COS 115-4
A meta-analysis of the magnitude and predictability of change in ecosystem functions following anthropogenic disturbances
It is widely recognized than anthropogenic disturbances can lead to shifts in ecosystem functions, potentially impairing the quality of services that an ecosystem can provide. There are a large number of studies reporting the impacts of disturbances on various ecosystem functions, yet these results have never been synthesized to compare changes in functions, and the predictability of these changes, across different disturbances. We conducted a meta-analysis to compare the effects of four major anthropogenic disturbances: species invasions, nutrient addition, acidification, and temperature increase on the mean change and response predictability (between replicate variance) in four ecosystem functions: carbon storage, decomposition, productivity, and respiration. The analysis included 88 papers with 188 experimental manipulations. All papers reported a mean and corresponding standard deviation of ecosystem function in a control and disturbed treatment. Response ratios (RR=ln [disturbance/control]) were used as the effect size for the analysis and were calculated for both the means and variances. Response predictability was calculated as the ratio between the variance RR and the mean RR to give a measure of how predictable the change in ecosystem function following the disturbance was.
Results/Conclusions
Across all disturbances the rate of productivity significantly increased in the disturbed treatments, and was the only function to significantly change. This increase was mainly driven by the nutrient addition responses. Across all disturbances the rate of decomposition had a significant decrease in response predictability, suggesting that magnitude and direction of change in decomposition following anthropogenic disturbances will be variable and hard to predict. Acidification lead to significant declines in decomposition while species invasions lead to significant declines in respiration. These results show that changes in ecosystem functions are common following anthropogenic disturbances, yet the magnitude of change for the various functions is dependent on disturbance type.