Boundary Shift of Potential Suitable Agricultural Area in Farming-grazing Transitional Zone in Northeastern China under Background of Climate Change During 20th Century

摘要

Climate change affected the agricultural expansion and the formation of farming-grazing transitional patterns during historical periods.This study analyzed the possible range of the boundary shift of the potential suitable agriculture area in the farming-grazing transitional zone in the northeastern China during the 20th century.Based on modern weather data,1 km-resolution land cover data,historical climatic time series,and estimation by using similar historical climatic scenes,the following was concluded:1)The climate conditions of suitable agriculture areas in the farming-grazing transitional zone in the northeastern China between 1971 and 2000 required an average annual temperature above 1℃or≥0℃accumulated temperature above 2500℃–2700℃,and annual precipitation above 350 mm.2)The northern boundary of the potential suitable agriculture area during the relatively warmer period of 1890–1910was approximately located at the position of the 1961–2000 area.The northern boundary shifted back to the south by 75 km on average during the colder period of the earlier 20th century,whereas during the modern warm period of the 1990s,the area shifted north by 100km on average.3)The western and eastern boundaries of the suitable agriculture area during the heaviest drought periods between1920s and 1930s had shifted northeast by 250 km and 125 km,respectively,contrasting to the boundaries of 1951–2008.For the wettest period,that is,the 1890s to the 1910s,the shift of western and eastern boundaries was to the southwest by 125 km and 200 km,respectively,compared with that in the 1951–2008 period.This study serves as a reference for identifying a climatically sensitive area and planning future land use and agricultural production in the study area.