关键词: 长序榆, MaxEnt优化模型, 适生区预测, ENMeval, 气候变化

Abstract: Ulmus elongatais one of the key rare and endangered species in China, with important scientific and economic values. Due to natural and anthropogenic disturbances, the natural resource of U. elongata is rare and scattered. The geographical distribution of plants is profoundly affected by climate change. In this study, we modeled the impacts of climate change on the geographical distribution of U. elongata in order to provide theoretical basis for the natural resource protection and introduction of this species. Based on the data of 42 natural distribution sites of U. elongata in China and 16 environmental factors, the MaxEnt optimization model and geographic information system were used to construct the suitable distribution model. We analyzed the key environmental factors affecting the potential suitable distribution of U. elongata and predicted the potential distribution area during the last interglacial, last glacial maximum, mid-Holocene, current and the climate scenarios of RCP2.6 and RCP8.5 in the future 2050s (2041-2060) and 2070s (2061-2080). Our results showed that the model was accurate and the predicted distribution range was consistent with the actual distribution when the feature combination (FC) was HPT (H: Hinge; P: Product; T: Threshold) and the regularization multiplier (RM) was 2. A comprehensive evaluation showed that precipitation in the driest month, annual precipitation, elevation, topsoil pH, minimum temperature of coldest month and maximum temperature of warmest month played important roles in the potential geographical distribution of U. elongata. Under the RCP 2.6 climate scenario, the increased temperature within 2 ℃ may provide a more suitable environmentfor U. elongata. Under the RCP 8.5 climate scenario, the centroid of U. elongata distribution will migrate from low latitude to high latitude from current to 2070s.

Key words: Ulmus elongata, MaxEnt optimization model, suitable area prediction, ENMeval, climate change.