Graduate Program in Behavior, Ecology, Evolution, and Systematics, University of Maryland, College Park, Maryland 20742, USA.
Ecology. 2011 Mar;92(3):765-76. doi: 10.1890/10-0157.1.
Spatial resource subsidies can greatly affect the composition and dynamics of recipient communities. Caves are especially tractable for studying spatial subsidies because primary productivity is absent. Here, we performed an ecosystem-level manipulation experiment to test the direct influence of detrital subsidies on community structure in terrestrial cave ecosystems. After performing baseline censuses of invertebrates, we removed all organic material from 12 caves and constructed exclusion boxes to prevent natural resource inputs. Next, we stocked each cave with standardized quantities of two major natural subsidies to caves: leaves (leaf packs) and carcasses (commercially supplied rodents), and measured the invertebrate colonization and utilization of these resources for 23 months. Over the course of the experiment, 102 morphospecies were observed. Diplopods and collembolans were most abundant on leaf packs, and dipteran larvae and collembolans were most abundant on the rats. On average, caves receiving either treatment did not differ in species richness, but abundance was significantly higher in rat caves over both the duration of the experiment and the temporal "life" of the individual resources, which were restocked upon exhaustion. Post-manipulation invertebrate communities differed predictably depending on the type of subsidy introduced. Over the course of the experiment, caves that received the same subsidy clustered together based on community composition. In addition, the invertebrate community utilizing the resource changed over the duration of the two-year experiment, and evidence of succession (i.e., directional change) was observed. Results from this study demonstrate how allochthonous resources can drive the community dynamics of terrestrial invertebrates in cave ecosystems and highlight the need for consideration of the surface environment when managing and protecting these unique habitats.
空间资源补贴会极大地影响受补贴社区的组成和动态。洞穴特别适合研究空间补贴，因为这里没有初级生产力。在这里，我们进行了一项生态系统水平的操纵实验，以测试碎屑补贴对陆地洞穴生态系统中群落结构的直接影响。在对无脊椎动物进行基线普查后，我们从 12 个洞穴中清除了所有有机物质，并构建了隔离箱以防止自然资源的输入。接下来，我们向每个洞穴中投放了两种主要的洞穴天然补贴物的标准数量：叶片（叶片包）和尸体（商业供应的啮齿动物），并测量了这些资源对无脊椎动物的定殖和利用情况，持续 23 个月。在实验过程中，观察到 102 个形态种。倍足纲动物和弹尾目最丰富的是叶片包，而双翅目幼虫和弹尾目最丰富的是老鼠。平均而言，接受任何一种处理的洞穴在物种丰富度上没有差异，但在整个实验期间和个体资源的时间“寿命”内，老鼠洞穴的丰度明显更高，资源在耗尽后会重新补充。操纵后，无脊椎动物群落根据引入的补贴类型而有可预测的差异。在实验过程中，接收相同补贴的洞穴根据群落组成聚类在一起。此外，在为期两年的实验过程中，利用资源的无脊椎动物群落发生了变化，并观察到了演替（即定向变化）的证据。本研究的结果表明，异源资源如何驱动陆地洞穴无脊椎动物的群落动态，并强调在管理和保护这些独特栖息地时需要考虑地表环境。
