Drivers of reptile and amphibian assemblages outside the protected areas of Western Ghats,India

Biodiversity conservation in forested landscapes outside protected areas is important to sustain populations of species with restricted ranges. However, such habitats face many anthropogenic threats, including logging, extraction of firewood and leaf-litter for mulch in plantations. In this study, we determined the effects of forest degradation on amphibians and reptiles in forests outside protected areas by measuring their species richness and community composition across a disturbance gradient from near pristine to highly degraded forests in Agumbe, Western Ghats, India. Twenty-one strip 15 m × 150 m transects were laid across the disturbance gradient and diurnal visual encounter surveys were conducted. Sampling was repeated three times per transect covering the dry, intermediate and wet seasons. Amphibian and reptile communities were affected by the decrease in canopy cover and leaf litter volume, respectively. Our results indicate that the collection of firewood and leaf-litter can severely affect amphibian and reptile populations. Structured conservation planning outside of protected areas is therefore imperative.     

Species turnover: the case of stream amphibians of rainforests in the Western Ghats, southern India

We examined species turnover in stream amphibians in rainforest in two hill ranges (Ashambu and Anamalai Hills) in the Western Ghats in south India. In each hill range, six stream segments (100 m in length) belonging to three drainage or rivers were surveyed three to four times in three seasons over 1 year. Species turnover (using 1-Sorenson's index) was estimated between all possible pairs of sites at three spatial scales – within drainage, between drainage and between hill ranges. Similar matrices were also developed for altitudinal difference and geographic distance between sites. A total of 30 species in four families were recorded from 3681 individuals. The hill ranges differed significantly in the composition of the stream community at both the species and family levels. Within the hill range, species turnover was correlated with altitudinal difference and not with geographic distance. Anamalai Hills had a greater species turnover than Ashambu Hills, both within and between drainage. There was also a high turnover between these two hill ranges, with only two shared species. This turnover explains the fact that only 30–40 species have been reported from different hill ranges, although regional diversity is high with about 130 species. The turnover also predicts that several undetected species should occur in hill ranges and drainage that have not been surveyed. The conservation model for mammals and birds, consisting of a few large protected areas, may not adequately address the conservation requirements of amphibians. Protection of rainforest frogs may require many protected areas in different drainages.     

Effects of Habitat Structure and Adjacent Habitats on Birds in Tropical Rainforest Fragments and Shaded Plantations in the Western Ghats, India

As large nature reserves occupy only a fraction of the earth’s land surface, conservation biologists are critically examining the role of private lands, habitat fragments, and plantations for conservation. This study in a biodiversity hotspot and endemic bird area, the Western Ghats mountains of India, examined the effects of habitat structure, floristics, and adjacent habitats on bird communities in shade-coffee and cardamom plantations and tropical rainforest fragments. Habitat and birds were sampled in 13 sites: six fragments (three relatively isolated and three with canopy connectivity with adjoining shade-coffee plantations and forests), six plantations differing in canopy tree species composition (five coffee and one cardamom), and one undisturbed primary rainforest control site in the Anamalai hills. Around 3300 detections of 6000 individual birds belonging to 106 species were obtained. The coffee plantations were poorer than rainforest in rainforest bird species, particularly endemic species, but the rustic cardamom plantation with diverse, native rainforest shade trees, had bird species richness and abundance comparable to primary rainforest. Plantations and fragments that adjoined habitats providing greater tree canopy connectivity supported more rainforest and fewer open-forest bird species and individuals than sites that lacked such connectivity. These effects were mediated by strong positive effects of vegetation structure, particularly woody plant variables, cane, and bamboo, on bird community structure. Bird community composition was however positively correlated only to floristic (tree species) composition of sites. The maintenance or restoration of habitat structure and (shade) tree species composition in shade-coffee and cardamom plantations and rainforest fragments can aid in rainforest bird conservation in the regional landscape.     

Experimental effects of habitat fragmentation on old-field canopy insects: community, guild and species responses

We examined the effects of habitat fragmentation on the species distributions, guild membership, and community structure of old-field insects using a fine-scale experimental approach. A continuous 1-ha goldenrod field was fragmented into four treatments that varied in both patch size and degree of isolation. Each treatment was replicated four times and arranged in a Latin square design. Canopy insects in fragmented patches were sampled with sweep nets during early and late summer 1995. The species richness of insects was significantly lower in fragmented than in unfragmented treatments during July, but was similar among treatments in September. Overall community abundance showed no treatment effect during either month. We also found significant row and column effects, suggesting there was spatial heterogeneity in species richness and abundance apart from treatment effects. Differences in species richness during July were primarily due to the loss of rare species in highly fragmented plots. Overall abundance was less responsive to community change because deletions of rare species in fragmented areas were not detected in abundance analyses. Four feeding guilds showed different responses to fragmentation: the species richness of sucking herbivores and the abundance of parasitoids were significantly reduced by fragmentation but predators and chewing herbivores were largely unaffected. Analyses of a subset of individual species within guilds suggest that the greater effects of fragmentation on sucking herbivores and parasitoids may be due to the degree of habitat specificity of guild members. The effects of small-scale habitat fragmentation were therefore detectable at the level of community, guild, and individual species. Changes in species richness, guild structure and species distributions were likely due to differential effects of habitat alteration on individual movements and patch selection rather than dispersal or demographic change. Nonetheless, the selective loss of rare species, differential guild effects and changes in species occupancy that we found in this small-scale experiment are also factors that are likely to operate in fragmented habitats over broader spatial scales. Received: 11 May 1998 / Accepted: 27 September 1998     

Patterns in the distribution of freshwater fishes in rivers of Central Western Ghats, India and their associations with environmental gradients

The community ecology of freshwater fishes in four river systems (Sharavati, Aghanashini, Bedti and Kali) of the central Western Ghats (India) has been studied for the first time. Patterns of fish species distributions were analysed and important stream and environmental parameters determining the species richness and composition of this region were identified. Upstream--downstream trends in species richness and diversity as well as changes in stream characteristics were studied using univariate correlation analyses. Preliminary analyses on changes in species composition and feeding guilds showed the presence of a gradual species turnover along the stream gradient. There were associated changes in the major feeding guild compositions, with a higher proportion of insectivore and algivore/herbivore composition in the upper reaches shifting to a predominance of omnivores and carnivores downstream. Pearsons product--moment correlation analyses along with stepwise multiple regression analyses identified stream depth and altitude as the important parameters determining species richness. Canonical correspondence analysis was performed to study species associations with environmental parameters. The analysis showed a strong species environmental correlation to the CCA axes, a high significance for the CCA axis 1 as well as for the overall test. The plots of the species and site scores on the CCA axes showed a clear segregation of species based on their relations with environmental and stream properties. This study is an important step in our understanding of the community structure of fish species of these rivers and would be helpful in future efforts on the conservation of aquatic communities and their habitats.     

Ground flora and associated arthropod communities of forest road edges in Connemara, Ireland

Forest road edges in a conifer plantation in Connemara, Ireland weresampled for ground flora and associated terrestrial invertebrates along thenorthern edge of a forest road bordered by conifers (Conifer 1 site),broadleaves (Broadleaf site) and a clearfelled area (Open site). In addition,the southern edges of the road bordered by a clearing (Scallop site) and of anadjacent forest road bordered by conifers (Conifer 2 site) were sampled. Medianground plant species richness per quadrat was lower at the Conifer sites than atthe other sites. A positive relationship between plant species richness andlight levels was apparent. Median arthropod morphospecies richness per sweep wassignificantly greater (P < 0.01) at the Broadleaf site(39.0) than at the Conifer 2 site (25.5). Median morphospecies richness forHemiptera was significantly greater at the Open (7.0) and Broadleaf (6.5) sitesthan at the Conifer 1 site (2.0, P < 0.001) and Conifer2 site (2.0, P < 0.01). For Diptera, medianmorphospecies richness was significantly greater at the Open site (13.5) than atthe Conifer 1 site (6.0, P < 0.01), Conifer 2 site (6.0,P < 0.001) and Scallop site (8.0, P< 0.05). There was a positive relationship between plant species richness andarthropod morphospecies richness with stronger species richness relationshipsevident between plants and Diptera and between plants and Hemiptera,respectively. The results of this study suggest that open spaces and broadleafplantings in this commercial conifer plantation in the west of Ireland could beimportant for biodiversity.     

Effects of fragmentation on forest structure and litter dynamics in Atlantic rainforest in Pernambuco, Brazil

This study evaluates the effects of fragmentation on the spatial and temporal dynamics of small litterfall production in Atlantic rainforest in Pernambuco State, Brazil. Litterfall was collected for 24 months at two 0.2 ha sites, located in the forest edge zone and the forest interior, within a rainforest patch of about 300 ha. Structural parameters of both forest sites were recorded. Litter was sorted into six fractions (foliage, twigs, buds/flowers, fruits/seeds, peduncles, rest), dried and weighed. The interior forest plot contained 314 live trees with a dbh 5 cm and a stand basal area of 41.8±8.7 m², whereas the forest edge contained 211 live trees and a stand basal area of 23.4±3.6 m². Total small litterfall was extraordinarily high and totalled 12.62±4.73 t ha⁻¹ yr⁻¹ in interior forest and 14.74±2.78 t ha⁻¹ yr⁻¹ in forest edge. High litterfall rates are probably due to a pronounced periodicity, edge effects alter litterfall strongly.     

The effects of habitat edges and trampling on understorey vegetation in urban forests in Helsinki,Finland

Question: How do habitat edges and trampling affect mesic (Myrtillus type) understorey vegetation in fragmented urban forests, and what are the relative strengths and spatial extent of these effects? Location: The city of Helsinki, southern Finland. Methods: Vegetation sample plots were placed at different distances from the forest edge. At each distance we selected plots on, next to and away from paths of different levels of wear, and the covers and frequencies of plant species were sampled. We used generalized linear mixed models and ordination techniques to test our hypotheses. Results: The effect of the edge penetrated up to 50 m into the forest interior. Only light effects of trampling were found in seemingly untrampled areas, in addition to the direct effects of trampling on the paths. Both trampling and edge effects changed the forest understorey species composition. Trampling changed plant species composition locally on paths, and provided opportunities for new species to establish in previously unbroken forest vegetation. Urban forest edges were characterised by species better adapted to sunny, warm and dry conditions. These species, such as grasses, replaced more sensitive forest species, such as dwarf shrubs and mosses. We observed a large number of light demanding deciduous trees at the edges, which may be one of the factors increasing soil fertility and consequently promoting the high abundance of fast growing species, such as grasses and herbs related to more fertile site types. Conclusions: We recommend that urban forest fragments left within urban development should be at least 2–3 ha in size and that the shape of the patch and the number of potential recreational users should be taken into account when preserving true forest understorey vegetation from the effects of edges and trampling.     

Habitat fragmentation and species diversity in competitive communities

Habitat loss is one of the key drivers of the ongoing decline of biodiversity. However, ecologists still argue about how fragmentation of habitat (independent of habitat loss) affects species richness. The recently proposed habitat amount hypothesis posits that species richness only depends on the total amount of habitat in a local landscape. In contrast, empirical studies report contrasting patterns: some find positive and others negative effects of fragmentation per se on species richness. To explain this apparent disparity, we devise a stochastic, spatially explicit model of competitive species communities in heterogeneous habitats. The model shows that habitat loss and fragmentation have complex effects on species diversity in competitive communities. When the total amount of habitat is large, fragmentation per se tends to increase species diversity, but if the total amount of habitat is small, the situation is reversed: fragmentation per se decreases species diversity.     

Ant communities,environmental characteristics and their implications for conservation in the Brazilian Pantanal

Studies about processes determining biodiversity in Pantanal are urgently needed and the use of invertebrates for this purpose may be an efficient tool. The purpose of this paper is to verify whether ants could be used to predict human impacts on Pantanal, assessing how environmental characteristics of gallery forest influence arboreal ant species richness. Specifically, we tested the hypotheses that: (i) resource availability (estimated by tree density) and (ii) diversity of environmental conditions (estimated by structural heterogeneity) positively influence arboreal ant species richness and composition. Ants were sampled in a gallery forest in the Miranda River. Ant species richness did not respond to tree density, but increased with structural heterogeneity. Species composition was affected both by tree density and structural heterogeneity. The species list produced in the present study showed a high similarity between arboreal ant faunas of Cerrado and Pantanal, which are contiguous biomes. The relationship of ant species richness with heterogeneity, as well as the observed changes of species composition with tree density and heterogeneity may be explained by the presence of a variation of environmental conditions, which create several micro-habitats in the forest. The response of the ant community can reflect human impacts on the forests of the studied region, which are usually modified to create patches for sport fishing and by pathways used in ecotourism.     

不同生境条件与管理方式对茶园蜘蛛群落结构及多样性的影响

蜘蛛在茶园的生态控制和生物防治中起到重要的作用,为了解不同生境条件和管理方式的茶园蜘蛛群落结构差异和多样性变化,于2011年3月份—2011年10月份,运用振落承接和过筛法对3种不同类型茶园的蜘蛛群落组成与多样性进行了调查。结果表明:(1)3种类型茶园蜘蛛群落组成:3种类型茶园蜘蛛群落在科、属、种的组成及个体数量上,均表现为有机茶园高,无公害茶园次之,普通茶园低,且在物种数和个体数存在显著差异。管巢蛛科和狼蛛科是3种类型茶园的优势类群,球蛛科、跳蛛科、狼蛛科、皿蛛科的物种优势度大于10%。(2)蜘蛛群落物种多样性的多重分析结果表明,有机茶园蜘蛛群落的个体数、物种数、物种多样性指数、物种丰富度指数和均匀度指数均高于无公害茶园和普通茶园,普通茶园最低,且达到显著水平(P0.05)。(3)多元数据分析结果表明,有机茶园蜘蛛群落组成与普通茶园差异较大,无公害茶园与普通茶园蜘蛛群落组成差异较小;3种类型茶园的茶丛蜘蛛群落个体数、物种数及物种多样性指数、丰富度指数和均匀度指数均高于地表,且表现为机茶园多,无公害茶园次之,普通茶园最少。蜘蛛的功能群采集发现,在3种茶园中结网蜘蛛少,而主要是游猎蜘蛛。(4)不使用化学农药的茶园,因其周边生境结构复杂(竹林、小灌木及杂草),植被丰富,形成植被缓冲带,改善了茶园小气候环境,增加了茶园土表覆盖度,可明显提高茶丛和地表游猎蜘蛛的物种数和个体数量。综合研究结果表明,在生态条件好、干扰少的有机茶园中的蜘蛛物种数量、群落多样性明显高于受损生态系统和人为干扰强的普通茶园。     

Spatial patterns of phylogenetic diversity and endemism in the Western Ghats,India: A case study using ancient predatory arthropods

The Western Ghats (WG) mountain chain in peninsular India is a global biodiversity hotspot, one in which patterns of phylogenetic diversity and endemism remain to be documented across taxa. We used a well‐characterized community of ancient soil predatory arthropods from the WG to understand diversity gradients, identify hotspots of endemism and conservation importance, and highlight poorly studied areas with unique biodiversity. We compiled an occurrence dataset for 19 species of scolopendrid centipedes, which was used to predict areas of habitat suitability using bioclimatic and geomorphological variables in Maxent. We used predicted distributions and a time‐calibrated species phylogeny to calculate taxonomic and phylogenetic indices of diversity, endemism, and turnover. We observed a decreasing latitudinal gradient in taxonomic and phylogenetic diversity in the WG, which supports expectations from the latitudinal diversity gradient. The southern WG had the highest phylogenetic diversity and endemism, and was represented by lineages with long branch lengths as observed from relative phylogenetic diversity/endemism. These results indicate the persistence of lineages over evolutionary time in the southern WG and are consistent with predictions from the southern WG refuge hypothesis. The northern WG, despite having low phylogenetic diversity, had high values of phylogenetic endemism represented by distinct lineages as inferred from relative phylogenetic endemism. The distinct endemic lineages in this subregion might be adapted to life in lateritic plateaus characterized by poor soil conditions and high seasonality. Sites across an important biogeographic break, the Palghat Gap, broadly grouped separately in comparisons of species turnover along the WG. The southern WG and Nilgiris, adjoining the Palghat Gap, harbor unique centipede communities, where the causal role of climate or dispersal barriers in shaping diversity remains to be investigated. Our results highlight the need to use phylogeny and distribution data while assessing diversity and endemism patterns in the WG.     

Predicting diversity of juvenile neotropical fish communities: patch dynamics versus habitat state in floodplain creeks

The species richness of communities should largely depend on habitat variability and/or on habitat state. We evaluated the ability of habitat variability and habitat state to predict the diversity of juvenile neotropical fish communities in creeks of a river floodplain. The young-fish fauna consisted of 73 taxa, and samples were well distributed over a wide range of relevant temporal and spatial habitat variability. We were unable to demonstrate clear patterns of richness in relation to temporal and spatial habitat variability (if habitat state variables were not included), regardless of the temporal variability scale, the grouping of sites (up- and downstream sites differed in temporal variability patterns), taxonomic units or life stages considered. Using stepwise multiple regression, 36% of the variance in species richness was explained for all data, and at best 47% was explained for all taxonomic units at upstream sites using temporal and spatial habitat variability and habitat state (bank length, mean width, mean water level before fishing and/or water turbidity). Using Monte Carlo simulations, we blindly predicted 31% (all data) and at best 37% (all upstream taxa) of the observed variance in species richness from these model types. This limited precision is probably because rare species produced most of the richness patterns in our creeks. The prediction of these rare species is generally difficult for various reasons, and may be a problem in many ecosystem types. Received: 6 July 1998 / Accepted: 16 November 1998     

Clustering of ant communities and indicator species analysis using self-organizing maps

To understand the complex relationships that exist between ant assemblages and their habitats, we performed a self-organizing map (SOM) analysis to clarify the interactions among ant diversity, spatial distribution, and land use types in Fukuoka City, Japan. A total of 52 species from 12 study sites with nine land use types were collected from 1998 to 2012. A SOM was used to classify the collected data into three clusters based on the similarities between the ant communities. Consequently, each cluster reflected both the species composition and habitat characteristics in the study area. A detrended correspondence analysis (DCA) corroborated these findings, but removal of unique and duplicate species from the dataset in order to avoid sampling errors had a marked effect on the results; specifically, the clusters produced by DCA before and after the exclusion of specific data points were very different, while the clusters produced by the SOM were consistent. In addition, while the indicator value associated with SOMs clearly illustrated the importance of individual species in each cluster, the DCA scatterplot generated for species was not clear. The results suggested that SOM analysis was better suited for understanding the relationships between ant communities and species and habitat characteristics.     

Influence of tree age, tree size and crown structure on lichen communities in mature Alpine spruce forests

Testing the relations between tree parameters and the richness and composition of lichen communities in near-natural stands could be a first step to gather information for forest managers interested in conservation and in biodiversity assessment and monitoring. This work aims at evaluating the influence of tree age and age-related parameters on tree-level richness and community composition of lichens on spruce in an Alpine forest. The lichen survey was carried out in four sites used for long-term monitoring. In each site, tree age, diameter at breast height, tree height, the first branch height, and crown projection area were measured for each tree. Trees were stratified into three age classes: (1) <100 years old, immature trees usually not suitable for felling, (2) 100–200 years old, mature trees suitable for felling, and (3) >200 years old, over-mature trees normally rare or absent in managed stands. In each site, seven trees in each age class were selected randomly. Tree age and related parameters proved to influence both tree-level species richness and composition of lichen communities. Species richness increased with tree age and related parameters indicative of tree size. This relation could be interpreted as the result of different joint effects of age per se and tree size with its area-effect. Species turnover is also suspected to improve species richness on over-mature trees. Similarly to species richness, tree-level species composition can be partially explained by tree-related parameters. Species composition changed from young to old trees, several lichens being associated with over-mature trees. This pool of species, including nationally rare lichens, represents a community which is probably poorly developed in managed forests. In accordance to the general aims of near-to-nature forestry, the presence of over-mature trees should be enhanced in the future forest landscape of the Alps especially in protected areas and Natura 2,000 sites, where conservation purposes are explicitly included in the management guidelines.     

Do biodiversity patterns in Dutch wetland complexes relate to variation in urbanisation,intensity of agricultural land use or fragmentation?

Red list species densities of birds (maximally 22 km⁻²), and angiosperms (maximally 39 km⁻²) were used as biodiversity indicators in 21 larger complexes of wetlands across the Netherlands. Their covariability with a range of indicators of human land use was assessed, including population, road and visitor density, area covered by agriculture, open water, forest and residential housing. Data were collected on the wetland complexes as well as for a perimeter with 10 km radius. In a principal components analysis (PCA) with all land use variables, it was found that the population-density-related complex of urbanisation, fragmentation (by roads), and intensity of fertilizer use together explained most of the variability present (i.e. the first PCA axis explained 50%), whilst land use within these complexes was second with an additional 19% and waterside recreation third with 12%. Red list bird species density did not correlate with that of angiosperms, nor with any of the indicators used. For the 13 complexes on organic peatland, we observed an increase in maximum red list angiosperm species density with the proportion of open marshland (P < 0.01, r ² > 0.55), which, in turn, was negatively and closely correlated with the first PCA axis reflecting an urbanisation gradient across the Netherlands.