van Rensburg B J, Chown S L, Gaston K J
Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.
Am Nat. 2002 May;159(5):566-77. doi: 10.1086/339464.
Energy and habitat heterogeneity are important correlates of spatial variation in species richness, though few investigations have sought to determine simultaneously their relative influences. Here we use the South African avifauna to examine the extent to which species richness is related to these variables and how these relationships depend on spatial grain. Taking spatial autocorrelation and area effects into account, we find that primary productivity, precipitation, absolute minimum temperature, and, at coarser resolutions, habitat heterogeneity account for most of the variation in species richness. Species richness and productivity are positively related, whereas the relationship between potential evapotranspiration (PET) and richness is unimodal. This is largely because of the constraining effects of low rainfall on productivity in high-PET areas. The increase in the importance of vegetation heterogeneity as an explanatory variable is caused largely by an increase in the range of vegetation heterogeneity included at coarse resolutions and is probably also a result of the positive effects of environmental heterogeneity on species richness. Our findings indicate that species richness is correlated with, and hence likely a function of, several variables, that spatial resolution and extent must be taken into account during investigations of these relationships, and that surrogate measures for productivity should be interpreted cautiously.
能量和栖息地异质性是物种丰富度空间变化的重要相关因素，不过很少有研究试图同时确定它们的相对影响。在此，我们利用南非鸟类来研究物种丰富度与这些变量的相关程度，以及这些关系如何依赖于空间粒度。考虑到空间自相关和面积效应，我们发现初级生产力、降水量、绝对最低温度，以及在较粗分辨率下的栖息地异质性，解释了物种丰富度的大部分变化。物种丰富度与生产力呈正相关，而潜在蒸散量（PET）与丰富度之间的关系呈单峰型。这主要是由于高PET地区低降雨量对生产力的限制作用。植被异质性作为一个解释变量的重要性增加，很大程度上是因为在粗分辨率下包含的植被异质性范围增加，也可能是环境异质性对物种丰富度产生积极影响的结果。我们的研究结果表明，物种丰富度与多个变量相关，因此可能是这些变量的一个函数，在研究这些关系时必须考虑空间分辨率和范围，并且对生产力的替代指标应谨慎解释。
