Data from: Incorporating intraspecific trait variation into functional diversity: impacts of selective logging on birds in Borneo

As conservation increasingly recognizes the importance of species’ functional roles in ecosystem processes, studies are shifting away from measuring species richness towards measures that account for the functional differences between species in a community. These functional diversity (FD) indices have received much recent attention and refinement, but their greatest limitation remains their inability to incorporate information about intraspecific trait variation (ITV).
We use an individual-based model to account for ITV when calculating the functional diversity of two avian communities in Borneo; one in primary (unlogged) forest and one in selectively logged forest. We deal with the scarcity of trait data for individual species by developing a simulation approach, taking data from the literature where necessary. Using a bootstrapping procedure, we produce a range of ecologically feasible FD values taking account of ITV for five commonly used FD indices, and we quantify the confidence that can be placed in these values, using a newly developed bootstrapping method: btFD.
We find that incorporating ITV significantly alters the FD values of all indices used in our models. The rank order of FD for the two communities, indicating whether diversity was higher in primary or selectively logged forest, is largely unchanged by the inclusion of ITV. However, by accounting for ITV, we are able to reveal previously unrecognized impacts of selective logging on avian functional diversity through a narrower dispersion of individuals in functional trait space in logged forest.
Our results highlight the importance of incorporating ITV into measures of functional diversity, whilst our simulation approach addresses the frequently encountered difficulty of working with sparse trait data and quantifies the confidence that should be placed in such findings.

随着保护生物学日益认知到物种在生态系统过程中的功能重要性，相关研究正从单纯测定物种丰富度，转向考量群落内物种间功能差异的多样性指标。近年来，功能多样性（Functional Diversity, FD）指数受到广泛关注并不断完善，但其最大局限仍在于无法纳入种内性状变异（Intraspecific Trait Variation, ITV）相关信息。
本研究采用基于个体的模型（Individual-based Model），在计算婆罗洲两个鸟类群落的功能多样性时纳入了ITV的影响：一个群落栖息于原生（未采伐）林，另一个栖息于择伐林。针对单物种性状数据稀缺的问题，我们开发了一种模拟分析方法，必要时引用已发表文献中的数据。通过自助抽样程序（Bootstrapping Procedure），我们针对五种常用的FD指数，生成了考虑ITV影响的一系列生态合理的FD数值，并利用新开发的自助抽样方法btFD，量化了这些数值的置信水平。
研究发现，纳入ITV会显著改变本研究所用全部指数的FD数值。两个群落的FD排序（即判断原生林与择伐林的多样性孰高孰低）在纳入ITV后基本保持不变，但通过考量ITV的影响，我们得以揭示择伐对鸟类功能多样性的此前未被认知的影响：择伐林中的个体在功能性状空间中的分布更为狭窄。
本研究结果凸显了将ITV纳入功能多样性测度的重要性，同时我们开发的模拟方法解决了性状数据稀缺时常见的分析难题，并量化了此类研究结果应具备的置信水平。