Responses of trace gas fluxes and N availability to experimentally elevated soil temperatures Export

@article{1229, abstract = {We are conducting a field study to determine the long-term response of belowground processes to elevated soil temperatures in a mixed deciduous forest. We established 18 experimental plots and randomly assigned them to one of three treatments in six blocks. The treatments are: (1) heated plots in which the soil temperature is raised 5 degree C above ambient using buried heating cables; (2) disturbance control plots (cables but no heat); and (3) undisturbed control plots (no cables and no heat). In each plot we measured indexes of N availability, the concentration of N in soil solutions leaching below the rooting zone, and trace gas emissions (CO2, N-2O, and CH-4). In this paper we present results from the first 6 mo of this study. The daily average efflux of CO2 increased exponentially with increasing soil temperature and decreased linearly with increasing soil moisture. A linear regression of temperature and the natural logarithm of CO2 flux explained 92\% of the variability. A linear regression of soil moisture and CO2 flux could explain only 44\% of the variability. The relationship between soil temperature and CO2 flux is in good agreement with the Arrhenius equation. For these CO2 flux data, the activation energy was 63 kJ/mol and the Q-10 was 2.5. The daily average uptake of CH-4 increased linearly with increasing soil temperatures and decreased linearly with increasing soil moisture. Linear regression could explain 46\% of the variability in the relationship between temperature and CH-4 uptake and 49 of the variability in the relationship between soil moisture and CH-4 uptake. We predicted the annual CO2 flux from our study site in 1991 using two empirical relationships: the relationship between air temperature and soil temperature, and the relationship between soil temperature and CO2 flux. We estimate that the annual CO2-C flux in 1991 was 712 g/m-2 from unheated soil and 1250 g/m-2 from heated soil. By elevating the soil temperature 5 degree C above ambient, we estimate that an additional carbon flux of 538 g cntdot m-2 cntdot yr-1 was released from the soil as CO2}, author = {Peterjohn, W. T. and Melillo, J. M. and Steudler, P. A. and Newkirk, K. M. and Bowles, F. P. and Aber, J. D.}, citeulike-article-id = {1307276}, journal = {Ecological Applications}, keywords = {air\_temperature, availability, carbon, carbon\_dioxide, carbon\_flux, carbon\_fluxes, ch4, co2, deciduous, deciduous\_forest, disturbance, ecosystem, ecosystems, efflux, elevated, emission, emissions, energy, field, fif, flux, fluxes, forest, gas\_fluxes, global\_climate\_change, heat, index, indexes, linear\_regression, long-term, long-term\_response, marine, methane, moisture, n2o, responses, site, soil, soil\_moisture, soil\_temperature, temperature, trace\_gas\_emissions, trace\_gas\_fluxes, usa, wood}, number = {3}, pages = {617--625}, posted-at = {2007-05-19 02:18:50}, priority = {2}, title = {Responses of trace gas fluxes and N availability to experimentally elevated soil temperatures}, volume = {4}, year = {1994} }

TY - JOUR ID - 1229 L3 - citeulike-article-id:1307276 N2 - We are conducting a field study to determine the long-term response of belowground processes to elevated soil temperatures in a mixed deciduous forest. We established 18 experimental plots and randomly assigned them to one of three treatments in six blocks. The treatments are: (1) heated plots in which the soil temperature is raised 5 degree C above ambient using buried heating cables; (2) disturbance control plots (cables but no heat); and (3) undisturbed control plots (no cables and no heat). In each plot we measured indexes of N availability, the concentration of N in soil solutions leaching below the rooting zone, and trace gas emissions (CO2, N-2O, and CH-4). In this paper we present results from the first 6 mo of this study. The daily average efflux of CO2 increased exponentially with increasing soil temperature and decreased linearly with increasing soil moisture. A linear regression of temperature and the natural logarithm of CO2 flux explained 92% of the variability. A linear regression of soil moisture and CO2 flux could explain only 44% of the variability. The relationship between soil temperature and CO2 flux is in good agreement with the Arrhenius equation. For these CO2 flux data, the activation energy was 63 kJ/mol and the Q-10 was 2.5. The daily average uptake of CH-4 increased linearly with increasing soil temperatures and decreased linearly with increasing soil moisture. Linear regression could explain 46% of the variability in the relationship between temperature and CH-4 uptake and 49 of the variability in the relationship between soil moisture and CH-4 uptake. We predicted the annual CO2 flux from our study site in 1991 using two empirical relationships: the relationship between air temperature and soil temperature, and the relationship between soil temperature and CO2 flux. We estimate that the annual CO2-C flux in 1991 was 712 g/m-2 from unheated soil and 1250 g/m-2 from heated soil. By elevating the soil temperature 5 degree C above ambient, we estimate that an additional carbon flux of 538 g cntdot m-2 cntdot yr-1 was released from the soil as CO2 IS - 3 JF - Ecological Applications EP - 625 TI - Responses of trace gas fluxes and N availability to experimentally elevated soil temperatures VL - 4 SP - 617 KW - air_temperature KW - availability KW - carbon KW - carbon_dioxide KW - carbon_flux KW - carbon_fluxes KW - ch4 KW - co2 KW - deciduous KW - deciduous_forest KW - disturbance KW - ecosystem KW - ecosystems KW - efflux KW - elevated KW - emission KW - emissions KW - energy KW - field KW - fif KW - flux KW - fluxes KW - forest KW - gas_fluxes KW - global_climate_change KW - heat KW - index KW - indexes KW - linear_regression KW - long-term KW - long-term_response KW - marine KW - methane KW - moisture KW - n2o KW - responses KW - site KW - soil KW - soil_moisture KW - soil_temperature KW - temperature KW - trace_gas_emissions KW - trace_gas_fluxes KW - usa KW - wood AU - Peterjohn, WT AU - Melillo, JM AU - Steudler, PA AU - Newkirk, KM AU - Bowles, FP AU - Aber, JD PY - 1994/// ER -