Belote R Travis, Sanders Nathan J, Jones Robert H
Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia 24061, USA.
Ecology. 2009 Oct;90(10):2940-7. doi: 10.1890/08-1908.1.
Whether biological diversity within communities is limited by local interactions or regional species pools remains an important question in ecology. In this paper, we investigate how an experimentally applied tree-harvesting disturbance gradient influenced local-regional richness relationships. Plant species richness was measured at three spatial scales (2 ha = regional; 576 m2 and 1 m2 = local) on three occasions (one year pre-disturbance, one year post-disturbance, and 10 years post-disturbance) across five disturbance treatments (uncut control through clearcut) replicated throughout the southern Appalachian Mountains, USA. We investigated whether species richness in 576-m2 plots and 1-m2 subplots depended on species richness in 2-ha experimental units and whether this relationship changed through time before and after canopy disturbance. We found that, before disturbance, the relationship between local and regional richness was weak or nonexistent. One year after disturbance local richness was a positive function of regional richness, because local sites were colonized from the regional species pool. Ten years after disturbance, the positive relationship persisted, but the slope had decreased by half. These results suggest that disturbance can set the stage for strong influences of regional species pools on local community assembly in temperate forests. However, as time since disturbance increases, local controls on community assembly decouple the relationships between regional and local diversity.
群落内部的生物多样性是受局部相互作用限制还是受区域物种库限制，仍然是生态学中的一个重要问题。在本文中，我们研究了实验性应用的树木采伐干扰梯度如何影响局部 - 区域丰富度关系。在美国阿巴拉契亚山脉南部，对五种干扰处理（从未砍伐对照到皆伐）进行了重复实验，在三个空间尺度（2公顷 = 区域尺度；576平方米和1平方米 = 局部尺度）上，于三个时间点（干扰前一年、干扰后一年和干扰后十年）测量了植物物种丰富度。我们研究了576平方米样地和1平方米子样地中的物种丰富度是否依赖于2公顷实验单元中的物种丰富度，以及这种关系在冠层干扰前后是否随时间变化。我们发现，在干扰之前，局部和区域丰富度之间的关系较弱或不存在。干扰一年后，局部丰富度是区域丰富度的正函数，因为局部地点是由区域物种库进行定殖的。干扰十年后，这种正相关关系仍然存在，但斜率下降了一半。这些结果表明，干扰可以为区域物种库对温带森林局部群落组装产生强烈影响奠定基础。然而，随着干扰后时间的增加，对群落组装的局部控制会使区域和局部多样性之间的关系脱钩。
