Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, CH-8092, Zürich, Switzerland.
Departamento de Ecologia, Universidade de Brasília, Asa Norte, Brasília-DF, Brazil.
New Phytol. 2012 Nov;196(3):816-823. doi: 10.1111/j.1469-8137.2012.04363.x. Epub 2012 Sep 24.
Although endangered and alien invasive plants are commonly assumed to persist under different environmental conditions, surprisingly few studies have investigated whether this is the case. We examined how endangered and alien species are distributed in relation to community biomass and N : P ratio in the above-ground community biomass in savanna vegetation in the Brazilian Cerrado. For 60 plots, we related the occurrence of endangered (Red List) and alien invasive species to plant species richness, vegetation biomass and N : P ratio, and soil variables. Endangered plants occurred mainly in plots with relatively low above-ground biomass and high N : P ratios, whereas alien invasive species occurred in plots with intermediate to high biomass and low N : P ratios. Occurrences of endangered or alien plants were unrelated to extractable N and P concentrations in the soil. These contrasting distributions in the Cerrado imply that alien species only pose a threat to endangered species if they are able to invade sites occupied by these species and increase the above-ground biomass and/or decrease the N : P ratio of the vegetation. We found some evidence that alien species do increase above-ground community biomass in the Cerrado, but their possible effect on N : P stoichiometry requires further study.
尽管人们通常认为濒危植物和外来入侵植物会在不同的环境条件下生存，但实际上很少有研究调查这种情况是否属实。我们研究了濒危物种（红色名录）和外来入侵物种在巴西塞拉多草原植被的地上生物量群落生物量中与群落生物量和 N : P 比值的分布关系。对于 60 个样方，我们将濒危植物和外来入侵植物的出现与植物物种丰富度、植被生物量和 N : P 比值以及土壤变量相关联。濒危植物主要出现在地上生物量相对较低、N : P 比值较高的样方中，而外来入侵物种则出现在生物量中等至高、N : P 比值较低的样方中。濒危或外来植物的出现与土壤中可提取的 N 和 P 浓度无关。在塞拉多，这些截然不同的分布情况意味着，如果外来物种能够入侵这些物种占据的栖息地，并增加地上生物量和/或降低植被的 N : P 比值，它们才会对濒危物种构成威胁。我们发现了一些证据表明，外来物种确实会增加塞拉多的地上生物量，但它们对 N : P 化学计量的可能影响需要进一步研究。
