间伐对马尾松人工林林下植物多样性的短期和长期影响

探讨不同间伐强度林下马尾松人工林植物多样性的动态变化，为确定合理的间伐强度提供理论依据。以南京溧水林场马尾松俨砌USmassonianaLamb．）中龄人工林为研究对象，于2007年和2011年对间伐1a和5a后各间伐林下植物多样性进行了调查和分析。结果表明：间伐la和5a后，与对照相比，中强度间伐林下植物种类、数量、丰富度Margalef指数、多样性Simpson、Sharmon-Weiner指数和均匀度JSW指数均显著提高（P〈O．05），林下植物的生态优势度指数显著降低（P〈O．05）；弱度间伐林下各指数在间伐1a后显著降低（P〈O．05），而在间伐5a后显著提高（P〈O．05o中强度间伐后林分各指数增幅最大，其中Shannon．Wiener指数对间伐措施更为敏感。间伐5a后，中强度间伐林下植物种类、数量和多样性指数比间伐1a后有所提高，弱度、中度、强度间伐后的林下植物种类比对照分别增加15、17和15种，总密度分别增加1．40、3．44和2．14倍。从短期和长期影响效果来看，中、强度间伐有利于植物多样性的提高。

Short-term and Long-term effects of thinning on the undergrowth diversity in the Pinus massoniana plantation

To investigate dynamic changes of plant diversity of Pinus massoniana Lamb plantation in different thinning intensities, and to provide a theoretical basis for determining reasonable thinning intensity. Hereby to take the middle-age Pinus massoniana Lamb plantation in Nanjing Lishui Forest Farm as the research object, and survey and analysis were conducted in terms of the diversity of each thinning stand undergoing thinning la and 5a in 2007 and 2011. The results showed that： after thinning la and 5a, compared with the control, the species, quantity, richness of Margalef index, diversity of Simpson, Shannon-Weiner index and evenness of JSW index of moderate-intensity thinning understory were significantly increased （ P〈0.05 ） , and the ecological dominance of undergrowth was significantly decreased（ P〈0.05 ）. Each index of light thinning understory was significantly decreased after Thinning la （ P〈0.05 ） , while significantly increased after Thinning 5a （ P〈0.05 ） . All indexes in medium and heavy thinning intensity had the largest amplification, wherein the Shannon-Wiener index was more sensitive to thinning measures. After thinning 5a, the species, quantity and diversity index of medium thinning understory were relatively improved in comparison to thinning la, the understory species in three thinning intensities were respectively increased 15, 17 and 15 species compared with the control, and the total density was increased 1.40, 3.44 and 2.14 times. So judging from the short- and long-term effects, medium and heavy thinning facilitate the increase of plant diversity.