Drever Mark C, Goheen Jacob R, Martin Kathy
Centre for Applied Conservation Research, Department of Forest Sciences, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada.
Ecology. 2009 Apr;90(4):1095-105. doi: 10.1890/08-0575.1.
Species-energy theory provides a framework through which to link two features commonly noted in local communities: episodic production of resources (i.e., resource pulses) and the regulation of local species richness through time. We examined the pathways through which a resource pulse, a large-scale outbreak of mountain pine beetles, was borne out in six foraging guilds comprising a forest bird community in British Columbia, Canada, 1997-2007. We investigated statistical relationships between richness and abundance in each guild to evaluate the prediction that the outbreak should be manifested in species most reliant upon bark beetles (i.e., the bark insectivore guild). We then employed randomization methods to evaluate whether the beetle outbreak obscured evidence for local regulation for the six foraging guilds. Density and richness of bark insectivores increased over the course of the outbreak. More species of bark insectivores were detected for a given number of individuals following the outbreak, consistent with an increase in the number and types of resources. Richness of bark insectivores showed no evidence of regulation. In contrast, densities of most other foraging guilds were not strongly correlated with the habitat changes resulting from the beetle outbreak and displayed only weak evidence of regulation of richness. We suggest that such weak regulation of richness may be a general feature of forest bird communities. Coupled with long-term data, resource pulses provide exceptional opportunities through which to test predictions of species-energy theory.
物种-能量理论提供了一个框架，通过这个框架可以将当地群落中两个常见特征联系起来：资源的间歇性产生（即资源脉冲）和当地物种丰富度随时间的调节。我们研究了1997年至2007年期间，在加拿大不列颠哥伦比亚省一个森林鸟类群落的六个觅食类群中，资源脉冲（即大规模的山松甲虫爆发）是如何体现的。我们调查了每个类群中丰富度和丰度之间的统计关系，以评估这样一个预测：即这种爆发应该在最依赖树皮甲虫的物种（即树皮食虫动物类群）中表现出来。然后，我们采用随机化方法来评估甲虫爆发是否掩盖了六个觅食类群的局部调节证据。在爆发过程中，树皮食虫动物的密度和丰富度增加了。在爆发后，对于给定数量的个体，检测到的树皮食虫动物种类更多，这与资源数量和类型的增加一致。树皮食虫动物的丰富度没有显示出调节的证据。相比之下，大多数其他觅食类群的密度与甲虫爆发导致的栖息地变化没有强烈关联，并且仅显示出对丰富度调节的微弱证据。我们认为，这种对丰富度的微弱调节可能是森林鸟类群落的一个普遍特征。结合长期数据，资源脉冲提供了绝佳的机会来检验物种-能量理论的预测。
