Abstract:Species-environment relationships have always been a central issue in ecology and biogeography. The adaptation of species to a changing natural environment, including topographical and climatic factors, determines its geographic distribution. Accumulating evidence has revealed that Northeast China has experienced the greatest temperature increase since the 1950s, which in turn affected species distribution in this region. Broadleaved Korea pine (Pinus koraiensis) mixed forest (BKF) is the native forest type in the southern part of Northeast China. The distribution area of this species has shrunk substantially due to historical overexploitation. It is important for forest managers to be able to predict the potential geographic distribution of BKF based on species-environment relationships. Although the distributions of individual species in BKF such as P. koraiensis and Quercus mongolica have been reported previously, few studies have focused on the potential geographic distribution of BKF. In this study, four dominant tree species -P. koraiensis, Q. mongolica, Tilia amurensis and Fraxinus mandshurica, which together account for more than 80% of the growing stock in primary BKF, were selected to represent this forest type. Nineteen climatic and three topographic variables in Northeast China that are considered to be most likely influences on the geographic distribution of tree species were selected as environmental factors. To identify the major climatic and topographic factors controlling BKF distribution and simulate the potential geographic distribution of BKF under current climatic condition, the geographic distribution records of the dominant tree species, together with the environmental factors, were used in the Maxent model. The future geographic distributions of BKF were consequently predicted for the 2020s, 2050s, and 2080s, based on three kinds of climate change scenarios (SRES-A2, SRES-A1B, SRES-B1) published by the Intergovernmental Panel on Climate Change (IPCC). For the four dominant tree species, the simulations showed that the area under the curve indexes (AUC) were 0.925, 0.890, 0.859, and 0.847, respectively. All these values exceeded 0.8, which indicates that the models had a good predictive performance. The major environmental factors affecting the distribution of BKF included annual precipitation, precipitation seasonality, elevation, annual mean temperature and mean temperature of wettest quarter. For the entire region, 11.69% of the total area was identified to be of high suitability for BKF distribution, 23% was of low suitability, and 65.31% of the area was unsuitable. Under the A2, A1B, and B1 scenarios, the model predicted that both the southern and northern boundary of the high suitability area for BKF will shift northward. Overall, the high suitability area in this region was predicted to decrease, with the extent of the decrease depending on the severity of climate change. For example, under the A2 and A1B scenarios, the high suitability area in Northeast China will be less than 1% of the region by the 2080s. Overall, the results indicate that if no effective measures are taken to mitigate climate change, there is a great possibility that BKF will disappear from Northeast China.