Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA.
Conserv Biol. 2011 Jun;25(3):618-22. doi: 10.1111/j.1523-1739.2010.01634.x. Epub 2011 Feb 1.
The degree to which changes in community composition mediate the probability of colonization and spread of non-native species is not well understood, especially in animal communities. High species richness may hinder the establishment of non-native species. Distinguishing between this scenario and cases in which non-native species become established in intact (lacking extensive anthropogenic soil disturbance) communities and subsequently diminish the abundance and richness of native species is challenging on the basis of observation alone. The red imported fire ant (Solenopsis invicta), an invasive species that occurs throughout much of the southeastern United States, is such an example. Rather than competitively displacing native species, fire ants may become established only in disturbed areas in which native species richness and abundance are already reduced. We used insecticide to reduce the abundance of native ants and fire ants in four experimental plots. We then observed the reassembly and reestablishment of the ants in these plots for 1 year after treatment. The abundance of fire ants in treated plots did not differ from abundance in control plots 1 year after treatment. Likewise, the abundance of native ants increased to levels comparable to those in control plots after 1 year. Our findings suggest that factors other than large reductions in ant abundance and species density (number of species per unit area) may affect the establishment of fire ants and that the response of native ants and fire ants to disturbance can be comparable.
群落组成变化在多大程度上调节了非本地物种的定居和扩散的可能性尚不清楚，特别是在动物群落中。物种丰富度高可能会阻碍非本地物种的建立。仅基于观察来区分这种情况和非本地物种在完整（缺乏广泛的人为土壤干扰）群落中建立并随后减少本地物种丰富度和丰度的情况是具有挑战性的。红火蚁（Solenopsis invicta）就是这样一个例子。红火蚁是一种入侵物种，分布于美国东南部的大部分地区，它并没有与本地物种竞争，而是仅在本地物种丰富度和丰度已经降低的受干扰地区建立。我们使用杀虫剂减少了四个实验样地中本地蚂蚁和红火蚁的数量。然后，我们在处理后 1 年内观察这些样地中蚂蚁的重新组合和重新建立。处理过的样地中红火蚁的数量与处理后 1 年内对照样地的数量没有差异。同样，经过 1 年，本地蚂蚁的数量增加到与对照样地相当的水平。我们的研究结果表明，可能有除了蚂蚁数量和物种密度（单位面积的物种数量）大幅减少以外的因素影响红火蚁的建立，并且本地蚂蚁和红火蚁对干扰的反应可能是相似的。
