亚热带马尾松疫木伐除对林分空间结构和林下植被更新的影响OA

To prevent the spread of pine wilt disease caused by Bursaphelenchus xylophilus on Masson pine(Pinus massoniana),the infected trees should be removed.Clarifying the impacts of removing infected trees on stand spa-tial structure,understory regeneration,and community succession can provide scientific basis for ecological restora-tion and stand construction of Masson pine forests suffered the wilt disease.We investigated the differences in stand spatial structure,understory species composition,density,diversity,and basal diameter/height distribution across stands with varying intensities of infected tree removal(undisturbed stand(CK),light logging(Ⅰ),moderate log-ging(Ⅱ),heavy logging(Ⅲ),and clear-cutting(Ⅳ)).We further explored the relationship between stand spa-tial structure and the diversity and basal diameter/height distribution of woody plant seedlings.The results showed that stand spatial structure(except for opening degree)differed significantly among logging intensities(P＜0.05).With increasing logging intensity,tree distribution became more uniform,mingling degree increased,and competi-tion index decreased.Seedlings and saplings in the treatments CK and Ⅰ had evenly distributed basal diameters and heights,whereas those in treatments Ⅱ,Ⅲ,and Ⅳ were concentrated in 0.15-1 cm and 0.2-1 m ranges,respec-tively.Seedling density in the treatment Ⅳ was significantly higher than that other stands(P＜0.05),and species diversity of seedlings in CK was significantly higher than that in logged stands(P＜0.05).Understory species diver-sity was mainly influenced by horizontal structure and competition,while seedling density was affected by competi-tion index and opening degree.In conclusion,the removal of infected Masson pines optimizes stand spatial struc-ture,promotes seedling-to-sapling transition,facilitates the succession of damaged Masson pine forest toward une-ven-aged mixed conifer-broadleaf forests,and thereby enhances resistance to pine wilt disease.However,high-in-tensity logging reduces understory species diversity.Therefore,we recommend adopting moderate and dynamic thinning in early stages of infestation to get a balance between disease control and biodiversity conservation.