Palm species richness,abundance and diversity in the Yucatan Peninsula,in a neotropical context

Species richness, abundance and diversity patterns in palm communities in the Yucatan Peninsula were compared at three sites with different forest types (semi‐deciduous, semi‐evergreen and evergreen), as well as different precipitation, geomorphology and soil depth. All individual palms, including seedlings, juveniles and adults, were identified and counted in forty‐five (0.25 ha) transects. A total of 46 000 individual palms belonging to 11 species from nine genera and two subfamilies were recorded. Palm richness, diversity and abundance were highest in the evergreen forest. Species from the subfamily Coryphoideae dominated the semi‐deciduous and semi‐evergreen forests while species from the subfamily Arecoideae dominated the evergreen forest. Seven species were found only in the evergreen forest. Chamaedorea seifrizii and Sabal yapa were found in all three forest types, while Thrinax radiata was found in the semi‐deciduous and semi‐ evergreen forests and Cocothrinax readii only in the semi‐evergreen forest. Compared to other neotropical palm communities, the richness and diversity in the Yucatan Peninsula are lower than in the western Amazon basin. Although palm richness and diversity on the Yucatan Peninsula were positively associated with precipitation, other variables, in particular soil depth and fertility as well as habitat heterogeneity (microtopography and canopy cover), need to be considered to better understand the observed patterns.     

The Conservation Value of Secondary Forests for Vascular Epiphytes in Central Panama

Secondary forests that develop following land abandonment could compensate for the losses of diversity and structure that accompany deforestation of old‐growth forests in tropical regions. Whether secondary forests can harbor similar species richness, density, and composition of old‐growth forests for vascular epiphytes remains largely unknown for secondary forests older than 50 yr. We examined community structure (species richness, density, and species composition) of vascular epiphytes in older secondary forests between 35 and 115 yr after land abandonment and nearby old‐growth forests to determine if the community structure of epiphytes in secondary forests approaches that of old‐growth forests over time. The recovery of epiphyte species richness was rapid with 55‐year‐old forests containing 65 percent of old‐growth epiphyte species richness. Secondary forest epiphyte communities were found to be statistically nested within secondary forests older in age and within old‐growth forests. Similarity of epiphyte communities to old‐growth forests increased to 75 percent, 115 yr after abandonment. This study suggests that secondary forests will likely recover old‐growth epiphyte richness and composition given enough time. Epiphyte densities did not recover quickly with 55‐year‐old forests having 14 percent and 115‐year‐old forests having only 49 percent of the density of old‐growth forest epiphytes. The low density of epiphytes in secondary forests could impact rainforest diversity and function. We conclude that in less than 115 yr, although secondary moist forests have high conservation value for some aspects of community structure, they are unlikely to compensate biologically for the loss of diversity and ecosystem function that high epiphyte densities provide.     

Diversity of plant evolutionary lineages promotes arthropod diversity

Large‐scale habitat destruction and climate change result in the non‐random loss of evolutionary lineages, reducing the amount of evolutionary history represented in ecological communities. Yet, we have limited understanding of the consequences of evolutionary history on the structure of food webs and the services provided by biological communities. Drawing on 11 years of data from a long‐term plant diversity experiment, we show that evolutionary history of plant communities – measured as phylogenetic diversity – strongly predicts diversity and abundance of herbivorous and predatory arthropods. Effects of plant species richness on arthropods become stronger when phylogenetic diversity is high. Plant phylogenetic diversity explains predator and parasitoid richness as strongly as it does herbivore richness. Our findings indicate that accounting for evolutionary relationships is critical to understanding the severity of species loss for food webs and ecosystems, and for developing conservation and restoration policies.     

Do riparian reserves support dung beetle biodiversity and ecosystem services in oil palm-dominated tropical landscapes?

Agricultural expansion and intensification are major threats to global biodiversity, ecological functions, and ecosystem services. The rapid expansion of oil palm in forested tropical landscapes is of particular concern given their high biodiversity. Identifying management approaches that maintain native species and associated ecological processes within oil palm plantations is therefore a priority. Riparian reserves are strips of forest retained alongside rivers in cultivated areas, primarily for their positive hydrological impact. However, they can also support a range of forest‐dependent species or ecosystem services. We surveyed communities of dung beetles and measured dung removal activity in an oil palm‐dominated landscape in Sabah, Malaysian Borneo. The species richness, diversity, and functional group richness of dung beetles in riparian reserves were significantly higher than in oil palm, but lower than in adjacent logged forests. The community composition of the riparian reserves was more similar to logged forest than oil palm. Despite the pronounced differences in biodiversity, we did not find significant differences in dung removal rates among land uses. We also found no evidence that riparian reserves enhance dung removal rates within surrounding oil palm. These results contrast previous studies showing positive relationships between dung beetle species richness and dung removal in tropical forests. We found weak but significant positive relationships between riparian reserve width and dung beetle diversity, and between reserve vegetation complexity and dung beetle abundance, suggesting that these features may increase the conservation value of riparian reserves. Synthesis and applications: The similarity between riparian reserves and logged forest demonstrates that retaining riparian reserves increases biodiversity within oil palm landscapes. However, the lack of correlation between dung beetle community characteristics and dung removal highlights the need for further research into spatial variation in biodiversity–ecosystem function relationships and how the results of such studies are affected by methodological choices.     

Can spatial variation in epiphyte diversity and community structure be predicted from sampling vascular epiphytes alone?

Aim Non‐vascular epiphytes have been largely ignored in studies examining the biotic and abiotic determinants of spatial variation in epiphyte diversity. Our aim was to test whether the spatial patterning of species richness, biomass and community composition across geographic regions, among trees within regions, and among branches within trees is consistent between the vascular and non‐vascular components of the temperate rain forest flora. Location Coastal lowland podocarp‐broadleaved forests on the west coast of the South Island of New Zealand. Methods We collected single samples (30 × 25 cm) from 96 epiphyte assemblages located on the inner branches of 40 northern rata (Metrosideros robusta) trees. For each sample, branch characteristics such as branch height, branch diameter, branch angle, branch aspect, and minimum and maximum epiphyte mat depth were recorded. The biomass for each individual epiphyte species was determined. Results Northern rata was host to a total of 157 species, comprising 32 vascular and 125 non‐vascular species, with liverworts representing 41% of all species. Within epiphyte mats, the average total organic biomass of 3.5 kg m^?2 of branch surface area consisted largely of non‐living biomass and roots. Vascular and non‐vascular epiphytes showed strikingly different spatial patterns in species richness, biomass and composition between sites, among trees within sites, and among branches within trees, which could not be explained by the branch structural characteristics we measured. The two plant groups had no significant association in community composition (r = 0.04, P = 0.08). However, the species richness of vascular plant seedlings was strongly linked to the presence/absence of lichens. Main conclusions Non‐vascular plants contributed substantially to the high species richness and biomass recorded in this study, which was comparable to that of some tropical rain forests. High variability in community composition among epiphyte mats, and very low correlation with any of the environmental factors measured possibly indicate high levels of stochasticity in seed or spore colonization, establishment success or community assembly among branches in these canopy communities. Although we found some evidence that vascular plant seedling establishment was linked to the presence of lichens and the biomass of non‐living components in the epiphyte mats, there was no correlation in the spatial patterning or determinants of species richness between non‐vascular and vascular plants. Consequently, variation in total epiphyte biodiversity could not be predicted from the measurement of vascular plant diversity alone, which highlights the crucial importance of sampling non‐vascular plants when undertaking epiphyte community studies.     

Species richness,composition, and spatial distribution of vascular epiphytes in Amazonian black-water floodplain forests

This study examines the occurrence of vascular epiphytic species in Central Amazonian black-water floodplain forests (igapó) and considers whether their horizontal and vertical distribution is influenced by the flood pulse, as is the case with tree species (phorophytes). Research was conducted in sixteen forest plots the Jaú National Park. In these, epiphytes on all phorophytes with DBH ≥ 10 cm were identified. We measured flood height using the watermark left by the last high-water period, then estimated the height relative to the ground of every epiphytic individual. We recorded 653 individuals in 37 species, distributed on 109 phorophytes. Igapó floodplain forests have much lower richness and abundance of vascular epiphyte species than do other Amazonian forests. This may reflect the limitation of available sites for colonization (only 24.9% of studied trees were occupied by epiphytes). Holoepiphytes predominated, and the combined presence of a flood-pulse, linked to the nutrient-poor soil poor seems to limit the occurrence of nomadic vines. Horizontal distribution of epiphytes followed the distribution of phorophytes, which in turn followed the flood-level gradient. Also flooding interacted strongly with vertical zonation to determine species richness. As already well-reported for trees, and unlike reports of epiphytes in other floodplains, flooding strongly influenced richness and distribution of vascular epiphytes in the studied igapó forests.     

Functional and phylogenetic approaches reveal the evolution of diversity in a hyper diverse biota

Ant communities in tropical forests may be governed by varying assembly mechanisms, depending on the particular habitat investigated. We compared phylogenetic diversity and structure across two forest biomes (dry and humid) and two vertical layers (arboreal and terricolous) in ant communities in Madagascar, and assessed the influence of invasive species on this community structure. We estimated phylogenetic signal and correlated evolution for habitat and several functional traits and tested for conservatism in relevant functional and habitat traits. Ancestral states were reconstructed to illuminate the evolution of habitat traits. All analyses utilized phylogenies estimated from newly generated data from three nuclear markers for 290 Malagasy ant taxa. Dry forests, although lower in species richness, were found to support equally high lineage diversity as humid forests. In contrast, phylogenetic diversity was much lower in arboreal than in terricolous communities. We observed significant phylogenetic clustering in the combined humid forest and in the arboreal–humid, arboreal–dry and terricolous–humid communities, whereas the combined dry forest community was overdispersed. Among ant communities in Madagascar, overdispersion and competition therefore may be more prevalent in dry forest, and habitat filtering may be more dominant in humid forest. Excluding invasive ant species had little overall effect on community structure. All investigated traits showed low to intermediate conservatism; strong support for correlated evolution was found for increased eye size and an arboreal lifestyle. Habitat transitions from humid to dry and from terricolous to arboreal occurred more frequently, and ancestors of most lineages were predicted to be terricolous or humid‐forest adapted. We conclude that most Malagasy ant clades first colonized humid forests and subsequently transitioned into dry forests, indicating that previous hypotheses on the evolution of Madagascar's hyperdiverse biota may not apply to ants and other arthropods.     

系统发育多样性与系统发育结构在岛屿植物群落保护中的意义——以蜈支洲岛为例

为探讨系统发育多样性和系统发育结构在岛屿植物群落保护决策制定中的作用,以海南三亚蜈支洲岛被子植物群系为例,分析物种丰富度和系统发育多样性的相关性。结果表明,蜈支洲岛植被可分为10种群系类型,22个样方的物种丰富度与系统发育多样性呈显著正相关,但系统发育多样性与物种丰富度对植物多样性保护优先顺序的指示有差异。森林群系的物种丰富度和系统发育多样性普遍高于灌木和草本群系,4个森林群系样方表现为系统发育结构发散,3个森林群系样方表现为系统发育结构聚集。灌木群系中露兜树(Pandanus tectorius)灌丛和草海桐(Scaevola sericea)灌丛系统发育多样性较高,草本群系中厚藤(Vitex trifolia)灌草丛系统发育多样性较高,灌木和草本群系大多倾向于系统发育结构聚集。距海或人类活动区较近的群系可能受环境过滤的作用,而远离海和人类活动区的群系主要受竞争排斥作用影响。因此,在岛屿植物多样性保护策略制定中应当综合考虑物种和系统发育维度,以及环境、演替阶段及用岛方式等因素的影响。     

Species Diversity and Growth Forms in Tropical American Palm Communities

To advance our understanding of the processes that govern the assembly of palm communities and the local coexistence of numerous palm species, we here synthesize available information in the literature on species diversity and growth-form composition in palm communities across the Americas. American palm communities surveyed had 4–48 (median 16) species in study plots covering 0.09–7.2 ha. Climate, soils, hydrology, and topography are the main factors determining palm community species richness. Tropical lowland terra firme rain forests are the most species-rich whereas forests that are inundated or grow on sandy soils or in areas with seasonal climate have much fewer species. Palm communities in the central-western Amazon and in Central America are significantly richer than the average region and those in the Caribbean significantly poorer in species. As for branching, the 789 species of tropical American palms belong to Corner’s model (solitary, 268 species, 33%), Tomlinsons model (cespitose, 521 species, 66%) and Schoute’s model (dichotomous branching, three species, <1%). We assigned the species to eight different growth forms: (i) Large tall-stemmed Palms (102 spp), (ii) Large-leaved medium–short-stemmed Palms (31 spp), (iii) Medium-sized Palms (95 spp), (iv) Medium/Small Palms with Stout Stem (42 spp), (v) Small Palms (423 spp), (vi) Large acaulescent Palms (28 spp), (vii) Small acaulescent Palms (56 spp), and (viii) Climbing Palms (12 spp). The eight growth forms are differently represented in the palm communities, and the categories Small Palms and Large tall-stemmed Palms dominate the communities both in terms of species richness and in number of individuals.     

Effect of Host Tree Traits on Epiphyte Diversity in Natural and Anthropogenic Habitats in Ecuador

Vascular epiphytes represent a highly diverse element of tropical rain forests, but they depend strongly on the structure and taxonomic composition of their tree communities. For conservation planning, it is therefore critical to understand the effect of host tree characteristics on epiphyte species richness in natural and anthropogenically transformed vegetation. Our study compares the effect of human land‐use on epiphyte diversity based on 220 study plots in a lowland rain forest and an Andean cloud forest in western Ecuador. We evaluate the relevance of host tree size and taxonomic identity for epiphyte species richness in contiguous primary forests, forest fragments, isolated remnant trees (IRTs), and secondary forests. At both study sites, epiphyte diversity was highest in primary forests, and it was lowest on IRTs and in secondary forests. Epiphyte species numbers of forest fragments were significantly reduced compared with the contiguous primary forest at the lowland study site, but not in the cloud forest area. Host tree size was a core predictor among secondary forests, but it had less significance within other habitat types. Taxonomic identity of the host trees also explained up to 61 percent of the variation in epiphyte diversity, especially for IRTs. The structural and taxonomic composition of the tree community in anthropogenically transformed habitat types proved to be fundamental to epiphyte diversity. This highlights the importance of deliberate selection of tree species for reforestation in conservation programs and the possible negative effects of selective logging in primary forests. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Conservation of Vascular Epiphyte Diversity in Shade Cacao Plantations in the Chocó Region of Ecuador

To assess the contributions of rustic shade cacao plantations to vascular epiphyte conservation, we compared epiphyte species richness, abundance, composition, and vertical distributions on shade trees and in the understories of six plantations and adjacent natural forests. On three phorophytes and three 10 × 10 m understory plots in each of the agroforestry plantations and natural forests, 54 and 77 species were observed, respectively. Individual-based rarefaction curves revealed that epiphyte species richness was significantly higher on forest phorophytes than on cacao farm shade trees; detailed analyses showed that the differences were confined to the inner and outer crown zones of the phorophytes. No differences in epiphyte species richness were found in understories. Araceae, Piperaceae, and Pteridophyta were less species-rich in plantations than in forests, while there were no differences in Orchidaceae and Bromeliaceae. Regression analysis revealed that epiphyte species richness on trunks varied with canopy cover, while abundance was more closely related to soil pH, canopy cover, and phorophyte height. For crown epiphytes, phorophyte diameter at breast height (dbh) explained much of the variation in species richness and abundance. There were also pronounced downward shifts in the vertical distributions of epiphyte species in agroforests relative to natural forests. The results confirm that epiphyte diversity, composition, and vertical distributions are useful indicators of human disturbance and showed that while the studied plantations serve to preserve portions of epiphyte diversity in the landscape, their presence does not fully compensate for the loss of forests.     

Influence of Habitat and Climate Variables on Arbuscular Mycorrhizal Fungus Community Distribution,as Revealed by a Case Study of Facultative Plant Epiphytism under Semiarid Conditions

In semiarid Mediterranean ecosystems, epiphytic plant species are practically absent, and only some species of palm trees can support epiphytes growing in their lower crown area, such as Phoenix dactylifera L. (date palm). In this study, we focused on Sonchus tenerrimus L. plants growing as facultative epiphytes in P. dactylifera and its terrestrial forms growing in adjacent soils. Our aim was to determine the possible presence of arbuscular mycorrhizal fungi (AMF) in these peculiar habitats and to relate AMF communities with climatic variations. We investigated the AMF community composition of epiphytic and terrestrial S. tenerrimus plants along a temperature and precipitation gradient across 12 localities. Epiphytic roots were colonized by AMF, as determined by microscopic observation; all of the epiphytic and terrestrial samples analyzed showed AMF sequences from taxa belonging to the phylum Glomeromycota, which were grouped in 30 AMF operational taxonomic units. The AMF community composition was clearly different between epiphytic and terrestrial root samples, and this could be attributable to dispersal constraints and/or the contrasting environmental and ecophysiological conditions prevailing in each habitat. Across sites, the richness and diversity of terrestrial AMF communities was positively correlated with rainfall amount during the most recent growing season. In contrast, there was no significant correlation between climate variables and AMF richness and diversity for epiphytic AMF communities, which suggests that the composition of AMF communities in epiphytic habitats appears to be largely determined by the availability and dispersion of fungal propagules from adjacent terrestrial habitats.     

Lichen epiphyte diversity: A species,community and trait-based review

The forest canopy is fundamentally important in biodiversity conservation and ecosystem function. Cryptogamic epiphytes are dominant tree bole and canopy elements in temperate and boreal forests, though remain neglected by mainstream forest ecology. This review makes ecological information on cryptogamic epiphytes available to a non-specialist audience, to facilitate their integration in forest biodiversity and ecosystem studies more generally. The review focuses specifically on lichen epiphytes, highlighting their diversity and ecosystem role. A principal task is to explore pattern and process in lichen epiphyte diversity – species composition and richness – therefore demonstrating the utility of lichens as an ecological model system. The review examines key themes in previous research. First, the extensive literature used to resolve species response to, and community turnover along environmental/resource gradients, consistent with the habitat niche. Second, the evidence for dispersal-limitation, which may constrain community composition and richness in isolated habitats. Third, these two processes – the habitat niche and dispersal-limitation – are used to explain stand-scale diversity, in addition to the role of neutral effects (habitat area). Fourth, the review moves from a taxonomic (pattern) to a functional (process) perspective, considering evidence for autogenic succession evidenced by competition and/or facilitation, and non-random trends in life-history traits. This functional approach provides a counter-point to an assumption that lichen epiphyte communities are unsaturated and non-competitive, a situation which would allow the long-term accumulation of species richness with temporal continuity. Finally, the review explores landscape-scale impacts on lichen epiphytes, with recommendations for conservation.     

Juxtaposition and Disturbance: Disentangling the Determinants of Lizard Community Structure

Disturbance alters the structure and dynamics of communities. Here, we examined the effects of seasonal flooding on the lizard community structure by comparing two adjacent habitats, a seasonally flooded and a non‐flooded forest, in a Cerrado–Amazon ecotone area, the Cantão State Park, Tocantins state, Brazil. Despite the strong potential impact of seasonal flooding, the only significant environmental difference detected was more termite mounds in non‐flooded forests. Species richness was significantly higher in the non‐flooded forest. Colobosaura modesta, followed by Mabuya frenata and Anolis brasiliensis, were the only species that differed in number of captures between sites. Colobosaura modesta was exclusively found in the non‐flooded forest, while Anolis brasiliensis was the most captured in the flooded forest. Mabuya frenata is indicated as an indicator species in the flooded forest, and Colobosaura modesta in the non‐flooded forest. We found a significant association between lizard abundances and habitat characteristics, with flooding, canopy cover, and logs being the best predictors. A phylogenetic community structure analysis indicated a lack of structure in both lizard assemblages. Overall, we show that seasonal flooding can strongly impact species richness and species occurrence patterns, but not phylogenetic community structure. The Amazon–Cerrado transition is undergoing pronounced transformations due to deforestation and climate change. Despite being species‐poor compared with central areas in Amazon or Cerrado, this ecotone harbors species with important adaptations that could hold the key to persistence in human‐disturbed landscapes or during periods of climate change.     

Birds,Cattle, and Bracken Ferns: Bird Community Responses to a Neotropical Landscape Shaped by Cattle Grazing Activities

Large areas of tropical moist forests have been converted to cattle pastures, generating complex landscapes where different habitats are represented by small patches with an uneven spatial distribution. Here, we describe how bird communities respond to the different elements present in a livestock landscape that was originally dominated by tropical moist forest. We surveyed six habitats: open pastures, pastures with shrubs, early‐ and middle‐secondary forests, mature forest, and pastures invaded by bracken ferns (Pteridium aquilinum). Bird diversity was high in secondary and mature forests, and low in fern‐invaded sites and open pastures. Fern‐dominated sites had the lowest bird species richness, and trophic guild diversity of all habitats. Habitat structure affected both bird species richness and densities in similar ways. Tree species richness was the habitat attribute that had a bigger positive effect on bird species richness. Bird community structure varied among sampled habitats, separating habitats in two major groups (forests and pastures). Our data indicate that bracken fern‐invaded pastures were the worst habitat condition for avian communities. To increase bird diversity, we recommend to eliminate or manage bracken fern and to increase shrub and tree cover in open pastures to provide food resources and shelter for birds. Finally, we encourage the maintenance of secondary and mature forest remnants as a strategy to conserve resident birds within a landscape dominated by livestock activities.     

The unseen invaders: introduced earthworms as drivers of change in plant communities in North American forests (a meta‐analysis)

Globally, biological invasions can have strong impacts on biodiversity as well as ecosystem functioning. While less conspicuous than introduced aboveground organisms, introduced belowground organisms may have similarly strong effects. Here, we synthesize for the first time the impacts of introduced earthworms on plant diversity and community composition in North American forests. We conducted a meta‐analysis using a total of 645 observations to quantify mean effect sizes of associations between introduced earthworm communities and plant diversity, cover of plant functional groups, and cover of native and non‐native plants. We found that plant diversity significantly declined with increasing richness of introduced earthworm ecological groups. While plant species richness or evenness did not change with earthworm invasion, our results indicate clear changes in plant community composition: cover of graminoids and non‐native plant species significantly increased, and cover of native plant species (of all functional groups) tended to decrease, with increasing earthworm biomass. Overall, these findings support the hypothesis that introduced earthworms facilitate particular plant species adapted to the abiotic conditions of earthworm‐invaded forests. Further, our study provides evidence that introduced earthworms are associated with declines in plant diversity in North American forests. Changing plant functional composition in these forests may have long‐lasting effects on ecosystem functioning.     

High Bird Species Diversity in Structurally Heterogeneous Farmland in Western Kenya

Tropical ecosystems are globally important for bird diversity. In many tropical regions, land‐use intensification has caused conversion of natural forests into human‐modified habitats, such as secondary forests and heterogeneous agricultural landscapes. Despite previous research, the distribution of bird communities in these forest‐farmland mosaics is not well understood. To achieve a comprehensive understanding of bird diversity and community turnover in a human‐modified Kenyan landscape, we recorded bird communities at 20 sites covering the complete habitat gradient from forest (near natural forest, secondary forest) to farmland (subsistence farmland, sugarcane plantation) using point counts and distance sampling. Bird density and species richness were on average higher in farmland than in forest habitats. Within forest and farmland, bird density and species richness increased with vegetation structural diversity, i.e., were higher in near natural than in secondary forest and in subsistence farmland than in sugarcane plantations. Bird communities in forest and farmland habitats were very distinct and very few forest specialists occurred in farmland habitats. Moreover, insectivorous bird species declined in farmland habitats whereas carnivores and herbivores increased. Our study confirms that tropical farmlands can hardly accommodate forest specialist species. Contrary to most previous studies, our findings show that structurally rich tropical farmlands hold a surprisingly rich and distinct bird community that is threatened by conversion of subsistence farmland into sugarcane plantations. We conclude that conservation strategies in the tropics must go beyond rain forest protection and should integrate structurally heterogeneous agroecosystems into conservation plans that aim at maintaining the diverse bird communities of tropical forest‐farmland mosaics.     

Diversity and biogeography of vascular epiphytes in Western Amazonia, Yasuní, Ecuador

Aim Although vascular epiphytes are important components of species richness and complexity of Neotropical forests, vascular epiphytes are under‐represented in large scale biogeographical analyses. We studied the diversity, biogeography and floristic relationships of the epiphytic flora of the Yasuní region (Western Amazonia) in a Neotropical context, with special emphasis on the influence of the Andean flora on floristic composition and diversity of surrounding lowland forests. Location Western Amazonian lowland rainforest, Tiputini Biodiversity Station (0°38′ S 76°09′ W, 230 m a.s.l., 650 ha), Yasuní National Park, Ecuador. Methods We compared the vascular epiphyte flora of Yasuní with 16 published Neotropical epiphyte inventories. Secondly, based on a floristic database with records of more than 70,000 specimens of vascular epiphytes from the Neotropics the elevational composition of eight selected inventories was analysed in detail. Results The vascular epiphyte flora of Yasuní is characterized by a very high species richness (313 spp.). A moderate portion of species is endemic to the Upper Napo region (c. 10%). However, this figure is much higher than previous analyses primarily based on woody species suggested. Geographical ranges of these species match with a proposed Pleistocene forest refuge. Compared with Northern and Central Amazonian sites, Western Amazonian epiphyte communities are characterized by a higher portion of montane and submontane species. Species richness of vascular epiphytes at the sites was correlated with the amount of rainfall, which is negatively correlated with the number of dry months. Main conclusion Recent and historic patterns of rainfall are the driving forces behind diversity and floristic composition of vascular epiphytes in Western Amazonia: high annual rainfall in combination with low seasonality provides suitable conditions to harbour high species richness. The proximity to the Andes, the most important centre of speciation for most Neotropical epiphytic taxa, in combination with the climatic setting has allowed a continuous supply of species richness to the region. At least for epiphytes, the borderline between the Andean and Amazonian flora is much hazier than previously thought. Moreover, the comparatively moist climate in Western Amazonia during the Pleistocene has probably led to fewer extinctions and/or more speciation than in more affected surrounding lowlands.     

Regional vs local drivers of phylogenetic and species diversity in stream fish communities

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Processes involved in species saturation of ground‐dwelling ant communities (Hymenoptera,Formicidae)

The species saturation hypothesis in ground‐dwelling ant communities was tested, the relationship between local and regional species richness was studied and the possible processes involved in this relationship were evaluated in the present paper. To describe the relationship between local and regional species richness, the ground‐dwelling ant fauna of 10 forest remnants was sampled, using 10 1 m² quadrats in each remnant. The ants were extracted from the litter by using Winkler sacs. Using regression analyses, an asymptotic pattern between local and regional species richness was detected. This saturated pattern may be related to three processes: (i) high interspecific competition; (ii) habitat species specialization; or (iii) stochastic equilibrium. It is concluded that non‐interactive processes, such as stochastic equilibrium and habitat specialization may act as factors regulating species richness in this community. The predominance of locally restricted species, in all sampled remnants, seems to indicate the occurrence of a high degree of habitat specialization by the ant species. This result is evidence for the hypothesis that community saturation has been generated by non‐interactive processes. Although ants are frequently described as highly interactive, it is possible that interspecific competition is not important in the structuring of ground‐dwelling ant communities.