青藏高原多年冻土区典型高寒草地生物量对气候变化的响应

Response of Alpine Cold Ecosystem Biomass to Climate Changes in Permafrost Regions of the Tibetan Plateau

多年冻土区冻土生态系统对气候变化极其敏感,利用在长江黄河源区实测的高寒草甸和高寒草原植被生物量数据以及青藏高原降水、气温以及地温等的空间分布规律,建立了长江黄河源区高寒草甸与高寒草原等主要高寒生态系统地上与地下现存生物量对气候要素变化的多元回归模型.预测分析表明:如果未来10 a气温增加0.44℃.(10a)-1,在降水量不变的情况下,高寒草甸和高寒草原地上生物量分别递减2.7%和2.4%,如果同时降水量小幅度增加8 mm.(10a)-1,则地上生物量可基本保持现状水平略有减少;在气温增加2.2℃.(10a)-1,在降水量不变的情况下,高寒草甸和高寒草原地上生物量年分别平均减少达6.8%和4.6%,如果同期降水量增加12 mm.(10a)-1,高寒草甸地上生物量可基本维持现状水平略有增加,而高寒草原地上生物量则递增5.2%.高寒草原植被地上生物量对气候增暖的响应幅度显著小于高寒草甸,而对降水增加的响应程度大于高寒草甸.明确高寒草地植被生物量随气候变化的演变趋势,对于青藏高原生态环境保护和研究气候变化对青藏高原生态系统碳循环和河源区水循环的影响具有重要意义.

Alpine cold ecosystem in permafrost environment is quite sensitive to climatic change. A few research results shown that air temperature in the Tibetan Plateau will rise 2.2~2.6℃ in the future 50 years. Using the field ecosystem biomass data of alpine cold meadow and alpine cold steppe in the source regions of the Yangtze and Yellow Rivers, and the spatial models of precipitation, air temperature and ground temperature, a model was developed to analyze the impacts of climate changes on the alpine ecosystems biomass based on the statistics methods. The research results showed that the climate changes have different influence on the biomass of different alpine ecosystem. Supposed air temperature increases 0.44℃ and precipitation does not change in the recent 10 years, the alpine cold meadow hiomass and steppe biomass will decrease by 2.7% and 2.4%, respectively, and if precipitation increase 8 mm/10a at the same time, the biomasses of the two typical grasslands will almost the same as present statue. Supposed air temperature increases 2. 2℃. （10a）^-1 in the fu ture, the biomass of alpine cold meadow ecosystem will decrease at the average of 6.8%, if precipitation dose not change. However, the biomass of al pine cold steppe will appear a certain increase （about 5.2%） and alpine cold meadow biomass will keep approximately the same as at present when precipitation increases 12 mm·（10a）^-1 at the same time. The response of alpine cold steppe biomass is significantly weaker than the alpine cold meadow biomass to air temperature change, but greater to precipitation changes, It is vitally important to definitely recognize the response characteristics of alpine cold ecosystems to climate changes and dynamic tendency of the ecosystem biomass for mainaining the stability of alpine cold ecosystems in he plateau, and is useful to research the carbon nd water cycles of alpine cold ecosystems in the lateau.