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Impact of invasive Ageratina adenophora on relative performance of woody vegetation in different forest ecosystems of Kumaun Himalaya,India
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作者 Bhawna NEGI Kavita KHATRI +3 位作者 Surendra S.BARGALI Kiran BARGALI Archana FARTYAL R.K.CHATURVEDI 《Journal of Mountain Science》 SCIE CSCD 2023年第9期2557-2579,共23页
Invasive plant Ageratina adenophora(Sprengel)R.King&H.Robinson has invaded majority of the temperate forests in Kumaun,Central Himalaya.Information on A.adenophora invaded forest types,their structural attributes,... Invasive plant Ageratina adenophora(Sprengel)R.King&H.Robinson has invaded majority of the temperate forests in Kumaun,Central Himalaya.Information on A.adenophora invaded forest types,their structural attributes,population demography and regeneration status are still at rudimentary level.Considering this,the present study was conducted to assess the impacts of A.adenophora on vegetational attributes and regeneration status of three forest types,viz.,Oak(Quercus oblongata D.Don),Pine(Pinus roxburghii Sarg.)and Cypress(Cupressus torulosa D.Don).We selected three sites for each forest type and each site was further purposively stratified into paired sampling plots of 1 ha each i.e.,A.adenophora invaded and uninvaded sites.Our results showed large densities of cut stumps or felled trees throughout invaded sites,but with fewer fire signs in comparison to uninvaded sites.In uninvaded sites,total density and basal area calculated for woody species were relatively higher than those in invaded sites,although results were insignificant(p>0.05).With the exception for Cypress forests,vegetation indices showed low woody species richness and diversity in invaded Oak and Pine forests.Also,regeneration of Q.oblongata,P.roxburghii and C.torulosa tree species did not differ significantly(p>0.05)between invaded and uninvaded sites.These insignificant differences clearly imply that A.adenophora's presence has not entirely changed the perennial plant communities in terms of composition,structure and natural regeneration.However,tree species with poor or no regeneration status requires special attention and needs management strategies involving control of invasive species in forest ecosystems. 展开更多
关键词 Ageratina adenophora Seedling density FORESTS population structure REGENERATION
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水稻旱育秧的移栽密度对群体结构和光能利用的影响 被引量:9
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作者 赵国平 陈志银 +1 位作者 张国平 Aomangdi 《浙江农业大学学报》 CSCD 北大核心 1998年第4期349-354,共6页
研究了早稻旱育秧不同移栽密度的群体结构、光能分布与利用特性及产量构成,结果表明:移栽密度较低时,群体的分蘖高峰期推迟,有效分蘖期延长,且旱育秧群体有较强的自动调节能力.双季早稻的适宜密度为23.3cm×13.3c... 研究了早稻旱育秧不同移栽密度的群体结构、光能分布与利用特性及产量构成,结果表明:移栽密度较低时,群体的分蘖高峰期推迟,有效分蘖期延长,且旱育秧群体有较强的自动调节能力.双季早稻的适宜密度为23.3cm×13.3cm;孕穗期群体叶面积的垂直分布状况因移栽密度而异,16.7cm×13.3cm,23.3cm×13.3cm的叶面积以30~45cm层为最大,30.0cm×13.3cm的最大叶面积出现在45~60cm层;群体的漏光率随移栽密度的提高而变小,光能吸收率随太阳高度的增大而减小,随密度提高而增大.栽植密度23.3cm×13.3cm的产量显著高于16.7cm×13.3cm,20.0cm×13.3cm和30.0cm×13.3cm,这与其穗粒重协调发展有关. 展开更多
关键词 水稻 旱育秧 移栽密度 群体结构 光能利用
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不同密度对落叶松苗期生长的影响 被引量:1
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作者 连友钦 宋久旺 杨光斗 《林业科学研究》 CSCD 北大核心 1992年第6期727-730,共4页
苗期合理播种密度是改善苗木质量的关键。育苗密度是直接调节因子,它是控制群体生长及苗木生长对微环境要求的标志。1981~1984年在黑龙江省绥棱县苗圃,研究和分析了兴安落叶松(Larix olgensis Henry)、长白落叶松(Larix gmelini Rupr.... 苗期合理播种密度是改善苗木质量的关键。育苗密度是直接调节因子,它是控制群体生长及苗木生长对微环境要求的标志。1981~1984年在黑龙江省绥棱县苗圃,研究和分析了兴安落叶松(Larix olgensis Henry)、长白落叶松(Larix gmelini Rupr.)和华北落叶松(Larix principis-rupprechtii Mayr) 展开更多
关键词 落叶松 育苗 密度 生长
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