中亚热带喀斯特常绿落叶阔叶林空间结构特征

喀斯特常绿落叶阔叶林是中国西南喀斯特地区非地带性顶极森林群落,该研究基于相邻木关系的角尺度、混交度和大小比数3个结构参数,对木论国家级自然保护区常绿落叶阔叶林25 hm^(2)大型固定监测样地整体、上木层、下木层及其优势物种的空间结构特征进行了分析,以期揭示其森林空间结构现状,为喀斯特植被恢复重建提供依据。结果表明:(1)样地群落整体为轻度聚集分布格局,接近随机分布,物种高度混交且个体间大小分化程度相近,上木层呈现随机分布、强度混交和中庸偏亚优势状态,下木层呈现聚集分布、强度混交和中庸偏劣势状态。(2)样地内优势物种大多处于轻度聚集分布、强度混交且中庸偏劣势的状态。(3)林木大小比数与胸径、树高均呈显著负相关关系,混交度与胸径、树高均呈显著正相关关系,随林木的生长发育,树种优势度逐渐增大,物种多样性逐渐增强。研究认为,木论常绿落叶阔叶林空间结构尚未完全稳定,正处于演替中后期,具有发育成顶极群落的潜力。     

集合种群竞争机制在庐山森林演替模拟中的应用

通过对森林植被群落的动态模拟,可以揭示森林植被的恢复过程和演替规律。本文将动物集合种群竞争模型引入森林演替模拟中,以庐山为研究区域选取10个优势乔木种进行了森林演替模拟。在MATLAB中分别对当前生境条件、生境破坏条件和生境恢复条件进行模拟,结合庐山森林演替动态曲线和各优势种对外界条件响应规律,总结了对不同物种续存的保护机制。结果表明:(1)庐山森林种群整体向常绿阔叶林方向演替,混生林中阔叶树占优势;(2)森林群落中的优势物种可分为3个等级:第一等级优势种对恶劣生态环境适应性强,但在生态环境得到保护时容易被低优势度物种侵占,应防止人工引进的外来物种对原有优势种造成过度侵占;第二等级优势种对生境变化敏感,生境严重破坏会造成这类物种灭绝,生境恢复能使之续存;第三等级优势种在生境恢复条件下也难以续存,应采取人工育林等措施进行保护。     

中国红河地区董棕林乔木树种的物种组成和地理亲缘关系

在中国和中南半岛的喀斯特地区,董棕(Caryota obtusa)林是一类外貌醒目、物种多样和生境独特的植物群落。由于其具有作为食物和用于园艺的潜在价值,董棕在自然生境中越来越稀少。为了弄清董棕林的群落特征和物种组成,我们在云南红河地区的一个喀斯特峡谷选取6个群落样方研究了董棕群落的物种多样性。在每个20 m×20 m样方中,调查了胸径(DBH)≥4 cm的乔木树种的胸径等生物学特征。通过相对多度、相对频度和相对显著度计算出研究区董棕林群落中每个乔木树种的重要值,确定了该群落的优势组成。一方面,我们分别通过分布区类型和自然地理单元两种地理分布样式来分析乔木树种的地理成分组成特点,从而确定董棕林的地理联系;另一方面,我们选择了群落中重要值排名前5位的乔木树种,通过地理分布图的绘制,分析比较了5个优势树种的地理分布特点及其关系,确定了所选取的研究群落在整个董棕分布区的地位。结果表明,云南红河地区董棕林由67种乔木树种组成,群落名称可定为董棕+双果桑群落(Caryota obtusa+Streblus macrophyllus community),群落中乔木物种的区系成分以中南半岛分布最多,且是在热带东南亚喀斯特地貌大背景下发育形成的。研究暗示我国的董棕群落已处于该类热带喀斯特植被的最北缘,在中南半岛这个全球生物多样性热点地区值得优先加以保护。     

华北山地典型天然次生林群落的树种空间分布格局及其关联性

关帝山华北落叶松、云杉、杨桦天然次生林植被类型是华北高海拔地带代表性的森林类型。以该地区上述3种典型的天然次生林群落为例,运用点格局分析中的单变量O-ring统计方法,分析各群落主要树种的种群空间分布格局;用双变量O-ring统计方法,分析各群落中树种间的空间关联性;并对同一树种在不同森林群落类型中种群空间分布格局和种间关联性的变化进行比较,以探讨华北山地次生林群落空间格局形成和种群维持与动态机制。研究结果表明,(1)各种群在相对小的尺度上聚集分布特征明显,随尺度增加树木种群的聚集性减弱并逐渐表现出随机分布的格局特征;(2)同一树种在不同森林群落类型中空间分布格局差异很大。红桦、白桦和山杨在阔叶林中呈明显的小尺度聚集分布格局,而在针叶林群落呈随机分布。在阔叶次生林中混生的小龄级华北落叶松呈现聚集性空间分布格局。在华北落叶松为优势树种的针叶林中,大龄级的华北落叶松表现出小尺度上均匀分布和较大尺度上随机分布的格局特征;(3)各群落中树种间的空间关联性主要表现在小尺度范围,随尺度加大空间关联性逐渐不明显;(4)在阔叶树占优势的次生林,小龄级华北落叶松与桦木的分布有较明显的空间正关联性,而在华北落叶松为优势树种的针叶林,桦与华北落叶松并未表现明显的空间关联性。种群分布格局和种群间的空间关联性随群落结构、空间尺度和龄级结构不同而有较大变化。     

基于大样地研究方法的辽宁西北部彰武县阿尔乡疏林地树种组成与群落结构

彰武县地处辽宁西北部科尔沁沙地南缘,其区域植被群落恢复与重建是研究的焦点。以往的研究因缺少群落个体的空间定位,无法准确描述群落物种的空间分布及动态变化。因此,本研究应用森林大样地监测方法,于2014年7月在彰武县阿尔乡建立了1块100 m×100 m的疏林地长期监测样地,对样地内所有胸径不小于1 cm的所有木本植物进行定位调查。结果表明:样地内物种数较少,共10个树种,分属于9科9属;样地内独立个体数为393,包含分枝的个体数为592;群落中优势树种明显,从重要值分析来看,山里红(Crataegus pinnatifida var.major)和加杨(Populus×canadensis)在群落中占有绝对优势(重要值分别为0.316、0.295);家榆(Ulmus pumila)和樟子松(Pinus sylvestris var.mongolica)在其中亦占有一定的比例(多度分别为47、26),更新较为良好;从物种的空间分布来看,主要树种除樟子松外并未表现出明显的聚集性分布,部分小乔木和灌木树种则表现出相对聚集性分布,但并没有表现出与地形明显的相关性。     

物种聚集分布与种间关系的多度不对称性

群落内物种的相对多度与其空间分布和种间关系存在内部联系,然而这种联系如何影响物种共存却存在很大的争议.本研究认为,植物群落中的常见种受到更强的种间作用,最终限制了其种群增长;稀有种呈现更强的聚集分布格局,有利于增强种内调节作用,减弱种间作用,从而实现与其他物种的共存.为验证该假设,本研究以长白山25 ha阔叶红松林样地内的主要大树树种(DBH≥10 cm)为研究对象,用空间统计的方法分析各树种间关联和树种聚集分布格局,并探讨其与树种多度之间的联系.结果发现,树种之间以负相关关系(排斥)为主,且呈现明显的多度不对称性,即常见种之间有更明显的排斥作用.在聚集分布格局下,树种的局部优势度在较小范围内(～5 m)没有明显的多度依赖性,这将有利于稀有种和常见种实现局部共存.上述结果表明,在森林群落中种间关系的整体强度主要源于常见种的作用,而物种呈现的聚集分布格局有利于稀有种,进而促进物种的长期共存.该研究揭示了物种空间分布的多度依赖性及其对物种共存的影响,有利于进一步认识温带森林群落的构建过程.     

茂兰喀斯特森林群落的种间分离特征

种间分离的研究对于揭示种间相互作用、群落组成与动态具有重要意义。为分析喀斯特原生性森林群落种间的分离特征,进而探讨喀斯特生境上物种的共存机制,以茂兰国家级自然保护区分布的亚热带区域原生性较强的典型常绿阔叶落叶混交林为研究对象,以建立的2块1hm2(100m×100m)样地群落学调查数据为基础,借助ArcG IS软件的空间分析功能,判定每个个体的最近邻体植株的种类与距离。在此基础上,采用N×N最近邻体列联表及其截表的方法,应用P ielou的分离指数量化了2块样地中各43个树种(多度≥20)的种间分离状况。研究结果表明:两种喀斯特森林群落类型中物种均以随机毗邻种对占优势(P1和P2样地分别为60.91%和63.34%),正分离种对次之(分别为38.76%和35.66%),负分离种对极少(分别为0.33%和1.0%),这种种间分离特征表明种间竞争排除作用减弱,群落已趋于稳定,反映出该森林正处于相对稳定的顶极状态。根据种间分离情况以及物种对环境的适应方式,将两个样地各43个物种分别划分为3个生态种组,各组间物种的生态学特性以及对生境的偏好存在明显差异。种间的分离特征与喀斯特森林高度的生境异质性明显相关,分布在不同生境类型上的物种间大多呈现正分离,而具有相似生境要求或分布广泛的物种间易形成随机毗邻或负分离,这一特征为群落中多物种的稳定共存提供了更大的可能性。因此,以生境的高度分化为基础的种间关系可能是喀斯特森林多物种稳定共存的重要机制之一。     

亚热带森林系统4种附生蓝藻地衣的分布对生境变化的响应

蓝藻地衣是附生植物类群的重要组成部分, 在森林生态系统的环境监测和养分循环中发挥着重要作用。该研究在云南哀牢山亚热带森林系统的2种原生和6种次生森林群落中, 以粉缘绵毛衣(Leioderma sorediatum)、天蓝猫耳衣(Leptogium azureum)、网肺衣(Lobaria retigera)和双缘牛皮叶(Sticta duplolimbata) 4种常见蓝藻地衣为对象, 共设立120个样地, 调查了它们在3600株树木0-2 m树干上的分布, 探讨其分布特征及与森林类群、宿主种类以及林龄等生境因子的关系。研究发现4种蓝藻地衣在森林群落间的分布模式明显不同。除双缘牛皮叶的盖度和频度在原生苔藓矮林中最高外, 其他3种蓝藻地衣的最高值均出现于次生林如厚皮香(Ternstroemia gymnanthera)林和滇山杨(Populus bonatii)林中; 而哀牢山地区广布的原生木果柯(Lithocarpus xylocarpus)林中, 4种蓝藻地衣极为少见。4种地衣都能生长于10多个树种上, 但明显表现出对厚皮香、滇山杨和硬壳柯(Lithocarpus hancei)等树种的偏好性, 以及对小花山茶(Camellia forrestii)等的排斥性。森林群落的林龄、胸径、最大胸径、林冠开阔度、基面积、树木密度和树种多样性等因子的变化均对4种附生蓝藻地衣的分布产生重要影响, 但在景观尺度上影响程度相对较小, 在不同森林群落内部却有各自的重要作用。其中, 林龄、林冠开阔度和宿主胸径是影响蓝藻地衣分布的最重要的生境因子。     

南岭东西段植物群落物种组成及其树种多样性垂直格局的比较

根据沿海拔梯度设置的样地的调查资料,对南岭东段的莽山和西段的猫儿山植物群落乔木层物种多样性的垂直分布格局进行了比较研究。莽山和猫儿山的植被类型差异不大,但相同植被类型的物种组成有比较明显的差异。随海拔的上升,两山体乔木的最大树高均呈现显著下降趋势。猫儿山乔木的最大胸径、胸高断面积之和以及立木密度在海拔梯度上呈单峰曲线变化趋势。莽山乔木的最大胸径、胸高断面积之和与海拔呈明显的负相关性,而立木密度的变化规律不明显。这种单峰曲线格局或负相关关系与中尺度上的海拔高度以及小尺度上的土壤特性、小地形以及人为干扰强度等因素有关。在海拔1000m以下的常绿阔叶林群落和1700m以上的山顶矮林群落,莽山乔木的物种丰富度均明显高于猫儿山。两山体的乔木种数与海拔之间都显示出负相关性,但莽山由于高海拔群落受人为干扰的影响,这种相关性不显著。乔木层α多样性沿海拔梯度没有表现出明显的变化规律,并且在两山体之间也看不出明显的差别。本文最后还对两山脉低海拔区段的常绿阔叶林群落的物种组成和多样性进行了对比分析,结果表明人为干扰导致猫儿山常绿阔叶林的物种丰富度(S)和α多样性(H’)明显低于莽山的原生性常绿阔叶林群落,而且落叶阔叶树种和毛竹(Phyllostachys pubescens)开始入侵到群落中。     

黄土高原子午岭森林群落演替与结构特征演化

森林群落演替机制的研究对于加速黄土高原地区的生态环境建设,特别是人工植被建设具有重要的理论意义。采用时空互代的方法研究了黄土高原子午岭林区不同演替阶段3种演替森林群落山杨(Populus davidiana)林、油松(Pinus tabulaeformis)林与辽东栎(Quercus liaotungensis)林的群落结构特征,结果表明,(1)子午岭林区群落自然进展演替过程中,群落物种丰富度、植物多样性以及个体密度均呈降低趋势。该区森林群落以地面芽植物占绝对优势,而高位芽植物比例较低。各演替阶段群落的空间成层现象明显,并发育有一定数量的层间植物。群落各层主要优势种的水平分布均表现为均匀连续分布状态,而多数非优势种则为零星分布特征。(3)茶条械在该地区具有较宽的生态位,建议作为人工造林树种考虑。     

A model of the species rank-abundance relation for a community in an open habitat

A mathematical model is proposed to describe the relationship between the abundance and the rank of species in order from the most abundant to the least in a community in an open habitat. This model is derived as a corollary of a species-area equation (Kobayashi , 1975) which could be expected in the case where the individuals of each species are uniformly distributed over a habitat area. Numerical simulation reveals that a rank-abundance curve for a universe results in different species-area or species-individual curves according to the spatial distribution of individuals, and that the relative abundance of each species in a sample varies with sample size unless the spatial distribution of individuals is uniform. A species-individual curve obtained bySanders 's (1968) rarefaction method agrees with that observed actually only for the spatially uniform distribution. Change in the pattern of rank-abundance curve with species diversity and with sample size is discussed in relation to the present model.     

基于枝条木材密度分级的鼎湖山南亚热带常绿阔叶林树高曲线模型

如何便捷准确地测量树高一直是林学及群落生态学所关心的问题。由于木材密度与树木生长密切相关, 因此基于木材密度建立树高曲线模型能够为测量树高提供新的方法。本文以鼎湖山南亚热带常绿阔叶林1.44 ha塔吊样地内119个物种的4,032个个体为研究对象, 利用树高、胸径和木材密度数据来探究基于枝条木材密度分级的树高曲线模型。首先, 对个体进行随机抽样, 将其划分为建模样本(占总样本量的70%)和检验样本(占总样本量的30%), 并通过聚类分析将所有个体的木材密度划分为4级。其次, 基于建模样本利用常见的5种理论生长方程(Richards、Korf、Logistic、Gompertz和Weibull方程)对不同分级建立树高-胸径模型; 基于检验样本检验模型精度, 并确定各分级的最适模型。最后, 构建基于物种分类的树高曲线模型, 并比较其与木材密度分级模型的差异。结果表明: 基于木材密度分级的模型, 各分级小组检验样本的平均绝对误差(MAE)和均方根误差(RMSE)最小值所对应的模型类型与建模样本结果一致, 确定Gompertz模型和Weibull模型为鼎湖山南亚热带常绿阔叶林最适树高模型类型。比较基于木材密度分级的模型与基于物种分类的模型, 发现二者的MAE、RMSE指数差异小。综上, 基于木材密度分级的树高曲线模型对树高估测精度高, 使用方便, 为树高预测提供了新方法, 可以更好服务森林调查等生产实践。     

The spatial pattern and canopy-understory association of trees in a cool temperate,mixed forest in western Japan

The spatial distribution pattern of trees and the association between canopy and understory individuals were examined with reference to the distribution of tree crowns in a cool temperate, mixed forest in Ohdaigahara, western Japan. Line transect and contact sampling methods were used to examine the pattern over various spatial scales. These methods are useful to detect patterns over a large study area. The dominance ofChamaecyparis obtusa on steep slopes forming large patches suggested that the distribution of this species is a consequence of landslides. UnderstoryFagus crenata showed a clumped distribution, and the relative coverage of this species was larger in canopy gaps than under a closed canopy. Understory individuals ofAbies homolepis showed a positive association with canopy trees ofF. crenata but a negative association with conspecific canopy individuals. These patterns suggested thatF. crenata regenerates in canopy gaps and is replaced byA. homolepis. The dynamics of these two species are consistent with the process of gap dynamics. The effects of both small- and large-scale disturbance must be evaluated to understand the mechanisms of patch formation and the coexistence of forest tree species.     

山西七里峪茶条槭的种群结构与空间分布格局

从生命表特征、径级结构、存活曲线及不同海拔种群和不同龄级个体空间分布格局等方面研究了山西七里峪茶条槭的种群结构和空间分布规律.结果显示:(1)七里峪茶条槭种群径级结构呈现幼苗比例大,幼树、小树比例次之的规律,为增长型种群;(2)不同海拔种群中,1 300～1 600m为增长型种群,随着海拔的升高,种群结构逐渐趋于稳定成熟;(3)茶条槭种群的存活曲线接近于Deevey-Ⅲ,除1 400m和1 700m种群外,其它海拔种群存活曲线为Deevey-Ⅱ型;茶条槭种群不同径级的个体呈现出集群分布或随机分布,其空间分布格局随龄级增加而发生改变;(4)不同海拔高度种群的分布格局表现出从集群分布趋向随机分布的规律.研究表明,七里峪茶条槭种群的生活史特征与空间分布具有较为明显的特性,其幼苗储备丰富、自身的生物学特性及种群依存的微环境因素是导致这种现象的主要原因.     

Aggregated spatial distributions of species in a subtropical karst forest,southwestern China

Aims Spatial distribution patterns of species reflect not only the ecological processes but also the habitat features that are related to species distribution. In karst topography, species distribution patterns provide more specific information about their environments. The objectives of this study are as follows: (i) to analyse and explain the spatial distribution patterns of conspecific trees in an old-growth subtropical karst forest; (ii) to investigate pattern changes at different spatial scales; (iii) to test the spatial pattern similarity (or dissimilarity) between trees at different abundances, diameter at breast height classes, canopy layers and different functional groups (shade tolerance and seed dispersal mode); (iv) to examine whether habitat heterogeneity has an important effect on the species spatial distribution.Methods The spatial distributions of woody species with ≥20 individuals in a 1-ha subtropical karst forest plot at Maolan in southwestern China were quantified using the relative neighbourhood density Ω based on the average density of conspecific species in a circular neighbourhood around each species.Important findings Aggregated distribution is the dominant pattern in the karst forest, but the ratio of aggregated species in total species number decreases with an increase in spatial scale. Less abundant species are more aggregated than most abundant species. Aggregation is weaker in larger diameter classes, which is consistent with the prediction of self-thinning. Seed dispersal mode influences spatial patterns, with species dispersed by animals being less aggregated than those dispersed by wind and gravity. Other species functional traits (e.g. shade tolerance) also influence the species spatial distributions. Moreover, differences among species habitat associations, e.g. with rocky outcrops, play a significant role in species spatial distributions. These results indicate that habitat heterogeneity, seed dispersal limitation and self-thinning primarily contribute to the species spatial distributions in this subtropical karst forest.     

Spatial patterns and vegetation–site relationships of the presettlement forests in western New York, USA

Aim The purposes of this study were to develop a Geographic Information System and spatial analytical methodology to reconstruct and represent the presettlement vegetation in a spatially continuous manner over large areas and to investigate vegetation–site relationships before widespread changes of the vegetation had taken place. Location The study area was the Holland Land Company Purchase in western New York, a 14,400 km² area extending across the physiographic provinces of the Erie–Ontario Lowlands and the Appalachian Uplands. Methods Bearing‐tree records from the Holland Land Company township surveys of western New York in c. 1800 were collected and analysed. The geostatistical method of indicator kriging was used to map spatially continuous representations of individual tree species. Rule‐based and statistically clustered approaches were used to analyse and classify the reconstructed tree species distributions in order to obtain the vegetation association distribution. Contingency table analysis was conducted to quantify species relationships with soil conditions. Results The presettlement vegetation at both the tree species and the vegetation association levels were easier to interpret and visually more effective as a spatially continuous representation than as a discontinuous distribution of symbols. The results for tree species were probability occurrences of species distribution, showing spatial patterns that were not apparent in discrete maps of points or in summary tables of species frequencies. Analysis of the 8792 bearing trees suggested the dominance of American beech (Fagus grandifolia) and sugar maple (Acer saccharum) in the forest composition 200 years ago. Both soil drainage and texture were important site determinants of the vegetation in western New York. The rule‐based and statistically clustered approaches had the advantage of summarizing vegetation compositional patterns in a single image, thus avoiding the need to delineate manually and subjectively the location of boundaries between adjacent vegetation associations. Main conclusions The study offers more insights into the spatial pattern of presettlement forests in western New York than do prior studies. The spatially continuous representation could also enable the comparison of vegetation distribution from data sources that have different sampling schemes, for example the comparison of presettlement vegetation from the presettlement land survey records with current vegetation from modern forest inventories. The results are of value, providing a useful benchmark against which to examine vegetation change and the impacts of human land use.     

永定桫椤群落的结构特征

在相邻格子抽样调查的基础上,分析了福建省永定桫椤[Alsophila spinulosa(Wall.ex Hook.)Tryon]群落的种类组成、重要值、种内与种间的竞争指数、水平结构和垂直结构特征。该群落共有植物186种,隶属于75个科132属,植物种类丰富。该群落乔木种群的重要值,以及桫椤与其他优势种群种内和种间的竞争指数表明,该群落由多个种群共建而成,初步认定有5个共建种群或优势种群。在水平空间上,5个可能的共建种群均服从聚集分布,在垂直空间上层次分化明显。通过分析表明永定桫椤群落是保存完好、结构典型、物种丰富多样的珍贵群落,应很好加以保护。     

Relationship between dominance and richness of local species: an analysis of the underlying reasons with arboreal and avian communities of the West Caucasus as an example

Dominance level is traditionally expressed as a ratio between the number of individuals belonging to the most abundant species and the total number of individuals in a biological community. It is known that local species richness is usually higher in biological communities with high dominance level than in communities with low one. Taking into account a complex nature of the dominance phenomenon, the underlying reasons (or mechanisms) may be diverse: 1. Dominance level may be determined by bioecological traits of the most abundant species as well as stochastic impacts. The more abundant is dominant species, the fewer amount of resources goes to concomitant species and, therefore, the lower is community species richness. 2. The part of community resources used by the dominant species may be not a special case but can be a reflection of general pattern of resources distribution among species under specific environmental conditions. Correspondingly, in communities with higher dominance level there might be more "strict" distribution of resources among concomitant species, which, in turn, might influence community species richness. 3. The relationship between dominance level and community species richness may be caused by their dependence on the third variable, namely regional species pool. In the present paper we tackle the problem using arboreal and insectivorous bird communities of the West Caucasus as a case study. The data were collected in different altitudinal belts on both macroslopes of the western part of the Main Caucasian Ridge. The number of tree species and individual trees was counted within homogenous patches of arboreal phytocenoses 300 m2 in area. Species richness and numbers of insectivorous birds were estimated in course of route surveys with a route length being about 5 km. An analysis of empirical data was carried out using univariate and multiple correlation-regression techniques. The results indicate that the relationship between dominance and local species richness is determined to a large extent (by 50-60%) by a dominant taking over greater or lesser amount of the resources (mechanism 1). The role of two other mechanisms (2 and 3) is not so prominent--together, they are responsible for 25-40% of the relationship power. Relative contribution of different mechanisms to the relationship under consideration depends on conformity of species abundance rank structure with the geometric series model. At those sites where this conformity is manifested, the relationship between dominance level and species richness is due mainly to mechanisms 1 and 2, i.e., is determined by local processes. At other sites, where the conformity of species abundance rank structure with the geometric series model is not so good, a certain role belongs to the size of regional species pool (mechanism 3).