Invasions can trigger cascades in ecological communities by altering species interactions. Following the introduction of cats and foxes into Australia, one tenth of Australia's terrestrial mammal species became extinct, due to predation, while many continue to decline. The broader consequences for Australian ecosystems are poorly understood. Soil-dwelling invertebrates are likely to be affected by the loss of fossorial native mammals, which are predators and disturbance agents. Using reintroductions as a model for ecosystems prior to species loss, we tested the hypothesis that mammal reintroduction leads to reduced vegetation cover and altered termite assemblages, including declines in abundance and biomass and changed species composition. We hypothesised that the magnitude of mammal reintroduction effects would diminish with increasing aridity, which affects resource availability. We compared six paired sites inside and outside three reintroduction sanctuaries across an aridity gradient. We sampled termite assemblages using soil trenches and measured habitat availability. Reintroductions were associated with increased bare ground and reduced vegetation, compared with controls. Aridity also had an underlying influence on vegetation cover by limiting water availability. Termite abundance and biomass were lower where mammals were reintroduced and the magnitude of this effect decreased with increasing aridity. Termite abundance was highest under wood, and soil-nesting wood-feeders were most affected inside sanctuaries. Ecological cascades resulting from exotic predator invasions are thus likely to have increased termite biomass and altered termite assemblages, but impacts may be lower in less-productive habitats. Our findings have implications for reserve carrying capacities and understanding of assemblage reconstruction following ecological cascades.

中文翻译：

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挖掘哺乳动物重新引入会减少白蚁生物量并沿干旱梯度改变组合组成。

入侵可以通过改变物种相互作用来触发生态群落的级联。随着猫和狐狸被引入澳大利亚，澳大利亚十分之一的陆生哺乳动物物种由于捕食而灭绝，而许多物种还在继续减少。对澳大利亚生态系统的更广泛影响知之甚少。栖息在土壤中的无脊椎动物很可能会受到作为捕食者和干扰剂的原生哺乳动物的丧失的影响。使用重新引入作为物种丧失之前的生态系统模型，我们测试了哺乳动物重新引入导致植被覆盖减少和白蚁组合改变的假设，包括丰度和生物量的下降以及物种组成的改变。我们假设哺乳动物重新引入影响的程度会随着干旱的增加而减弱，这会影响资源的可用性。我们在干旱梯度上比较了三个重新引入保护区内外的六个配对地点。我们使用土壤沟对白蚁组合进行采样并测量栖息地的可用性。与对照相比，重新引入与增加的裸露地面和减少的植被有关。干旱还通过限制水的可用性对植被覆盖产生潜在影响。在重新引入哺乳动物的地方，白蚁丰度和生物量较低，并且这种影响的程度随着干旱的增加而降低。木材下的白蚁丰度最高，而在保护区内，土壤筑巢的木材饲养者受到的影响最大。因此，外来捕食者入侵导致的生态级联可能会增加白蚁生物量并改变白蚁组合，但在生产力较低的栖息地中影响可能较低。我们的研究结果对生态级联后的储备承载能力和对组合重建的理解具有重要意义。