Feeding a growing world population while minimizing negative environmental externalities is a major global challenge. Agricultural technologies have raised global crop yields, yet increasing negative environmental impacts as a result of agricultural intensification are accumulating. In collaboration with ALUS Canada and the Food From Thought and Biodiversity Resilience Network research groups, I research farm management techniques to improve water quality, provide habitat for biodiversity, and create more resilient agricultural systems in the face of climate change.
Vegetation feedbacks to ecosystem processes represent a major source of uncertainty in climate change scenarios. In Southern California’s historically shrub-dominated ecosystems, increasing drought severity and invasions by exotic species represent two major consequences of global change. Overall, this research showed that invasion increases ecosystem sensitivity to drought in both aboveground and belowground processes.
In collaboration with theNutrient Network, this work investigates the controls on ecosystem productivity and diversity worldwide. I am working with collaborators to understand how nutrient additions shape changes in species community composition.
Climate change is disproportionately impacting high elevation and high latitude regions. Hotter, dryer weather and shifting species ranges are obvious changes, but the influence on carbon loss via altered decomposition patterns is equally important. Our findings highlight how shifting species composition, through processes such as range expansions, can influence ecosystem responses to climate change.
Serpentine grasslands have historically been more resistant to invasion by exotic species due to low fertility soils. Anthropogenic nitrogen deposition has made these systems more susceptible to invasion. Land managers often graze cattle in grasslands to reduce the impact of invasive species. This research looked at the dynamics of these two factors - N deposition and grazing - on soil microbial functionality.
As much as 90% of tallgrass prairie was converted to agriculture and urban areas since European settlement. Conversion of prairie to agriculture has had significant ecosystem consequences, including effects on soil C and nutrient pools - losses of 89% of original carbon and 75% of original nitrogen has been reported. This work found that diverse prairie restorations rapidly accumulate carbon as a result of fast turnover of annual and biennial early successional species.