We investigated the interrelations between environmental variables (proxies for water availability and soil physico-chemical properties) and tree community patterns (diversity, composition and structure) along pond-upland topographic gradients within depressional watersheds in the upper Uruguay River basin in southern Brazil. Sampling plots were allocated in four topographic habitats: (1) inside ponds (wetland sites) and (2) immediately outside them, and in areas with (3) 60 cm and (4) 120 cm of elevation in relation to their limits (upland sites). Environmental conditions and forest composition varied along pond-upland gradients, but the diversity and structure of tree communities did not. Species turnover was associated with changes in topography-driven environmental conditions, notably water availability. Depressional watersheds show regionally unique abiotic and biotic features but are virtually unprotected by Brazilian private land legislation.

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沿池塘-高地地形梯度的树木群落模式，乌拉圭河流域上游，巴西南部

我们调查了巴西南部乌拉圭河流域上游坳陷流域内沿池塘-高地地形梯度的环境变量（水资源可用性和土壤理化特性的代表）和树木群落模式（多样性、组成和结构）之间的相互关系。采样地被分配在四个地形栖息地中：(1) 池塘内（湿地地点）和 (2) 直接在它们外面，以及 (3) 60 厘米和 (4) 120 厘米相对于其界限（高地网站）。环境条件和森林组成沿池塘-高地梯度变化，但树木群落的多样性和结构没有变化。物种周转与地形驱动的环境条件的变化有关，尤其是可用水量。