Institute for Botany, University of Cologne, Köln, Germany.
Oecologia. 2012 Jan;168(1):175-86. doi: 10.1007/s00442-011-2061-6. Epub 2011 Jul 7.
Increased biological diversity due to invasion by non-indigenous species (NIS) is a global phenomenon with potential effects on trophic interactions and ecosystem processes in the invaded habitat. We assessed the effects of resource availability and invasion of three non-indigenous invertebrate grazers (two crustaceans and a snail) on secondary production, relative dominance of NIS grazers and resource depletion in experimental freshwater mesocosms. The relative dominance of NIS grazers increased with increasing initial resource availability, although the effect was largest for one of the three species. The effect was due to the fact that all the included non-indigenous grazers were able to expand their populations quickly in response to resource addition. For the most dominating species, the increased grazer diversity due to invasion in turn resulted in higher production of grazer biomass and a more efficient depletion of the periphyton resource. The effect was largest at high initial resource availability, where NIS dominance was most pronounced. Our results show that an invasion-induced increase in species diversity can increase resource depletion and consequently production, but that the effect depends on identity of the introduced species. The results also suggest that properties of the recipient system, such as resource availability, can modulate ecosystem effects of NIS by affecting invader success and dominance.
由于非本地物种（NIS）的入侵而导致的生物多样性增加是一种全球现象，可能对入侵栖息地的营养相互作用和生态系统过程产生影响。我们评估了资源可利用性和三种非本地无脊椎草食动物（两种甲壳类动物和一种蜗牛）的入侵对实验性淡水中型生境中次生生产力、NIS 草食动物的相对优势和资源枯竭的影响。NIS 草食动物的相对优势随着初始资源可利用性的增加而增加，尽管这种影响对三种物种中的一种最大。这种影响是由于所有包括的非本地草食动物都能够迅速响应资源添加而扩大其种群。对于最占优势的物种，入侵引起的草食动物多样性的增加反过来又导致了更高的草食动物生物量的产生和更有效地消耗附生生物资源。这种影响在初始资源可用性较高的情况下最大，此时 NIS 的优势最为明显。我们的研究结果表明，入侵引起的物种多样性增加可以增加资源枯竭，从而增加生产力，但这种效应取决于引入物种的身份。结果还表明，接受系统的特性，如资源可利用性，可能通过影响入侵物种的成功和优势来调节 NIS 的生态系统效应。
