Effects of short-term warming and increasing precipitation on soil respiration of desert steppe of Inner Mongolia

Abstract

Aims Our objective was to examine the effects of global warming inducing environmental and biological changes on soil respiration of desert steppe. Methods We used infrared heaters to carry out the interactive simulation of warming and increasing precipitation in a desert steppe of Inner Mongolia from June to September 2011. Our experimental design was set up with two temperature levels (control and warming) and three precipitation treatments (control, 15% and 30% increase of the average precipitation during 1987–2007), using a complete randomized block arrangement. Soil respiration rate was measured by a LI-8100 carbon flux system in these six different treatments. We analyzed the relationships between soil respiration and environmental factors, aboveground biomass, and belowground biomass at different soil layers (0–10, 10–20 and 0–20 cm). Important findings Soil respiration in the desert steppe reached its peak value in the middle of the growing season. The average soil respiration rate of the desert steppe from July to August was 1.35 μmol CO 2 ·m –2 ·s –1 . The soil respiration rate was 2.08 and 0.63 μmol CO 2 ·m –2 ·s –1 in July and August, respectively. Increasing soil moisture and temperature significantly influenced daily soil respiration, but their interaction had no significant effect on soil respiration. Soil moisture had greater impact on monthly soil respiration than soil temperature. Soil respiration rate showed a power function relationship with belowground biomass at different soil depths. The belowground biomass at 0–10 cm soil was the major part of the belowground biomass and could explain more variation of soil respiration rate (79.2%) than that at 10–20 cm (31.6%). Under the future climatic changes scenarios, soil moisture was a principal environmental factor affecting plant biomass, while belowground biomass was a major biological factor controlling soil respiration in the desert steppe. Soil moisture might control the heterogeneity of soilrespiration by influencing the distribution of belowground biomass at different soil depths.