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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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(J_(sw))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。
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 inDatong 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 standsⅠ andⅢ was significantly lower than that of standsⅡ,Ⅳ andⅤ(P<0.05).The order of leaf area index of each forest wasⅢ,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 standsⅡ andⅣ was significantly higher than that of those of forest standsⅠ,Ⅲ and Ⅴ(P<0.05),in which total understory PPFD and understory diffuse PPFD wereⅡ>Ⅳ>Ⅴ>Ⅰ>Ⅲ,the understory direct PPFD wasⅡ>Ⅳ>Ⅰ>Ⅲ>Ⅴ;K of the standsⅡ,Ⅳ and Ⅴ was significantly higher than Ⅰ andⅢ;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(J_(sw))and mean leaf angle(P<0.01)and significantly positive correlation between Pielou index(J_(sw))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.
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 inDatong 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 standsⅠ andⅢ was significantly lower than that of standsⅡ,Ⅳ andⅤ(P<0.05).The order of leaf area index of each forest wasⅢ,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 standsⅡ andⅣ was significantly higher than that of those of forest standsⅠ,Ⅲ and Ⅴ(P<0.05),in which total understory PPFD and understory diffuse PPFD wereⅡ>Ⅳ>Ⅴ>Ⅰ>Ⅲ,the understory direct PPFD wasⅡ>Ⅳ>Ⅰ>Ⅲ>Ⅴ;K of the standsⅡ,Ⅳ and Ⅴ was significantly higher than Ⅰ andⅢ;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(J_(sw))and mean leaf angle(P<0.01)and significantly positive correlation between Pielou index(J_(sw))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.
引文
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[2]鲍文,包维楷,何丙辉,等.森林生态系统对降水的分配与拦截效应[J].山地学报,2004,22(4):483-491.BAO W,BAO W Z,HE B H,et al.Distribution and interception effects of forest ecosystems on precipitation[J].Journal of Mountain Science,2004,22(4):483-491.
[3]陈高,代力民,周莉.受干扰长白山阔叶红松林林分组成及冠层结构特征[J].生态学杂志,2004,23(5):116-120.CHEN G,DAI L M,ZHOU L.Composition and canopy structure characteristics of disturbed Changbai Mountain broad-leaved Korean pine forest[J].Journal of Ecology,2004,23(5):116-120.
[4]区余端,苏志尧.粤北山地常绿阔叶林自然干扰后冠层结构与林下光照动态[J].生态学报,2012,(18):5 637-5 645.OU Y D,SU Z Y.Canopy structure and undergrowth illumination dynamics of natural evergreen broad-leaved forests in northern Guangdong Province[J].Chinese Journal of Ecology,2012,(18):5 637-5 645.
[5]PROMIS A,SCHINDLER D,REIF A,et al.Solar radiation transmission in and around canopy gaps in an uneven-aged Nothofagus betuloides forest[J].International Journal of Biometeorology,2009,53(4):355-367.
[6]PIIROINEN T,NYEKO P,ROININEN H.Canopy openness in gaps determines the influence of herbaceous climbers and insect folivory on the survival of a tropical pioneer tree,Neoboutonia macrocalyx Pax[J].African Journal of Ecology,2014,52(1):41-49.
[7]崔宁洁,张丹桔,刘洋,等.马尾松人工林不同大小林窗植物多样性及其季节动态[J].植物生态学报,2014,38(5):477-490.CUI N J,ZHANG D J,LIU Y,et al.Plant species diversity and seasonal dynamics of different size gaps in Pinus massoniana plantation[J].Journal of Plant Ecology,2014,38(5):477-490.
[8]胡砚秋,柯娴氡,徐明锋,等.亚热带森林群落草本植物对林下光环境的响应[J].中南林业科技大学学报,2016,36(8):72-76.HU Y Q,KE X D,XU M F,et al.Response of herbaceous plants in subtropical forest communities to undergrowth light environment[J].Journal of Central South University of Forestry and Technology,2016,36(8):72-76.
[9]任海,彭少麟,张祝平,等.鼎湖山季风常绿阔叶林林冠结构与冠层辐射研究[J].生态学报,1996,(2):174-179.REN H,PENG S L,ZHANG Z P,et al.Study on canopy structure and canopy radiation of monsoon evergreen broadleaved forest in Dinghu Mountain[J].Acta Ecological Sinica,1996,(2):174-179.
[10]崔佳玉,曾焕忱,王永强,等.银瓶山自然保护区阔叶林冠层结构与辐射消减效应[J].西北林学院学报,2015,30(4):45-49.CUI J Y,ZENG H Z C,WANG Y Q,et al.Canopy structure and radiation reduction effect of broad-leaved forest in Yinpingshan Nature Reserve[J].Journal of Northwest Forestry University,2015,30(4):45-49.
[11]BEAUDET M,MESSIER C.Variation in canopy openness and light transmission following selection cutting in northern hardwood stands:an assessment based on hemispherical photographs[J].Agricultural and Forest Meteorology,2002,110(3):217-228.
[12]刘晓东,朱春全,雷晶品,等.杨树人工林冠层光合辐射分布的研究[J].林业科学,2000,36(3):27-38.LIU X D,ZHU C Q,LEI J P,et al.Study on the distribution of photosynthetic radiation in canopy of poplar plantation[J].Forestry Science,2000,36(3):27-38.
[13]卢训令,丁圣彦,游莉,等.伏牛山自然保护区森林冠层结构对林下植被特征的影响[J].生态学报,2013,33(15):4 715-4 723.LU X L,DING S Y,YOU L,et al.Effects of forest canopy structure on the characteristics of understory vegetation in Funiu Mountain Nature Reserve[J].Acta Ecological Sinica,2013,33(15):4 715-4 723.
[14]谭一波,何琴飞,郑威,等.珠江流域中上游防护林冠层结构对林下植被的影响[J].生态学杂志,2016,35(12):3 148-3 156.TAN Y B,HE Q F,ZHENG W,et al.The influence of canopy structure of the upper protection forest on the understory vegetation in the Pearl River Basin[J].Journal of E-cology,2016,35(12):3 148-3 156.
[15]丁圣彦,卢训令,李昊民.天童国家森林公园常绿阔叶林不同演替阶段群落光环境特征比较[J].生态学报,2005,(11):70-75.DING S Y,LU X L,LI H M.Comparison of light environmental characteristics of different succession stages of evergreen broad-leaved forest in Tiantong National Forest Park[J].Acta Ecological Sinica,2005,(11):70-75.
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