Factors Influencing C Sequestration in Northern Great Plains Grasslands.

Soil development is influenced by the five soil forming factors; parent material, climate, landscape, organisms and time.  We examined the effects of landscape and organisms (vegetation) on carbon (C) in Conservation Reserve Program (CRP), restored grasslands, and undisturbed grasslands across the northern Great Plains of the U. S. using statistical methods.  The effects of vegetation, slope, and aspect on C sequestered in the surface 30 cm of the soil were evaluated for 997 sites sampled across portions of Iowa, Minnesota, Montana, and North and South Dakota.  Statistical models were developed and evaluated to perform the analysis.  For the vegetation component of these models, cool season grasses with or without legumes showed higher levels of soil organic C than warm season grasses with or without legumes or mixed cool and warm season grass regimes. When slopes were evaluated, slopes less than 3 % showed higher levels of sequestered C than slopes greater than 3 %. Southern and western aspects showed higher soil C levels than other aspects.  Interactions between vegetation, slope and aspect will also be discussed.