Department of Biology, University of Florida, Gainesville, FL, USA.
Mpala Research Centre, Nanyuki, Kenya.
Ecol Lett. 2021 May;24(5):1052-1062. doi: 10.1111/ele.13725. Epub 2021 Mar 21.
Invasive ants shape assemblages and interactions of native species, but their effect on fundamental ecological processes is poorly understood. In East Africa, Pheidole megacephala ants have invaded monodominant stands of the ant-tree Acacia drepanolobium, extirpating native ant defenders and rendering trees vulnerable to canopy damage by vertebrate herbivores. We used experiments and observations to quantify direct and interactive effects of invasive ants and large herbivores on A. drepanolobium photosynthesis over a 2-year period. Trees that had been invaded for ≥ 5 years exhibited 69% lower whole-tree photosynthesis during key growing seasons, resulting from interaction between invasive ants and vertebrate herbivores that caused leaf- and canopy-level photosynthesis declines. We also surveyed trees shortly before and after invasion, finding that recent invasion induced only minor changes in leaf physiology. Our results from individual trees likely scale up, highlighting the potential of invasive species to alter ecosystem-level carbon fixation and other biogeochemical cycles.
入侵蚂蚁塑造了本地物种的组合和相互作用，但它们对基本生态过程的影响还知之甚少。在东非，巨大头蚁已入侵金合欢属的单优林，消灭了本地的蚂蚁防御者，使树木容易受到脊椎动物食草动物对树冠的损害。我们使用实验和观察来量化入侵蚂蚁和大型食草动物在两年时间内对 A. drepanolobium 光合作用的直接和交互影响。在关键的生长季节，被入侵至少 5 年的树木的整棵树的光合作用降低了 69%，这是由于入侵蚂蚁和脊椎动物食草动物之间的相互作用导致了叶片和树冠层面光合作用的下降。我们还在入侵前后对树木进行了调查，发现最近的入侵只导致叶片生理发生了很小的变化。我们从单棵树获得的结果很可能会扩大，突出了入侵物种改变生态系统水平碳固定和其他生物地球化学循环的潜力。
