Using a grassland chronosequence to identify the strength of various plant community and soil factors on soil microbial community structure and function

For the past 25 years our laboratory has been using the tallgrass prairie reconstructions at Fermilab to investigate the feedbacks between plants and microbes and their influence on soil structure and organic matter accrual.  Initially these studies were directed at understanding the soil restoration process and were directed at quantifying the contributions of roots, mycorrhizal fungi, and MBC on the creation and stabilization of soil structure.  More recent studies have demonstrated a chronosequence approach can be useful for identifying and isolating the relative contributions of plants and microbes on soil carbon accrual.  Specifically, we have identified that mycorrhizal fungi play a particularly important role in the stabilization of soil aggregates.  Also, we find that both fungal and bacterial biomass increases with restoration age, however, mycorrhizal fungal biomass increases at a greater rate than either bacterial or saprophytic fungal biomass.  The increase in proportion of mycorrhizal fungal biomass suggests the efficiency of carbon utilization within the system increases with restoration age as demonstrated by a greater proportion of the plant community’s photosynthate is being sequestered in mycorrhizal fungal biomass (direct utilization) rather than via biomass production through the rendering of already formed detrital materials.   These studies will be placed within the context of how chronosequence studies can be utilized to better evaluate our attempts at ecosystem restoration and further inform pedogenic processes.