Monday, 6 October 2008: 2:30 PM
George R. Brown Convention Center, 361AB
Silvopastoral systems integrate trees in pasture production systems. The contribution of these trees to enhance soil carbon (C) storage is in these land-use systems is not known. To quantify the relative soil C contribution from woody vegetation (C3) vs. warm-season grass vegetation (C4) in silvopastoral systems, soil samples were collected from silvopastures of slash pine (Pinus elliottii) + bahiagrass (Paspalum notatum), and adjacent open pasture at six depths up to 125 cm, at two sites, representing Spodosols and Ultisols. The plant sources of C in whole soil and three soil fraction-sizes (250 – 2000, 53 – 250 and <53 µm) of each soil layer were traced using stable C isotope signatures. In both soil orders, the C3 plant (slash pine) contributed more C than the C4 plant (bahiagrass) at all soil depths, particularly at the lower depth. In the relatively stable size fraction (<53µm), higher proportion of C was derived from tree components (C3 plants) in both pasture systems. The results suggest that the tree based-pasture system has greater potential for C sequestration compared with the treeless system.