Data from: The combined impacts of experimental defaunation and logging on seedling traits and diversity

Animals can have both positive (e.g. via seed dispersal) and negative (e.g. via herbivory) impacts on plants. The net effects of these interactions remain difficult to predict and may be affected by overhunting and habitat disturbance, two widespread threats to tropical forests. Recent studies have documented their separate effects on plant recruitment but our understanding of how defaunation and logging interact to influence tropical tree communities is limited. From 2013-2016, we followed the fate of marked tree seedlings (n = 1489) from 81 genera in and outside experimental plots. Our plots differentially excluded small, medium, and large-bodied mammal herbivores in logged and unlogged forest in Malaysian Borneo. We assessed the effects of experimental defaunation and logging on taxonomic diversity and plant trait (wood density, specific leaf area, fruit size) composition of seedling communities. Although seedling mortality was highest in the presence of all mammal herbivores (44%), defaunation alone did not alter taxonomic diversity nor plant trait composition. However, herbivores (across all body sizes) significantly reduced mean fruit size across the seedling community over time (95% CI: -0.09 to -0.01), particularly in logged forest (95% CI: -0.12 to -0.003). Our findings suggest that impacts of mammal herbivores on plant communities may be greater in forests with a history of disturbance and could subsequently affect plant functional traits and ecological processes associated with forest regeneration.

动物对植物兼具正向（例如通过种子传播）与负向（例如通过植食作用）的调控作用。这类种间相互作用的净效应仍难以预测，且可能受到过度狩猎与栖息地干扰的影响——这二者是当前热带森林面临的两大全球性威胁。已有研究分别记录了二者对植物种群补充的独立影响，但我们对动物种群耗竭（defaunation）与伐木活动如何共同作用以影响热带树木群落的认知仍较为有限。2013至2016年间，我们追踪了马来西亚婆罗洲实验样地内外来自81个属的1489株标记树木幼苗的动态变化。本研究在该区域的伐木森林与未伐木森林中设置了差异化实验样地，分别排除小型、中型与大型哺乳类植食动物。我们评估了实验性动物种群耗竭与伐木活动对幼苗群落的分类多样性以及植物性状（木材密度、比叶面积（specific leaf area）、果实尺寸）组成的影响。尽管在所有哺乳类植食动物均存在的样地中，幼苗死亡率最高（44%），但仅通过实验排除植食动物并不会改变幼苗群落的分类多样性与植物性状组成。然而，随着时间推移，所有体型类群的植食动物均显著降低了幼苗群落的平均果实尺寸（95%置信区间：-0.09至-0.01），这一效应在伐木森林中尤为显著（95%置信区间：-0.12至-0.003）。本研究结果表明，哺乳类植食动物对植物群落的影响在具有干扰历史的森林中可能更为显著，并可进一步影响植物功能性状以及与森林更新相关的生态过程。