三江源区生态系统和土壤保持服务对未来气候变化的响应特征

Response characteristics of ecosystems and soil conservation services to future climate change in the Three-Rivers region, China

气候变化条件下的生态系统响应特征对生态系统服务的提升和生态环境保护具有重要意义。现有气候变化评估多以全球或区域大尺度研究为主,不适合局地小尺度。以2015年为基准,根据局地特征改进了综合顺序分类系统(CSCS),模拟了未来不同温室气体排放模式下三江源地区自然植被分布,同时分析了植被覆盖度及土壤保持功能的时空变化。研究结果表明:(1)在2080年的不同排放情境下,三江源地区的降水和气温增长主要发生在生长季(5-9月)和半湿润地区,其中,高排放情境的增幅最大(42.21 mm和4.93℃);(2)三江源地区潜在自然植被主要由草地转化为森林,植被覆盖度和土壤保持服务在不同排放情境下均呈现由西北向东南增加的趋势,与水热规律一致,其中高排放情境的增幅最大,低排放最小;(3)利用三江源地区原生裸地演替特点和多年NPP改进的CSCS模型,模拟精度提高了24%。研究成果为局地小尺度生态系统气候响应特征提供了必要的手段和规律认识。

Assessing the response characteristics of ecosystems under climate change is critical to improve ecosystem services and protect ecological environments. Existing climate change assessment models are mostly based on large-scale(global and regional) research, and are not suitable for smaller geographical scales(local). Based on the data from 2015, this study improved the Comprehensive Sequential Classification System(CSCS) using local characteristics, simulated the natural vegetation distribution, and analyzed the spatial and temporal changes in vegetation coverage and soil conservation services in the Three-Rivers region under different future greenhouse gas emission patterns. The results indicated the following:(1)Under different emission scenarios in 2080, increased precipitation and temperature mainly occurred in the growing season(from May to September) and in semi-humid areas, and the largest increases occurred under the high-emission scenario(42.21 mm and 4.93 ℃).(2)The potential natural vegetation type was mainly transformed from grassland to forest, and increases in vegetation coverage and soil conservation services followed a descending trend from northwest to southeast under the three scenarios, which is consistent with the trend observed for water-heat conditions. The highest increases occurred under the high emission scenario and the lowest increases under the low emission scenario.(3)Accuracy was improved by 24% when the CSCS was revised using local glacial bare land succession characteristics and multi-year NPP(Net Primary Production). These results provided necessary methods for assessing the response characteristics of ecosystems under climate change at smaller geographical scales.