Do dense layers of invasive plants elevate the foraging intensity of small mammals in temperate deciduous forests? A case study from Pennsylvania, USA
Do dense layers of invasive plants elevate the foraging intensity of small mammals in temperate deciduous forests? A case study from Pennsylvania, USA
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密集的入侵植物层是否会提高温带落叶林中小型哺乳动物的觅食强度？
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
W. Carson
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文献类型：
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作者：
R. Utz;A. Slater;Hannah R. Rosche;W. Carson
入侵植物的单种林分可以极大地重建动物的栖息地，从而提高种群密度或促进在改变的栖息地中受益的消费物种的觅食。例如，密集的入侵植物林可以保护小型哺乳动物免受捕食者的侵害，这反过来又可能增加小型哺乳动物赖以为生的种子的觅食压力。我们使用了前后对照影响实验设计来测试小型哺乳动物捕获率是否更高，放弃密度（GUDs）是否更低，在小檗（Berberis thunbergii）密集的林下，小檗是一种入侵灌木，在北美东部的范围迅速扩大。我们的实验设计包括3个样地类型：1)黄僵菌严重入侵的样地，2)缺乏入侵灌木覆盖的对照样地，3)入侵样地，我们在研究过程中根除了黄僵菌。虽然我们的小哺乳动物总体捕获率较低，但与对照区相比，大鼠贝氏杆菌入侵生境的小哺乳动物捕获率高出65%，而灭杀使小哺乳动物捕获率降低了77%。与对照区相比，桐贝氏杆菌的GUDs高26%，而根除使GUDs降低65%。我们的研究结果表明，小型哺乳动物认为密集的森林是相对安全的觅食栖息地。先前在研究地点的调查显示，黄柏属植物的树苗密度明显下降，因此入侵植物可能会促进小型哺乳动物的密集觅食，减少种子或幼苗被觅食的物种的补充。
Monospecific stands of invasive plants can dramatically restructure habitat for fauna, thereby elevating population densities or promoting foraging of consumer species who benefit in the altered habitat. For example, dense stands of invasive plants may protect small mammals from predators, which in turn could increase foraging pressure on seeds that small mammals feed upon. We used a before-after, control-impact experimental design to test whether small mammal capture rates were higher and giving-up densities (GUDs) lower beneath dense stands of Berberis thunbergii, an invasive shrub with a rapidly expanding range throughout eastern North America. Our experimental design included three plot categories: 1) plots heavily invaded by B. thunbergii, 2) control plots lacking invasive shrub cover, and 3) invaded plots where we eradicated B. thunbergii midway through the study. Although our overall small mammal capture rate was low, small mammal captures were 65% higher in B. thunbergii invaded habitat relative to control plots and eradication lowered capture rates by 77%. GUDs were also 26% higher within B. thunbergii relative to control plots and eradication decreased GUDs by 65%. Our findings suggest that small mammals perceive dense stands of B. thunbergii as relatively safe foraging habitat. Prior surveys within our study locations revealed dramatically depressed tree seedling densities under B. thunbergii, thus invasive plants may promote intensive foraging by small mammals and reduce recruitment for species with foraged seeds or seedlings.