Classical theory predicts that herbivores impact herb assemblages and soil nitrogen (N) cycling through selective plant consumption and the deposition of N-rich waste, with effects dependent upon ecosystem N availability. Herbivores are predicted to accelerate N cycling when N availability is high and decelerate cycling when availability is low. However, experimental tests of these theories in natural systems are limited and have yielded contradictory results. California’s widespread chaparral shrublands provide a tractable system in which to test these theories. They are prone to periodic crown-fire, which temporarily removes living shrub cover, deposits mineral N on soils, and allows diverse herbaceous assemblages to dominate the landscape for 3-5 years. Chaparral is also increasingly vulnerable to herbaceous invasion; mammalian herbivory may limit the establishment of non-native herbs in the shrub understory.

中文翻译：

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火后丛林中的哺乳动物食草影响草本成分，但不影响氮和碳循环

古典理论预测，草食动物通过选择性的植物消耗和富氮废物的沉积来影响草本植物的组合和土壤氮（N）的循环，其影响取决于生态系统氮的可用性。预计草食动物在氮素利用率高时会加速氮素循环，而在氮素利用率低时会降低氮素循环。但是，在自然系统中对这些理论的实验测试是有限的，并且产生了矛盾的结果。加利福尼亚州广泛的丛林灌木丛提供了可测试这些理论的易处理系统。它们容易发生周期性的树冠大火，这会暂时清除活动的灌木覆盖物，使土壤中的矿物质N沉积，并使各种草本组合在3-5年内占据主导地位。丛林也越来越容易受到草本植物的侵袭。