[M-IS01] ENVIRONMENTAL, SOCIO-ECONOMIC, AND CLIMATIC CHANGES IN NORTHERN EURASIA

[MIS01-16] Quantifying the combined impacts of environmental factors and human activities on the Mongolian dryland ecosystem under the future climate scenarios

*江 嘉敏^1,2,3、黒崎 泰典⁴、衣笠 利彦⁴、Nandintsetseg Banzragch^3,4、篠田 雅人³ (1.理化学研究所、2.香川大学、3.名古屋大学、4.鳥取大学)

キーワード：Mongolia、Drylands、Climate change、Environmental factors、Human activities

People, who live in the Mongolian drylands, are primarily dependent on livestock rearing, and this livelihood is closely related to ecosystem dynamic processes (e.g., soil-plant-water relationships). Future climate projections in the Mongolian area showed a significant increase in temperature and a slight increase in precipitation by the end of the century. These combined effects of elevated temperature and variable precipitation on the Mongolian dryland ecosystem are still uncertain. To identify this uncertainty, a process-based DAYCENT ecosystem model was applied to predict vegetation dynamics over Mongolian grasslands under different climatological scenarios of the downscaling Coupled Model Intercomparison Project Phase 5 (CMIP5) datasets during 1980—2100. We used the DAYCENT model to quantitatively estimate the effects of environmental factors (i.e., water, temperature, and nutrients) and human effects (i.e., grazing) on plant productions. In the first step, two target sites in Mongolia (Tsogt-Ovoo in the desert steppe and Bayan-Unjuul in the steppe) were chosen to simulate under two climate scenarios (RCP4.5 and RCP8.5) of a downscaling CMIP5 dataset (HadGEM, Hadley Centre Global Environmental Model). The simulated aboveground biomass (AGB) was validated and showed a good agreement with a long-term field observation. Results of the simulated AGB, no significant difference between the two scenarios in the desert steppe indicates a weak climate effect whereas a lower value in the grazing case suggests that human activity may become a major factor. In the steppe, the simulated AGB in RCP8.5 suddenly decreases by half after 2040 and is 50% less than that in RCP4.5 by the end of this century (2100). This implied that environmental factors under climate change significantly impact vegetation dynamics. In the next step, we will quantify these different environmental factors not only at these two target sites, but also over Mongolian grasslands, and attempt to explore their temporal and spatial distributions at the 100-year scale.