Understanding the impacts of human driven global change on biodiversity is a key ecological question and conservation challenge. While spatial changes in species assemblages following human disturbance are well documented, little work has quantified the impacts of global change drivers on temporal community dynamics, both within and across years. Whether or not humans alter the rate and temporal scale at which communities are structured remains an open question, limiting our capacity to understand and predict the full extent of human impacts on biodiversity. Using 19 years of bird censuses in forest, diversified agriculture, and intensive monoculture landscapes across four regions of Costa Rica, we ask how conversion to agriculture and intensification impact patterns of temporal beta-diversity and community dynamics.
Results/Conclusions
We found that all communities experienced extensive compositional turnover through time. However, compared to forested communities, temporal beta-diversity was 50% higher in intensive monocultures and 12% lower in diversified agriculture. In addition, intensive monocultures communities were most strongly structured across years, whereas diversified agriculture and forested communities were structured seasonally, with little and no trends in community composition across years, respectively. Finally, we found a large increase in the percentage of species pairs that showed positive temporal covariance in abundance in intensive monoculture sites, resulting in highly nested temporal community shifts through time. Together, these results suggest that intensive agricultural practices create transient community dynamics that result in rapid community turnover through time and shift the temporal scale at which communities are structured. These findings also point to the ability of diversified agricultural practices to conserve temporal community dynamics similar to those found in natural forested communities, providing valuable and temporally consistent habitat for species to persist in outside of protected areas.