【作者】 卜文圣；

【导师】 臧润国；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2013， 博士

【摘要】 全球生态系统正在遭遇剧烈的变化，从而加快了物种灭绝的速率。全球生物多样性减少和丧失对生态系统功能的影响是当前生态学最为关注的领域之一。大量关于生物多样性与生态系统功能关系(BEF)的研究结果表明生物多样性对生态系统功能具有显著的影响。目前，大多数有关生物多样性与生态系统功能关系(BEF)的研究主要是通过对草本植物的控制实验来进行的，由于其选择的物种数量有限再加之控制的条件与野外群落的实际生态条件有较大差异，因此其结果与野外实际情况的吻合性还有待证实。基于野外实地的调查观察也还很少，尤其在森林生态系统中更是这样。但基于野外调查的研究更加符合生物多样性与生态系统功能关系的实际情况。此外，以往的研究主要侧重于物种丰富度如何影响生态系统功能，而较少关注生物多样性的其他方面(例如功能多样性和谱系多样性)的作用。本文以海南岛霸王岭自然保护区刀耕火种后处于不同演替阶段的热带低地雨林、尖峰岭自然保护区不同海拔梯度的老龄林以及尖峰岭自然保护区30公顷热带山地雨林大样地为研究对象，通过群落学调查、功能性状测定及环境因子分析，探讨了功能性状和生物多样性(包括物种多样性、功能多样性及谱系多样性)及生态系统主要功能(本文仅分析林分地上部分生物量)随时间(演替阶段)和空间(海拔梯度和生境类型)的变化，并评估了群落演替过程中，评估环境因子如何影响功能性状及生物多样性；研究了生物多样性不同指标之间、功能性状及生物多样性与生态系统功能(林分地上部分生物量)之间的关系随时间(演替阶段)和空间(海拔梯度和生境类型)的变化规律；并运用结构方程模型(SEM)阐述环境因素如何影响功能性状或者生物多样性，并影响生态系统功能。本文是少有的基于野外实际调查测定所进行的关于森林生物多样性与生态系统功能关系(BEF)的研究，对于进一步深入开展生物多样性的理论分析和生态系统服务功能评估都具有较大的参考价值。主要研究结果如下：(一)、热带天然林功能性状、生物多样性及地上部分生物量的时空变化1.在霸王岭的不同演替阶段(15年、30年、60年次生林和老龄林)的热带低地雨林中，随着次生演替的进行：(1)比叶面积、叶片氮含量、叶片磷含量和叶片总有机碳含量逐渐降低，叶片干物质含量、木材密度和潜在最大高度逐渐升高，而叶片钾含量则变化不大；(2)物种丰富度和Shannon-Weaver指数均增加，Pielou’s均匀度指数在次生林中差异不大但都小于老龄林；(3)功能丰富度、功能均匀度、功能离散度和Rao’s二次熵均呈先下降后增加的趋势，而功能分散度随演替的进行逐渐增加，但60年以后有所下降；(4)物种对的平均谱系距离和谱系多样性逐渐增大，净谱系亲缘关系指数和平均最近相邻谱系距离逐渐减小，最近分类单元指数在在次生演替各阶段中差异不大但都大于老龄林，群落谱系结构由聚集逐渐转向发散；(5)林分地上部分生物量逐渐增大;(6)在不同的演替阶段，影响功能性状和生物多样性指标(物种多样性、功能多样性、谱系多样性)的关键因素不同，其中影响15年、30年、60年次生林和老龄林的关键环境因子依次为pH值与有机质、林冠开阔度、全钾与有效磷、以及土壤磷含量。2.在尖峰岭的不同海拔范围内的老龄林中，随着海拔的升高：(1)比叶面积和潜在最大高度逐渐降低，叶片干物质含量和木材密度逐渐增大；(2)物种丰富度和Shannon-Weaver指数逐渐增大；(3)功能丰富度逐渐增大，功能均匀度、功能分散度、功能离散度和Rao’s二次熵均则逐渐降低；(4)谱系多样性逐渐增大，群落谱系结构由发散转向聚集；(5)林分地上部分生物量增大。3.在尖峰岭30公顷热带山地雨林老龄林大样地中，随着生境从沟谷、下坡、中坡、上坡逐渐到山顶的变化：(1)比叶面积逐渐减小，叶片干物质含量、木材密度和潜在最大高度逐渐增大；(2)物种丰富度和Shannon-Weaver指数呈逐渐降低趋势；(3)功能丰富度、功能均匀度、功能离散度和Rao’s二次熵逐渐减小，而功能分散度呈先降低后增加的格局；(4)谱系多样性呈逐渐降低趋势，从沟谷经下坡至中坡，群落谱系结构由聚集逐渐走向发散，而从中坡经上坡至山顶则由发散逐渐趋于随机，但群落总体格局趋于随机状态；(5)林分地上部分生物量逐渐增大。(二)、热带天然林不同生物多样性指标之间的关系4.在各种不同类型的林分中，物种丰富度、功能丰富度与谱系多样性之间均存在显著的正相关，物种丰富度与谱系多样性的相关性最大。在霸王岭不同演替阶段的热带低地雨林中，随着演替的进行，物种丰富度与谱系多样性的相关性逐渐增大，而物种丰富度与功能丰富度的相关性及谱系多样性与功能丰富度的相关性在15年次生林和60年次生林中较高。在尖峰岭不同海拔范围内的老龄林中，与高海拔(>800m)相比，低海拔(<800m)群落中物种丰富度解释了更多的谱系多样性的变异。在尖峰岭30公顷热带山地雨林老龄林大样地中，随着生境从沟谷、下坡、中坡、上坡逐渐到山顶的变化，物种丰富度与功能丰富度的相关性逐渐增大。物种丰富度与谱系多样性的关系在沟谷和山顶均较强，而在下坡时较弱。谱系多样性和功能丰富度的关系在沟谷时最弱，而在下坡最强。(三)、热带天然林植物功能性状及生物多样性与地上部分生物量关系随时空的变化规律5.在霸王岭不同演替阶段的热带低地雨林中，前三个演替阶段的天然次生林地上部分生物量与比叶面积和叶片干物质含量相关性不显著，而老龄林地上部分生物量与比叶面积负相关，而与叶片干物质含量正相关。不同演替阶段林分的地上部分生物量均与木材密度呈正相关。与30年次生林相反，15年次生林和老龄林地上部分生物量与潜在最大高度正相关，而在60年的次生林中二者相关性不显著。在尖峰岭不同海拔范围的老龄林中，低海拔地区地上部分生物量与功能性状相关性不显著，而在高海拔地区林分地上部分生物量与比叶面积负相关，而与叶片干物质含量和木材密度正相关，但与潜在最大高度的相关性不显著。在尖峰岭30公顷热带山地雨林大样地中，在沟谷和下坡生境，林分地上部分生物量与比叶面积负相关，与叶片干物质含量及木材密度正相关。在中坡、上坡及山顶生境下，林分地上部分生物量只与木材密度的正相关，而与其它功能性状的相关性不显著。随着生境从沟谷、下坡、中坡、上坡逐渐到山顶的变化，林分地上部分生物量与潜在最大高度相关性均不显著，而与其他功能性状的相关性逐渐减弱。6.在霸王岭不同演替阶段的热带低地雨林中，林分地上部分生物量与生物多样性各指标均呈显著正相关。在15年次生林和老龄林中，生物多样性解释了较多的林分地上部分生物量变异，而在30年和60年次生林中，生物多样性所解释的林分地上部分生物量变异较少。在尖峰岭不同海拔范围的老龄林中，林分地上部分生物量与生物多样性的相关性均不显著。在尖峰岭30公顷老龄林热带山地雨林大样地中，在沟谷生境下林分地上部分生物量与物种丰富度和谱系多样性均显著正相关，但物种丰富度解释了更多的林分地上部分生物量变异，而林分地上部分生物量与功能丰富度相关性不显著。在其它四种生境下，林分地上部分生物量与生物多样性的相关性都不显著。(四)、环境因素对功能性状及生物多样性与林分地上部分生物量关系的调控机制7.假设结构方程模型是环境因素影响群落特征(包括功能性状或者生物多样性)，群落特征进而对生态系统功能(地上部分生物量)产生影响，而演替阶段对环境因素、群落特征及生态系统功能均产生影响。最终的结构方程模型运算结果表明比叶面积与木材密度、地上部分生物量存在负相关，而木材密度与地上部分生物量存在正相关，生物多样性与地上部分生物量存在正相关，与地上部分生物量相关性由小到大的多样性指标依次为物种丰富度、谱系多样性和功能多样性。群落演替阶段对地上部分生物量的影响最大。功能性状及生物多样性比环境因素解释了更多的地上部分生物量变异。本研究表明在海南岛热带天然林中，植物功能性状及生物多样性对生态系统功能具有决定性的作用，而不同的环境因素通过影响功能性状及生物多样性对生态系统功能进行不同程度的调控。更多还原

【Abstract】 The ecosystems in the globe are experiencing unexpected change. Biodiversity is thebackbone of ecosystems.The relationships between biodiversity and ecosystem functioning(BEF) is a central issue in ecology. Many experiments on BEF showed that the loss ofbiodiversity will significantly affect ecosystem functioning. Until recently, most of the controlexperiments on BEF have beenconducted in grassland by manipulating combinations ofherbaceous species richness. Due to the limited numbers of species and the controlledenvironment,the consistency of these experiental results with the actual field situations stillneed to be proven.Actual field ecosystems are far more complex than the ones designed bycontrolled experiments.Up to now, few studies on BEF have been done in the actual naturalecosystems, especially in complex ecosystems such as the tropical rainforests. Observationsbased on natural ecosystems may reveal the actual relationships between biodiversity andecosystem functioning. Furthermore, those controlled experiments have been mainly designedto assess how species richness affected ecosystem functioning and ignored other facets ofbiodiversity such as functional diversity and phylogenetic diversity. In this thesis,based on fieldinvestigations of communities and measurements of functional traits and environmental factorsin the tropical lowland rainforests of different successional stages after shifting cultivation inthe Bawangling Nature Reserve,in the old growth forests distributed in different elevationalranges in the Jianfengling Nature Reserve,as well asin the tropical montane rianforests locatedin different habitat types within a30haforest dynamics plot(FDP)in the Jianfengling NatureReserve,we explored the relationships between biodiversity and ecosystem functioning in thenatural tropical forests on Hainan Island,China.We did this research by the four followingsteps:Firstly,the variations of functional trait, biodiversity (including species diversity,functional diversity, phylogenetic diversity) and ecosystem function (stand abovegroundbiomass,AGB) with successional stages,elevations,habitat types and their influences by environmental factors were assessed;Secondly,the correlations among different facets ofbiodiversity(species/functional/phylogenetic diversity) were probed;Thirdly, the relationshipsbetween functional traits versusAGBand different facets of bidiversity versus AGB undervaried conditions (i.e.different successional stages, elevations and habitat types) wereexamined. Finally, the influence of environmental factors on the relationships betweenbiodiversity and ecosystem functioning through functional traits were comprehensivelyanalyzed by the structural equation modeling (SEM) approach. This thesis was one of the fewstudies on BEF based on actual field observationsin forest ecosystems,which is helpful infurther exploring the theory of biodiversity and for evaluating ecosystem functioning andservices. The main results are as follows:1. For tropical lowland rainforests with different successional stages (15-,30-and60-year-old secondary forests and old growth forest) in Bawangling Nature Reserve,(1)specific leaf area, leaf nitrogen content, leaf phosphorus content, leaf total organic carboncontent decreased and leaf dry matter content, wood density, potential maximum heightincreased with the process of succession. Leaf potassium content changed non-significantlywith the processof succession;(2) Species richness and Shannon-Weaver index increased withthe process of succession. There was a no significant change for Pielou’s index in the secondaryforests, but the value of Pielou’s index in secondary forests was lower than that in old growthforest;(3) Functional richness, functional evenness, functional dispersion and Rao’s entropydecreased first and then increased with the process of succession. Functional divergencereached peak in the60-year-old secondary forest;(4) Mean phylogenetic distance andphylogenetic diversity increased while net relatedness index and mean nearest phylogenetictaxon distance decreased with the process of succession. Nearest Taxon Index in the secondaryforests changed no significantly but were higher than that in old growth forest. Phylogeneticstructure transferred from clustering to overdispersion with the process of succession;(5) AGBincreased with the process of succession;(6) Functional traits and biodiversity (speciesdiversity, functional diversity and phylogenetic diversity) in different successional stages affected by different environmental factors. The key environmental factors to drive functionaltraits and biodiversity in15-,30-,60-year-old secondary forest and old-growth forest were pHand soil organic matter, canopy openness, soil total potassium content and availablephosphorus content, soil phosphorus content successively.2. For old growth forests distributed in different elevations in Jianfengling Nature Reserve,(1) specific leaf area and potential maximum height decreased while leaf dry matter contentand wood density increased with the increase of elevation;(2) Species richness andShannon-Weaver index increased with the increase of elevation;(3) Functional evenness,functional divergence, functional dispersion and Rao’s entropy decreased whereas functionalrichness increased with the increase of elevation;(4) Phylogenetic diversity enhanced andphylogenetic structure transferred from overdispersion to clustering with the increase ofelevation;(5) AGBincreased significantlywith the increase of elevation.3. For the tropical montane rainforests distributedin different habitat types (valley, downhill,middle slope, uphill and mountaintop successively) in the30ha.FDP on Jianfengling NatureReserve,(1) specific leaf area decreased while leaf dry matter content, wood density andpotential maximum height increased from valley to mountaintop;(2) There was a reducingtrend for species richness and Shannon-Weaver index from valley to mountaintop;(3)Functional richness, functional evenness, functional dispersion and Rao’s entropy decreasedwhile functional divergence decreased at first and then increased from valley to mountaintop;(4) Phylogenetic diversity decreased from valley to mountaintop. Phylogenetic structuretransferred from clustering to overdispersion from valley to middle slope whereas phylogeneticstructure transferred from overdispersion to random from middle slope to mountaintop. Thewhole phylogenetic structure of the30ha FDP was close to random;(5) AGB increased fromvalley to mountaintop.4. The correlations among species richness, functional richness and phylogenetic diversitywere positive in tropical forests under different conditions. The correlation between speciesrichness and phylogenetic diversity was higher than the other correlationsin all study area. For tropical lowland rainforests with different successional stages in Bawangling Nature Reserve,the correlation between species richness and phylogenetic diversity increased with the processof succession; The correlations between species richness and functional diversity as well as thecorrelation between phylogenetic diversity and functional diversity were higher in15-and60-year-old secondary forests. For old growth forests in different elevational ranges inJianfengling Nature Reserve, species richness explained more variation of phylogeneticdiversity in the low elevations(<800m) than that in the high elevations(>800m). For the oldgrowth tropical montane rainforest in the30ha.FDP in Jianfengling Nature Reserve, thecorrelations between species richness and functional diversity increased from valley tomountaintop. The correlation between species richness and phylogenetic diversity was lower indownhill than that in valley or mountaintop, while the correlation between phylogeneticdiversity and functional diversity was higher in downhill than that in valley ormountaintop.5. For tropical lowland rainforests with different successional stages in Bawangling NatureReserve, AGB in secondary forest (15-,30-and60-year-old forest) was not significantlyinfluenced by specific leaf area or leaf dry matter content; AGB in old growth forest decreasedmonotonously with the increase of species leaf area or the decrease of leaf dry matter content;AGB was positively related to wood density in all successional stages; Contrasting with30-year-old secondary forest, AGB in15-year-old secondary forest or old growth forest waspositively related to potential maximum height, but this relationship was not significant in60-year-old secondary forest. For old growth forests with different elevations in JianfenglingNature Reserve, AGB was not significantly related to functional traits in low elevation; specificleaf area was negatively related to AGB,leaf dry matter content and wood density werepositively related to AGB and potential maximum height was not significantly related toAGBin high elevation. For the old growth tropical montane rainforest in the30ha.FDP inJianfengling Nature Reserve, AGB decreased with the increase specific leaf area and increasedwith the increase of leaf dry matter content and wood density in valley and downhill; AGBonly increased with the increase of wood density from middle slope to mountaintop; Potential maximum height were not significantly related to AGB in all habitat types and the correlationsbetween other functional traits and AGB declined from valley to mountaintop.6. For tropical lowland rainforests with different successional stages in Bawangling NatureReserve, there was a significant and positive effect of biodiversity on AGB; Biodiversityexplained more variation of AGB in the15-year-old secondary forest and old growth forestthan those in the30-and60-year-old secondary forests. For old growth forests with differentelevations in Jianfengling Nature Reserve, biodiversity was not related to AGB both in low orhigh elevations. For the old growth tropical montane rainforest in the30ha.FDP in JianfenglingNature Reserve, species richness and phylogenetic diversity were positively to related to AGBin valley while the effect of species richness on AGB was greater than that of phylogeneticdiversity; Biodiversity was not significantly related to AGB from downhill to mountaintop.7.Initial SEM hypothesized that: the community characteristic (functional traits orbiodiversity) responded to environmental factors and affected ecosystem functioning (AGB)and environmental factors/community characteristic/ecosystem functioning were influencedby successional stage. Final SEM showed that specific leaf area was negatively related to wooddensity or AGB whereas wood density was positively related to AGB; Biodiversity waspositively related to AGB and the order for the effect of biodiversity on AGB was speciesrichness, phylogenetic diversity, functional diversity successively; The successional stage hadthe maximum effect on AGB and functional traits/biodiversity had a larger effect on AGB thanenvironmental factors. Overall, our results suggest functional traits or biodiversity are themajor drivers of ecosystem functioning and environmental factors regulate ecosystemfunctioning indirectly through functional traits or biodiversity in the tropical natural forests ofHainan Island.更多还原