Lenssen J P M, Menting F B J, Van der Putten W H
Netherlands Institute of Ecology, PO Box 40, 6666 ZG Heteren, the Netherlands.
Present address: University of Nijmegen, Department of Ecology, Toernooiveld 1, 6525 ED Nijmegen, the Netherlands.
New Phytol. 2003 Feb;157(2):281-290. doi: 10.1046/j.1469-8137.2003.00666.x.
• Community ecologists often assume a hierarchy of environmental sieves to predict the impact of multiple stresses on species distribution. We tested whether this assumption corresponds to physiological responses using impact of water level and shade in wetland vegetation as a model. • Seedlings of four wetland species were grown under full light and simulated canopy shade, both in drained and waterlogged soils. When subject to both stresses simultaneously, waterlogging and shade independently affected growth of the two waterlogging tolerant species. For the intolerant species, however, waterlogging had the largest impact and the additional effect of shade was smaller than the effect of shade in drained soil. Soil flooding decreased specific leaf area but only if plants were in full light. Waterlogging did also not constrain a higher investment in stems of shaded plants. • These results demonstrate that light limitation in flooded habitats only plays a role if species can tolerate waterlogging and therefore correspond with the notion that water level determines the potential species pool and that standing crop consequently determines which species can actually persist.
• 群落生态学家通常假设存在一个环境筛选层次结构，以预测多种胁迫对物种分布的影响。我们以湿地植被中水位和遮荫的影响为模型，测试了这一假设是否与生理反应相符。
• 四种湿地物种的幼苗在排水良好和水涝的土壤中，分别在全光照和模拟树冠遮荫条件下生长。当同时受到两种胁迫时，水涝和遮荫分别影响两种耐水涝物种的生长。然而，对于不耐水涝的物种，水涝的影响最大，遮荫的额外影响小于排水土壤中遮荫的影响。土壤水淹会降低比叶面积，但前提是植物处于全光照下。水涝也不会限制遮荫植物对茎的更高投资。
• 这些结果表明，只有当物种能够耐受水涝时，水淹生境中的光照限制才会起作用，因此这与水位决定潜在物种库、现存生物量进而决定哪些物种能够实际存活的观点相符。
