Modelling of plant species richness along altitudinal gradient: Asalem Watershed basin,temperate deciduous forests in northern Iran

Among the various topographical factors, effects of altitudinal factor on species diversity, richness, composition and biological functions patterns are considerable. This study was done to investigate plant species richness along altitudinal gradient in the Asalem watershed basin, northern forests of Iran. For these purpose, 13 altitudinal transects were established from 100 to 2500 m, according to altitude ranges within 200 m intervals. Data collection was done in 216 circular plots of 1000-m² area with a distance of 150 m from each other. In total, 576species of 325 genus and 96 families were recorded. The highest number of species was belonged to Asteracese، Fabaceae and Lamiaceae families. The results indicated that forbs with 414 species belong to54 families and ferns with 31 species belong to10 families were the largest and smallest group of plants in study area respectively. In herbaceous layer, the mean number of species was increased along altitudinal gradients (P ≤ 0.005). The lowest and highest value of species number was belonged to 500 and 2500 m altitudes, respectively. Generally, there was a gradual decline of species number at 100 to 500 m. Fitted models indicated that variation patterns at altitudinal gradients were significant and the proposed polynomial model had a high conformity with changes of species richness. The lowest value of species number in woody layer was belonged to 1900 m altitude and 2100 m had the highest value. Three peak points were recorded at the beginning, middle and the end of gradient, respectively. Sinusoidal models showed a correlation between species richness and altitudinal changes by high coefficient of determination. Results of β –diversity indicated that species change rate was fixed at 700 m altitude, but it was decreased by increasing altitude. Fluctuations of β diversity were followed of the sinusoidal models. In the study area, destructive factors including road construction, tourism and over-exploitation are a serious threat for the ecosystem and this study can be considerable to develop targeted strategies for conservation of plant diversity. In addition, study of habitat conditions in each altitudinal gradients is necessary to reconstruction stands with low species diversity and appropriate species selection to establish stands with high density.     

长白山森林生态系统凋落物层和土壤层跳虫物种多样性和功能多样性对海拔梯度的响应

山脉是生物多样性研究的热点地区,以往关于山脉的研究多集中于地上植物和脊椎动物,无脊椎动物相关的研究明显滞后。跳虫(Collembola)是土壤无脊椎动物的主要类群之一,在分解有机质、疏松和活化土壤过程中发挥着重要的作用。以跳虫为研究对象,采用梯度格局法,在长白山北坡自海拔800 m至1700 m,每隔150 m进行凋落物层和土壤层样品的采集,对比分析了土壤层和凋落物层的群落组成与群落结构,采用4个物种多样性指数(丰富度指数、Pielou均匀度指数、Shannon-Weiner多样性指数和Simpson多样性指数)和4个功能多样性指数(功能丰富度FRic指数、功能均匀度FEve指数、二次熵Rao''s Q指数和功能离散FEiv指数),探讨了多样性沿海拔梯度的分布格局。共获得跳虫5542头,隶属于12科42属83种,其中等节跳科为绝对优势类群(相对密度>50%)。非度量多维尺度分析结果表明,凋落物层和土壤层的跳虫群落结构差异显著,长角跳科、鳞跳科和疣跳科物种多分布于凋落物层,而棘跳科物种多分布于土壤层。线性或二次回归模型结果表明,在凋落物层跳虫的丰富度指数,Shannon-Weiner多样性指数和Simpson多样性指数沿海拔梯度的变化呈增加格局;但在土壤层跳虫物种多样性指数沿海拔梯度的变化无明显趋势。在凋落物层,跳虫的功能丰富度指数和功能离散度Rao''s Q指数随海拔梯度的变化呈现单峰分布格局;在土壤层,跳虫的功能丰富度指数随海拔梯度的变化也呈现单峰分布格局,但其他功能多样性指数沿海拔梯度的变化无明显趋势。研究表明凋落物层和土壤层跳虫的群落组成,群落结构及多样性存在显著差异,跳虫的物种多样性指数和功能多样性指数对海拔梯度变化的响应不同,未来在探讨土壤动物沿海拔梯度的分布格局及其物种共存机制时,应综合考量垂直分层(凋落物层和土壤层)和多个度量维度(物种多样性和功能多样性)。     

The effect of altitude,patch size and disturbance on species richness and density of lianas in montane forest patches

The species richness and density of lianas (woody vines) in tropical forests is determined by various abiotic and biotic factors. Factors such as altitude, forest patch size and the degree of forest disturbance are known to exert strong influences on liana species richness and density. We investigated how liana species richness and density were concurrently influenced by altitude (1700–2360 m), forest patch size, forest patch location (edge or interior) and disturbance intensity in the tropical montane evergreen forests, of the Nilgiri and Palni hills, Western Ghats, southern India. All woody lianas (≥1 cm dbh) were enumerated in plots of 30 × 30 m in small, medium and large forest patches, which were located along an altitudinal gradient ranging from 1700 to 2360 m. A total of 1980 individual lianas were recorded, belonging to 45 species, 32 genera and 21 families, from a total sampling area of 13.86 ha (across 154 plots). Liana species richness and density decreased significantly with increasing altitude and increased with increasing forest patch size. Within forest patches, the proportion of forest edge or interior habitat influenced liana distribution and succession especially when compared across the patch size categories. Liana species richness and density also varied along the altitudinal gradient when examined using eco-physiological guilds (i.e. shade tolerance, dispersal mode and climbing mechanism). The species richness and density of lianas within these ecological guilds responded negatively to increasing altitude and positively to increasing patch size and additionally displayed differing sensitivities to forest disturbance. Importantly, the degree of forest disturbance significantly altered the relationship between liana species richness and density to increasing altitude and patches size, and as such is likely the primary influence on liana response to montane forest succession. Our findings suggest that managing forest disturbance in the examined montane forests would assist in conserving local liana diversity across the examined altitudinal range.     

Distribution of Leguminosae tree species in different altitudinal levels along the Atlantic Rain Forest in the Brazilian coast

The Atlantic Forest is one of the most threatened tropical forests in the world. Leguminosae, by its great richness and dominance among arboreal stratum elements, is of major importance in the floristic composition and structure of this forest. We investigated the distribution of legume species on an altitudinal gradient to find out the altitudinal zones with higher richness of species; the altitudinal zones with greater floristic similarity; the possible presence of species that may be exclusive to certain vegetation types and the altitudinal amplitudes of those species, as well as the occurrence of species substitution along the altitudinal gradient. Therefore, thirty one studies conducted in different altitudinal levels between 5° S and 29° S were analyzed. A matrix with 142 tree species distributed in altitudinal zones (every 100 m) from sea level to 2100 m was built. The greatest species richness was observed in the Submontane Forest (50–500 m) with 92 species. The cluster analysis revealed a strong dissimilarity of the 1400–2100 m (Upper Montane) and 0–10 m zones (Restinga Forest). The Submontane and the Montane Forest share the highest number of species (38 ssp.). Forty species are unique to Submontane. Substitution of species was verified. Some species have their preferred habitat located at a specific altitudinal amplitude, as is the case of Inga laurina and I. subnuda (0–10 m), I. lanceifolia and Machaerium scleroxylon (800–1200 m). The Leguminosae, although well adapted to the first colonization and establishment of diverse environment, was poorly represented above 1500 m altitude.     

Regional and local patterns of ectomycorrhizal fungal diversity and community structure along an altitudinal gradient in the Hyrcanian forests of northern Iran

? Altitudinal gradients strongly affect the diversity of plants and animals, yet little is known about the altitudinal effects on the distribution of microorganisms, including ectomycorrhizal fungi. ? By combining morphological and molecular identification methods, we addressed the relative effects of altitude, temperature, precipitation, host community and soil nutrient concentrations on species richness and community composition of ectomycorrhizal fungi in one of the last remaining temperate old-growth forests in Eurasia. ? Molecular analyses revealed 367 species of ectomycorrhizal fungi along three altitudinal transects. Species richness declined monotonically with increasing altitude. Host species and altitude were the main drivers of the ectomycorrhizal fungal community composition at both the local and regional scales. The mean annual temperature and precipitation were strongly correlated with altitude and accounted for the observed patterns of richness and community. ? The decline of ectomycorrhizal fungal richness with increasing altitude is consistent with the general altitudinal richness patterns of macroorganisms. Low environmental energy reduces the competitive ability of rare species and thus has a negative effect on the richness of ectomycorrhizal fungi. Because of multicollinearity with altitude, the direct effects of climatic variables and their seasonality warrant further investigation at the regional and continental scales.     

Effects of altitude and climate in determining elevational plant species richness patterns: A case study from Los Tuxtlas,Mexico

Altitudinal changes of composition and richness of montane plant assemblages are complex, depending on the taxonomic group and gradient conditions, with different factors involved that are directly altitude-dependent (e.g., temperatures, air pressure) and altitude-independent (e.g., precipitation, cloud cover, area). In order to assess the relative impacts of temperature, precipitation, air humidity, and area of altitudinal belts on plant diversity, we analyzed diversity patterns of five species-rich groups, mostly herbaceous plants, in 74 forest plots along three climatically contrasting elevational transects from humid tropical lowland vegetation up to cloud forests at Los Tuxtlas, Mexico. We recorded 278 plant species, with ferns being the most species-rich group followed by orchids, bromeliads, aroids, and piperoids. The most striking results were the contrasting patterns and model results for terrestrial and epiphytic taxa. Whereas the richness of all terrestrial species taken together did not change significantly with elevation, vascular epiphytes showed increasing species numbers with altitude. However, a number of individual terrestrial taxa showed also significant elevation-related changes: aroids showed a marked decline with hight, orchids and piperoids increased, and ferns displayed a hump-shaped pattern with highest richness in mid-altitudes. Among the epiphytes, aroids declined while most other groups increased with altitude. This distinction is relevant for projections of responses of plant communities to climate change, which will lead to increased temperatures and to changing precipitation and cloud condensation regimes and thus will likely affect terrestrial and epiphytic species in different ways.     

福建梅花山常绿阔叶林植物物种多样性及其海拔梯度格局

常绿阔叶林是福建梅花山国家级自然保护区地带性植被。采用样带与典型群落调查法对区内的常绿阔叶林14400m2样地展开调查,并对植物多样性海拔梯度格局进行分析,结果表明：（1） 群落植物物种丰富度、Gleason丰富度指数、Simpson指数、Shannon Wiener指数和Pielou均匀度指数的均值分别为64.42、10.75、5.75、3.50、0.58,且这5种指数在各样带间差异极为显著,并随海拔的升高均呈单峰曲线变化,峰值出现在海拔700m~900m。（2） 群落各层次的植物物种丰富度、Shannon Wiener指数均呈现灌木层（包括幼树和层间植物）〉乔木层〉草本层的特征。乔木、灌木层物种丰富度与乔木层Shannon Wiener指数在海拔梯度上的样带间差异极显著,变化趋势与群落相似;灌木层与草本层Shannon Wiener指数以及草本层物种丰富度随海拔梯度变化不明显。因此,梅花山自然保护区常绿阔叶林植物物种多样性的海拔梯度格局呈现单峰分布,并支持中间高度膨胀模式（mid domain model）。     

Species Diversity and Altitudinal Gradient Patterns of Evergreen Broad leaved Forest in MeihuashanNational Natural Reserve,Fujian Province

In China, evergreen broad leaved forests (EBLFs) is one of the most important vegetation types which was widly distributed in subtropical area, and it plays a very important role in the global biological diversity and natural environment conservation also. In order to reveal species diversity and altitudinal gradient patterns of evergreen broad leaved forest in Meihuashan National Natural Reserve, Fujian Province. Five altitude transects were set up at a vertical interval of 200m between 375m and 1300m above sea level in the EBLFs distribution areas, and twenty four quadrats(14400m2) had been surveyed. Species richness(S), species richness index (dGl), Simpson index (D), Shannon Wiener index (H′), Pielou evenness index (J) had been used for analysis of species diversity and altitudinal gradient pattern of EBLFs. The average value of S, dGl, H′,J and D were 64.42, 10.75, 5.75, 3.50, 0.58 respectively. The difference of community species diversity index(S, dGl, D, H′, and J) was extremely significant between transects, and the altitudinal gradient patterns of species diversity presented the unimodal variable trend, with a peak in the mid altitude(700m-900m). The species richness and Shannon Wiener index of different layer were ranked as shrub layer (include young tree and the plants between layers)>arbor layer>herb layer. The species richness of tree and shrub layer, and Shannon Wiener index of tree layer were significantly different between at transects, and trends of altitude gradient was similar to community. The Shannon Wiener index of shrub layer and herb layer, and the species richness of herb layer did not change significantly along elevation gradient. Therefore, plant species diversity distribution pattern presented a unimodal variable trend along an elevation gradient, and supported “mid domain model” in EBLFs of Meihuashan National Nature Reserve.     

Species richness and trait composition of butterfly assemblages change along an altitudinal gradient

Species richness patterns along altitudinal gradients are well-documented ecological phenomena, yet very little data are available on how environmental filtering processes influence the composition and traits of butterfly assemblages at high altitudes. We have studied the diversity patterns of butterfly species at 34 sites along an altitudinal gradient ranging from 600 to 2,000 m a.s.l. in the National Park Berchtesgaden (Germany) and analysed traits of butterfly assemblages associated with dispersal capacity, reproductive strategies and developmental time from lowlands to highlands, including phylogenetic analyses. We found a linear decline in butterfly species richness along the altitudinal gradient, but the phylogenetic relatedness of the butterfly assemblages did not increase with altitude. Compared to butterfly assemblages at lower altitudes, those at higher altitudes were composed of species with larger wings (on average 9 %) which laid an average of 68 % more eggs. In contrast, egg maturation time in butterfly assemblages decreased by about 22 % along the altitudinal gradient. Further, butterfly assemblages at higher altitudes were increasingly dominated by less widespread species. Based on our abundance data, but not on data in the literature, population density increased with altitude, suggesting a reversed density–distribution relationship, with higher population densities of habitat specialists in harsh environments. In conclusion, our data provide evidence for significant shifts in the composition of butterfly assemblages and for the dominance of different traits along the altitudinal gradient. In our study, these changes were mainly driven by environmental factors, whereas phylogenetic filtering played a minor role along the studied altitudinal range.     

新疆天山南坡中段种子植物区系垂直分布格局分析

对植物多样性垂直分布格局及其维持机制的研究可以有效揭示植物物种多样性分布特征及其环境影响因子。本文通过野外调查、查阅标本并结合相关文献资料,对天山南坡中段种子植物区系沿海拔梯度的分布格局进行了系统研究。结果显示,在大区域尺度上,科属种的物种丰富度随海拔升高均呈先增加后减少的趋势,且最高值出现在中低海拔1900~2000 m处;不同生活型植物沿海拔梯度的变化格局有所不同,其中,乔木、一年生草本、藤本及寄生植物表现出随海拔升高物种丰富度逐渐降低的趋势,灌木、多年生草本及二年生草本植物物种丰富度则呈先增加后减少的变化趋势;从植物区系地理成分来看,世界分布所占的比重沿海拔梯度升高呈先增加后减少的趋势;温带地理成分所占的比重沿海拔梯度升高呈缓慢上升趋势;古地中海地理成分所占的比重沿海拔梯度升高呈先增加后减少然后再增加的变化趋势;热带地理成分所占的比重沿海拔升高呈逐渐下降的趋势;东亚地理成分所占的比重沿海拔梯度升高呈先增加后减少然后再增加的变化趋势。对该分布格局与当地干旱的气候条件及海拔梯度上热量和水分条件的变化相适应。     

Species richness and altitude: a comparison between null models and interpolated plant species richness along the Himalayan altitudinal gradient, Nepal

We compare different null models for species richness patterns in the Nepalese Himalayas, the largest altitudinal gradient in the world. Species richness is estimated by interpolation of presences between the extreme recorded altitudinal ranges. The number of species in 100-m altitudinal bands increases steeply with altitude until 1,500 m above sea level. Between 1,500 and 2,500 m, little change in the number of species is observed, but above this altitude, a decrease in species richness is evident. We simulate different null models to investigate the effect of hard boundaries and an assumed linear relationship between species richness and altitude. We also stimulate the effect of interpolation when incomplete sampling is assumed. Some modifications on earlier simulations are presented. We demonstrate that all three factors in combination may explain the observed pattern in species richness. Estimating species richness by interpolating species presence between maximum and minimum altitudes creates an artificially steep decrease in species richness toward the ends of the gradient. The addition of hard boundaries and an underlying linear trend in species richness is needed to simulate the observed broad pattern in species richness along altitude in the Nepalese Himalayas.     

Changes in structure and composition of evergreen forests on an altitudinal gradient in the Venezuelan Guayana shield

There have been several ecological studies in forests of the Guayana Shield, but so far none had examined the changes in structure and composition of evergreen forests with altitude. This study describes and analyzes the structure, species composition and soil characteristics of forest stands at different altitudinal zones in Southeastern Venezuelan Guayana, in order to explain the patterns and the main factors that determine the structure and composition of evergreen forests along the altitudinal gradient. Inventories of 3 948 big (>10cm DBH) and 1 328 small (5-10cm DBH) woody stems were carried out in eleven plots, ranging from 0.1 to 1.0ha, along a 188km long transect with elevations between 290 and 1 395masl. It has been found that 1) hemiepihytes become more dominant and lianas reduce their dominance with increasing altitude and 2) the forest structure in the study area is size-dependent. Five families and 12 genera represented only 9% of the total number of families and genera, respectively, recorded troughout the gradient, but the two groups of taxa comprised more than 50% of the Importance Value (the sum of the relative density and the relative dominance) of all measured stems. Moreover, the results suggest that low species richness seems to be associated with the dominance of one or few species. Stand-level wood density (WD) of trees decreased significantly with increasing elevation. WD is an indicator of trees'life history strategy. Its decline suggests a change in the functional composition of the forest with increasing altitude. The Canonical Correspondence Analysis (CCA) indicated a distinction of the studied forests on the basis of their altitudinal levels and geographic location, and revealed different ecological responses by the forests, to environmental variables along the altitudinal gradient. The variation in species composition, in terms of basal area among stands, was controlled primarily by elevation and secondarily by rainfall and soil conditions. There are other interacting factors not considered in this study like disturbance regime, biological interactions, productivity, and dispersal history, which could affect the structure and composition of the forests in the altitudinal gradient. In conclusion, it appears that the structural and floristic variability observed in the studied transect is produced by a combination of different climates and randomly expressed local processes interacting across a complex physical landscape.     

Beta diversity of aquatic invertebrates increases along an altitudinal gradient in a Neotropical mountain

Mountains harbor rich biodiversity and high levels of endemism, particularly due to changes in environmental conditions over short spatial distances, which affects species distribution and composition. Studies on mountain ecosystems are increasingly needed, as mountains are highly threatened despite providing ecosystem services, such as water supply for half of the human population. We aimed to understand the patterns and drivers of alpha and beta diversities of aquatic invertebrates in headwater streams along an altitudinal gradient in the second largest South American mountain range, the Espinhaço mountains. Headwater streams were selected at each 100 m of elevation along an altitudinal gradient ranging from 800 to 1400 m asl, where three substrate types per stream were sampled: leaf litter, gravel, and cobbles. Environmental variables were sampled to represent local riparian canopy cover, instream physical habitat, water quality, climatic data, and land use. Generalized linear models and mixed models were used to test relationships between altitude and the richness and abundance of invertebrates and to assess the influence of environmental variables on the same metrics. Patterns of spatial variation in aquatic invertebrate assemblages along the altitudinal gradient were assessed using multiplicative beta diversity partitioning. The richness and abundance of aquatic invertebrates decreased with increasing altitude, whereas beta diversity increased with increasing altitude. Significant differences in assemblage composition and in relative abundance of invertebrates were observed for both substrates and altitude. We thus show that the high regional beta diversity in aquatic ecosystems in the studied site is due to the high turnover among areas. Abstract in Portuguese is available with online material.     

Assessing the origin of Neotropical mountain dung beetle assemblages (Scarabaeidae: Scarabaeinae): the comparative influence of vertical and horizontal colonization

Aims The fauna of mountains and their surrounding regions are likely to be influenced principally by two biological processes: horizontal colonization along similar altitudinal levels by elements originating from lineages inhabiting higher latitudes; and vertical colonization by lineages from the same latitude, but at lower altitudes. We examine whether the expected patterns derived from the latter process can be observed in mountain dung beetle assemblages. Specifically, we study the variation in species composition and richness with altitude in five regions spanning elevation gradients, analysing whether the altitudinal rates of change in the number of species and genera differ, and whether beta‐diversity scores for adjacent sites in each altitudinal gradient are different for species and genera. Location Eastern Cordillera of the Colombian Andes. Methods Field work was carried out in 1997–99 at 27 sites in five regions with elevation gradients, with 10–32 pitfall traps placed in each site. For each altitudinal level the numbers of species and genera were analysed with respect to altitude, and the slope of the linear regression between these variables was calculated. The slope of the curve of the altitude against the cumulative number of species and genera was also calculated for each altitudinal gradient to describe the compositional change between adjacent sites (beta diversity). Species and generic slopes were compared using analysis of covariance. The turnover of species along each altitudinal gradient was measured using presence/absence data and Cody's beta‐diversity index between adjacent pairs of sites. A cluster analysis was used to detect faunistically homogeneous groups of localities. Results Species richness always decreased with altitude, although the slopes did not differ significantly from zero. The number of genera also decreased with increasing altitude, but generally at a significantly slower rate than for species. Variation in the species beta‐diversity scores between altitudinal levels did not follow a homogeneous pattern in the different regions. Two main altitudinal groups of sites with a boundary c. 1500–1750 m a.s.l. can be detected with respect to faunistic similarity. Low‐ and mid‐altitude sites are inhabited by all of the genera (19) and 80% of all species collected. Eight genera and 61 species (c. 60% of the total) are unable to inhabit high‐altitude sites, and only 20 species appear to be exclusive to these high‐altitude environments (> 2000 m a.s.l.). Main conclusions The dominant processes explaining dung beetle composition in the high north‐eastern Andean mountains are probably those of vertical colonization. The limited role of horizontal colonization processes, or colonization from northern or southern lineages, could be a consequence of the isolation and recent geological origin of these mountains.     

青藏高原高寒草甸物种多样性的海拔梯度分布格局及对地上生物量的影响

植物物种多样性在海拔梯度上的变化规律以及物种多样性与生产力的关系是生态学研究的热点, 至今还没有得出一般性规律。本文以青海省海南藏族自治州贵德县的拉脊山(36°21′ N, 101°27′ E, 海拔3,389-3,876 m)和果洛藏族自治州的玛沁县军牧场山体(34°22′ N, 100°30′ E, 海拔4,121-4,268 m)为研究对象, 对植物高度、盖度、地上生物量和物种多样性随海拔高度的变化进行调查和统计分析, 以探讨青藏高原高寒草甸的物种多样性和地上生物量在海拔梯度上的变化规律及两者的关系。结果表明: (1)两条山体样带上地上生物量与物种多样性随海拔的变化规律一致: 随着海拔的升高, 地上生物量线性降低; Shannon-Wiener指数、Simpson指数和物种丰富度都呈单峰曲线, 在中间海拔最大, 而Pielou指数随海拔的升高线性增加。结合目前针对青藏高原高寒草甸的研究数据, 发现物种丰富度随海拔高度的变化均呈单峰曲线, 说明随着海拔的升高物种多样性先升高后降低可能是青藏高原物种多样性分布的普遍规律。(2)地上生物量与物种多样性的关系在两条山体样带上表现一致: 地上生物量随Shannon- Wiener指数、Simpson指数和Pielou指数的升高而线性降低, 但与物种丰富度不相关。综合两条山体样带所有样方数据, 发现地上生物量与Shannon-Wiener指数、Simpson指数不相关, 而随物种丰富度的升高线性增加。结合目前在青藏高原的相关研究数据, 发现地上生物量与物种丰富度呈S型曲线(logistic model)。     

Species Richness of Nonvolant Small Mammals Along Elevational Gradients in Northwestern Argentina

The Nevados del Aconquija (5500 m) and Cumbres Calchaquíes (4600 m) are isolated mountain ranges that contain at least three physiognomic units in their eastern slopes: Neotropical rainforests, Andean grasslands and High Andean Steppes. Despite phytogeographical similarities, the two ranges differ in the amount and spatial distribution of rainfall over the elevation gradient. We studied terrestrial small mammals by direct trapping in two altitudinal transects on the eastern slope of the two mountain ranges. We recorded the changes in richness and species composition, as well as the relationships between species and microhabitats at each altitudinal level. The results show a similar structure of the small mammal assemblage in the two ranges. The largest differences, in terms of species composition, were registered at lower elevation forests, and faunal affinities increased with elevation to the point of finding identical species composition at the top of the mountains. Species richness showed a clear curvilinear pattern with a peak at the upper limit of the forests. Our findings suggest that total rainfall has an important influence on the composition and abundance of small mammal species but apparently not on the species richness along the elevation gradient. The highest values of species richness were observed at the sites where a contact between two different physiognomic units exists. These results indicate that habitat heterogeneity plays an important role in allowing the juxtaposition of small terrestrial mammal assemblages of the highlands and lowlands at a given point, contributing significantly to the considerable diversity of species observed in intermediate altitudinal sites.
     

Butterfly Community Composition Across a Successional Gradient in a Human‐disturbed Afro‐tropical Rain Forest

Knowledge of the recovery of insect communities after forest disturbance in tropical Africa is very limited. Here, fruit‐feeding butterflies in a tropical rain forest at Kibale National Park, Uganda, were used as a model system to uncover how, and how fast, insect communities recover after forest disturbance. We trapped butterflies monthly along a successional gradient for one year. Traps were placed in intact primary forest compartments, heavily logged forest compartments with and without arboricide treatment approximately 43 years ago, and in conifer‐clearcut compartments, ranging from 9 to 19 years of age. The species richness, total abundance, diversity, dominance, and similarity of the community composition of butterflies in the eight compartments were compared with uni‐ and multivariate statistics. A total of 16,728 individuals representing 88 species were trapped during the study. Butterfly species richness, abundance, and diversity did not show an increasing trend along the successional gradient but species richness and abundance peaked at intermediate stages. There was monthly variation in species richness, abundance, diversity and composition. Butterfly community structure differed significantly among the eight successional stages and only a marginal directional change along the successional gradient emerged. The greatest number of indicator species and intact forest interior specialists were found in one of the primary forests. Our results show that forest disturbance has a long‐term impact on the recovery of butterfly species composition, emphasizing the value of intact primary forests for butterfly conservation.     

Plant diversity patterns and their relationships with soil and climatic factors along an altitudinal gradient in the middle Tianshan Mountain area, Xinjiang, China

Patterns of plant diversity along the altitudinal gradient of Tianshan in central Xinjiang, China were examined. Plant and environment characteristics were surveyed from higher, south of Bogeda peak, to lower, north of Guerbantonggute desert. There were a total of 341 vascular plant, 295 herbage, 41 shrub, and seven tree species in the sampled plots. The plant richness of vegetation types generally showed a unimodal pattern along altitude, with a bimodal change of plant species number at 100-m intervals of altitudinal samples. The two belts of higher plant richness were in transient areas between vegetation types, the first in areas from dry grass to forest, and the second from forest to sub-alpine grass and bush. The beta diversity varied with altitudinal changes, with herbaceous species accounting for most species, and thus had similar species turnover patterns to total species. Matching the change of richness of plant species to environmental factors along altitude and correlating these by redundancy analysis revealed that the environmental factors controlling species richness and its pattern were the combined effects of temperature, precipitation, soil water, and nutrition. Water was more important at low altitude, and temperature at high altitude, and soil chemical and physical characters at middle altitudes. This study provides insights into plant diversity conservation of Bogeda Natural Reserve Areas in Tianshan Mountain. Nomenclatures: the scientific name for plants follows Flora of China (Compiling Committee of Flora of China).     

Species Diversity and Life-Form Patterns in Steppe Vegetation along a 3000 m Altitudinal Gradient in the Alborz Mountains, Iran

Biodiversity pattern and life-form spectra were studied along a 3,000 m altitudinal gradient from a semi-desert area to the alpine peak of Tochal Mountain. The gradient is located on the southern slopes of Central Alborz with a Mediterranean continental climate. DCA ordination was applied to 1,069 relevés and 7 quantitative variables to discover the relation of diversity and altitude. A biodiversity pattern was obtained by relating values for species richness and Shannon-Wiener’s index to 100-m altitudinal sections. Altitude was determined as the major ecological gradient. Both diversity indices are negatively correlated with altitude and show a decreasing trend beyond a peak in species richness at 1,800–1,900 m a.s.l. towards a very low diversity in the high alpine zone. The biodiversity peak does not match with the potential tree line in the area (2,500–3,000 m a.s.l.). The high diversity in foothills can be related to habitat heterogeneity, longer suitable climatic conditions, and diverse disturbance factors, while unfavorable conditions at high-altitude alpine and low-altitude desert areas reduce the number of species at both extremes. Life-form patterns clearly change along altitudinal gradient. Annuals with decreasing trend, and hemicryptophytes and chamaephytes with increasing trend along the altitudinal gradient are notable patterns of life form in the area. Temperature, soil moisture and nutrients are the main factors that explain the ecological influence of altitude on species diversity and life-form patterns in the semi-arid steppe vegetation of the area.     

Long-term protection effects of national reserve to forest vegetation in 4 decades: biodiversity change analysis of major forest types in Changbai Mountain Nature Reserve,China

The Changbai Mountain Nature Reserve (CNR) was established in 1960 to protect the virgin Korean pine mixed hardwood forest, a typical temperate forest of northeast China. We conducted systematic studies of vascular diversity patterns on the north slope of the CNR mountainside forests (800–1700 m a.s.l.) in 1963 and 2006 respectively. The aim of this comparison is to assess the long-term effects of the protection on plant biodiversity of CNR during the interval 43 years. The research was carried out in three types of forests: mixed coniferous and broad-leaved forest (MCBF), mixed coniferous forest (MCF), and sub-alpine coniferous forest (SCF), characterized by different dominant species. The alpha diversity indicted by species richness and the Shannon-Wiener index were found different in the same elevations and forest types during the 43-year interval. The floral composition and the diversity of vascular species were generally similar along altitudinal gradients before and after the 43-year interval, but some substantial changes were evident with the altitude gradient. In the tree layers, the dominant species in 2006 were similar to those of 1963, though diversity declined with altitude. The indices in the three forest types did not differ significantly between 1963 and 2006, and these values even increased in the MCBF and MCF from 1963 to 2006. However, originally dominant species, P. koraiensis for example, tended to decline, while the proportion of broad-leaved trees increased, and the species turnover in the succession layers trended to shift to higher altitudes. The diversity pattern of the under canopy fluctuated along the altitudinal gradient due to micro-environmental variations. Comparison of the alpha diversity in the three forests shows that the diversity of the shrub and herb layer decreased with time. During the process of survey, we also found some rare and medicinal species disappeared. Analysis indicates that the changes of the diversity pattern in this region are caused by both nature and human factors. Meteorological records revealed that climate has changed significantly in the past 43 years. We also found the most severe human disturbance to the CNR forests in the process of another field survey that is the exploitation of herb medicines and Korean pine nuts. We hope this research would give some guidance to the future reserve management in Changbai Mountain area.