Geographical Distribution Pattern And Dominant Environmental Factors Of Wild Impatiens L. Plants In Chin

Impatiens L.are rich in species,with peculiar flowers and high ornamental value,and are famous as ornamental flowers,and China is one of the centers of species diversity of Impatiens.In this study,we took wild Impatiens plants in China as the research object,and updated the list of wild Impatiens plants in China by systematically searching the literature related to the genus in China.The species diversity,endemism index,and similarity among provinces of wild Impatiens in China were statistically analyzed.Using Arc GIS software,we analyzed the species richness of wild Impatiens plants in China at provincial and county levels and the geographic distribution pattern of wild Impatiens plants in China.Based on the geographic distribution data of wild Impatiens in China obtained from multiple sources,combined with 19 bioclimatic data and one topographic data,the Maxent maximum entropy model was used to screen the dominant environmental factors affecting the distribution of Impatiens and analyze the response curves and threshold ranges of each dominant environmental factor to further predict the potential habitat of the subgenus Clavicarpa.The results of the study are as follows:(1)There are 358 species of two subgenera in China,of which 271 species are endemic to China,accounting for 75.5% of the total number of species,and 157 species are endemic at the provincial level,accounting for 43.7% of the total number of species.The province with the largest endemism index of wild Impatiens in China is Tibet,followed by Yunnan.At the county scale,there are 714 county-level administrative regions with wild Impatiens.The three county-level administrative regions with the highest species richness and endemism richness in China are Gongshan,Tengchong and Fugong counties in Yunnan Province,and the county with the highest endemism richness at the provincial level is Emeishan City in Sichuan.Yunnan,Guizhou and Guangxi are the three provinces with the largest distribution of the subgenus Clavicarpa,which is concentrated in the karst region at the border of Yunnan-Guizhou-Guizhou provinces.(2)Comparing the similarity among provinces,the highest similarity was found in Hunan and Jiangxi,and the lowest similarity was found in Tibet and Zhejiang.The vertical distribution pattern of species richness of wild Impatiens in China shows a single-peaked curve pattern,with species richness increasing and then decreasing with elevation.The highest species richness range is between 1200 and 1500 m,containing45.8% of the total number of Impatiens.The distribution of wild Impatiens in China generally shows a pattern of spreading from tropical subtropical regions to high latitudes and high altitudes,with the Hengduan Mountains in the broad sense,southern Tibet,Yunnan-Guizhou-Guangxi Karst region,Qinlin-Daba Mountain region and southeastern low mountainous areas being the main distribution areas of Impatiens in China.(3)Four dominant environmental factors affecting the distribution of wild Impatiens in China were obtained based on the cumulative contribution rate,namely,mean annual precipitation(bio12),min temperature of the coldest month(bio6),altitude(alt)and temperature annual range(bio7),and the cumulative contribution rate of these four environmental variables reached 93.7%.The mean annual precipitation(bio12)and min temperature of the coldest month(bio6)contributied >10%,which was the most important climatic factor influencing the distribution of Impatiens.The distribution of Impatiens shows a positive correlation with the minimum temperature of the coldest month,and the higher the minimum temperature of the coldest month,the higher the probability of the presence of Impatiens.When the altitude exceeds 4,000 m,the probability of the existence of species of the genus Impatiens gradually decreases.The probability of the presence of Impatiens species decreases sharply when the annual temperature range exceeds 30℃,indicating that the distribution of Impatiens species is more sensitive to the annual temperature change,and the larger the annual temperature change range,the lower the probability of the presence of Impatiens species.(4)The four most important environmental factors affecting the distribution of the subgenus Clavicarpa were obtained according to the cumulative contribution rate,namely,the driest monthly rainfall(bio14),the average annual rainfall(bio12),the altitude(alt)and the monthly average diurnal temperature difference(bio2),with a cumulative contribution rate of 93.7%.The presence probability of the subgenus Clavicarpa showed a positive correlation with the rainfall in the driest month,and the higher the rainfall in the driest month,the higher the presence probability of the species.The subgenus Clavicarpa has a greater overall demand for mean annual rainfall than the genus Impatiens.The distribution of the subgenus Clavicarpa was negatively correlated with the monthly mean diurnal temperature difference,and the greater the monthly mean diurnal temperature difference,the lower the probability of the species’ existence.The provincial and county-level distribution patterns of the subgenus Clavicarpa were generally similar to the predicted results of the species habitat.Combining the two results,the karst region at the border of Yunnan-Guizhou-Guangxi provinces is the center of the richness distribution of the subgenus Clavicarpa,and there is obvious spatial heterogeneity in the distribution pattern of the species.