Climate change effects on biological soil crusts: What should we expect for future biocrust structure and function?

Background/Question/Methods

Climate change is predicted to have significant effects on dryland ecosystems, yet our understanding and predictive capacity regarding climate change affects on biological soil crusts (biocrusts) remains notably poor. Due to the global extent of biocrust communities and to their substantial role in regulating ecosystem structure and function, this lack of understanding greatly hinders our ability to consider the effects of a changing climate at the global-scale. In addition, biocrusts are completely absent from most Earth System modeling efforts, calling into question the accuracy of these models, as well as offering exciting opportunities to include biocrusts in modeling approaches. This talk will consist of two elements. First, we will synthesize results from a long-term (10 yr) climate manipulation plots on the Colorado Plateau, U.S.A. to explore how altered climate has affected biocrust community composition and function. We will bring together observational field data from temperature and precipitation manipulation plots, as well as data from laboratory experiments that elucidate the mechanisms behind crust community responses. Second, we will explore the potential for explicitly incorporating biocrusts into coupled Earth Systems models and will discuss how such incorporation could affect predictions of future climate.

Results/Conclusions

Data from our climate manipulation plots support other research in suggesting that predicted changes in climate will likely have significant effects on biocrust community structure, and also suggest notable biogeochemical causes (e.g., carbon starvation) and consequences of these climate-induced changes to community (i.e., large affects on carbon and nitrogen cycling). In addition, the data suggest that different types of biocrust organisms (e.g., mosses versus lichens) may respond to climate manipulation through different mechanisms and along different timescales. For example, mosses showed a dramatic die-off in response to altered precipitation patterns, but lichens are responding more to temperature, and lichen responses took longer to emerge. Taken together these data show that biocrust communities have the potential to respond dramatically to climate change, including the observation of rapid mortality events, and that these changes will likely have marked effects on the cycling of carbon and nitrogen. In addition, due to these effects and to some important similarities between vascular plants and biocrusts, such biocrust responses to climate change may be relatively straightforward to incorporate into Earth System models and could have substantial effects on model results and implications.