Plant Water Use Affects Competition for Nitrogen: Why Drought Favors Invasive Species in California
Plant Water Use Affects Competition for Nitrogen: Why Drought Favors Invasive Species in California
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DOI：
10.1086/648557
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发表时间：
2010-01-01
影响因子：
2.9
通讯作者：
de Mazancourt, Claire
中科院分区：
文献类型：
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作者：
Everard, Katherine;Seabloom, Eric W.;de Mazancourt, Claire
经典的资源竞争理论通常将资源供应率视为独立的;然而，营养物质的供应可能会受到植物的间接影响，这对模型预测有重要影响。我们证明了这一普遍现象，通过使用一个模型，在该模型中，氮的竞争是介导的土壤水分，竞争的结果，包括共存和多个稳定状态，以及竞争性排斥。在该模型中，土壤水分调节氮的有效性，通过土壤水分的微生物过程，淋溶和植物吸收的依赖。通过影响水的可用性，植物也间接影响氮的可用性，因此可能会改变竞争的结果。来自地中海的外来一年生物种已经取代了加州的大部分本地多年生草。氮和水已被证明是潜在的限制在这个系统中。我们参数化的加州草地模型，并表明土壤水分介导的氮竞争可以解释一年生物种的优势，在干燥地区，预计在潮湿地区共存。这些结果与美国太平洋各州草原入侵的大规模地理模式一致，其中一年生禾草入侵了加州大部分炎热干燥的草原，但多年生禾草主导了加州北方、俄勒冈州和华盛顿的潮湿草原。
Classic resource competition theory typically treats resource supply rates as independent; however, nutrient supplies can be affected by plants indirectly, with important consequences for model predictions. We demonstrate this general phenomenon by using a model in which competition for nitrogen is mediated by soil moisture, with competitive outcomes including coexistence and multiple stable states as well as competitive exclusion. In the model, soil moisture regulates nitrogen availability through soil moisture dependence of microbial processes, leaching, and plant uptake. By affecting water availability, plants also indirectly affect nitrogen availability and may therefore alter the competitive outcome. Exotic annual species from the Mediterranean have displaced much of the native perennial grasses in California. Nitrogen and water have been shown to be potentially limiting in this system. We parameterize the model for a Californian grassland and show that soil moisture-mediated competition for nitrogen can explain the annual species' dominance in drier areas, with coexistence expected in wetter regions. These results are concordant with larger biogeographic patterns of grassland invasion in the Pacific states of the United States, in which annual grasses have invaded most of the hot, dry grasslands in California but perennial grasses dominate the moister prairies of northern California, Oregon, and Washington.