关键词: 气候适宜性, MaxEnt模型, 气候变化, 时空特征, 油茶

Abstract:

Based on research into climate suitability and employing a species distribution model, this paper examines climatic data from six periods from the mid-Holocene (MH), 1970-2000 (the 1980s), RCP4.5 and 8.5 under 2041-2060 (2050s4.5, 2050s8.5) and 2061-2080 (2070s4.5, 2070s8.5), combined with data from Camellia oleifera specimens. The study uses the MaxEnt model to analyze the temporal and spatial characteristics of the suitability of C. oleifera growth under climate change scenarios. The suitability results are divided into four levels, from low to high, and the spatial distribution changes of the suitability of each transition period, the change of the northern boundary and the geometric center, and the displacement of the most suitable area are analyzed. The results show that: 1) According to the specimens and growth habits, C. oleifera is mainly distributed in the hilly areas of southern China, with latitude and longitude ranging from 18°31' to 33°15' N and 101°34' to 121°51' E, respectively, and the area is mainly in the subtropical East Asian monsoon climatic belt and has plenty of sunshine and heat. 2) The area under the curve (AUC) values of the training data set and the test data set of the MaxEnt model are 0.848 and 0.817, respectively, and the evaluation results reach the "good" standard, so that this model can be used for climate suitability analysis for the growth of C. oleifera. Taking the distribution probability P≥0.35 as the standard, the annual precipitation ≥1 100 mm, precipitation of the wettest quarter ≥550 mm, a mean temperature of the warmest quarter ≥20℃, a temperature seasonality <8.9, precipitation of the driest month ≥15 mm, a mean temperature of the wettest quarter 17-28℃, and a mean temperature of the coldest quarter ≥4℃ are the seven main environmental factors and ranges suitable for the growth of C. oleifera. Their contribution rates are all over 4%, and the cumulative contribution rate reaches 90.1%. 3) The areas with the highest climate suitability for C. oleifera in China are mainly south of the Yangtze River and east of the Yunnan-Guizhou Plateau, with a range of south of 30°N and east of 107°E. In general, the suitable level and above accounted for 34.9%-61% of the study area, and Hunan, Jiangxi, and Guangdong areas are the most suitable. Concerning the suitability changes, the southwest region fluctuates in space, and the most suitable area in the southeast hilly area is relatively stable. The areas of stable type and decrease type account for a relatively high proportion, which is 58.1%-71.5% and 9.3%-33.6%, respectively. 4) The northern boundary of the most suitable region for C. oleifera mainly lies between 24 ° N and 33 ° N in the central subtropical zone, which varied greatly in Qinling Mountains, Chongqing, Guizhou, and Guangxi in different periods. On the whole, it moved to the south from the middle Holocene to the 1980s, and moved northward from the 1980s to the 2050s and 2070s. The geometric center and displacement shifted to the East and North as a whole, and the most suitable center was located in Chenzhou, Hunan Province, in the middle Holocene. In the 1980s, it moved southeast to Shaoguan, Guangdong Province, in the 2050s, it will move northeast to Ji'an, Jiangxi Province, and in 2070s, it will move to the southwest and northeast in the RCP4.5 and 8.5 scenarios, but will still be present in Ji'an. 5) When climate scenario data and the MaxEnt species distribution model are used to analyze the temporal and spatial characteristics of C. oleifera climatic suitability in southern China, the results have a good correspondence with similar research results and China's C. oleifera production statistics. This correlation indicates that the results are reliable and can be used as a reference for C. oleifera planting divisions.

Key words: climatic suitability, MaxEnt model, climate change, temporal and spatial characteristics, Camellia oleifera