Impact indicators: Effects of land use management on functional trait and phylogenetic diversity of wild bees

Abstract

Changes in land use and management intensification, especially in agriculture, have led to alarming declines in bee populations and the important ecological services they provide. Little is known how wild bee communities respond to these landscape changes at the phylogenetic level. Phylogenetic diversity was found to be correlated to functional trait diversity, since the former reflects a species evolutionary history while the later reflects the traits a species has accumulated. Here we use a mix of traditional measures of biodiversity and phylogenetic methods to examine differences in wild bee assemblages at six landscapes associated with grazing pressure and different management schemes. We found that grazing pressure strongly influences bee abundance, species richness and functional trait diversity while management intensity has little effect. Interestingly, wild bee phylogenetic diversity was not highly affected by land use, management, or grazing pressure as landscapes retained high levels of phylogenetic evenness. We additionally found evidence of phylogenetic signaling of examined traits. Our findings reveal that wild bee communities can maintain functional trait diversity even with low abundance and species richness. Furthermore, our study supports the notion that trait conservation through evolutionary lineages may only occur for some traits.