广西马尾松林植物功能多样性与生产力的关系

探索植物多样性与生产力的关系可为森林经营与管理提供科学基础。本研究以广西4个地区的马尾松(Pinus massoniana)人工林群落为研究对象, 通过计算物种多样性、功能多样性和功能优势值, 运用相关分析、自动线性建模和方差划分等方法, 分析了多样性与生产力的关系。研究发现, 生产力与物种丰富度、Shannon指数、功能丰富度、功能均匀度极显著正相关(P < 0.01), 与物种均匀度、功能多样性、功能离散度、功能团个数、坡向显著正相关(P < 0.05), 与林龄极显著负相关(P < 0.01), 4个功能多样性参数和4个物种多样性参数两两之间皆为显著正相关; 未发现初始生物量制约生产力的提高; 方差划分最优模型中, 功能多样性参数效应、功能优势值效应和林龄效应分别解释生产力方差的56%、43%和33%, 功能多样性参数效应和功能优势值效应重叠部分高达27%; 生态位互补效应主要由功能丰富度和功能均匀度产生, 选择效应主要由生长型优势值产生; 生长型优势值为灌木的样地生产力较高, 次优种或过渡种对生态系统功能也有重要作用。以生产力为响应变量的自动线性建模最佳子集包括重要性由大到小的5个因素: 林龄、生长型优势值、功能丰富度、功能均匀度、功能团个数。建议维护森林功能多样性, 加强林下叶层植物保护, 用好功能重要的物种, 通过林下叶层的补偿性光合作用和生长竞争, 有效地提高生产力和生物多样性。     

高山草地植物群落数量特征沿海拔梯度变化及其影响因素

为了探索青藏高原湿润地区草地的演变规律和未来对气候变化的响应,以雅家埂高山带不同海拔草地为对象,研究了草地群落特征沿海拔梯度的变化,并分析了气候因子和土壤因子对群落特征的影响。结果表明:(1)沿海拔梯度草地群落特征具有明显分异,地上生物量随海拔升高呈现显著降低,而地下生物量和群落的根冠比呈现显著增加。群落多样性指数在较低海拔间呈现显著变化,而在较高海拔间变化不明显。总体而言,随海拔升高群落多样性增大,均匀度增大。(2)不同海拔群落特征差异主要由气候因子控制,且温度起主导作用,土壤因子的解释度可忽略。(3)整个海拔梯度上群落多样性指数与生物量呈负相关关系,支持根竞争和光竞争假说。     

亚热带次生常绿阔叶林植物功能性状及多样性对人工抚育的响应

亚热带次生常绿阔叶林普遍存在生长滞缓、固碳功能和经济价值低下等问题,迫切需要通过人工抚育提高其生态系统功能。对植物功能性状及其多样性的深入研究,能够找寻植物共存与群落稳定发展的内在机制,为提升森林生态系统功能的实践提供基础。为了探究人工抚育对亚热带次生常绿阔叶林质量提升的影响,以杭州午潮山国家森林公园内的次生常绿阔叶林为研究对象,实施了不同强度的抚育措施,通过群落植被复查,分析群落植物功能性状以及功能多样性对不同强度人工抚育的响应。结果发现:抚育2年后,群落最大潜在树高与叶片氮、磷、钾含量显著上升,而叶片干物质含量和叶片叶绿素含量均有显著下降,比叶面积有下降趋势,两种强度的抚育之间差异不显著;叶片干物质含量、叶绿素含量与叶片氮含量间的相关性由不显著变为了显著负相关,而叶片干物质含量与叶片叶绿素含量,叶片磷、钾含量与叶片氮含量,叶片磷含量与叶片钾含量间的相关性由不显著变为显著正相关;在20%强度抚育下,功能丰富度指数均值从对照的0.52显著下降为0.16,功能均匀度指数与功能分离度指数的均值则分别上升到0.61和0.67,显著高于对照组的0.51和0.56;在10%强度抚育下,功能丰富度有所下降,功能均匀度与功能分离度均有所上升,但差异不显著。研究表明,人工抚育在一定程度上改变了群落水平的植物功能性状与功能多样性,提高了群落植物利用资源的能力和效率;而适度的抚育强度更能解放资源空间,对群落产生的影响更加明显。该结果为亚热带次生常绿阔叶林的经营与管理提供依据与参考。     

海南尖峰岭热带山地雨林林冠层树种功能多样性特征

以海南尖峰岭热带山地雨林3块1 hm²样地为研究对象,利用11个林冠功能性状结合样地地形及林冠乔木树种样地清查数据,分别基于单维性状和多维性状比较物种多度加权对群落功能离散度指数——平均成对距离(MPD)和平均最近类群距离(MNTD)的影响;同时分析林冠层功能丰富度(FRic)与物种丰富度之间的关系,最后利用零模型探讨不同生境类型下标准化效应MPD和MNTD(经过物种多度加权且剔除群落物种丰富度差异影响)的变化,进而评价林冠层群落水平功能多样性格局及其对局域生境异质性的响应.结果表明: 功能性状维度和物种多度对MPD的影响强烈,不同维度功能性状多度加权前后MPD相关性较弱(R=0.359～0.628);但对MNTD的影响相对较弱,不同维度功能性状多度加权前后MNTD相关性较强(R=0.746～0.820);未经物种多度加权的MPD和MNTD均普遍高估了林冠层的功能离散度.林冠层功能丰富度与物种丰富度基本呈指数相关关系(F=128.20;R²=0.632;AIC=97.72;P＜0.001),且功能丰富度很有可能存在一定的物种丰富度阈值.基于不同维度功能性状的林冠层功能多样性格局及其生境响应存在一定的差异性.在生物竞争激烈的低沟生境中,林冠层功能多样性倾向于比预期零模型随机产生的功能多样性高,林冠树种功能性状表现出离散分布;而在其他生境类型中,林冠层功能多样性倾向于接近或低于随机产生的功能多样性,林冠树种功能性状随机或聚集分布.     

When are buttresses and stilt roots necessary for a tree in terra-firme Amazonian forests?

Determinants of the occurrence of buttress and stilt roots are still poorly understood. These may be linked to individual's properties as a way to increase stability as trees get higher, to environmental factors that increase falling risks or interactions of both. We took advantage of a large dataset (presence of buttress, stilt roots, and tree diameter in 8415 trees from 35 1-ha plots in central Amazonia) to investigate how tree and environmental properties interact to determine the occurrence of support structures. We also made detailed measurements of allometry and canopy size in 67 trees of two dominant species. The probability of occurrence of support structures was modeled with multiple logistic regressions and boosted regression trees. We established a best-fitting subset model based on AIC ranking using unsupervised model selection. At the landscape scale, support structures were more common in large trees (b_std = 0.88, p < .001) and valleys (b_std = −0.09, p < .01), due to species turnover along topography and also due to intraspecific variation in the development of buttresses within species, linked to interactions of tree size and topography. The relationship between height and diameter (Height:Diameter) was the most important determinant of buttress occurrence (b_std = −1.57, p < .001). We conclude that less stable soils select a higher frequency of trees with support structures. However, coordinated allometric relationships among stem and crown sizes also influence the need of support structures. Thus, the presence of support structures depends on the interplay of individual plant's allometry and environmentally imposed conditions of instability. Abstract in Portuguese is available with online material.     

午潮山常绿次生阔叶林主要木本植物功能群及其演替特征

为了理解午潮山次生林群落结构和演替特征,分析了不同演替阶段功能群物种的生态位和种间关系。对研究区70个20×20 m森林样地内胸径≥1 cm的木本植物进行分析调查,并按照11个功能性状（叶片氮含量、叶片磷含量、叶片钾含量、比叶面积、木材密度、叶片干物质含量、叶片叶绿素含量、生长型、寿命、喜光性和最大潜在树高）将主要的45个物种划分为4个功能群：早期先锋树种（PFG1）、中期中性树种（PFG2）、中后期树种（PFG3）和后期耐阴树种（PFG4）。结果表明种间正负联结比接近1,但显著正联结多于显著负联结,群落整体稳定,而演替中后期功能群（PFG2、PGF3和PFG4）的种间生态位重叠和种间联结强度较高,种间竞争激烈。午潮山森林群落正向演替后期发展,可伐除部分与演替中后期树种相互竞争的早期树种加速演替,并且补植有价值的喜阳先锋种减少开放地,为修复森林生态系统和加速群落演替提供策略。     

星斗山常绿落叶阔叶混交林木本植物叶功能性状及其多样性特征分析

为探究亚热带常绿落叶阔叶混交林中木本植物叶功能性状的变异特征,以及群落功能多样性在海拔梯度下的响应规律。该研究以鄂西南地区的星斗山国家级自然保护区海拔1 200～1 700 m的常绿落叶阔叶混交林为研究对象,对群落内木本植物的叶面积(LA)、比叶面积(SLA)、叶干物质含量(LDMC)、叶厚度(LT)、叶氮含量(LNC)、叶磷含量(LPC)6种叶功能性状的变异特征进行了分析,并分析了群落水平下木本植物叶功能性状和功能多样性对海拔变化的响应。结果表明:(1)星斗山保护区内木本植物叶面积、比叶面积、叶干物质含量、叶厚度、叶氮含量和叶磷含量平均值分别为151.49 cm~2、247.98 cm~2/g、34.08%、0.21 mm、16.59 mg/g和0.04 mg/g,其变异幅度依次为206.96%、57.00%、28.15%、52.38%、24.83%和76.92%。(2)在植物科、叶习性、生活型和树高4个因素中,科类群对6种叶功能性状的影响最大,其次为叶习性。(3)海拔对叶面积、叶干物质含量、叶磷含量影响极显著(P0.001),但对比叶面积、叶厚度和叶氮含量无显著影响(P0.05)。(4)不同海拔梯度上群落生物承载量、功能丰富度、功能分离度和功能离散度均达到显著差异(P0.05),仅功能均匀度在海拔梯度上差异不显著。     

热带森林植物功能群及其动态研究进展

热带森林极高的物种多样性和结构复杂性给生态学研究带来了很多挑战。植物功能群是对特定环境响应相似或对主要的生态过程具有相似作用的物种组合。应用植物功能群的方法是有效减少热带森林群落复杂性,并揭示其格局和过程的良好途径。在介绍植物功能群概念和划分途径的基础上,分析了热带森林植物功能群的时空动态规律。一般来讲,划分植物功能群通常有3种途径,并可通过5个步骤来完成。热带森林植物功能群的空间分布常受景观格局的制约,而环境异质性往往是影响不同植物功能群组配比例变化的直接原因。不同类型的植物功能群随演替过程发生显著的替代,而干扰体系和全球气候变化对功能群的动态过程具有重要的驱动作用。以功能群为基础的动态模型在模拟热带林群落动态和预测植被潜在分布等方面具有广阔的发展前景。探索有效的植物功能分类方法、构建完善的植物功能性状数据库、开发更为精确的功能群动态模型以及加强基于景观水平的植物功能群动态机制的认识等是未来热带森林植物功能群及其动态研究的重要方向。     

天坑森林植物群落叶功能性状、物种多样性和功能多样性特征

以天坑内部-边缘-外部森林植物群落为研究对象,通过调查植物的群落结构、叶功能性状,探究天坑内外森林植物群落叶功能性状、物种多样性和功能多样性变化特征及其内在关联,为深入了解负地形森林生态系统的功能和恢复退化喀斯特地区的植被提供一定参考。研究结果如下：（1）比叶面积（SLA: 198.75 cm2/g)）、叶面积（LA: 42.70 cm2）、叶磷含量（LPC: 1.70 g/kg）和叶钾含量（LKC: 10.27 g/kg）在天坑内部最高,叶组织密度（LTD: 0.32 g/cm3）和叶干物质含量（LDMC: 0.41 g/g）在天坑外部最高,天坑内外森林均易受到磷限制,表明随天坑内部-边缘-外部生境变化,植物对环境的适应机制和生存策略发生了部分调整,物种的防御策略增强,生长投入策略减弱。（2）Shannon-Wiener指数（2.82）、Simpson指数（0.92）和Pielou’s均匀度指数（0.87）均以天坑外部最高,功能丰富度（1.05）、功能离散度（1.88）和Rao’s二次熵（4.52）以天坑内部最高,表明随天坑内部-边缘-外部生境的变化,植物功能性状的差异减少,物种分布及其功能性状分布总体上更为均匀、物种数量增多。（3）物种多样性指数之间、功能多样性指数之间存在较强的相关性,表明物种多样性指数之间、功能多样性指数之间存在不同的制约关系。（4）叶功能性状与物种多样性、功能多样性的相关性强,物种多样性和功能多样性之间相关性较弱,表明叶性状对生态学过程的变化较为敏感,叶功能性状与物种多样性之间存在较强的耦合关系。     

Winners and losers: tropical forest tree seedling survival across a West African forest–savanna transition

Forest encroachment into savanna is occurring at an unprecedented rate across tropical Africa, leading to a loss of valuable savanna habitat. One of the first stages of forest encroachment is the establishment of tree seedlings at the forest–savanna transition. This study examines the demographic bottleneck in the seedlings of five species of tropical forest pioneer trees in a forest–savanna transition zone in West Africa. Five species of tropical pioneer forest tree seedlings were planted in savanna, mixed/transition, and forest vegetation types and grown for 12 months, during which time fire occurred in the area. We examined seedling survival rates, height, and stem diameter before and after fire; and seedling biomass and starch allocation patterns after fire. Seedling survival rates were significantly affected by fire, drought, and vegetation type. Seedlings that preferentially allocated more resources to increasing root and leaf starch (starch storage helps recovery from fire) survived better in savanna environments (frequently burnt), while seedlings that allocated more resources to growth and resource‐capture traits (height, the number of leaves, stem diameter, specific leaf area, specific root length, root‐to‐shoot ratio) survived better in mixed/transition and forest environments. Larger (taller with a greater stem diameter) seedlings survived burning better than smaller seedlings. However, larger seedlings survived better than smaller ones even in the absence of fire. Bombax buonopozense was the forest species that survived best in the savanna environment, likely as a result of increased access to light allowing greater investment in belowground starch storage capacity and therefore a greater ability to cope with fire. Synthesis: Forest pioneer tree species survived best through fire and drought in the savanna compared to the other two vegetation types. This was likely a result of the open‐canopied savanna providing greater access to light, thereby releasing seedlings from light limitation and enabling them to make and store more starch. Fire can be used as a management tool for controlling forest encroachment into savanna as it significantly affects seedling survival. However, if rainfall increases as a result of global change factors, encroachment may be more difficult to control as seedling survival ostensibly increases when the pressure of drought is lifted. We propose B. buonopozense as an indicator species for forest encroachment into savanna in West African forest–savanna transitions.     

马尾松林向香樟林改造林下植物功能多样性研究

在生物多样性研究中,功能多样性比物种多样性可以更直接地反映生态系统的结构和功能,从而在群落生态学研究中受到越来越多的推崇。马尾松次生纯林是一种亟待改造的森林类型,而在亚热带地区香樟是马尾松林改造的理想树种之一。为了完善马尾松林向香樟林改造的研究,以更好地指导马尾松林改造的实践,本文用空间代替时间的方法,选取马尾松林向香樟林改造过程中4种不同阶段群落为研究对象,对林下灌木层和草本层植物的功能性状及其多样性展开了研究。结果表明:(1)随着森林改造的进行,林下植物的物种数目、功能性状多样性均表现为先上升后下降的变化趋势,其中功能丰富度和功能均匀度在改造前期达到峰值,而物种数目和功能离散度则在改造中期表现最高。(2)比较森林改造的4个时期,林下植物功能多样性的综合表现大致为:改造前期>改造中期>改造后期>未改造时期。(3)森林改造过程中,林下植物"光响应性状"和"繁殖性状"的功能多样性变化趋势相似,但前者比后者对改造的响应更敏感。(4)在森林改造过程中,林下植物的生长、发育和扩散受到林下光照资源的影响,并在长时间的生物竞争中逐渐表现为物种种类、多度和空间分布格局的变化,最终影...     

林木基因组学研究进展

林木基因组学研究进展迅速。结构基因组学方面,已构建了近40个主要造林树种的遗传连锁图谱,在不同树种中定位了30余个重要的数量性状位点,在部分树种中开展了基因组比较和综合图谱构建研究,杨树的全基因组测序已经完成,桉树的全基因组测序正在进行。功能基因组学方面,已分析了主要造林树种多种组织的转录组EST序列,对林木次生生长与木材形成、开花和抗寒性的形成等过程开展了功能基因组学研究。另外,探讨了林木基因组学研究的发展趋势,以期为我国林木基因组学研究提供有益的参考。     

中亚热带几种针、阔叶树种凋落物混合分解对土壤微生物群落碳代谢多样性的影响

土壤微生物群落功能如何响应凋落物物种组成的改变,对于指导我国的人工林种植具有重要意义。通过小盆模拟试验,用BIOLOG微平板培养的方法研究了南方红壤丘陵区典型物种马尾松和湿地松的凋落物分别与白栎和青冈的凋落物混合,与单一针叶凋落物分解时相比,针阔混合凋落物分解过程中土壤微生物群落功能多样性的差异。结果表明：(1)针叶和阔叶混合分解提高了土壤微生物群落碳代谢的强度、丰富度以及多样性,针阔混合凋落物分解时土壤微生物群落的碳源代谢方式与单一针叶分解时差异显著;(2)凋落物分解前期土壤微生物群落碳代谢强度、丰富度和多样性与凋落物初始C/N呈显著负相关,分解后期土壤微生物群落碳代谢强度与凋落物初始木质素/N比呈显著负相关,碳代谢多样性与初始P含量呈显著正相关;(3)通过改变凋落物物种组成,进而改变凋落物元素组成(C/N、木质素/N和P),能显著影响土壤微生物群落的碳代谢强度和代谢多样性。在南方红壤丘陵区,针-阔叶混合的凋落物比单一针叶凋落物更有利于提高土壤微生物群落的功能。     

Daily and seasonal courses of gas exchange and niche partitioning among coexisting tree species in a tropical montane forest

We investigated the seasonal gas exchange patterns of three different functional types of tropical afromontane trees, namely Podocarpus falcatus (Thunb.) Mirb. (evergreen gymnosperm), Prunus africana (Hook. f.) Kalkm. (broad-leaf evergreen), and Croton macrostachyus Hochst. ex Del. (broad-leaf deciduous) which grow side-by-side in the Munessa forest, southern Central Ethiopia. The hypothesis is that the trees can make different use of the environmental conditions which change seasonally and also from year to year. These changes can be understood as fluctuating niches, the utilization of which allows coexistence through balanced carbon gain. In this study, light and moisture were considered the two main fluctuating niches. Porometry was used to measure the daily and seasonal responses of the leaves to environmental variables under dry and wet season conditions in the course of the climatically differing years 2009 and 2010. Correlations of the patterns of these responses were analyzed by regression analysis. From daily integrated rates of irradiation, photosynthesis and transpiration, light and water use efficiencies of photosynthetic carbon gain and their mutual interdependences were determined. Except an extended dry season in 2009 when C. macrostachyus had shed its foliage, all three species continued photosynthetic net CO₂ uptake concomitant with transpiration at all seasons, although at varying rates. Ecophysiological performance of P. falcatus leaves is mainly light-driven and responds relatively little to a change in moisture conditions. Its carbon and water relations are striving for stability rather than flexibility. As of a typically subdominant species of the forest, P. africana leaves can efficiently use low light intensities but suffer from photoinhibition at full light. Their performance, showing more dynamic response to the environment than P. falcatus, P. africana appears driven more by moisture than by light. Compared to the two evergreens C. macrostachyus exhibited the highest flexibility in its leaves’ physiological responses to environmental conditions, in particular to the light climate which is additionally potentiated by the fast turnover of its foliage. This species optimizes its carbon gain during the wet season and during the early dry period when cloud cover is minimal. Our findings thus reveal that elasticity of the response to fluctuating environmental conditions is an additional aspect in the assessment of the utilization of temporally fluctuating niches by adult tree individuals.     

海南天然林与橡胶林蜘蛛多样性比较

为探索天然林和橡胶林蜘蛛多样性现状,于2010年8月在海南黎母山自然保护区选取天然林和橡胶林,采用扫网法、陷阱法和单位面积法收集蜘蛛标本,分析两种林型之间蜘蛛组成、多样性和功能群差异,并以蜘蛛科和数量分布为属性进行主成分分析(PCA),探讨林型中样方之间蜘蛛群落的相似性。共采集蜘蛛标本3609头,用于统计分析的成蛛969头,归属于23科,162种。天然林20科,100种,优势类群为跳蛛科、球蛛科和园蛛科;橡胶林17科,87种,优势类群为肖蛸蛛科、狼蛛科和猫蛛科。从蜘蛛的数量分布看,橡胶林蜘蛛个体密度显著高于天然林;而天然林多样性指数和丰富度指数显著高于橡胶林。橡胶林中结圆网型和游猎型蜘蛛显著高于天然林,结皿网型显著低于天然林,伏击型不存在显著性差异。PCA分析结果表明,24个样方趋于分成天然林和橡胶林2组,并且天然林样方之间相似性极高,而橡胶林样方之间相似性相对较低。以上结果表明:(1)橡胶林替代天然林后蜘蛛群落结构发生变化,多样性降低;(2)增加生境结构的复杂性和减少人为干扰对保护和恢复物种多样性有重要意义。     

Functional composition trajectory: a resolution to the debate between Suganuma,Durigan, and Reid

The selection of ecological indicators is an important step toward more effective restoration monitoring. The debate between Reid (2015) and Durigan and Suganuma (2015) regarding the usefulness of species composition for monitoring restoration trajectory is timely and salient, but it lacks a middle way proposal to balance ecological relevance and practical viability. We propose a way forward to resolving this debate, namely using easily measurable functional traits, a type of compositional measure, as an indicator. Assessing functional composition trajectory may help overcome some limitations with taxonomic identification and provide more meaningful outcomes to evaluate restoration success.     

Comparative root system structure of post-fire Pinus halepensis Mill. and Cistus monspeliensis L saplings.

To describe root system topology of Pinus halepensis and Cistus monspeliensis saplings co-inhabiting natural post-fire sites, 55 P. halepensis and 26 C. monspeliensis saplings were extracted by the total excavation method from a burnt pine stand. Seedlings were individually labelled when emerging after fire and extracted three years later, at the sapling phase. In order to evaluate the effect of inter-specific competition of C. monspeliensis on P. halepensis root system, a stratified sampling was carried out according to density and height of the saplings. Topological parameters considered in the analysis were magnitude, total external pathlength, and altitude of the root systems. Weight and length of roots were also measured in order to estimate the specific root length, an index commonly used in morphological studies. Results clearly evidenced greater variability in root system topology of P. halepensis than C. monspeliensis saplings. Herringbone architecture (i.e., the most ordered pattern possible, with branching confined to the main axis) characterised small pine saplings, regardless of competition from C. monspeliensis, which changed to random branching in large saplings. In medium sized saplings, the root system was affected by inter-specific competition, which delayed changes in root branching. In contrast, C. monspeliensis invariably adopted randomly branched architecture, regardless of intra-specific competition. It is concluded that such different topological patterns make C. monspeliensis more competitive during the early stages of post-fire succession, because its root system is much more transport-efficient in the nutrient-rich environment. Those pines which finally branch roots by random pattern will reach higher stem height and magnitude, a factor which allows them to successfully compete with C. monspeliensis for soil nutrients and water. The morphological analysis showed a significant increase in the specific root length with competition, both in P. halepensis and C. monspeliensis saplings, which could be interpreted as a consequence of the reduction of root diameter in response to nutrient depletion.