About - We are investigating the causes and consequences of changes in biodiversity. We study how biodiversity and ecosystem functioning respond to global environmental changes, such as land use changes, nutrient enrichment, exotic species introductions, and climate extremes. We also study the responses of ecosystem functioning and ecosystem services to changes in biodiversity.
- How do global environmental changes impact biodiversity and ecosystems?
- How do changes in biodiversity influence ecosystems?
- How do species coexist in diverse communities?
Isbell et al. 2011 Nature
Here we show that 84% of the 147 grassland plant species studied in 17 biodiversity experiments promoted ecosystem functioning at least once. Different species promoted ecosystem functioning during different years, at different places, for different functions and under different environmental change scenarios. Our results suggest that although species may appear functionally redundant when one function is considered under one set of environmental conditions, many species are needed to maintain multiple functions at multiple times and places in a changing world.
Isbell et al. 2013 PNAS
Here we found that although chronic nitrogen enrichment initially increased productivity, it also led to loss of plant species, including initially dominant species, which then caused substantial diminishing returns from nitrogen fertilization. In contrast, elevated CO2 did not decrease grassland plant diversity, and it consistently promoted productivity over time. Our results support the hypothesis that the long-term impacts of anthropogenic drivers of environmental change on ecosystem functioning can strongly depend on how such drivers gradually decrease biodiversity and restructure communities.
Isbell et al. 2013 Ecol. Lett.
Our 30-year grassland experiment shows that plant diversity decreased well below control levels after 10 years of chronic high rates of nitrogen addition, and did not recover to control levels 20 years after nitrogen addition ceased. Furthermore, we found a hysteretic response of plant diversity to increases and subsequent decreases in soil nitrate concentrations. Our results suggest that chronic nutrient enrichment created an alternative low-diversity state that persisted despite decreases in soil nitrate after cessation of nitrogen addition, and despite supply of propagules from nearby high-diversity plots.
Isbell et al. 2015 Nature
We found that biodiversity increased ecosystem resistance for a broad range of climate events, including wet or dry, moderate or extreme, and brief or prolonged events. By a year after each climate event, ecosystem productivity had often fully recovered, or over-shot, normal levels of productivity in both high- and low-diversity communities, leading to no detectable dependence of ecosystem resilience on biodiversity. Our results suggest that biodiversity mainly stabilizes ecosystem productivity, and productivity-dependent ecosystem services, by increasing resistance to climate events.