Soil respiration response to precipitation reduction in a grassland and a Mongolian pine plantation in semi-arid northeast China

Climate change is predicted to alter global precipitation regimes. However, the response of soil carbon and nitrogen cycles and soil microorganisms to precipitation reduction is poorly understood but is dependent on ecosystem type. To evaluate the impacts of reduced precipitation on soil respiration, soil inorganic nitrogen (i.e., NH4+-N and NO3--N), nitrogen mineralization, and soil microbial community composition, a precipitation manipulation experiment was initiated in a Mongolian pine plantation and a naturally restored grassland in semi-arid northeast China. Precipitation reduction led to decreases of soil respiration rates by 14 and 8% in 2014 and 2015 in the Mongolian pine plantation but no changes in the grassland. Soil inorganic nitrogen, ammonification and nitrification rate, and soil phospholipids fatty acids were not significantly changed by reduced precipitation but significantly differed between the two ecosystems and among growing seasons. Our results suggest that the impacts of precipitation reduction on soil respiration were different between the Mongolian pine plantation and the grassland, and that ecosystem type and growing season had more pronounced impacts on soil carbon and nitrogen cycles.