Dynamic characteristics of suitable forage grass habitats on the Qinghai-Tibet Plateau under climate change

Determining the long-term impacts of climate change on suitable growing areas for highland forage is important for Plateau animal husbandry, facilitating a sustainable balance between grass and livestock. In this study, the spatial distribution of potential suitable zones for Elymus sibiricus, E. nutans, and Stipa purpurea were simulated using ArcGIS and the maximum entropy model (MaxEnt). The main environmental factors affecting forage distribution on the Qinghai-Tibet Plateau and potential suitable area distributions and spatial pattern changes of forage grass on under paleoclimate (last interglacial period, last glacial maximum, middle Holocene), present (1970－2000) and, future climate (80 years RCP 2.6 and RCP 8.5, RCP as a representative concentration pathway in future climate models) scenarios were obtained. The principal climatic factor affecting the distribution of E. sibiricus and E. nutans was temperature, while the main climatic factor affecting the distribution of S. purpurea was precipitation; S. purpurea had the strongest cold and drought tolerance. From the last interglacial period to the middle Holocene, suitable growth areas for E. sibiricus and E. nutans increased, while that of S. purpurea decreased. In the future, suitable growth areas for E. sibiricus and E. nutans will increase and expand to the alpine steppe, while the suitable area of S. purpurea will decrease. At present, E. sibiricus and E. nutans are mainly distributed in humid areas of the southeastern Qinghai-Tibet Plateau, while S. purpurea is mainly distributed in arid areas of the Plateau. Under RCP 2.6 and RCP 8.5 scenarios, there are differences in the centroid locations of suitable growing areas for E. sibiricus, E. nutans, and S. purpurea, which are affected by the spatial distribution of suitable growing areas. The centroid positions of E. sibiricus and E. nutans will shift to higher latitudes, while that of S. purpurea will only change a small amount. At present, the most suitable mixed sowing areas of the three forage grasses are mainly distributed around the Hehuang Valley. However, the area of suitable mixed sowing area of forage grass will likely decrease in the future, mainly because the suitable area of S. purpurea will decrease.