Abstract:

Many studies have shown multiple confounding factors influencing soil respiration in the field, which often hampers a correct separation and interpretation of effects of soil temperature and soil water content on respiration. Undisturbed soil cores in the 0～20 cm upper depth were taken from a natural Quercus aliena var. acuteserrata stand in the transitional area of northern subtropics to warm temperate zone, and incubated under five gradients of soil temperatures(15、20、25、30、35 ℃)and soil water contents(0.20、0.25、0.30、0.35、0.40 kg·kg^-1 ). The soil respiration rates were measured when the soil temperatures and water contents met the experiment requests. Results indicate that there are significant effects of soil temperature, water content and their interaction on soil respiration rate(P<0.01). The soil respiration rate is positively correlated to soil temperature at 15～35 ℃, and the variation pattern of soil respiration rate with soil water content increase is unimodal curve, increasing at 0.20～0.35 kg·kg^-1 then decreasing at 0.35～0.40 kg·kg^-1. The highest soil respiration rate is under the condition of soil temperature at 35 ℃and soil water content at 0.35 kg·kg^-1 .The calculated Q₁₀ value based on soil temperature is 1.36～3.10(mean is 2.13), and decreases with soil temperature increase, the variation pattern of Q₁₀ with soil water content increase is same as soil respiration rate. The regression models indicate that the relationship between soil respiration rate and soil temperature is significant exponential function(P<0.01) and the relationship between soil respiration and water content is quadratic function, soil temperature and soil water content can explain 73.26 and 21.85 percent of variation in soil respiration rate respectively, they can together explain 86.40 percent of variations, the effect of soil temperature on soil respiration rate is greater than soil water content.

Key words: Quercus aliena var. acuteserrata forest, soil respiration rate, soil temperature, soil water content