Study on the habitat and niche of Sassafras tzumu (Hemsl.) Hemsl. in Zhejiang Province

Vegetation habitat is the material basis of communities and whole ecosystems. Niche breadth,niche overlap,and interspecific relationships play important roles in community ecology. Therefore,the study of niche and interspecific relationships based on the characteristics of vegetation habitat is fundamental to understanding ecosystem functions. A principal component analysis showed that soil nutrients and altitude played an importantrole in restricting the growth and distribution of Sassafras tzumu( Hemsl.) Hemsl. Trend fitting to the environmental factors concluded that typical habitats of S. tzumu in Zhejiang Province included the regions with altitude of 400-800 m,shady slope of 20-40°,and thick and fertile soil. There were 149 tree species in the 189 monitoring plots of S. tzumu,and the dominant species were:Cunninghamia lanceolata,Pinus massoniana Lamb.,Schima superba,Liquidambar formosana Hance,Cyclobalanopsis glauca( Thunb) Oerst,Castanopsis sclerophylla,Lithocarpus glaber( Thunb.) Nakai,and S. tzumu. The niche breadth values of the community are arranged in size order: C. lanceolata,S. tzumu,P. massoniana,S. superba,L. formosana,C.glauca,C. sclerophylla,and Castanea mollissima. It can be seen that C. lanceolata,S. tzumu,P. massoniana,and S.superba have strong adaptability to the external environment,which appears higher with each environmental factor,and the advantage of resource utilization becomes more obvious. The niche breadth of S. tzumu was 61. 65,which was second to89.64 of C. lanceolata,and was followed by 57.28 of P. massoniana,which indicated that in total S. tzumu has a good community status in the research area. The niche overlap value of S. tzumu and Cerasus serrula( Franch) Yüet Li was as high as 0.9,and the overlap values of Phoebe chekiangensis C.B.Shang,Broussonetia papyrifera,and Acer palmatum Thunb.were 0.831,0.785,and 0.531,respectively. This showed that the habitat requirements of S. tzumu are similar to those of C.serrula,P. chekiangensis, B. papyrifera, and A. palmatum. Therefore, in the case of abundant resources, mixed afforestation could be carried out. The interspecific analysis of 11 dominant species in the monitoring plots showed that S.tzumu and C. lanceolata,P. massoniana and S. superba had significant positive relationships( their PC-values were 0.75,0.45,0.42),and L. formosana,C. sclerophylla,and C. glauca had a positive relationship( their PC-values were 0.34,0.25,0.22). Moreover,it can have niche breadth close to t