Variations of soil respiration rate and its temperature sensitivity among different land use types in the agro-pastoral ecotone of Inner Mongolia

Abstract

Aims Our objectives are to compare soil respiration rate and its temperature sensitivity at different land use types and discuss soil respiration response to soil temperature (Ts) and soil water content at different soil depths. Methods Periodic measurements of soil respiration rates (Rs) were made during August–October 2009 with a LI-8100 portable automated soil CO2 flux system in three agro-pastoral ecotone land use types: cropland, aban-doned cultivated land and grazing enclosure. Soil temperature and soil water content at 0–5, 5–10 and 10–15 cm depths were measured simultaneous adjacent to the soil collar. Important findings Rs is significantly different among the three land use types and greatest in cropland. Rs ex-hibited a unimodal curve during 6:00–18:00, with a maximum during 12:00–15:00. Rs decreased with Ts, so Rs was significantly higher in August than in September and October. With the Van’t Hoff model, we concluded there is a positive, exponential relationship between measured Ts and Rs. In addition, temperature sensitivity of soil res-piration (Q10), which is derived from the Van’t Hoff model, was largest in cropland. In contrast, Rs was negatively related to soil water content in different soil depths at the sites.