In order to simulate and predict the suitable habitat distribution of rare and endangered Dipterocarpaceae tree species in China, conduct conservation priority area and conservation GAP analysis, and to provide a basis for their protection and management.

Based on climate, terrain, soil, and human impact factors, MaxEnt model optimized was used with R language to simulate and predict the suitable habitats and changing trends of eight rare and endangered Dipterocarpaceae trees in China. The Marxan model was combined to identify priority areas for the protection of rare and endangered Dipterocarpaceae tree species and conducted a protection GAP analysis.

The results showed that: 1) The optimized MaxEnt model simulated the suitability zone of various tree species with high accuracy, with AUC values greater than 0.971; 2) Rare and endangered Dipterocarpaceae plants in China are mainly distributed in southern tropical regions such as Yunnan, Hainan, and Guangxi, with a relatively concentrated distribution range; 3) Annual mean temperature, isothermality, and human impact factors are the dominant factors affecting the distribution of the suitable habitat of Dipterocarpaceae tree species. Among these, annual mean temperature has the greatest impact on Dipterocarpaceae tree species, with an average contribution rate of 52.9%; 4) Under the SSPs126 and SSPs585 scenarios, the suitable areas for Dipterocarpus retusus, Hopea chinensis, Parashorea chinensis, Vatica mangachapoi decrease by 0.29% to 60.00%, and the center of gravity of the suitable areas shifts southwestward. Shorea assamica and Vatica guangxiensis expand by 8.60% to 52.22%, migrating northwest and northeast, respectively. The suitable areas for Hopea hainanensis and Hopea reticulata land decrease by 21.70% and 1.61%, respectively, under the SSPs126 scenario, and expand by 26.14% and 13.01%, respectively, under the SSPs585 scenario, with their centers of gravity shifting northeastward; 5) The priority areas for the protection of rare and endangered tree species of the Dipterocarpaceae family are mainly distributed in southern Yunnan Province and central Hainan Province. Currently, the protected area is only 0.515 6×10⁴ km².

The optimized MaxEnt model can effectively predict the suitable habitats of various tree species in the Dipterocarpaceae. The priority suitable habitats are not sufficiently protected, so efforts should be made to strengthen their protection and expand the distribution range of each tree species.

The rare and endangered species of Cupressaceae in China are the key wild plants under national protection. To predict their potential distribution in different climate scenarios in China in the future, we hope to provide scientific basis for the management and protection of the species.

Based on the geographic distribution information of 13 tree species and 37 environmental factors data, the MaxEnt model optimized by R language was used to analyze the dominant environmental factors affecting the distribution of their potential habitat areas and their responses under climate change.

1) After the optimization of MaxEnt model, the AUC values of each tree species were all greater than 0.9, indicating that the prediction accuracy of the model was excellent. 2) The distribution range of the 13 tree species were relatively narrow, except for the Thuja koraiensis mainly distributed in the northeast Changbai Mountain area, the other tree species mainly distributed in the Qinling Mountains and Huaihe River south area.3) The key environmental factors affecting the distribution of tree species were: precipitation of the driest month (BIO14, PC=35%) > temperature annual range (BIO7, PC=17.1%) > altitude (ALT, PC=9.2%) > isothermality (BIO3, PC=8.5%) > slope (SLO, PC=7.2%) > minimum temperature of the coldest month (BIO6, PC=5.3%). 4) Under the future climate scenario, with the increase of carbon emission concentration, the total habitat area of Cupressus gigantea, Cupressus torulosa, Calocedrus macrolepis, Taiwania cryptomerioides and Xanthocyparis vietnamensis would show expanding trends. The total suitable areas of Glyptostrobus pensilis, Thuja sutchuenensis, Calocedrus rupestris, Chamaecyparis formosensis, Fokienia hodginsii and Thuja koraiensis would show decreasing trends. The total suitable area of Metasequoia glyptostroboides and Cupressus chengiana would show different expanding and decreasing trends under different climate scenarios.

The optimized MaxEnt model could well simulate the response of rare and endangered Cupressaceae species to climate change, and the distribution of suitable areas of each species was mostly discontinuous. It is suggested to expand the range of suitable areas and strengthen the protection of their habitats.