An index for measuring functional extension and evenness in trait space

Most existing functional diversity indices focus on a single facet of functional diversity. Although these indices are useful for quantifying specific aspects of functional diversity, they often present some conceptual or practical limitations in estimating functional diversity. Here, we present a new functional extension and evenness (FEE) index that encompasses two important aspects of functional diversity. This new index is based on the straightforward notion that a community has high diversity when its species are distant from each other in trait space. The index quantifies functional diversity by evaluating the overall extension of species traits and the interspecific differences of a species assemblage in trait space. The concept of minimum spanning tree (MST) of points was adopted to obtain the essential distribution properties for a species assembly in trait space. We combined the total length of MST branches (extension) and the variation of branch lengths (evenness) into a raw FEE₀ metric and then translated FEE₀ to a species richness‐independent FEE index using a null model approach. We assessed the properties of FEE and used multiple approaches to evaluate its performance. The results show that the FEE index performs well in quantifying functional diversity and presents the following desired properties: (a) It allows a fair comparison of functional diversity across different species richness levels; (b) it preserves the essence of single‐facet indices while overcoming some of their limitations; (c) it standardizes comparisons among communities by taking into consideration the trait space of the shared species pool; and (d) it has the potential to distinguish among different community assembly processes. With these attributes, we suggest that the FEE index is a promising metric to inform biodiversity conservation policy and management, especially in applications at large spatial and/or temporal scales.     

山东蒙山植物多样性及其海拔梯度格局

2007年7月和2008年7月,采用典型取样法,沿海拔梯度对蒙山自然植被进行调查,发现区域地带性植被为麻栎(Quercus acutissima)林,主要植被类型为麻栎群落、赤松(Pinus densiflora)群落、油松(Pinus tabuliformis)群落、日本落叶松(Larix kaempferi)群落、黑松(Pinus thunbergii)群落和刺槐-麻栎(Robinia pseudoacacia-Q.acutissima)群落,麻栎群落略占优势,已具备继续向温带落叶阔叶林演替的条件基础.蒙山各层次植物物种丰富度呈现出草本层>灌木层>乔木层特征,Shannon-Wiener多样性指数和Simpson多样性指数整体规律为灌木层>草本层>乔木层.以蒙山森林群落不同层次的各种物种多样性指数和森林群落总体重要值为测度指标,均判断蒙山植被演替正处于亚顶极群落阶段.蒙山植物多样性沿海拔梯度呈现出近似中海拔高的单峰格局,这除受温度、湿度、人为干扰与面积外,蒙山植被亚顶极群落演替现状与所调查区域仅有800 m的海拔梯度也是重要影响因素.     

A comparison of fungal endophytic community diversity in tree leaves of rural and urban temperate forests of Kanto district,eastern Japan

To clarify the effects of forest fragmentation and a change in tree species composition following urbanization on endophytic fungal communities, we isolated fungal endophytes from the foliage of nine tree species in suburban (Kashiwa City, Chiba) and rural (Mt. Wagakuni, Ibaraki; Mt. Takao, Tokyo) forests and compared the fungal communities between sites and host tree species. Host specificity was evaluated using the index of host specificity (Si), and the number of isolated species, total isolation frequency, and the diversity index were calculated. From just one to several host-specific species were recognized in all host tree species at all sites. The total isolation frequency of all fungal species on Quercus myrsinaefolia, Quercus serrata, and Chamaecyparis obtusa and the total isolation frequency of host-specific species on Q. myrsinaefolia, Q. serrata, and Eurya japonica were significantly lower in Kashiwa than in the rural forests. The similarity indices (nonmetric multidimensional scaling (NMS) and C_MH) of endophytic communities among different tree species were higher in Kashiwa, as many tree species shared the same fungal species in the suburban forest. Endophytic fungi with a broad host range were grouped into four clusters suggesting their preference for conifer/broadleaves and evergreen/deciduous trees. Forest fragmentation and isolation by urbanization have been shown to cause the decline of host-specific fungal species and a decrease in β diversity of endophytic communities, i.e., endophytic communities associated with tree leaves in suburban forests were found to be depauperate.     

Phytosociological typology and phytoindicator value of young oak and larch forest communities near Pinczów (southern Poland)

Oak (Quercus petraea Liebl.) and larch (Larix decidua Mill.) forest plantations of the study area Mlodzawy in Poland were analysed. Changes in the syntaxonomic composition and of Ellenberg's indices (light, continentality, moisture, reaction and nitrogen index) were determinated. The results obtained mostly conform to the assumption that the herb layer of both plantations becomes, gradually with tree growth, more similar to each other and to that of mature oak-hornbeam forests. Such statement is justified by: an increase in the share of species common to both plantation types, a significant increase in the number and cover of the Querco-Fagetea character-species, accompanied by a decrease in the number and cover of other character-species, a general decrease in the share of species with extreme climatic and edaphic requirements, accompanied by a gradual increase in the share of number and cover of species with average demands. From the studies it may be concluded that the developmental mechanisms w which determine the direction and trends of changes in the herb layer are mainly common to both plantation types, whereas tree stand species, in spite of different habit, ecological demands, and effect on soil properties, have only slight modification influence.     

塔里木荒漠河岸林异质生境物种多样性比较与其测度指标筛选及评价

选择合适的物种多样性测度指标与多样性指数是进行群落多样性研究的基础工作。依据塔里木河上游荒漠河岸林样地调查资料,分别采用重要值、盖度和多度为测度指标比较了反映群落物种丰富度、多样性、均匀度和优势度12种多样性指数与异质生境群落多样性特征,并对多样性指数进行了相关分析与评价。结果表明,荒漠河岸林异质生境群落物种组成种类差异明显,轮南镇胡杨群落物种丰富度与多样性指数最高,水工三连灰胡杨群落多样性最低,土壤水盐的空间异质性是引起荒漠植被空间分布与群落多样性差异的主导因子。表征荒漠群落多样性以重要值和盖度为测度指标优于多度指标,其中以重要值为测度指标来反映群落多样性更为合理。相关与主成分分析表明,均匀度与多样性指数间的相关性高于丰富度与多样性指数,且多样性指数受均匀度、优势度指数受丰富度影响较大,反映出荒漠河岸林群落多样性主要决定于物种分布的均匀程度。12种多样性指数中Margalef丰富度指数（Ma）、Shannon-Weiner多样性指数（H）与Simpson多样性指数（D）能客观真实地反映异质生境荒漠植物群落多样性。同时,针对高度生境异质性的荒漠植物群落,还应综合考虑群落物种组成与生境特征,选择合适的多样性指数组合可更客观地反映荒漠河岸林群落多样性变化。     

西双版纳热带山地雨林群落乔木树种多样性研究

根据块样地资料对西双版纳热带山地雨林树种多样性特征进行了分析.结果表明,在2 500m²的样地上,随着起测胸径递增,各样地乔木个体数和树种丰富度均表现为依次递减;低海拔带上(850～1000 m)的山地雨林(1、2号样地)的各指数值无一定变化规律,较高海拔带上(1200～2000 m)的山地雨林(3～6号样地)的Shannon-Wiener指数和Simpson指数均表现为依次递减,而Pielou均匀度指数则呈依次递增的趋势.较高海拔带上的山地雨林在较小乔木起测胸径(≥2 cm、≥5 cm、≥10 cm)的树种丰富度、多样性和均匀度指数均要明显大于低海拔带上的山地雨林,而两者在较大乔木起测胸径(≥20 cm、≥30 cm、≥50 cm)的各指数值无明显差异.随着取样面积的递增,各样地树种丰富度、多样性和均匀度指数在取样面积递增到2 000m²处均已趋于平缓.     

西双版纳国家级自然保护区蚂蚁-树互作网络空间变异

网络分析(network analysis)可以同时分析群落中的物种多样性和种间关系, 为了解生态群落的稳定性机制提供了新的分析思路和方法。本研究从西双版纳国家级自然保护区的纳板河、勐仑和勐腊(补蚌)三个地点采集了树栖性蚂蚁及树木的种类和数量数据, 对蚂蚁-树组成的二分网络进行了分析, 探讨了3个采样点物种的多样性、网络指标以及群落指标之间的关系。我们采用零模型的方法比较了3个样点的标准化网络参数差异。结果表明: 蚂蚁和树木的物种数以及树的异质性指数(Shannon-Wiener多样性指数、Simpson多样性指数)都呈现出勐仑 > 纳板河 > 补蚌的趋势。树木-蚂蚁的灭绝曲线系数大小关系同样为勐仑 > 纳板河 > 补蚌, 灭绝曲线与树的物种数及异质性指数大小趋势一致, 而与蚂蚁的异质性指数并不吻合。根据Z值的绝对值来看, 网络参数(加权嵌套性、平均连接数、特化水平、模块性、连接度)与群落参数(灭绝曲线系数、生态位重叠)的大小趋势相同, 表现出勐仑 > 纳板河 > 补蚌的趋势。综上所述, 蚂蚁-树互作网络的稳定性(灭绝曲线系数)主要由树的数量和异质性指数决定。网络的加权嵌套性和网络中节点的平均连接数也能促进群落的稳定性。而在一个特化的(数值越大表示专性互作越多)和模块化(具有较多密切互作的节点单元)的网络中, 当低营养级物种灭绝时高营养级物种数量将迅速减少。     

Plant communities in broad-leaved deciduous forests in Hordaland county, Western Norway

The vegetation of broad-leaved deciduous forests in Hordaland, Western Norway is described with regards to species composition and structure. The investigation is based on phytosociological analyses of native forest stands dominated by Corylus avellana, Fraxinus excelsior, Ulmus glabra , or Tilia cordata. Two-way-indicator analysis (TWINSPAN) and correspondence analysis (CA) are used to distinguish different vegetation types and assess possible gradients in the vegetation data. The vegetation types are discussed in relation to equivalent forest communities and to syntaxonomical units. Two forest types are described at the first hierarchical TWINSPAN level: 1) A hygrophilous and slightly thermophilous Fraxinus excelsior-Cirriphyllum piliferum forest characterised by an open tree canopy, a dense field layer of tall herbs and ferns, and a high cover of bryophytes. 2) A thermophilous and less hygrophilous Corylus avellana-Brachypodium sylvaticum forest characterised by a dense tree layer, a more open field layer with larger elements of small herbs, and a somewhat lower bryophyte cover. The CA analysis clearly separates the samples from the first TWINSPAN division along the first ordination axis. Five forest types have been described at the second hierarchical level, mainly associated with differences in mesotrophic and eutrophic species, but there is clearly a gradient structure in the species composition between these plant communities. In relation to syntaxonomy, the first TWINSPAN division supports the separation of the west Norwegian broad-leaved deciduous forests into a hygrophilous plant community, the Eurhynchio-Fraxinetum (Blom 1982) Øvstedal 1985 and a drier and more thermophilous community, the Primulo-Ulmetum (Blom 1982) Øvstedal 1985.     

Multisite and multispecies measures of overlap,co‐occurrence,and co‐diversity

Several indices measure the association or segregation between two species and the similarity or differentiation between two sets of species. These indices are based on the overlap in the distribution of species (measured with the number of co‐occurrences) or on the overlap in species composition of sites (measured with the number of species that are shared between two sites). This paper shows that when evaluating more than two species the number of overlaps and the number of pairwise co‐occurrences are not equal, as it is the case for two species. Equivalently, when comparing more than two species assemblages, the number of overlaps differ from the number of instances of species sharing by pairs of sites (the ‘co‐diversities’). Considering this distinction, two different types of multispecies and multisite indices can be derived: indices of general overlap and indices of co‐occurrence or co‐diversity. Here I present a complete series of the two types of indices that correspond to the popular Jaccard, Sørensen, and Simpson two‐species or two‐site indices. Indices of general overlap are defined by three parameters (the total number of species, the total number of sites, and the total number of occurrences), whereas indices of co‐occurrence or co‐diversity depend on those parameters plus an additional one that is defined by the values of species richness or range size. Consequently, the two types of indices respond differently to null models, depending on the parameters that are fixed or randomized. All indices correlate well with the mean of the traditional indices calculated pair by pair, and the correspondence is extremely close for the new indices of co‐occurrence and co‐diversity. These properties should be useful in clarifying some of the confusion that exists in the current discussion about the advantages and disadvantages of pairwise vs community‐wide approaches in the analysis of diversity.     

湖南德夯河谷特殊生境典型植物群落特征研究

对德夯河谷特殊生境区典型植物群落的研究表明:1)不同群落物种的组成、结构和多样性均存在较大差异,常绿落叶阔叶混交林的物种最多,达74种;常绿落叶阔叶林的乔木种类最为丰富,有20种;次生竹林的物种多样性指数最高,Shannon-Wiener指数和均匀度分别为6.70、3.83;2)科层次上,各群落内热带分布科数量明显高于温带分布科;属层次上,温带分布成分进一步发展,各个群落内均以温带性质为主.除自然生境条件的差异外,人类不同强度的干扰可能是造成各群落特征变化的主要原因.     

The bottom Oligochaeta communities in sand pits of different trophic status in Upper Silesia (Southern Poland)

Oligochaeta, occurring in the littoral zones of two sand pits, were sampled in order to determine the relationship between the oligochaete species and the waters’ trophic level. Differences between sand pits attributable to community structure and to an overall higher abundance of oligochaetes, especially tubificids, were observed in Dzierżno Małe. Multivariate analyses (correspondence analysis [CA] and canonical correspondence analysis [CCA]) reveal correlations between the distribution patterns of oligochaete species and the concentration of nitrates, phosphates and dissolved oxygen. Some species, e.g. Dero digitata, Limnodrilus hoffmeisteri, Potamothrix hammoniensis, Nais simplex, Limnodrilus claparedeanus, Limnodrilus udekemianus and Tubifex tubifex, were more abundant in eutrophic sites. The results of the study showed that the richness of Oligochaeta species is not a good method for estimating the trophic levels of the studied sand pits. Indicators based on the share of oligo-, meso- and eutrophic species in Oligochaeta communities are better for evaluating the water quality in the studied reservoirs.     

Calculation of collated indices of abundance of butterflies based on monitored sites

Abstract.

• 1 The Butterfly Monitoring Scheme uses regular transect counts on fixed sites to establish annual indices of abundance of butterfly species in the United Kingdom. The annual change in collated index for each species has hitherto been calculated as a simple ratio between total counts summed over all participating sites.
• 2 A revised method for calculation of collated indices is proposed, which applies a logarithmic transformation to site values so as to downweight the influence on the index of the sites with greatest numbers of a species. Zero counts are handled comparably with non-zero values. An alternative method using geometric mean ratios is also examined.
• 3 Indices calculated using the logarithmic transformation are compared with those calculated using the traditional method. Two internal tests of dependency of collated indices on the sites with highest abundance are made. Another evaluation uses regression analysis for the effects of temperature and rainfall on collated indices of butterfly abundance.
• 4 The first internal test shows that logarithmic transformation reduces the dependence of the collated index on the sites of highest abundance for twenty-five out of twenty-seven species examined; while a second test shows a reduction for twenty-six out of forty-two species, and an increase for one species. The number of significant regressions on temperature variables increases with the use of the logarithmic transformation from 11% to 13% of tests made, and on rainfall from 10% to 11%.
• 5 The geometric mean ratio method introduces considerable biases in its treatment of zero values, for which a remedy is not available.
• 6 Although the revised collated indices calculated using logarithmic transformation are broadly comparable with traditionally calculated values, the reductions in dependency on sites with the most abundant populations render the revised indices less subject to perturbation due to local ‘noise’, and so more suitable for research on factors influencing butterfly abundance.

     

Diatom Model Affinity (DMA), a New Index for Water Quality Assessment

A new index, diatom model affinity (DMA) was erected as a reference-based community metric, derived from generic and species composition. DMA provides an assessment of water quality by the calculation of percent similarity to a model community, which can be viewed as a reference standard. High similarity to the model indicates communities that are minimally disturbed, while lower similarity suggests water quality problems. The index is similar to that developed for macroinvertebrate communities by Novak & Bode (1992, Journal of the North American Benthological Society 11: 80-85). The index correlated well with environmental factors operating on hierarchical scales. Compared to other commonly used diatom indices, DMA-based community assessments demonstrated high correspondence to patterns derived from multivariate statistics.     

Chironomid communities as water quality indicators

Recent mathematical indices summarizing biological communities of indicators are recapitulated. Improvements of these indices based on weighting according to width of trophic ranges of each species are suggested. Their principle deficiencies, however, are pointed out.
Revised lists of characteristic profundal as well as littoral and sublittoral chironomids in Nearctic and Palearctic lakes show that at least 15 characteristic chironomid species communities can be delineated, 6 in each of the oligotrophic and the eutrophic ranges and 3 in the mesotrophic range. It is proposed that these communities be lettered consecutively in the Greek alphabet from α (alpha) to o (omikron). A key to the 15 divisions based on the species associations in the profundal zone of harmonic lakes is put forward. There is very good correlation between the 15 divisions and the ratios of average total phosphorus to mean lake depth and average chlorophyll a to mean lake depth.
The ratio of chironomids to oligochaetes and the distribution patterns of single species have proven useful in pin-pointing localized areas of pollution. The primary mechanism governing the distribution of chironomid communities in oligotrophic and mesotrophic lakes appears to be the availability of food materials rather than the annual hypolimnetic oxygen concentration. In eutrophic lakes the relationships between organic matter accumulation and oxygen levels are so interdependent as to be inseparable.     

The Usefulness of Various Numerical Methods for Assessing the Specific Effects of Pollution on Aquatic Biota

The data obtained during an extensive multidisciplinary investigation of a polluted harbor basin in Hamburg were analyzed in various ways in order to determine which statistical methods are easiest to interpret and permit the most accurate evaluations. The methods analyzed include the species deficit, index of species similarity, and saprobity index, as well as the more complex cluster and gradient analyses, which revealed a variety of relationships among the biotic communities at the various sampling sites and some ecological tolerance limits of various species. The shortcomings of numerical indices for characterizing water bodies are discussed. It is suggested that biostatistical methods are much more valuable for the empirical evaluation of data than for artificially classifying ecosystems.     

浙江天童常绿阔叶林演替阶段共有种的树木构型

树木构型是木本植物为响应光照变化在其空间建造结构上的配置模式和形态体现。研究演替不同阶段共有种构型的变化可以剔除植物谱系的影响, 反映植物构型特征与光资源供给性的关系。该研究在浙江宁波天童、南山和北仑3个次生演替序列上选择了5个演替共有种, 分4个群落高度层级, 对照分析了树高、冠幅深度和面积、枝条伸展方向、基径、叶片盖度和聚集度构型性状随演替的变化, 并分析了与冠幅曝光指数的线性关系。结果表明: 1)随着演替进行, 冠幅厚度和面积、叶片盖度、叶片聚集度和基径逐步增加, 但在个别相邻演替阶段增加不显著; 2)随着演替进行, 植物的垂直枝比例降低, 水平枝比例增加; 3)演替过程中植物冠幅曝光指数在各层级内都呈现出减小趋势; 4)构型性状和植物冠幅曝光指数间存在显著的线性回归关系(p < 0.001)。总之, 随着常绿阔叶林演替进行, 演替共有种构型的变化反映了物种功能类群由阳性先锋植物向耐阴植物的转化, 其中, 植物对光资源的适应是导致构型变化的主要原因。     

北京东灵山地区植物群落多样性的研究Ⅱ丰富度、均匀度和物种多样性指数

本文以１２５块植物群落调查样地资料为基础,从不同类型、层次的丰富度、均匀度和物种多样性指数及其与海拔的关系等方面对东灵山地区植物群落多样性进行了分析。本区亚高山草甸植物群落多样性沿海拔梯度的变化规律是：物种丰富度和物种多样性指数随海拔升高而下降;物种均匀度则随海拔升高而增加。植物生长型与群落多样性指数的关系表现为“乔木层、灌木层物种丰富度指数相近且明显低于草本层;灌木层和草本层的均匀度指数相近,群落间变异幅度较小,乔本层则变异幅度很大;物种多样性指教则表现出草本层＞乔本层＞灌木层的规律。物种盖度和地上生物量作为测度指标计算群落多样性所得结果相近,且优于以株数作为测度指际计算的结果。     

深圳小南山与应人石山地植物多样性比较研究

该文对深圳市小南山处在封育状态下的3个植物群落和应人石山地荒弃果林处于半自然恢复状态群落以及果林周边半自然状态发育的群落进行了调查,比较分析两区域植物群落的组成及多样性特征。结果表明：在群落科、属、种的数量组成上,两者的差异虽不很明显,但小南山的科和种类的数量稍多于后者;在群落各层次的种类组成上,则小南山乔木层种类较明显地多于应人石的群落,前者的灌木层及草本层的发育也较好,种类也较多;虽然应人石的灌木层及草本层的种类数也较多,而且灌木层种类数高于前者,但乔木层种类则明显少,草本层种类的数量也略低于小南山的2个群落。在物种的生物多样性Simpson指数、Shannon-Wiener指数和丰富度指数方面,小南山的3个群落各层次的大多指标及所有的整体指标值均高于后者。这说明小南山在较长期受到人为保护的状态下,植被的结构发育较好,各层次的种类数均较为丰富。而后者虽然是处于半自然状态发育的群落,但由于受到人为干扰和影响的印迹依然还没有消除,仍处在恢复初期或中间状态。这为目前争论较多的究竟是自然林生物多样性高,还是人工林高？或者是人为较多干扰的次生林高的理论问题提供了一个较好的证据和理论参考。在各群落的相似性系数方面,各层次的系数值均处在相对较低状态,表明同区域不同地点及不同区域相互间各群落在种类组成上差异较大,说明深圳这两个区域在大区域范围的植物多样性水平是较高的。     

基于引力模型的林木竞争分析

引力模型是否可以应用于森林群落林木竞争关系分析是值得研究的问题。基于引力模型建立林木相对活力圈能反映竞争木活力大小,基于竞争木的相对活力圈建立引力竞争指数能准确反映林木生长与林木竞争的关系。以浙江省天目山国家级自然保护区针阔混交林为研究对象,将V_Hegyi竞争指数、引力竞争指数分别与胸径进行相关分析,胸高断面积生长量分别与2种竞争指数进行相关分析,胸径生长率与2期引力竞争指数的比值(2021年与2006年的引力竞争指数之比)进行相关分析,此外,对相对活力圈直径与胸径进行相关分析,并比较分析了活立木与枯死木的竞争指数大小。结果表明: 2种竞争指数与胸径均呈显著负相关,且均服从幂函数关系。林木胸高断面积生长量与2种竞争指数均呈显著负相关,但引力竞争指数比V_Hegyi竞争指数更能反映林木生长与林木竞争的关系。相对于V_Hegyi竞争指数的比值,2期引力竞争指数的比值更能说明林木生长与林木竞争的关系。在针阔混交林中,阔叶树种的生长与竞争的相关性>针叶树种生长与竞争的相关性。林木枯损受竞争的显著影响。林木相对活力圈大小与林木胸径大小呈显著负相关。引力模型是反映空间相互作用的重要模型之一,可以应用于林木竞争关系的研究,且基于引力模型建立的引力竞争指数可以作为评价林木竞争和林木活力的一个空间结构指标,比V_Hegyi竞争指数更能反映林木生长与林木竞争的关系。     

西双版纳热带山地雨林的植物多样性研究

 根据6块样地的调查资料,分析了西双版纳热带山地雨林植物多样性特征。结果表明：在2 500 m2的样地上,西双版纳热带山地雨林群落共有植物物种99～181种。其中乔木层的物种丰富度（S）为54～113,Shannon-Wiener指数（H′）为1.648 7～4.049 1,Simpson指数（λ）为0.503 5～0.969 5,Pielou 均匀度指数（Jsw）为0.413 3～0.854 9。灌木层的S为35～89,H′为2.413 2～3.716 2,λ为0.762 7～0.958 2,Jsw为0.678 8～0.859 3。草本层的各指数值：S为31～65,H′ 为2.792 1～3.499 2,λ为0.902 0～0.938 2,Jsw为0.729 3～0.838 2。低海拔带上的山地雨林（Ⅰ号、Ⅱ号样地）的各指数值（H′、λ、Jsw）在群落不同层次中均表现为草本层 > 灌木层 > 乔木层,而物种丰富度在不同层次中无一定变化规律;高海拔带上山地雨林（Ⅲ号、Ⅳ号、Ⅴ号、Ⅵ号样地）的物种丰富度和多样性指数（H′、λ）表现为乔木层 > 灌木层 > 草本层,而均匀度指数（Jsw）在不同层次中则无一定变化趋势。高海拔带上的山地雨林乔木层和灌木层的物种丰富度、多样性和均匀度指数均明显高于低海拔带上的山地雨林,这是由于前者所处生境较为优越。沿着海拔梯度,群落乔木层的物种丰富度、多样性和均匀度指数均在中等海拔高度地带（约1 200～1 220 m）达到最高值,这是由于中等海拔高度的山地雨林位于生境条件最为优越的沟谷地带,而且与低地季节雨林毗邻,热带雨林植物成分丰富。