不同气候变化情景下荒漠草原生态系统碳动态模拟

荒漠草原生态系统对气候变化十分敏感,但其碳循环过程如何响应气候变化尚不明确。基于Biome-BGC模型和1958—2017年的气象观测资料,模拟了宁夏盐池荒漠草原生态系统在4种不同气候情景下的碳储量变化。结果表明:(1)4种气候情景下,盐池荒漠草原生态系统年均总碳储量在2.3208—2.3652 kg/m^2,土壤碳储量占总碳储量的94.03%,枯落物与植被碳储量分别占4.03%和1.94%。(2)近60 a间,基准情景下的土壤碳储量以每年0.0020 kg/m^2的速度累积,总碳储量呈波动性上升趋势。(3)植被、枯落物碳储量的年内变化与季节变化紧密相关,土壤碳储量在夏秋季较低,冬春较高。(4)单独的气温升高会导致土壤碳、植被碳及枯落物碳储量的略微降低,而单独降水波动增加会导致碳储量的明显增高,二者综合作用会导致碳储量的升高;此外,枯落物碳储量对气候变化的响应最敏感,其次是植被碳储量,土壤碳储量对气候变化的响应敏感度最低。研究结果揭示了荒漠草原碳储量随不同气候变化情景的变化规律,可为地方政府制定应对气候变化策略和生态恢复政策提供科学依据。

Carbon dynamic simulation of desert steppe ecosystem in different climate scenarios

Desert steppe ecosystems are sensitive to climate change. How does the carbon cycle respond to climate change is still ambiguous. This study simulated the carbon dynamic of desert steppe ecosystems in four kinds of climate scenarios using the Biome-Bio Geochemical Cycles (Biome-BGC) model based on meteorological data set from 1958 to 2017 in Yanchi county, Ningxia province. The results indicated that the average annually total carbon storage of desert steppe ecosystem ranged from 2.3208 kg/m² to 2.3652 kg/m² in the four climate scenarios. The soil carbon storage accounts for 94.03% of the total carbon storage. The litter and vegetation carbon storage account for 4.03% and 1.94% of the total carbon storage, respectively. In the past 60 years, the soil carbon storage in the benchmark scenario, which means in the scenario without climate change, accumulated at the rate of 0.0020 kg/m² per year while the total carbon storage presented a rising trend in fluctuation. The annual change of vegetation and litter carbon storage were closely related to the change of seasons. The soil carbon storage was lowest in summer and autumn over the whole year. The increasing temperature resulted in the minor decrease of a variety of carbon storage, whereas, the increasing of precipitation led to the significant rise of these carbon storages. Therefore, the combination of temperature and precipitation explains the increment of carbon storage in climate change. In addition, the litter carbon storage is the most sensitive kind of carbon to climate change, followed by vegetation carbon storage and soil carbon storage. The results revealed the changing laws of carbon storage in desert steppe ecosystem in various climate scenarios. These can provide scientific basis for local governments to adopt proper strategies for adapting climate change and to make policies for the ecological restoration.