人工灌丛化对荒漠草原生态系统碳储量的影响

Abstract

宁夏盐池县从20世纪70年代开始在荒漠草原上人工种植柠条灌木用以防风固沙和生态恢复，这一人为措施极大地改变了区域生态系统的植被结构和碳循环，而定量评估人工灌丛化对荒漠草原生态系统碳储量的影响，不仅能够揭示人类活动的碳循环反馈机制，而且可为地方政府生态治理提供理论指导。结合Biome-BGC模型和Logistics生长模型模拟了1958-2017年间荒漠草原人工灌丛化前后的碳储量变化，定量分析了人工灌丛化对生态系统碳储量和组分的影响。结果表明：（1）结合Biome-BGC模型和Logistics生长模型可以较准确地模拟出荒漠草原人工灌丛化过程中生态系统碳储量的变化。（2）人工灌丛化会快速改变荒漠草原的碳储量累积特征，柠条灌木种植后的快速生长阶段极大增强了生态系统的总碳储量，导致生态系统的碳储量特征由草地型向灌木型转变。（3）人工灌丛化改变了生态系统各类型碳储量的组分结构，其对地上植被和枯落物碳储量的影响非常明显，灌丛化后生态系统的植被和枯落物碳分别增加了6倍和1.76倍；因植被碳向土壤碳转化过程较慢，故人工灌丛化对地下土壤碳储量的影响在短期内较为微弱。以上结果显示，荒漠草原人工灌丛化能显著增强生态系统的碳固持能力，为碳中和及应对气候变化提供可行路径。;Cultivation of Caragana liouana, which is also known as planted shrub encroachment, has greatly changed the vegetation structure and carbon cycles of regional ecosystem in Yanchi County since 1970. However, there are insufficient studies to quantitatively evaluate the effects of this anthropogenic measurement on carbon storage in the desert steppe ecosystem. Meanwhile, the work to understand the effects of planted shrub encroachment on carbon storage of desert steppe ecosystem not only expose the feedback mechanism of carbon cycle on the anthropogenic activity but also provide a scientific basis for local government on the ecological restoration project. In this study, we combined Biome-BGC and Logistics growth model to simulate the carbon storage dynamics in desert steppe before and after planting shrub during 1958-2017, and quantitatively analyzed the effects of the planted shrub encroachment on 4 kinds of carbon storage in the ecosystem. The results are as follows:(1) combination of Biome-BGC and Logistics growth model could accurately simulate the carbon storage dynamic changes during the process of the planted shrub encroachment in the desert steppe ecosystem. (2) Characteristics of carbon storage accumulation were changed a lot by planting shrubbery. Rapid growth stages of Caragana liouana greatly enhanced the total carbon storage of desert steppe ecosystem, while led to the transformation from grassland to shrub ecosystem. (3) The planted shrub encroachment changed the ratio of various types carbon in total carbon storage, especially affected vegetation and litter carbon storage, which significantly increased by 6 times and 1.76 times, respectively, while the soil carbon storage has not changed clearly in the short term, because the conversion process of vegetation carbon to soil carbon was slow. These results indicated that the planted shrub encroachment could significantly enhance the carbon sequestration capacity of the desert steppe ecosystem, and provide a feasible path to carbon neutrality and addressing climate change.