Diversity of response and effect traits provides complementary information about avian community dynamics linked to ecological function

Functional diversity metrics based on species traits are widely used to
investigate ecosystem functioning. In theory, such metrics have different
implications depending on whether they are calculated from traits
mediating responses to environmental change (response traits) or those
regulating function (effect traits), yet trait choice in diversity metrics
is rarely scrutinized. Here, we compile effect and response traits for
British bird species supplying two key ecological services – seed
dispersal and insect predation – to assess the relationship between
functional diversity and both mean and stability of community abundance
over time. As predicted, functional diversity correlates with stability in
community abundance of seed dispersers when calculated using response
traits. However, we found a negative relationship between functional
diversity and mean community abundance of seed dispersers when calculated
using effect traits. Subsequently, when combining all traits together, we
found inconsistent results with functional diversity correlating with
reduced stability in insectivores, but greater stability in seed
dispersers. Our findings suggest that trait choice should be considered
more carefully when applying such metrics in ecosystem management.

基于物种性状的功能多样性指标（functional diversity metrics）已被广泛应用于生态系统功能研究。理论上，这类指标的生态学内涵会因计算所用性状的不同而产生差异——若性状介导生物对环境变化的响应（即响应性状（response traits）），或是调控生态系统功能（即效应性状（effect traits）），但当前功能多样性指标中所选用的性状却极少受到严格审视。本研究收集了提供两种关键生态系统服务——种子传播与昆虫捕食——的英国鸟类的效应性状与响应性状，以此探究功能多样性与群落多度的均值及其时间稳定性之间的关联。正如预期，当使用响应性状计算功能多样性时，种子传播者的群落多度稳定性与其功能多样性呈显著相关。然而，当使用效应性状计算功能多样性时，我们发现种子传播者的功能多样性与其群落多度均值呈负相关关系。随后，当整合所有性状开展分析时，我们得到了不一致的结果：功能多样性与食虫鸟类的群落多度稳定性呈负相关，即稳定性降低，但与种子传播者的群落多度稳定性呈正相关，即稳定性提升。本研究结果表明，在生态系统管理中应用此类功能多样性指标时，应更加审慎地考量性状的选择。