PS 16-153 - What role do graminoids play in prairie ecosystem functioning?

Background/Question/Methods

Studying the relationship between biodiversity and ecosystem function (BEF) allows us to better predict consequences of environmental change in endangered ecosystems such as tallgrass prairies. Graminoids are critical components of prairie vegetation communities because they are a food source, provide cover and habitat, affect nutrient cycling and decomposition, and are often principal components of prairie productivity. Despite graminoids making up a large percentage of prairies, little focus has been placed on their influence on ecosystem function amidst environmental change; we especially lack data on their influence in prairies that have differing levels of functional diversity. To examine how different ratios of graminoids affect ecosystem function across different levels of functional diversity, we will measure productivity and litter decomposition in a prairie BEF experiment and compare results to real prairie communities at Nachusa Grasslands Preserve. The prairie BEF experiment is modeled after vegetation communities at Nachusa Grasslands, and contains non-random, realistic multi-species assemblages with 60 plots, 12 species, and three levels of functional diversity. By comparing results from the experimental plots and results from Nachusa Grasslands we will see how graminoid influence differs between experimental and field sites and determine if experimental plots are reasonable surrogates for real prairie communities.

Results/Conclusions

Preliminary results from analyzing 20 sites at Nachusa Grasslands show that productivity and litter decomposition increase as functional diversity increases, with bison and fire (respectively) producing marginal effects. However, the variation in these ecosystem functions was minimally explained by functional diversity. This suggests that the variation in productivity and litter decomposition is largely attributed to some other factor, likely community plant composition. Our next step will be to determine if the ratio of graminoids in the community affects ecosystem function across different levels of functional diversity. The results of studying graminoid influence in realistic, functionally diverse assemblages will empower prairie restoration managers to create informed decisions and influence biodiversity management where optimal plant assembly and associated functions are a priority.