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识到物种在生态系统过程中的功能作用的重要性，相关研究正从单纯测量物种丰富度，转向考量群落内物种间功能差异的多样性度量方法。这类功能多样性（functional diversity, FD）指数近年来受到广泛关注并得到不断完善，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。
本研究针对婆罗洲的两个鸟类群落——一处位于原始（未采伐）林，另一处位于择伐林——计算其功能多样性时，采用基于个体的模型纳入种内性状变异信息。针对单个物种的性状数据稀缺的问题，我们开发了一套模拟方法，必要时从公开文献中调取相关数据。我们借助自助法流程，针对5种常用的功能多样性指数，计算得到一系列考虑种内性状变异的、生态上可行的功能多样性数值，并采用一种新开发的自助法btFD，量化了这些数值的置信水平。
本研究发现，纳入种内性状变异会显著改变所有所用指数的功能多样性数值。用于判断原始林与择伐林多样性高低的两个群落的功能多样性排序，在纳入种内性状变异后基本保持不变。然而，通过考量种内性状变异，我们得以揭示择伐林内个体在功能性状空间中的分布更为狭窄这一特征，进而发现择伐对鸟类功能多样性存在此前未被认知的影响。
本研究结果凸显了将种内性状变异纳入功能多样性度量的重要性，同时我们开发的模拟方法解决了性状数据稀缺时常见的研究难题，并量化了此类研究发现应具备的置信度。