Sala O E, Lauenroth W K
Natural Resource Ecology Laboratory, Colorado State University, 80523, Fort Collins, Colorado, USA.
Department of Range Science, Colorado State University, 80523, Fort Collins, Colorado, USA.
Oecologia. 1982 Jun;53(3):301-304. doi: 10.1007/BF00389004.
Small precipitation events account for a large proportion of the precipitation received in semiarid regions, and their potential ecological importance has previously been ignored. We investigated the effect of a small rainfall event (5 mm) upon Bouteloua gracilis, the dominant grass species of the central and southern Great Plains of North America. An effect of a small event on leaf water potential and leaf conductance to water vapor was observed in less than 12 h and lasted for up to two days.The remarkable short response time of Bouteloua gracilis to a rainfall stimulus enables this species to utilize small events and, therefore, may influence its persistence as a dominant species in the steppe region.We proposed response times to be one of the major species characteristics determining capacity for utilizing different portions of the water resource of the region. We suggest that small precipitation events are ecologically significant and a qualitatively distinct resource for ecosystems in semiarid regions.
小降水事件在半干旱地区的降水总量中占很大比例，其潜在的生态重要性此前一直被忽视。我们研究了一场小降雨事件（5毫米）对北美大平原中部和南部的优势草种细茎针茅的影响。在不到12小时内就观察到小降雨事件对叶片水势和叶片水汽导度的影响，且这种影响持续长达两天。细茎针茅对降雨刺激的显著短响应时间使其能够利用小降雨事件，因此，可能会影响其作为草原地区优势物种的持久性。我们提出响应时间是决定该地区水资源不同部分利用能力的主要物种特征之一。我们认为小降水事件具有生态重要性，是半干旱地区生态系统中一种性质不同的资源。
