Carbon dioxide, methane and nitrous oxide dynamics in a northern hardwood forest under experimental manipulation of soil temperature

Heating cables were buried (5 cm depth) in four 10 x 10 m plots. Three plots (2.5, 5.0 and 7.5{dollar}spcirc{dollar}C above reference) were heated from May through September during 1993 and 1994. Gas fluxes {dollar}rm(COsb2, CHsb4{dollar} and N{dollar}sb2{dollar}O) were quantified using closed chambers and from concentrations in soil air samples (1994 only). Soil temperature, soil moisture and precipitation data were also monitored.; The reference plot had average fluxes (using closed chambers) of 71 and 74 mg CO{dollar}sb2{dollar}-C {dollar}rm msp{lcub}-2{rcub} hsp{lcub}-1{rcub}{dollar}, 60 and 52 {dollar}rmmu9 CHsb4{dollar}-C {dollar}rm msp{lcub}-2{rcub} hsp{lcub}-1{rcub}{dollar} (uptake), and 0.8 and 4.1 {dollar}rmmu g Nsb2{dollar}O-N {dollar}rm msp{lcub}-2{rcub} hsp{lcub}-1{rcub}{dollar} in 1993 and 1994, respectively. Carbon dioxide and N{dollar}sb2{dollar}O efflux (1994 only) and CH{dollar}sb4{dollar} uptake (both years) were negatively correlated with soil moisture. Soil temperature was positively correlated with CO{dollar}sb2{dollar} efflux and CH{dollar}sb4{dollar} uptake in both years, and with N{dollar}sb2{dollar}O efflux in 1994. The rate of response (Q{dollar}sb{lcub}10{rcub}{dollar}) of CO{dollar}sb2{dollar} efflux and CH{dollar}sb4{dollar} uptake to soil temperature was reduced with increased heat, suggesting the depletion of labile C.