Soils are the critical and dynamic center for the majority of ecosystem processes in both natural and managed terrestrial ecosystems. Although soil communities generally are thought to regulate many of these processes (e.g. decomposition, nutrient cycling), there are suprisingly little data on the factors that affect soil community structure and function, or the relation of soil biodiversity to ecosystem function. Central questions of this project are: (A) How do plants influence belowground biodiversity? and (B) What are the consequences of soil biodiversity to ecosystem processes? Specific hypotheses and manipulative field experiments will be used to test controls on soil community structure and diversity. The controls to be examined in the experiments to test controls on soil community structure and diversity. The controls to be examined in the experiments include plant species diversity, plant functional diversity (C3 vs. C4 species), resource quality, net primary productivity, and soil abiotic characteristics. Field experiments will test the effects of soil biodiversity on the decomposition of homogeneous and heterogeneous substrates. Main experiments will be at the Konza Prairie Long-Term Ecological Research (KNZ LTER) site, a site with substantial background information on ecosystem properties, soil processes and soil invertebrates. Analysis of targeted soil invertebrate communities known to be important in ecosystem function in grasslands will be examined at a fine taxonomic resolution throughout the experiment. A one time sampling at the Cedar Creek Natural History Area LTER site will also provide an additional test of the hypothesis that soil nematode diversity tracks plant biodiversity. The studies will form the basis for a collaborative and coordinated effort with a grasslands site in the UK (parallel proposal funded by UK-NERC). The partnership between ecosystem scientist and invertebrate taxonomists in the comparative US-UK field experiments will provide a unique contrib ution determining the relative importance of factors affecting belowground biodiversity and ecosystem functioning. Simulation modeling at the USA KNZ LTER site will be used to synthesize, interpret and explore the nature of controls and consequences of soil biodiversity, and then to compare with parameters of the UK site.
