School of Biological Sciences, Washington State University, Pullman, Washington, United States of America.
Department of Biology (mc WB 816), Roosevelt University, Chicago, Illinois, United States of America.
PLoS One. 2020 Jul 2;15(7):e0235210. doi: 10.1371/journal.pone.0235210. eCollection 2020.
Ongoing habitat loss and fragmentation alter the functional diversity of forests. Generalising the magnitude of change in functional diversity of fragmented landscapes and its drivers is challenging because of the multiple scales at which landscape fragmentation takes place. Here we propose a multi-scale approach to determine whether fragmentation processes at the local and landscape scales are reducing functional diversity of trees in the East Usambara Mountains, Tanzania. We employ a structural equation modelling approach using five key plant traits (seed length, dispersal mode, shade tolerance, maximum tree height, and wood density) to better understand the functional responses of trees to fragmentation at multiple scales. Our results suggest both direct and indirect effects of forest fragmentation on tree functional richness, evenness and divergence. A reduction in fragment area appears to exacerbate the negative effects resulting from an increased amount of edge habitat and loss of shape complexity, further reducing richness and evenness of traits related to resource acquisition and favouring tree species with fast growth. As anthropogenic disturbances affect forests around the world, we advocate to include the direct and indirect effects of forest fragmentation processes to gain a better understanding of shifts in functional diversity that can inform future management efforts.
持续的生境丧失和破碎化改变了森林的功能多样性。由于景观破碎化发生在多个尺度上，因此概括破碎化景观功能多样性变化的幅度及其驱动因素具有挑战性。在这里，我们提出了一种多尺度方法，以确定坦桑尼亚东乌桑巴拉山脉的局部和景观尺度的破碎化过程是否正在降低树木的功能多样性。我们采用结构方程模型方法，使用五个关键植物特征（种子长度、传播模式、耐荫性、最大树高和木材密度）来更好地了解树木在多个尺度上对破碎化的功能响应。我们的结果表明，森林破碎化对树木功能丰富度、均匀度和发散度既有直接影响，也有间接影响。片段面积的减少似乎加剧了由于边缘生境增加和形状复杂性丧失而导致的负面影响，进一步降低了与资源获取相关的特征的丰富度和均匀度，并有利于生长迅速的树种。由于人为干扰影响着世界各地的森林，我们提倡包括森林破碎化过程的直接和间接影响，以更好地了解功能多样性的变化，为未来的管理工作提供信息。
