【作者】 张俊艳；

【导师】 臧润国；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2014， 博士

【摘要】 天然针叶林主要分布在温带和寒温带地区，但是在热带地区仍然有一定面积的分布。热带天然针叶林对维持热带地区生态系统的多样性和生境异质性具有特殊意义。海南省霸王岭林区是我国热带天然针叶林集中分布面积最大的区域，以南亚松(Pinus latteri)为绝对优势种但混生一定数量阔叶物种，分布在与热带低地雨林和热带季雨林相同的低海拔范围内。当这三种低海拔的热带林受到干扰破坏后，常常会形成针叶林与阔叶林的群落交错区。群落交错区指两种群落类型的过渡区间，其环境因子和群落结构与相邻的两种群落往往也有一定差异。尽管以往对热带阔叶林已开展了大量的生态学研究，但针对热带针叶林的研究还很少，而有关热带针叶林-阔叶林交错区的群落学研究还没有开展过。本文以海南岛霸王岭林区典型的热带天然针叶林及其与热带低地雨林或热带季雨林形成的热带针叶林-阔叶林交错区为对象，通过横穿针叶林区、交错区和阔叶林区三个林分区域的19条典型样带，进行了群落学调查以及主要植物功能性状和环境因子的测定，研究了环境因子、群落结构、植物功能性状和生物多样性（物种及功能多样性）特征随林分区域的变化规律，探讨了热带针叶林-阔叶林交错区的群落组配机制。主要研究结果如下：1.通过对3个不同林分区域11个环境因子的对比分析表明：(1)针叶林区林冠开阔度、凋落物厚度和土壤全钾含量显著高于阔叶林区和交错区，但阔叶林区中的pH值、土壤有机质、土壤全氮、有效氮、有效磷和有效钾显著高于针叶林区和交错区；而土壤含水量和土壤全磷在三个区域无显著差异。(2)环境因子的主成分分析结果表明，土壤pH值、土壤有机质、凋落物厚度和林冠开阔度对第一轴的贡献性最大，而全氮和有效磷对第二轴的贡献性最大。(3)影响不同林分区域物种分布的主要环境因子是林冠开阔度、凋落物厚度、土壤pH值、土壤有机质和土壤全钾。2.三个林分区域的种、属和科-多度曲线及不同的生活型和高度级物种丰富度均表现为阔叶林区>交错区>针叶林区；而平均树高、最大树高、平均胸径、最大胸径、胸高断面积都表现为针叶林区>交错区>阔叶林区。海南岛热带林区的针叶林-阔叶林交错区可能是由阔叶林中阔叶树种逐渐向针叶林中侵入而形成。3.通过对三个林分区域比叶面积(SLA)、叶片干物质含量(LDMC)、木材密度(WD)、叶绿素含量(CC)、叶氮含量(LNC)、叶磷含量(LPC)、叶钾含量(LKC)、潜在最大高度(Hmax)等8个功能性状的分析表明：(1)针叶林区植物Hmax、LDMC和LPC显著高于阔叶林区和交错区，但阔叶林区植物SLA、CC、LNC和LKC显著高于针叶林区和交错区，而交错区的植物功能性状居于中间位置。(2)针叶林区较低的土壤含水量和土壤养分含量是限制资源获取性状特征(如高SLA、高叶片养分含量)的主要因子，而在阔叶林区高的土壤养分特征和适宜的光照条件则不利于具有保守性性状（如高LDMC、高WD）特征的植物生存。4.通过分析热带针叶林-阔叶林交错区的香浓指数、丰富度指数、均匀度指数、Simpson指数、功能丰富度、功能均匀度、功能分散度和功能离散度等8个多样性指标的变化特征，对结果表明，(1)除Simpson指数外，其他7个多样性指标均表现为阔叶林区>交错区>针叶林区。(2)物种多样性和功能多样性与环境因子的多元逐步回归分析表明，在针叶林区中土壤pH值和土壤有效钾对物种和功能多样性影响显著，在交错区中土壤全氮、林冠开阔度和凋落物厚度对物种和功能多样性影响显著，而在阔叶林区土壤有机质、土壤有效氮和土壤有效钾对物种和功能多样性影响显著。5.应用零模型建立随机群落的方法，从植物功能性状分布范围和物种亲缘关系探讨了热带针叶林-阔叶林交错区植物群落的组配机制。结果表明：针叶林区和交错区受环境筛作用明显，表明环境筛多发生在环境条件较差的地段，而在阔叶林区环境筛作用作用较小，而生物竞争作用较大，物种功能性状和亲源关系呈发散分布。环境筛和生物竞争在不同林分区域群落组配中的相对作用不同。更多还原

【Abstract】 Although natural coniferous forests are mainly distibuted in the temperate and cold tremperateregions on earth,they occupy a proportion of specific areas in the tropics.Natural tropicalconiferous forests play a unique role in maintaining the biodiversity and heterogeneity oftropical forest ecosystems. In the tropical regions of southern China, most of the land isdominated by broadleaved trees and shrubs. However, in some specific places and habitatswhere environmental conditions are stressful for broadleaved trees, a few species of conifersare dominant. Due to their unusual environmental and floristic conditions, tropical coniferousforests often have a distinct community structure and contain flora and fauna that are differentfrom those of adjacent tropical rainforests. The widest distribution of natural tropicalconiferous forest is found on Hainan Island in China, and most of this type of forest is in theBawangling forest region (BFR). Most of the tropical coniferous forest on Hainan Island isdominated by the conifer Pinus latteri. A transition zone exists between conifers andbroadleaved trees of tropical lowland rain forest and tropical monsoon forest species, due toextensive shifting cultivation and logging of the coniferous forest and then invasion bybroadleaved trees into disturbed regions.No studies have explored the communitycharacteristics of the ecotone representing the transition between coniferous forest andbroadleaved forest. In this study, we conducted the field vegetation investigation and measuredthe plant fuctional traits and some environmental factors in19transects, spanning three standzones: the coniferous forest zone (CZ), the ecotone zone (EZ), and the broadleaved forest zone(BZ). We compared the varaitions in environmental condition, speices composition,community structure, community-wide plant fuctional traits, biodiversity (including speciesdiversity and functional diversity) and relationships between environmental factors and thecommunity features across the ecotones. The main results are as follows: 1. As the stand changed from coniferous forest zone to broadleaved forest zone acrossecotone,11environmental factors showed that,(1) soil pH value,soil organic matter content,total N, available N, available P and available K had a trend of increasing; total K, litter depthand canopy openness had a trend of decreasing; Soil water content and soil total P had nosignificant differences among the three stand zones.(2) Principal component analysis for themeasured environmental factors in the three stand zones showed that soil pH value,soil organicmatter content, litter depth, available P, total N and canopy openness were the maindeterminants for the distribution range of the three different stand zones.2. The compositional and structural features of the three stand zones were compared interms of stand factors, size class distribution, growth-form, and species, genus andfamilyrank-abundance distributions. Stem abundance and species richness increased as thevegetation zones changed from CZ through EZ to BZ. In each stand zone, stem abundance andspecies richness declined as the size class increased. The coniferous-broadleaved forest ecotonerevealed compositional and structural features between its adjacent forest stands.3. With the variation of vegetation from CZ through EZ to BZ,community plant functionaltraits of SLA, LDMC, WD, CC, LNC, LPC, LKC and Hmaxchanged in accordance with thechanges in soil and light regimes.(1) CZ had the highest values of Hmax, LDMC and LPC; BZhad the highes values of SLA, CC, LNC and LKC.(2) the low soil nutrients and high light inCZ were the major constraints for most lowland rain forest species with acquisitive traits tosurvive and grow, while high soil nutrients and low light in BZ were the major environmentalfilters for the conifer and tropical monsoon rain forest species with conservative traits. The EZcould afford environmental conditions for species of both strategies. The soil and lightconditions were the major determinants for the functional community structure of thevegetation types across the tropical coniferous-broadleaved forest ecotones.4. From CZ through the EZ to BZ, the eight diveristy indices including biodiveristyindicesand functional diversity indices changes.(1) there was significant difference in sevendiversity indices across three stand zones and showed gradually increasing trend except for Simpson’s diversity index.(2) multiple stepwise regression results showed that species andfunctional diveristy of CZ was strongly influenced by soil pH and available potassium, EZaffected largely by total nitrogen, canopy openness and litter thickness. Soil organic matter,available nitrogen and available potassiumwere the main factors significantly affecting speciesand functional diveristy in BZ.5.Assembly rulesof plant communities across the natural tropical coniferous-broadleavedforest ecotones were explored by using the null model approach.We tested the differencesbetween calculated and null simulated patterns of the distribution in plant functional traits andphylogenetic structure across the ecotones. The results showed that environment filtering wasthe dominant assembly rule in CZ and EZ,whilebiotic competition was the dominant assemblyrule in BZ. As the stand zones changed from CZ through EZ to BZ,community wide plantfunctional traits and phylogenetic structure transferred from cluster to overdispersion.Therelative effects of environmental filtering vs. biotic competition changed in accordance withthe variation of vegetations and their abiotic and biotic conditions across the ecotones.更多还原