ABOVE- AND BELOWGROUND COMMUNITY DIVERSITY: ASSESSING BIOTIC DRIVERS OF CARBON STORAGE AND SOIL QUALITY IN RANGELANDS

Grasslands are the most widespread, as well as one of the most threatened, terrestrial ecosystems. Grasslands provide a suite of key ecosystem goods and services, many of which are threatened as a result to loss of grassland cover. The loss of grasslands across the globe, coupled with their importance in providing ecosystem goods and services, has fuleled a growing interest in the role of grassland biodiversity in maintaining these processes. The overarching goal of the proposed research is to determine the relative influence of plant community diversity, composition and AM fungal community structure on soil carbon, soil aggregate stability, and soil microbial abundances.Objective 1:The first objective of my proposed work is to determine the relative influence of plant species richness, diversity, and phylogenetic dispersion on soil aggregate stability and carbon storage. Initial results from this experiment indicate a positive relationship between plant community diversity and productivity. Initial results also indicates that plant phylogenetic dispersion tended to increase productivity. However, the resultant impacts of increased species diversity and phylogenetic dispersion of plant communities on soil quality (i.e. aggregate stability, soil carbon, and overall AM fungal abundance and AM fungal diversity) is not known.Objective 2:The second objective of my proposed research is to determine the relative influence of AM fungal community assemblage on soil aggregate stability and carbon storage. Much like plant communities, AM fungal communities also likely play a considerable role in the maintenance of soil carbon storage, but the mechanisms by which AM fungi do so is not well understood. For example, AM fungal community assemblage influences plant productivity, as well as AM fungal diversity and biomass. We hypothesize that AM fungal community inoculation indirectly influence soil carbon storage through the effects of enhanced plant productivity and AM fungal biomass and composition on soil aggregate stability.Objective 3:The third objective of my proposal is to test for interactive effects of plant species richness, phylogenetic dispersion, and AM fungal community structure and abundance, and the importance of potential causal pathways influencing soil aggregate stability and soil carbon. While all of these interacting and interrelated mechanisms are likely influencing soil aggregate stability, and therefore soil carbon storage, the degrees to which and pathways by which each does so is complex and remains, for the most part, unexplored.