| Since the 20th century,the global climate has shown a major trend of warming,and climate is considered to be the most important environmental factor affecting plant distribution.In the context of climate change,the potential distribution habitats of plants will change accordingly,and therefore it is necessary to predict the effects of climate change on the potential geographic distribution patterns of plants.Chinese fir(Cunninghamia lanceolata(Lamb.)Hook.)is a fast-growing timber species endemic to southern China and plays a pivotal role in plantation forest production practices.In this study,four ecological niche models(Maxent,GARP,Bioclim,Domain)were used to predict the potential suitable habitats of Chinese fir in China under the present climate scenario,and through the comprehensive evaluation of the prediction results of the four models,the model with the best performance in the prediction was selected.The model was then used to predict the potential suitable habitats for Chinese fir in the future 2050s(2040-2060)and 2070s(2060-2080)different climate scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0 and SSP5-8.5),and to evaluate the climatic factors that limit the distribution of Chinese fir,and combined with the land use type map,the optimal afforestation areas for Chinese fir in the present and future were obtained.The following key findings were obtained:(1)The Maxent model has the lowest complexity and degree of overfitting after ENMeval package optimization parameters,and its optimization parameters are RM=0.5 and FC=LQ.The average AUC values of the predictions of the four ecological niche models were listed in order from largest to smallest:Maxent>Bioclim>Domain>GARP,among which the predictions of the Maxent model had higher accuracy and stability,and the potential suitable habitats of the Chinese fir predicted by it under the present climate scenario were most consistent with the actual situation.Therefore,the Maxent model was selected as the optimal model and participated in the prediction of potential suitable habitats for future.(2)Under the present climate scenario,the potential suitable habitats of Chinese fir are mainly distributed in the subtropical regions of China,of which the high suitable habitats are concentrated in the central and southern regions of the subtropics,which is the most suitable area for the growth of Chinese fir,and it is suitable for the planting and cultivation of large-diameter high-quality Chinese fir.The moderate suitable habitats are distributed in the north and west of the subtropics,where the climate suitability of Chinese fir is low,and it is recommended to carry out a Chinese fir cultivation mode based on short-term small and medium-diameter timber.Low suitable habitats are mainly distributed in the southern warm temperate zone and the central region of Yunnan Province.The climate of Chinese fir is very low,and it is not recommended to carry out large-scale planting activities of Chinese fir here.(3)Under different climatic scenarios in the 2050s and 2070s,the area of high suitable habitats of Chinese fir showed a decreasing trend,indicating that climate change will have a certain negative impact on the suitability of Chinese fir.However,on the whole,the suitability in more than 90%of the suitable habitats remains stable,indicating that the impact of climate change on the potential geographical distribution of Chinese fir is limited and does not threaten its survival.Under the background of climate change,the boundary of the potential suitable habitats of Chinese fir expands to the north and shrinks to the south,the suitability of some high-altitude areas increases,and the centroid of the high-suitable area migrates northward,indicating that the potential suitable area of Chinese fir shows a trend of migration to the north and to high-altitude areas.(4)The potential geographical distribution of Chinese fir under modern climatic conditions is mainly affected by temperature factors(minmum temperature of coldest month,maxmum temperature of warmest month)and precipitation factors(annual precipitation,precipitation of driest month),which correspond to the range distribution suitable for the growth of Chinese fir,which are 1.01-9.76℃ in the minmum temperature of coldest month,28.94-41.30℃ in the maxmum temperature of warmest month,1358.34-3258.80 mm in the annual precipitation,and 28.62-125.05 mm in the precipitation of driest month,respectively.The maxmum temperature of warmest month is the climate variables with the highest degree of dissimilar compared with modern times under future climate change,and are also the most important drivers of changes in the potential suitable habitats of Chinese fir in the future.(5)Under modern climatic conditions,the optimal afforestation area of Chinese fir is 69.99 ×104 km2,which is mainly distributed in Hunan,Jiangxi,Zhejiang,Fujian,Guangdong,Guangxi and Taiwan provinces.In addition to existing woodlands,afforestation activities in non-forested areas may be considered in high-cover grasslands.In the 2050s and 2070s,the optimal afforestation area of Chinese fir was 59.78 × 104 km2 and 59.93 × 104 km2,respectively,which was reduce 10.21 × 104 km2 and 10.06 × 104 km2 compared with modern times,and the areas reduced in the two years were mainly concentrated in Sichuan,Chongqing,Guizhou and other places in the southwest region,as well as the southern regions of Guangdong and Guangxi.The results of this study obtain the distribution of potential suitable habitats and optimal afforestation areas of Chinese fir in China under different climate scenarios in the present and future,explore the impact of climate change on the distribution of potential suitable habitats of Chinese fir,analyze the main climatic factors that limit its distribution,which can provide a scientific theoretical basis for the long-term planning and planting of current and future Chinese fir plantations in China,and have far-reaching significance for the large-scale promotion and application of Chinese fir in China and the stability and sustainable development of plantation ecosystems. |
