Quantifying regional scale ecosystem response to changes in precipitation: Not all rain is created equal
Quantifying regional scale ecosystem response to changes in precipitation: Not all rain is created equal
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DOI：
10.1029/2010wr009762
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发表时间：
2011-07-20
影响因子：
5.4
通讯作者：
Schlegel, Melissa
中科院分区：
文献类型：
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作者：
Brooks, Paul D.;Troch, Peter A.;Schlegel, Melissa
初级生产力和植被覆盖度与降水如何划分为地表径流、储存和蒸散（ET）密切相关。因此，在区域尺度上量化降水和植被变化之间的反馈是预测气候和土地覆盖变化时碳平衡和水资源的关键一步。我们使用了一个集水区为基础的方法来量化降水分区，并比较这些水文通量遥感植被绿度（NDVI）在86 U。S.从2000年到2008年。降水可能提供给植被（集水区湿润; W）的分数范围从0.64至0.99，表明高达36%的降水是不可用的植被。ET的比例：W（霍顿指数（HI）），范围从0.07到1.0，表现出更大的变化，集水区湿润的分数作为ET。负斜率之间的年度霍顿指数和最大的年度NDVI值表示在干旱年份在大多数集水区生态系统的水限制。毫不奇怪，草原比森林对干旱更敏感。然而，在9个最湿润（HI < 0.66）的集水生态系统中，NDVI值随着HI的增加而增加，这表明在干燥条件下植被生产力更高。我们的研究结果表明，流域尺度的水文分区提供了信息的降水和植被使用的分数。它们的比率（HI）确定水和能量限制之间的变化，以及基于流域生态系统内的植被类型对干旱的不同敏感性。因此，流域尺度分区提供了有用的信息，缩放点观测和量化区域生态水文响应气候或植被变化。
Primary productivity and vegetation cover are strongly related to how precipitation is partitioned into surface discharge, storage, and evapotranspiration (ET). Thus, quantifying feedbacks between changes in precipitation and vegetation at regional scales is a critical step toward predicting both carbon balance and water resources as climate and land cover change. We used a catchment-based approach to quantify partitioning of precipitation and compared these hydrologic fluxes to remotely sensed vegetation greenness (NDVI) in 86 U. S. catchments between 2000 and 2008. The fraction of precipitation potentially available to vegetation (catchment wetting; W) ranged from 0.64 to 0.99 demonstrating that up to 36% of precipitation was not available to vegetation. The ratio of ET: W (Horton Index (HI)), ranged from 0.07 to 1.0 demonstrating even greater variability in the fraction of catchment wetting used as ET. Negative slopes between annual Horton Index and maximum annual NDVI values indicated water limitation during dry years in most catchment ecosystems. Not surprisingly, grasslands were more sensitive to drying than forests. However, in nine of the wettest (HI < 0.66) catchment ecosystems, NDVI values increased as HI increased suggesting greater vegetation productivity under drier conditions. Our results demonstrate that catchment-scale hydrologic partitioning provides information on both the fractions of precipitation available to and used by vegetation. Their ratio (HI) identifies shifts between water and energy limitation, and differential sensitivity to drying based on vegetation type within catchment ecosystems. Consequently, catchment-scale partitioning provides useful information for scaling point observations and quantifying regional ecohydrological response to climate or vegetation change.