent elsewhere, it suggests that the processes controlling the T and E fluxes are coupled in a way to maintain a stable ratio. ©2016. American Geophysical Union. All Rights Reserved.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/77843
Appears in Collections:气候变化事实与影响

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作者单位: Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL, United States; College of Earth, Ocean and Atmospheric Sciences, Oregon State University, Corvallis, OR, United States; Department of Applied Mathematics, University of Colorado Boulder, Boulder, CO, United States; Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, United States; Department of Geography, University of Colorado Boulder, Boulder, CO, United States; National Center for Atmospheric Research, Boulder, CO, United States; Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO, United States; Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, CO, United States

Recommended Citation:
Berkelhammer M,, Noone D,C,et al. Convergent approaches to determine an ecosystem's transpiration fraction[J]. Global Biogeochemical Cycles,2016-01-01,30(6)
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