Wild herbivores enhance resistance to invasion by exotic cacti in an African savanna
Wild herbivores enhance resistance to invasion by exotic cacti in an African savanna
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DOI：
10.1111/1365-2745.14010
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发表时间：
2022-10
影响因子：
5.5
通讯作者：
Harry B. M. Wells;Ramiro D. Crego;Jesse M. Alston;S. Kimani Ndung'u;Leo M. Khasoha;Courtney G. Reed
中科院分区：
文献类型：
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作者：
Harry B. M. Wells;Ramiro D. Crego;Jesse M. Alston;S. Kimani Ndung'u;Leo M. Khasoha;Courtney G. Reed
野生食草动物是否具有抵抗外来植物入侵的能力，一直是生态学中的一个关键问题。有证据表明，野生食草动物可以阻止外来植物的入侵，但目前尚不清楚这是否以及如何在具有不同野生食草动物多样性和植物功能群的生态系统中推广，特别是在长期（十年）的时间框架内。利用肯尼亚中部三个长期（13至26年）封闭实验的数据，我们测试了野生食草动物对外来入侵仙人掌、仙人掌和O.无花果（统称为仙人掌），是全球最严重的入侵物种之一。我们还研究了野生食草动物丰富度和大象发生概率之间的关系，其概率为O。stricta在景观一级的存在（6 150平方公里）。仙人掌密度低74%至99%，在几乎所有的地块访问野生食草动物相比，封闭地块。仙人掌密度也随着时间的推移增加得更快，在不包括野生食草动物的地块。这些影响主要是由大型食草动物（≥1000公斤），特别是大象驱动的。在景观水平上，模拟的仙人掌发生概率与野生食草动物的估计物种丰富度和大象发生概率呈负相关。平均而言，O.当野生食草动物丰富度从6种增加到10种时，stricta发生概率从~0.56下降到~0.45，当大象发生概率从~0.41增加到~0.84时，stricta发生概率从~0.57下降到~0.40。这些多尺度的结果表明，野生食草动物对仙人掌的任何促进作用（例如种子/植物传播）都被抑制（例如消费，连根拔起，践踏）所覆盖。合成.我们的实验和观察发现，野生食草动物赋予外来仙人掌入侵的抵抗力，增加了证据，保护和恢复本地食草动物组合（特别是巨型食草动物）可以增加社区抵抗植物入侵。
Whether wild herbivores confer biotic resistance to invasion by exotic plants remains a key question in ecology. There is evidence that wild herbivores can impede invasion by exotic plants, but it is unclear whether and how this generalises across ecosystems with varying wild herbivore diversity and functional groups of plants, particularly over long‐term (decadal) time frames. Using data from three long‐term (13‐ to 26‐year) exclosure experiments in central Kenya, we tested the effects of wild herbivores on the density of exotic invasive cacti, Opuntia stricta and O. ficus‐indica (collectively, Opuntia), which are among the worst invasive species globally. We also examined relationships between wild herbivore richness and elephant occurrence probability with the probability of O. stricta presence at the landscape level (6150 km2). Opuntia densities were 74% to 99% lower in almost all plots accessible to wild herbivores compared to exclosure plots. Opuntia densities also increased more rapidly across time in plots excluding wild herbivores. These effects were largely driven by megaherbivores (≥1000 kg), particularly elephants. At the landscape level, modelled Opuntia stricta occurrence probability was negatively correlated with estimated species richness of wild herbivores and elephant occurrence probability. On average, O. stricta occurrence probability fell from ~0.56 to ~0.45 as wild herbivore richness increased from 6 to 10 species and fell from ~0.57 to ~0.40 as elephant occurrence probability increased from ~0.41 to ~0.84. These multi‐scale results suggest that any facilitative effects of Opuntia by wild herbivores (e.g. seed/vegetative dispersal) are overridden by suppression (e.g. consumption, uprooting, trampling). Synthesis. Our experimental and observational findings that wild herbivores confer resistance to invasion by exotic cacti add to evidence that conserving and restoring native herbivore assemblages (particularly megaherbivores) can increase community resistance to plant invasions.