Background/Question/Methods
Environmental drivers are changing at local to global scales with corresponding effects on ecological dynamics. Comparisons of sensitivity of different ecosystems to global change have primarily focused on trends in specific drivers, such as temperature or precipitation. However, sensitivity of ecosystems involves two components: a suite of interacting drivers and the ability of an ecosystem to respond. Here we present a comprehensive analysis of trends in multiple global change drivers (climate, atmospheric chemistry, human activities) and trends in ecological responses for 50 sites representing terrestrial (deserts, grasslands, forests) and aquatic (freshwater, marine) systems. We use long-term data in multivariate statistical analyses to examine relative sensitivities of each ecosystem type to the suite of drivers, and to identify the key driver(s) related to variability in primary production or biomass as a key response.

Results/Conclusions Our results show regional- and continental-scale variability in both drivers and ecological responses. Trends in climate, atmospheric deposition, and human population density were generally unrelated at the continental scale, but showed important relationships for specific regions. Relationships between drivers and responses varied by ecosystem type (grasslands, forests, coastal). Our results suggest that ecosystems have differential sensitivity to multiple, interacting global change drivers. Long-term experiments conducted across a range of spatial scales will be needed to test hypotheses developed from this initial analysis.