globalchange  > 影响、适应和脆弱性
DOI: 10.1111/gcb.13389
论文题名:
Global variations in ecosystem-scale isohydricity
作者: Konings A.G.; Gentine P.
刊名: Global Change Biology
ISSN: 13541013
出版年: 2017
卷: 23, 期:2
起始页码: 891
结束页码: 905
语种: 英语
英文关键词: diurnal cycle ; drought stress ; isohydricity ; leaf water potential ; stomatal closure ; vegetation height ; vegetation optical depth ; water use efficiency
英文摘要: Droughts are expected to become more frequent and more intense under climate change. Plant mortality rates and biomass declines in response to drought depend on stomatal and xylem flow regulation. Plants operate on a continuum of xylem and stomatal regulation strategies from very isohydric (strict regulation) to very anisohydric. Coexisting species may display a variety of isohydricity behaviors. As such, it can be difficult to predict how to model the degree of isohydricity at the ecosystem scale by aggregating studies of individual species. This is nonetheless essential for accurate prediction of ecosystem drought resilience. In this study, we define a metric for the degree of isohydricity at the ecosystem scale in analogy with a recent metric introduced at the species level. Using data from the AMSR-E satellite, this metric is evaluated globally based on diurnal variations in microwave vegetation optical depth (VOD), which is directly related to leaf water potential. Areas with low annual mean radiation are found to be more anisohydric. Except for evergreen broadleaf forests in the tropics, which are very isohydric, and croplands, which are very anisohydric, land cover type is a poor predictor of ecosystem isohydricity, in accordance with previous species-scale observations. It is therefore also a poor basis for parameterizing water stress response in land-surface models. For taller ecosystems, canopy height is correlated with higher isohydricity (so that rainforests are mostly isohydric). Highly anisohydric areas show either high or low underlying water use efficiency. In seasonally dry locations, most ecosystems display a more isohydric response (increased stomatal regulation) during the dry season. In several seasonally dry tropical forests, this trend is reversed, as dry-season leaf-out appears to coincide with a shift toward more anisohydric strategies. The metric developed in this study allows for detailed investigations of spatial and temporal variations in plant water behavior. © 2016 John Wiley & Sons Ltd
资助项目: The isohydricity data are available from the authors on request. We are grateful to three anonymous reviewers for helpful comments that significantly improved the manuscript. We thank Jordi Martínez-Vilalta for providing the species-specific database, including geographic information and Kaighin McColl for providing the processed Gini–Simpson index data used in Fig. S6. Alexandra Konings acknowledges funding from the Stanford University Department of Earth System Science, while Pierre Gentine acknowledges funding from DOE GoAmazon grant DE-SC0011094, DOE early career DE-SC0014203, NSF CAREER EAR-1552304, and NASA ROSES grant NNX15AB30G.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/61084
Appears in Collections:影响、适应和脆弱性

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作者单位: Department of Earth and Environmental Engineering, Columbia University, New York, NY, United States; Department of Earth System Science, Stanford University, Stanford, CA, United States; Earth Institute, Columbia University, New York, NY, United States

Recommended Citation:
Konings A.G.,Gentine P.. Global variations in ecosystem-scale isohydricity[J]. Global Change Biology,2017-01-01,23(2)
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