青海大通典型林分冠层结构与林下植被物种多样性关系研究
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引用本文:王 莉,林 莎,李远航,陈梦飞,贺康宁.青海大通典型林分冠层结构与林下植被物种多样性关系研究[J].西北植物学报,2019,39(3):524~533
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王 莉,林 莎,李远航,陈梦飞,贺康宁* (北京林业大学 水土保持学院国家林业局水土保持重点实验室北京市水土保持工程技术研究中心林业生态工程教育部工程研究中心北京100083) 
基金项目:国家重点研发计划重点专项(2017YFC0504604)
中文摘要:为探究青海高寒山区典型林分冠层结构与林内光环境中维持林下植被物种多样性稳定的关键因素,该研究以青海大通县青海云杉林(Ⅰ)、青杨林(Ⅱ)、华北落叶松 青海云杉混交林(Ⅲ)、青杨 白桦混交林(Ⅳ)和白桦 青海云杉混交林(Ⅴ)5种典型人工林分为研究对象,运用冠层分析仪采集数据,并结合实地调查,研究冠层结构与林内光环境特征及其对林下植被的影响。结果表明:(1)林分Ⅰ、Ⅲ的林冠开度显著低于林分Ⅱ、Ⅳ、Ⅴ(P<0.05),各林分叶面积指数大小顺序为Ⅲ>Ⅰ>Ⅱ>Ⅴ>Ⅳ,总体表现为阔叶林的林冠开度大于针叶林,但其叶面积指数小于针叶林;林分Ⅱ、Ⅳ的直射辐射、散射辐射及总辐射均显著高于林分Ⅰ、Ⅲ、Ⅴ(P<0.05),其中林下总辐射与散射辐射表现为Ⅱ>Ⅳ>Ⅴ>Ⅰ>Ⅲ,直射辐射为Ⅱ>Ⅳ>Ⅰ>Ⅲ>Ⅴ;林分Ⅱ、Ⅳ、Ⅴ的消光系数均显著高于Ⅰ、Ⅲ,总体上均表现为阔叶林>针叶林。(2)相关分析结果表明,林冠开度与林下光照指标呈极显著正相关关系(P<0.01),叶面积指数与林下光照指标呈极显著负相关关系(P<0.01),且其对林下散射辐射的控制能力最强;典型相关分析表明,纯林的林冠开度对冠层结构的贡献和解释能力较叶面积指数和平均叶倾角大,混交林的叶面积指数对林下光照的影响大于纯林。(3)混交林的林下物种多样性指数(H)及丰富度指数(P)均高于纯林;林下草本层物种多样性指数(H)及丰富度指数(P)与林冠开度及林下光辐射呈显著正相关关系,与叶面积指数呈显著负相关关系(P<0.05);物种均匀度(Jsw)与平均叶倾角呈极显著负相关关系(P<0.01),与林下散射辐射呈显著正相关关系(P<0.05)。研究认为,在人工纯林改造和结构调整中,对乔木层适当补植伴生树种,并逐步调整为多树种混交林,增加冠层结构和林下光照异质性,将更有利于林下植被物种多样性的维持。
中文关键词:人工林  冠层结构  林内光环境  林下植被  物种多样性
 
Relationship between Typical Canopy Structure and Understory Vegetation Diversity in Datong, Qinghai
Abstract:In order to explore the key factors of maintaining the understory vegetation diversity in forest light condition and canopy structure in the alpine region of Qinghai, we observed five typical plantations in Datong County, Qinghai Province, including Picea crassifolia forest (Ⅰ), Populus cathayana forest (Ⅱ), Larix principis rupprechti Picea crassifolia mixed forest (Ⅲ), Betula platyphylla Populus cathayana mixed forest (Ⅳ), and Betula platyphylla Picea crassifolia mixed forest (Ⅴ), to study the characteristics of the canopy structure and light conditions and their effects on understory vegetation. Data were collected using a canopy analyzer and combined with field investigations. The results showed that: (1) the canopy openness of stands Ⅰ and Ⅲ was significantly lower than that of stands Ⅱ, Ⅳ and Ⅴ (P<0.05). The order of leaf area index of each forest was Ⅲ, Ⅰ, Ⅱ, Ⅴ and Ⅳ. The canopy openness of broad leaved forest was larger than that of coniferous forest, but its leaf area index was lower than that of coniferous forest. The understory direct PPFD, understory diffuse PPFD and total understory PPFD of stands Ⅱ and Ⅳ was significantly higher than that of those of forest stands Ⅰ, Ⅲ and Ⅴ (P<0.05), in which total understory PPFD and understory diffuse PPFD were Ⅱ>Ⅳ>Ⅴ>Ⅰ>Ⅲ, the understory direct PPFD was Ⅱ>Ⅳ>Ⅰ>Ⅲ>Ⅴ; K of the stands Ⅱ, Ⅳ and Ⅴ was significantly higher than Ⅰ and Ⅲ; broadly expressed as broad leaved forest > coniferous forest.(2)The canopy openness of each stand was very significantly positively correlated with the understory light indices (P<0.01), the leaf area index was significantly negatively correlated with the understory light indices (P<0.01); and it had the strongest control ability for understory diffuse PPFD. Canonical correlation analysis showed that canopy openness of pure forest had greater contribution and interpretation of canopy structure than leaf area index and mean leaf angle. The leaf area index of mixed forest had greater influence on the understory light than that of pure forest. (3) The understory species Shannon Wiener index (H) and Patrick index (P) of mixed forest were higher than that of pure forest; The Shannon Wiener index (H) and Patrick index (P) of the undergrowth herb layer were positively correlated with canopy openness and understory light radiation and negatively correlated with leaf area index (P<0.05); there was a very significantly negative correlation between Pielou index (Jsw) and mean leaf angle (P<0.01) and significantly positive correlation between Pielou index (Jsw) and understory diffuse PPFD (P<0.05). It is more conductive for the maintenance of understory vegetation diversity to replant associated tree species in the arbor layer, gradually adjust to multi tree mixed forest and increase canopy structure and the understory heterogeneity.
keywords:plantation  canopy structure  intercropping light conditions  understory vegetation  species diversity
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