Magliano Patricio N, Breshears David D, Fernández Roberto J, Jobbágy Esteban G
Ecol Appl. 2015 Dec;25(8):2094-100. doi: 10.1890/15-0550.1.
Effectively managing net primary productivity in drylands for grazing and other uses depends on understanding how limited rainfall input is redistributed by runoff and runon among vegetation patches, particularly for patches that contrast between lesser and greater amounts of vegetation cover. Due in part to data limitations, ecohydrologists generally have focused on rainfall event size to characterize water redistribution processes. Here we use soil moisture data from a semiarid woodland to highlight how, when event size is controlled and runoff and interception are negligible at the stand scale, rainfall intensity drives the relationship between water redistribution and canopy and soil patch attributes. Horizontal water redistribution variability increased with rainfall intensity and differed between patches with contrasting vegetation cover. Sparsely vegetated patches gained relatively more water during lower intensity events, whereas densely vegetated ones gained relatively more water during higher intensity events. Consequently, range managers need to account for the distribution of rainfall event intensity, as well as event size, to assess the consequences of climate variability and change on net primary productivity. More generally, our results suggest that rainfall intensity needs to be considered in addition to event size to understand vegetation patch dynamics in drylands.
有效管理旱地用于放牧及其他用途的净初级生产力，取决于了解有限的降雨输入如何通过径流和漫流在植被斑块间重新分配，尤其是对于植被覆盖量有差异的斑块。部分由于数据限制，生态水文学家通常专注于降雨事件规模来描述水分再分配过程。在此，我们利用半干旱林地的土壤湿度数据，以突出当在林分尺度上控制事件规模且径流和截留可忽略不计时，降雨强度如何驱动水分再分配与冠层和土壤斑块属性之间的关系。水平水分再分配变异性随降雨强度增加，且在植被覆盖不同的斑块间存在差异。植被稀疏的斑块在较低强度降雨事件中获得相对更多的水分，而植被茂密的斑块在较高强度降雨事件中获得相对更多的水分。因此，牧场管理者需要考虑降雨事件强度以及事件规模的分布，以评估气候变异性和变化对净初级生产力的影响。更普遍地说，我们的结果表明，除了事件规模外，还需要考虑降雨强度，以了解旱地植被斑块动态。
