Over the past decade, an increasing number of studies have experimentally reduced the number of species in a community and examined how diversity loss impacts important ecosystem processes such as primary production. Studies have generally been performed in simple environments that maximize experimental control, and under these conditions, results suggest that relatively few species are needed to maintain ecosystem productivity. But would this conclusion hold true in more natural habitats where spatial and temporal heterogeneity are pervasive? Or would a greater number of species be required to maintain productivity in complex environments that are inherently variable? This project takes an empirical approach to address these questions using a model system of freshwater algae. Field and laboratory experiments will be performed to compare how algal diversity impacts primary production in stream ecosystems that have simplified flow regimes, to more natural systems that exhibit pronounced spatial and temporal variation in flow. Global loss of biodiversity ranks among the pervasive environmental changes of our time. Although we understand the primary causes of extinction, much less is known about the environmental impacts of extinction. The goal of this research is to determine which types of ecosystems are most sensitive to species loss.
