浙江省檫木林生境与生态位研究

植被生境是群落乃至整个生态系统的物质基础,生态位宽度、生态位重叠、种间关系在群落生态学研究领域也具有重要地位,因此在植被生境基础之上展开的生态位、种间关系研究对了解生态系统功能具有重要意义。主成分分析表明:土壤养分和海拔因子对檫木生长分布起着重要的限制性作用;通过重要值对环境因子趋势拟合得出檫木在浙江省的典型生境为:海拔400—800 m,坡度20°—40°,阴坡半阴坡,土壤厚度大且肥沃的区域;在出现檫木的189个监测样地中,共出现的乔木树种有149种,主要优势树种(以重要值排序)为杉木Cunninghamia lanceolata、马尾松Pinus massoniana Lamb.、木荷Schima superba、枫香Liquidambar formosana Hance、青冈Cyclobalanopsis glauca (Thunb) Oerst、苦槠Castanopsis sclerophylla、石栎Lithocarpus glaber(Thunb.) Nakai、檫木Sassafras tzumu (Hemsl.) Hemsl.等。生态位宽度大小依次为杉木、檫木、马尾松、木荷、枫香、青冈、苦槠、板栗Castanea mollissima等,可见杉木、檫木、马尾松、木荷对外部环境有较强的适应能力,在各个资源位中出现较多,对资源的利用优势比较明显,檫木的生态位宽度达到了61.65,仅次于杉木的89.64,甚至大于马尾松的57.28,也说明檫木能在研究区拥有较好的群落地位;檫木与野樱桃Cerasus serrula (Franch.) Yüet L的生态位重叠值高达0.9以上,和浙江楠Phoebe chekiangensisC. B. Shang、构树Broussonetia papyrifera、鸡爪槭Acer palmatum Thunb.的生态位重叠值分别达0.831、0.785、0.531,说明檫木和野樱桃、浙江楠、构树、鸡爪槭对生境要求比较相近,在生态资源充足的情况下可尝试混交造林;通过监测样地中11个优势树种的种间联结分析,显示檫木与杉木、马尾松、木荷的种间具有显著的正联结关系,与枫香、苦槠和青冈也存在正联结关系,可见在研究区内檫木能够与这些树种互相吸引。

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 to 89.64 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 those of C. lanceolata and P. massoniana in the community, indicating that S. tzumu is not likely to be easily replaced by the two tree species during community succession. It can be seen that S. tzumu could be attracted to each other in the study area.