Disturbance aspects interact to affect invasion and diversity: Evidence from theoretical and empirical studies

Background/Question/Methods

Disturbance has long been known to affect diversity and the outcome of biological invasions.  However, empirical results have proven difficult to reconcile, with markedly different patterns arising in different studies.  We have developed a conceptual framework for environmental disturbance, addressing the frequency, intensity, duration, extent, timing, and pace of disturbances.  We use models for competing plant species to explore why theoretically-expected relationships between diversity and disturbance are not consistently observed in empirical systems.  We then demonstrate how the framework can be used to improve experimental design and biological interpretation in an invasive plant system, which in turn leads to more efficient management.

Results/Conclusions

Peaked diversity-disturbance relationships have been documented in nature, and are expected from commonly-taught theory.  However, increasing, decreasing, uniform and U-shaped relationships have also been reported in numerous empirical studies.  We demonstrate all of these possible outcomes in our model, and further confirm the presence of multiple disturbance-diversity relationships in an empirical microbial system.  For the plant invader, conventional management focuses on frequency and intensity of management efforts; we demonstrate empirically that timing and intensity are in fact the most important variables for this system.  Our conceptual, aspect-based framework has the potential to reconcile apparently conflicting empirical results on the effects of disturbance on diversity and invasion in a wide variety of ecological systems.