NRES Departmental Seminar by Dr. Julie Jastrow, Terrestrial Ecologist, Argonne National Laboratory.
Title: Prairie restoration below ground: The time and space of carbon sequestration
Nearly ideal conditions for soil aggregate formation and stabilization exist in the rhizosphere. In grassland soils with their legacy of exploration by roots, a hierarchical aggregate structure often develops across multiple spatial scales. This aggregate hierarchy creates a comparable hierarchy of pores, which feeds back to impact decomposer access to substrates, air, water, and nutrients, and thereby affects decomposition and soil carbon cycling and sequestration. These processes were explored through a series of studies capitalizing on the gradients provided by a chronosequence of tallgrass prairie restorations on soils where long-term cultivation depleted plow-layer carbon stocks. Early chronosequence studies investigated the effects of roots and microorganisms on aggregate stabilization and demonstrated the spatial scale at which these effects operate. More recent research has confirmed this rhizosphere-dominated system has steadily accrued soil carbon for >30 years and investigated the nature and spatial location of accumulated carbon. The dynamics of carbon recovery differed among various carbon pools. I will explore potential mechanisms behind these results and the possibility that several "transient steady states" could occur in some carbon pools before the system recovers to whole-soil steady state, which might take centuries to achieve.
Speaker's website: http://www.bio.anl.gov/PI/jastrow.html