林窗对格氏栲天然林更新层物种生态位的影响

采用改进更新生态位宽度和更新生态位重叠模型分析林窗干扰对福建三明市格氏栲天然林更新层物种生态位的影响。结果表明:林窗中格氏栲更新生态宽度值大于林下,林窗在促进格氏栲更新过程中具有重要作用。林窗和林下更新生态位宽度最大的为桂北木姜子,其与格氏栲更新生态位重叠值也较大。林窗中的格氏栲与其它物种更新生态位重叠值低于0.6,林窗微生境的异质性导致格氏栲与其它树种间对资源的利用存在明显的共享趋势,促进了物种间共存。林下的格氏栲与木荷、木荚红豆和短尾越桔的更新生态位重叠值均高于0.6,格氏栲与这些物种相互争夺资源与空间,种间竞争较强。格氏栲天然林未来树种组成中,主要由桂北木姜子、木荷、矩圆叶鼠刺与格氏栲等组成的混交群落,整个群落正向物种组成多样化的方向演变。

Effects of forest gaps on species niche in regeneration layers of Castanopsis kawakamii natural forest

Effects of forest gaps on species niche in regeneration layers was conducted by improved models of regeneration niche width and niche overlap of Castanopsis kawakamii natural forest in Sanming city , Fujian Province.The results showed that the regeneration niche width of C.kawakamiiin forest gaps was higher than that of forest understory , which indicated that forest gaps played an important role in improving the regeneration of C.kawakamii population.The regeneration niche width of Litsea subcoriaceain forest gaps and understory was the maximum , while regeneration niche overlaps between L.subcoriaceaand C.kawakamii were relatively high in forest gaps and understory.The regeneration niche overlaps between the population of C.kawakamii and other species were less than 0.6in forest gaps , showing an obvious trend of resource utilization existing between the C.kawakamii population and other species in forest gaps owing to the micro-habitat heterogeneity.The regeneration niche overlaps between the population of C.kawakamii and Schima superba , Ormosia xylocarpa , Vaccinium carlesii were above 0.6in forest understory , which indicated that the population competition between C.kawakamii and other species were relatively high as aresult of striving for resources and space.The future tree species composition in C.kawakamii natural forest was a mixed community which mainly consisted of L.subcoriacea , S.superba , Itea chinensis and C.kawakamii population. The whole community now is changing in complex direction with diversity species composition.