南亚热带4个苗木的生态位

在模糊超体积生态位理论的基础上，研究了南亚热带4个不同演替阶段树种苗木的生态位，探索森林群落演替的规律．以所测定的净光合作用强度值为指标，度量包括pH值、矿物质营养浓度、土壤含水量三个生态因子的三维生态位．结果表明：生态位宽度的大小次序为马尾松（0．4056），荷木（0．3614），藜蒴（0．3108）和黄果厚壳桂（0．3068），正好对应演替不同阶段的优势种；生态位重叠最小值为0．6827，表示总体上物种对资源的竞争较激烈；种间竞争系数介于0．6359和0．7357之间，表示物种问有回避竞争的趋势，这往往有助于物种共存；利用Cody和May的原则会带来生态位重叠的偏差最大为0．1262，最小为0．0361，因此应该避免使用Cody和May的原则．

Niches of 4 tree species in south subtropical zone

Based on the theory of fuzzy hypervolume niche,the niches of 4 tree species in south subtropical zone are studied in order to find the rule of forest succession.3-dimensional niche,which is formed by the ecological factors of pH value,nutrients and moisture,is measured by the net photosynthesis rate.The results indicate as following: niche width of these seedlings can be ordered as Pinus massoniana(0.405 6),Schima super ba(0.361 4),Castanopsis fissa(0.310 8) and Cryptocarya concinna(0.306 8),which corresponds to the dominant(tree) species' order at different successional stages.Niche overlaps of these seedlings show the rather intense interspecific competition in the mass because of the minimum value 0.682 7.The competition coefficient in the interval 0.635 9,0.735 7] showes the tendency of the species avoiding competition which administers the species coexistence.The maximum difference of 0.126 2 and the minimum difference of 0.036 1 for niche overlap can be gained by using the principle of Cody & May and thus it is a good practice to avoid this principle.mathematical ecology;niche;fuzzy hypervolume;niche width;niche overlap;net photosynthesis rate;competition coefficient