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Soil CO2 efflux, soil organic matter and root development in newly planted loblolly pine plantations.
Maier, Chris1, Dougherty, Phillip2, Anderson, Pete1, 1 2
ABSTRACT- We measured soil CO2 efflux, soil carbon and root biomass in newly planted loblolly pine plantations in an effort to understand how site preparation, soil physical characteristics, microclimate and root development influenced soil carbon fluxes. Measurements were made in the coastal plain of South Carolina on five soil types that differed in drainage class and clay content. All sites were bedded creating three distinct micro-sites: beds, inter-beds and troughs. In each of these micro-sites, soil CO2 efflux (Sf), soil temperature, soil moisture (), root biomass (Rb), coarse (COM) and fine (FOM) organic matter and mineral soil carbon (Cms) and nitrogen (Nms) were measured quarterly for two years. There were significant site differences in COM, FOM, Cms and Nms. Mean Sf for all sites ranged from 0.5 to 2.0 mol m-2 s-1 during the winter to 6 to 10 mol m-2 s-1 during the summer. Soil temperature accounted for 62% of the variation in Sf across all sites; however, significant site differences existed in basal Sf (corrected to 20 oC) and Q10 (1.9 to 3.1). Basal Sf was negatively correlated to (r2 = 0.30 to 0.70). Within sites, COM, FOM, Rb, C, N and Sf were greater in the beds than in inter-beds or troughs. Rb was the single best variable explaining micro-site variation in Sf (r2=0.20 to 0.40). These results suggest that site-specific factors control soil CO2 efflux.
KEY WORDS: soil CO2 efflux, soil respiration, soil carbon, loblolly pine