Department of Ecology and Genetics, Limnology, Uppsala University, Uppsala, Sweden.
Ecology. 2012 May;93(5):1173-82. doi: 10.1890/11-1210.1.
Cross-ecosystem movements of material and energy, particularly reciprocal resource fluxes across the freshwater-land interface, have received major attention. Freshwater ecosystems may receive higher amounts of subsidies (i.e., resources produced outside the focal ecosystem) than terrestrial ecosystems, potentially leading to increased secondary production in freshwaters. Here we used a meta-analytic approach to quantify the magnitude and direction of subsidy inputs across the freshwater-land interface and to determine subsequent responses in recipient animals. Terrestrial and freshwater ecosystems differed in the magnitude of subsidies they received, with aquatic ecosystems generally receiving higher subsidies than terrestrial ecosystems. Surprisingly, and despite the large discrepancy in magnitude, the contribution of these subsidies to animal carbon inferred from stable isotope composition did not differ between freshwater and terrestrial ecosystems, likely due to the differences in subsidy quality. The contribution of allochthonous subsidies was highest to primary consumers and predators, suggesting that bottom-up and top-down effects may be affected considerably by the input of allochthonous resources. Future work on subsidies will profit from a food web dynamic approach including indirect trophic interactions and propagating effects.
物质和能量的跨生态系统运动，特别是淡水-陆地界面的反向资源流动，受到了极大的关注。与陆地生态系统相比，淡水生态系统可能会接收更多的补贴（即，在焦点生态系统之外产生的资源），这可能导致淡水中的次级生产量增加。在这里，我们使用元分析方法来量化跨淡水-陆地界面的补贴输入的幅度和方向，并确定接受者动物的后续反应。陆地和淡水生态系统在接收的补贴数量上存在差异，水生生态系统通常接收的补贴比陆地生态系统多。令人惊讶的是，尽管幅度存在很大差异，但从稳定同位素组成推断出的这些补贴对动物碳的贡献在淡水和陆地生态系统之间没有差异，这可能是由于补贴质量的差异。异源补贴对初级消费者和捕食者的贡献最大，这表明，自上而下和自下而上的影响可能会受到异源资源输入的极大影响。关于补贴的未来工作将受益于包括间接营养相互作用和传播效应的食物网动态方法。
