CARBON DYNAMICS OF THE CONSERVATION AND WETLAND RESERVE PROGRAMS

Data from the Conservation (CRP) and Wetland (WRP) Reserve Programs we re analyzed to quantify the carbon (C) dynamics of associated cropland converted to grassland or forestland. Land-area enrollments were mult iplied by grassland- and forestland-C densities to calculate C pools a nd fluxes 50 years into the future. The CRP began in 1986 and by 1996 consisted of 14.7 Mha (3.6x10(7) a) of grassland and 1.5 Mha (3.7x10(6 ) a) of forestland CRP1 scenario simulated the likely outcome of the C RP as contracts expire in 1996 with the return of 8.7 Mha (2.1x10(6) a ) of grassland and 0.4 Mha (9.9x10(5) a) of forestland to crop product ion. CRP2 scenario assumed that the CRP continued with no land being r eturned to agricultural use. CRP3 scenario was an expansion of CRP2 to include afforestation of 4 Mha (9.9x10(6) a) of new cropland. The WRP began in 1996 with 2 Mha (4.9x10(6) a) of river bottomland taken out of crop production and planted to hardwood trees. Conclusions of the r esearch were (1) that cropland converted to forestland gained C at a r ate about 7 times greater than cropland converted to grassland; (2) ma intaining the existing CRP grassland will provide a substantial C sequ estration potential because of the large area involved; and (3) affore station of additional cropland would increase the potential to sequest er atmospheric C for many years.