With BIOME-BGC Model On Carbon Exchange Of Grassland Ecosystem In The Semi-arid Loess Plateau

Grassland occupied 20% area of the world’s land and mainly in arid and semi-arid regions, grassland carbon cycle is mainly limited by precipitation and plays an important regulatory role on terrestrial ecosystem. Study on response of carbon cycle to precipitation changes can provide a theoretical basis and technical support to grassland ecosystem carbon sink prediction and management in semi-arid region under the context of global change. We simulate and analyze the response of seasonal and inter-annual changes of GEP、NEE、Re and Rs on precipitation change with BIOME-BGC model in typical grassland ecosystem in semi-arid Loess Plateau. This research predicted the grassland carbon cycle changes under three kinds of temperature gradient and nine kinds of precipitation patterns rely on the meteorological date of past 50 years and the future global climate changes prediction of IPCC. There are main conclusions:(1) Observed and simulated carbon exchange were significant positive correlation. It demonstrated that BIOME-BGC model are feasible in study site.(2) The result of daily and seasonal variation of GEP、NEE、Re and Rs were raised with increased precipitation in 2013~2015. The maximum result were mainly seen in May、June、July, and it would postponed with the increase in precipitation.(3) The primary factor that influent grassland ecosystem carbon exchange is precipitation in past 50 years of this study site. The simulated GEP 、Re and Rs are significant positive correlation with precipitation(P<0.05), NEE showed lower positive correlation.(4) The simulated result of grassland ecosystem carbon exchange under 27 climate scenarios demonstrated: the maximum GEP、NEE、Re appeared if precipitation decreased in draught season and temperature unchanged; if the temperature changed, GEP in normal precipitation scenario was highest; the maximum Rs appeared and the ecosystem carbon were released if precipitation increased in wet season.