Measurement and Modeling of the heterotrophic soil respiration response to temperature in grazing and grazing exclosure rangeland

Soil heterotrophic respiration, which is the result of soil organic matter decomposition, is affected by environmental factors, especially temperature. A variety of models have been proposed to understanding the respiration response of the soil to temperature and respiration sensitivity to temperature (Q10). The aim of this study was to evaluate the respiration response of soil to temperature variations using incubation technique and to examine variety of models in two different management systems. For this purpose, Intact soil samples were collected from a grazing and grazing exclosure in Fandoghlo Ardebil, incubated for 4 weeks at 10, 20 and 30 ° C temperature. Soil respiration was measured by alkaline adsorption method. Nonlinear regression method and The Levenberg-Marquardt algorithm were used to determine the parameters of models. Both ecosystem showed an exponential increase in Soil heterotrophic respiration with temperature. The rate of respiration in soil of grazing, at all three temperature levels, was higher than grazing exclosure. Most models describing the relationship between soil respiration and temperature showed a good fit to the experimental data, especially in the grazing exclosure. Q10 in the grazing (1.21) was higher than the grazing exclosure (0.97). In general, based on the coefficients of the models and the Q10 analysis, the Arrhenius model can be better than the others of model for expressing the relationship between soil respiration with temperature, as well as good numerical estimation for Q10 of soil.