College of Resources and Environment, Huazhong Agricultural University, Wuhan, China.
Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China.
Ecology. 2024 Sep;105(9):e4387. doi: 10.1002/ecy.4387. Epub 2024 Jul 17.
Exotic plant invaders can promote others via direct or indirect facilitation, known as "invasional meltdown." Increased soil nutrients can also promote invaders by increasing their competitive impacts, but how this might affect meltdown is unknown. In a mesocosm experiment, we evaluated how eight exotic plant species and eight Eurasian native species responded individually to increasing densities of the invasive plant Conyza canadensis, while varying the supply and fluctuations of nutrients. We found that increasing density of C. canadensis intensified competitive suppression of natives but intensified facilitation of other exotics. Higher and fluctuating nutrients exacerbated the competitive effects on natives and facilitative effects on exotics. Overall, these results show a pronounced advantage of exotics over native target species with increased relative density of C. canadensis under high nutrient availability and fluctuation. We integrate these results with the observation that exotic species commonly drive increases in soil resources to suggest the Resource-driven Invasional Meltdown and Inhibition of Natives hypothesis in which biotic acceleration of resource availability promotes other exotic species over native species, leading to invasional meltdown.
外来植物入侵种可以通过直接或间接的促进作用来促进其他物种的生长，这种现象被称为“入侵性崩溃”。增加土壤养分也可以通过增加其竞争影响来促进入侵种的生长，但这种影响如何影响崩溃尚不清楚。在一项中观实验中，我们评估了八种外来植物物种和八种欧亚大陆本地物种在不同养分供应和波动条件下，对入侵植物加拿大蓬（Conyza canadensis）密度增加的个体反应。我们发现，加拿大蓬密度的增加加剧了对本地物种的竞争抑制作用，但同时也加剧了对其他外来物种的促进作用。较高和波动的养分加剧了对本地物种的竞争效应和对外来物种的促进作用。总的来说，这些结果表明，在高养分供应和波动条件下，加拿大蓬相对密度增加时，外来物种相对于本地目标物种具有明显的优势。我们将这些结果与外来物种通常会增加土壤资源的观察结果相结合，提出了“资源驱动的入侵性崩溃和本地物种抑制假说”，即生物加速资源供应会促进其他外来物种的生长，从而导致入侵性崩溃。
