Bregman Tom P, Lees Alexander C, MacGregor Hannah E A, Darski Bianca, de Moura Nárgila G, Aleixo Alexandre, Barlow Jos, Tobias Joseph A
Edward Grey Institute, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
Global Canopy Programme, 23 Park End Street, Oxford OX1 1HU, UK.
Proc Biol Sci. 2016 Dec 14;283(1844). doi: 10.1098/rspb.2016.1289.
Vertebrates perform key roles in ecosystem processes via trophic interactions with plants and insects, but the response of these interactions to environmental change is difficult to quantify in complex systems, such as tropical forests. Here, we use the functional trait structure of Amazonian forest bird assemblages to explore the impacts of land-cover change on two ecosystem processes: seed dispersal and insect predation. We show that trait structure in assemblages of frugivorous and insectivorous birds remained stable after primary forests were subjected to logging and fire events, but that further intensification of human land use substantially reduced the functional diversity and dispersion of traits, and resulted in communities that occupied a different region of trait space. These effects were only partially reversed in regenerating secondary forests. Our findings suggest that local extinctions caused by the loss and degradation of tropical forest are non-random with respect to functional traits, thus disrupting the network of trophic interactions regulating seed dispersal by forest birds and herbivory by insects, with important implications for the structure and resilience of human-modified tropical forests. Furthermore, our results illustrate how quantitative functional traits for specific guilds can provide a range of metrics for estimating the contribution of biodiversity to ecosystem processes, and the response of such processes to land-cover change.
脊椎动物通过与植物和昆虫的营养相互作用在生态系统过程中发挥关键作用，但在热带森林等复杂系统中，这些相互作用对环境变化的响应难以量化。在此，我们利用亚马逊森林鸟类群落的功能性状结构，探讨土地覆盖变化对两个生态系统过程的影响：种子传播和昆虫捕食。我们发现，在原始森林遭受伐木和火灾后，食果鸟和食虫鸟群落的性状结构保持稳定，但人类土地利用的进一步强化大幅降低了性状的功能多样性和离散度，并导致群落占据了性状空间的不同区域。这些影响在次生林恢复过程中仅部分得到逆转。我们的研究结果表明，热带森林丧失和退化导致的局部物种灭绝在功能性状方面并非随机发生，从而破坏了调节森林鸟类种子传播和昆虫食草作用的营养相互作用网络，对人类改造的热带森林的结构和恢复力具有重要影响。此外，我们的结果说明了特定类群的定量功能性状如何能够提供一系列指标，用于估计生物多样性对生态系统过程的贡献，以及这些过程对土地覆盖变化的响应。
