Stabilization of carbon sequestration in a Chinese desert steppe benefits from increased temperatures and from precipitation outside the growing season

摘要

The carbon (C) dynamics of desert steppes play an important role in the C budget of temperate steppes. Using the Terrestrial Ecosystem Regional model (TECO-R) model for desert steppes, we examined the dynamics and potential driving mechanisms for C stocks at different temporal and spatial scales from 2000 to 2017 in northern China. The ecosystem C density averaged 2.73 kg C m(-2) and soil organic C accounted for 91.6%. The grassland biome stored 2.85 kg C m(-2), which is higher than the shrub biome (2.19 kg C m(-2)). The ecosystem storage increased by an average of 27.75 g C m(-2) yr(-1), with the fastest increase in the southeastern part of the study area. The grassland biome storage increased by an average of 33.54 g C m(-2) yr(-1), versus 25.74 g C m(-2) yr(-1) for the shrub biome. The desert steppe C stock totaled 288.29 Tg C, and increased at 3.09 Tg C yr(-1). An average of >45% of the aboveground biomass was browsed by livestock. The growing season precipitation was significantly positively correlated with changes in the C stock. Increasing temperature was negatively correlated with the C stock, especially for soil carbon. Precipitation was an important driving factor, but warming interacted with precipitation to affect C sequestration during the growing season. Outside the growing season, the increased precipitation and temperature stabilized C sequestration in the desert steppe. This improved understanding of feedbacks between the desert steppe's C cycle and climate will improve predictions of C dynamics in terrestrial ecosystems and of the impacts of climate change. (c) 2019 Elsevier B.V. All rights reserved.