Functional traits—not nativeness—shape the effects of large mammalian herbivores on plant communities

Large mammalian herbivores (megafauna) have experienced extinctions and declines since prehistory. Introduced megafauna have partly counteracted these losses yet are thought to have unusually negative effects compared to native megafauna. Using a meta-analysis of 3,995 plot-scale plant abundance and diversity responses from 221 studies, we found no evidence that megafauna impacts were shaped by nativeness, ‘invasiveness’, ‘feralness’, coevolutionary history, or functional and phylogenetic novelty. Nor was there evidence that introduced megafauna facilitate introduced plants more than native megafauna. Instead, we found strong evidence that functional traits shaped megafauna impacts, with larger-bodied and bulk-feeding megafauna promoting plant diversity. Our work suggests that trait-based ecology provides better insight into interactions between megafauna and plants than concepts of nativeness.

大型哺乳类植食动物（megafauna）自史前时代以来便经历了物种灭绝与种群衰减。外来引入的巨型动物群在一定程度上抵消了这些种群损失，但相较于本土巨型动物群，人们普遍认为其会带来异乎寻常的负面影响。本研究通过对221项研究中的3995个样地尺度植物丰度与多样性响应数据开展元分析（meta-analysis），未发现任何证据表明巨型动物群的生态影响受本土性、‘入侵性’、‘野化性’、协同进化历史或功能与系统发育新颖性所调控。亦未发现证据表明外来引入的巨型动物群相较于本土巨型动物群，更能促进外来植物的存活与扩张。与之相反，本研究找到了充分证据表明，功能性状才是调控巨型动物群生态影响的核心因素：体型更大、取食量大的巨型动物群能够提升植物多样性。本研究结果表明，相较于本土性相关概念，基于功能性状的生态学理论能够更深入地阐释巨型动物群与植物之间的相互作用关系。