Document: MAR-3-59-47

Ecosystem consequences of land cover change in eastern Kansas.

NORRIS, M.D.*, J.M.BLAIR and L.C.JOHNSON

Kansas State University, Manhattan, KS, 66506, USA ¹

Abstract:
In recent decades, a substantial amount of tallgrass prairie has been lost to the establishment of forests dominated by eastern redcedar (Juniperus virginiana). With this shift in dominant plant life form, we expected accompanying changes in standing stocks of biomass, NPP, and biogeochemical cycles. The goals of this project were to determine and compare plant productivity, and major pools and fluxes of nitrogen in closed-canopy forest and adjacent prairie. Estimated NPP in the forest was 1.5 times that of the prairie. Additionally, there was a large shift from belowground biomass and productivity in prairie to aboveground in the forest. In forest sites, aboveground biomass was 148600 kg/ha, average litterfall was 500 g/m²/yr, and standing stock of litter was 32 kg/m². These values represent a considerable increase in aboveground biomass accumulation and surface litter inputs compared to tallgrass prairie. In a reciprocal transplant decomposition study, we found no significant effects of habitat on decay rates of leaf or root litter after the first year. However, decomposing grass root litter exhibited patterns of N loss whereas redcedar roots accumulated N. This difference may help explain differences in soil N dynamics. Although there were few differences between forest and prairie soil N pools and fluxes, forest sites had significantly lower mineralization rates in May. This difference in the early growing season resulted in lower cumulative N mineralized annually in forest (14.3 mg/g/yr) compared to prairie to (18.1 mg/g/yr). These basic shifts in ecosystem patterns and processes may alter regional biogeochemistry and carbon storage in eastern Kansas.

Keywords: Juniperus virginiana, land cover change, C storage, tallgrass prairie

This abstract is being presented at: 2:45 PM in session:
Oral Session #67: Decomposition Processes.