Research On Suitable Habitat And Community Characteristics Of Precious Tree Machilus Thunbergii

It is important for species protection,extension and plantation construction to understand the adaptive area,community characteristics and environmental factors that restrict the distribution of species.This study take 172 Machilus thunbergii position community sample plot in zhejiang province as the main research object,(1)integrate the data of 277 distribution points of Machilus thunbergii in the Chinese Herbarium,177 distribution points of Machilus thunbergii in Zhejiang were obtained by selecting out the missing and repeated data of sample sites and sample points,by using maximum entropy(Max Ent)model and Arc GIS spatial analysis technology,to predict the suitable area of 277 Machilus thunbergii distribution points in Chinese and 177 simulations of Machilus thunbergii in zhejiang,and to explore the influence of environmental factors on the distribution;(2)the TWINSPAN and CCA were used to analyze the species composition,interspecific relationship and community types of 172 Machilus thunbergii habitats in zhejiang province by combining interspecific association,ecological niche calculation and diversity index.Main findings include:(1)The maximum entropy value(Max Ent)model shows that the AUC results of the model in different time periods and different climate backgrounds are all greater than 0.9,indicating that the accuracy of the simulation and prediction results is excellent.The eastern part of the subtropical zone of China is the fitness area of the Machilus thunbergii.The total area is 118.47×104km2: the middle and high fitness areas are concentrated in the east of the wuyi mountains,luoxiao mountains,xuefeng mountains,nanling mountains and Taiwan mountains.With the climate change,the middle and high fitness areas migrate to the east,while the low fitness areas tend to expand to the west and north.The total area of Machilus thunbergii in the fitness area of zhejiang province is 9.22×104km2,and most areas have a high level of suitability,the high fitness area presents a continuous distribution,which is concentrated in the areas of kucangshan mountain,donggong mountain,xianxia mountain and putuo mountain in the east of zhejiang.(2)The average rainfall in the coldest season,the driest month and the average annual rainfall have the most significant influence on the distribution of Machilus thunbergii in the fitness area of China.The distribution of fitness area in Zhejiang province is related to the temperature difference of stable climate.The above indicates that the rainfall,especially in winter,and the suitable and stable temperature environment determine the geographical distribution of Machilus thunbergii.(3)A total of 167 species of plants of 120 genera and 54 families were recorded in the native communities of Machilus thunbergii,mainly plants of the family fagaceae,family camphoraceae,family magnoliaceae,family rosaceae,etc.The main dominant species included Cunninghamia lanceolata,Schima superba,Cyclobalanopsis glauca,Pinus massoniana,Castanopsis eyrei,Lithocarpus glaber,etc.The larger niche width-values in the community were Cunninghamia lanceolata,Machilus thunbergii,Schima superba,Cyclobalanopsis glauca,Castanopsis eyrei,Toxicodendron vernicifluum,Albizia julibrissin,etc.Ulmus pumila,Albizia julibrissin,Lithocarpus glaber,Quercus fabri,Liquidambar formosana,Platycarya strobilacea,Machilus thunbergii was positively correlated with Cunninghamia lanceolata,Schima superba,Castanopsis eyrei and Cyclobalanopsis glauca,but not with other dominant species in the community.(4)TWINSPAN divided 172 endemic communities of Machilus thunbergii in Zhejiang province into 8 community types.8 groups cluster a number of diversity index is almost the same change trend,single advantages Lin(such as association ? Cunninghamia lanceolata forest)tree species composition is relatively simple,with significantly lower diversity index.The results of CCA sequencing showed that elevation and slope were the dominant environmental factors,and the Machilus thunbergii community had more distribution in the areas with medium and low elevations and low slopes,and the dominant species also tended to the low-elevation areas with gentle slopes.