Soil and microbial respiration in a loblolly pine plantation in response to seven years of irrigation and fertilization |
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| Authors: | Lisa Samuelson Reji Mathew Tom Stokes Yucheng Feng Doug Aubrey Mark Coleman |
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| Affiliation: | aSchool of Forestry and Wildlife Sciences, 3301 SFWS Building, Auburn University, Auburn, AL 36849-5418, USA;bDepartment of Agronomy and Soils, 201 Funchess Hall, College of Agriculture, Auburn University, Auburn, AL 36849-5412, USA;cWarnell School of Forest Resources, University of Georgia, 180 East Green St., Athens, GA 30602-2152, USA;dCollege of Natural Resources, University of Idaho, PO Box 441133, Moscow, ID 83844-1133, USA |
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| Abstract: | Because soil CO2 efflux or soil respiration (RS) is the major component of forest carbon fluxes, the effects of forest management on RS and microbial biomass carbon (C), microbial respiration (RH), microbial activity and fine root biomass were studied over two years in a loblolly pine (Pinus taeda L.) plantation located near Aiken, SC. Stands were six-years-old at the beginning of the study and were subjected to irrigation (no irrigation versus irrigation) and fertilization (no fertilization versus fertilization) treatments since planting. Soil respiration ranged from 2 to 6 μmol m−2 s−1 and was strongly and linearly related to soil temperature. Soil moisture and C inputs to the soil (coarse woody debris and litter mass) which may influence RH were significantly but only weakly related to RS. No interaction effects between irrigation and fertilization were observed for RS and microbial variables. Irrigation increased RS, fine root mass and microbial biomass C. In contrast, fertilization increased RH, microbial biomass C and microbial activity but reduced fine root biomass and had no influence on RS. Predicted annual soil C efflux ranged from 8.8 to 10.7 Mg C ha−1 year−1 and was lower than net primary productivity (NPP) in all stands except the non-fertilized treatment. The influence of forest management on RS was small or insignificant relative to biomass accumulation suggesting that NPP controls the transition between a carbon source and sink in rapidly growing pine systems. |
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| Keywords: | Pinus taeda Microbial respiration Microbial biomass Soil CO2 efflux Intensive forest management |
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