Richness Of Vascular Epiphytes Research Articles

Linking different resources to recognize vascular epiphyte richness and distribution in a mountain system in southeastern Mexico

Mesoamerican mountains are important centers of endemism and diversity of epiphytes. The Sierra Madre of Chiapas in southeastern Mexico is a mountainous region of great ecological interest due to its high biological richness. We present the first checklist of epiphytes for this region based on a compilation of various information sources. In addition, we determined the conservation status for each species based on the Mexican Official Standard (NOM-059-SEMARNAT-2010), endemism based on geopolitical boundaries, spatial completeness with inventory completeness index, richness distribution with range maps, and the relationship between climatic variables (temperature and rainfall) with species richness using generalized additive models. Our dataset includes 9,799 records collected between 1896 and 2017. Our checklist includes 708 epiphytes within 160 genera and 26 families; the most species-rich family was Orchidaceae (355 species), followed by Bromeliaceae (82) and Polypodiaceae (79). There were 74 species within a category of risk and 59 species considered endemic. Completeness of epiphyte richness suggests that sampling is still largely incomplete, particularly in the lower parts of the mountain system. Species and family range maps show the highest richness at high elevations, while geographically richness increases towards the southeast. Epiphyte richness increases with increased rainfall, although a unimodal pattern was observed along the temperature gradient with a species richness peak between 16 and 20 C°. The Sierra Madre of Chiapas forms a refuge to more than 40% of all epiphytes reported for Mexico and its existing network of protected areas overlaps with the greatest epiphyte richness.

Successional forests stages influence the composition and diversity of vascular epiphytes communities from Andean Montane Forests

• Communities of late succession present greater richness and density of epiphytes. • Elevation and precipitation explained the composition of the epiphytes. • Tree crown height explains the richness and density of vascular epiphytes. • Late-successional trees recorded higher vascular epiphyte richness and density. • Preferential and indifferent epiphytes are on indicator trees of successional stages. Vascular epiphytes layer is an important component of the forests; to understand their contribution to the ecosystem, it is imperative to assess the factors which affect their distribution, composition, and diversity. We studied the ecology of vascular epiphytes in Andean Mountain Forests of different successional stages, in a scenario that allowed us to determine some relationships between the composition of the epiphyte community and the tree communities, along with environmental and historic land use gradients. The research design included the sampling of 22 plots with a total of 3248 trees, including tree ferns with DBH ≥10 cm. Each tree was measured and identified to species level and was divided into three vertical strata, recording the diversity and frequency of vascular epiphytes present in each stratum. In these forests, we evaluated the variation of the composition, richness, and density of vascular epiphytes using the ADONIS analysis, evaluating the influence of two factors: the successional stage of the forest community and the tree vertical strata. We then explored which predictor variables, such as climate, spatial correlation, and host tree characteristics, explained the variation in epiphytes, using linear and variance partitioning models. In addition, we determined the preference of epiphytes for host tree species, using indicator tree species of successional stages. For each host tree species, we identified associated vascular epiphytes and their indicator species level was analyzed to determine epiphyte-host species with traits of specialist species. We found that epiphyte species richness and density were significantly higher in older forest communities. Epiphyte density was higher in the upper canopy of the hosts. The climate affected the composition of the epiphytes, while precipitation, elevation, crown height, and basal area significantly explained epiphyte richness and density. Preferential and indifferent epiphytes on indicator host species of intermediate and late succession suggest the existence of complex associations. The age of the forest succession, climatic factors, and certain characteristics of the host species have a major impact on the ecology of vascular epiphytes.

Edge effect on vascular epiphytes in a subtropical Atlantic Forest fragment

Epiphytes are efficient indicators of environmental quality. The Atlantic Forest is a hotspot for epiphyte richness; however, it is experiencing one of the highest rates of degradation, exposing epiphytes to edge effects. This study aimed to evaluate the floristic composition and richness of vascular epiphytes and their relationship with phorophyte features and microenvironmental variables at the edge and in the interior of a subtropical Atlantic Forest fragment in Brazil. Twenty-five trees were analyzed, respectively, at the edge and in the interior of the fragment. Height and diameter of phorophytes, temperature, relative air humidity, photosynthetically active radiation and canopy opening were measured. A total of 41 epiphytic species were recorded, 40 occurring in the interior and 23 at the edge. Orchidaceae, Bromeliaceae, and Polypodiaceae were the richest families, representing 75% of all species. The average number of species per tree in the interior was twice that for the edge. Pleopeltis pleopeltifolia, Microgramma squamulosa, M. vacciniifolia and Rhipsalis teres concentrated great biomass in both environments, with twice as much in the interior. Epiphyte richness and biomass was lower on thinner trees with more open canopies at the edge. Our results indicate that the forest interior is more beneficial for epiphytes, which are sensitive to environmental changes caused by the edge effect. The contrast between the epiphytic communities of the edge and the interior reveals the need to increase richness and abundance of native trees and prevent cattle grazing, the planting of exotic species and more human settlements in the habitat matrix.

Distribución de epífitas vasculares sobre cuatro especies arbóreas en un bosque xerofítico del Chaco Húmedo, Argentina

Fil: Alvarez Arnesi, Eugenio. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina

Elevational and phytophysiognomic gradients influence the epiphytic community in a cloud forest of the Atlantic phytogeographic domain

Biological communities vary in composition and structure according to changes in the environment, such as in mountainous areas where temperature and moisture change with elevation, leading to gradual changes in vegetation. The altitudinal gradient is considered mirrors of the latitudinal gradient, although the richness peak can occur in the middle of the gradient, due to the greater total availability of moisture and/or due to the mid-domain effect. We aimed to test whether there was an intermediary peak in the richness of vascular epiphytes in two environmental gradients represented by elevation (around 1200–1700 m.s.m.) and by three subphysiognomies of cloud dwarf-forest in the Brazilian Atlantic Forest. For this purpose, 24 plots of 10 × 20 m were established and divided into eight sets in each subphysiognomy, along the altitudinal gradient. The community structure was analyzed by calculating the Shannon diversity index (H′), the Pielou uniformity index (J), and taxonomic diversity indices (Δ+ and Λ+). In total, 568 phorophytes were sampled, resulting in 3771 occurrences of epiphytes, distributed in 146 species. The diversity was different between the physiognomies of dwarf-forest and along the elevation gradient, and was specifically greater with higher elevation. The value of Δ+ was lower than expected in one plot, and represented a potential human impact. The obtained results highlight the diversity of this region and the important contribution of the epiphytes, as well as the sensitivity of epiphytic communities to the different vegetation physiognomies and the climatic variations caused by the elevation.

Diversity and composition of vascular epiphytic plant on tree ferns (Cyathea spp.) at Cibodas Botanic Garden, West Java

Nasution T, Junaedi DI. 2017. Diversity and composition of vascular epiphytic plant on tree ferns (Cyathea spp.) at Cibodas Botanic Garden, West Java. Pros Sem Nas Masy Biodiv Indon 3: 453-460. Tree ferns are important horticultural commodities for ornamental plant and planting medium. These ferns are also ecologically important for the habitat of vascular epiphytes. The information on the relationship of tree ferns and vascular epiphytes is still limited, so that it is important to be studied for supporting its management in Cibodas Botanic Garden. This study aimed to study the diversity and composition of vascular epiphytes on wild tree ferns in Cibodas Botanic Garden. The census of vascular epiphytes on 30 individuals of Cyathea contaminans and 30 individuals of Cyathea junghuhniana had been conducted. About 3,034 individuals of vascular epiphytes were recorded belongs to 138 species and 51 families. The species richness of vascular epiphytes on C. contaminans was 95 species and higher than C. junghuhniana (86 species). The abundance of vascular epiphytes on C. contaminans was 1,820 individuals and higher than C. junghuhniana (1,214 individuals). Shannon-Wiener index of vascular epiphytes on C. contaminans was 3.13 and lower than C. junghuhniana (3.67). The species composition of both hosts comprised 108 species of spermatophytes and 31 species of ferns. The highest species richness on C. contaminans was Polypodiaceae, followed by Poaceae and Orchidaceae, whereas Moraceae, Polypodiaceae and Urticaceae were the highest species richness on C. junghuhniana. The vascular epiphytes of tree ferns in Cibodas Botanic Garden had a relatively high diversity. The management of tree ferns would support the conservation of vascular epiphytes in Cibodas Botanic Garden.

Ecosystem engineering by Fascicularia bicolor in the canopy of the South-American temperate rainforest

Ecosystem engineers are organisms that modify habitats and resource flows, they therefore could have a disproportionate impact on the diversity of ecological communities. Evidence suggests that trash basket epiphytes (TBE) can be considered ecosystem engineers of forest canopies, due to their relationship with arboreal soil availability and treetop communities. Here we evaluated whether the TBE Fascicularia bicolor (Bromeliaceae), modulates temperature and humidity in the forest canopy. We also investigated if this bromeliad is related with greater arboreal soil accumulation and is associated to higher diversity of other epiphytic plants and invertebrates in the canopy of the South-American temperate rainforest (SATR), in Chile. We measured temperature and humidity in ten trees within the forest before and after the experimental addition of F. bicolor. We also related the presence of F. bicolor with occurrence of soil macro-fauna and other canopy dwelling plants in a comparative field survey.Temperature variability in the canopy was reduced by F. bicolor. Soil availability was higher in sites with mats of F. bicolor. The richness of vascular epiphytes was unaltered by the presence of F. bicolor, but species composition differed between sites with and without mats on each tree. At the group level, the cover of lichens and bryophytes was greater in sites without F. bicolor, while vascular epiphytes show a larger cover in sites with F. bicolor. The species richness of invertebrates increased in treetop sites colonized by F. bicolor but species composition was not different from soil in branch bifurcations. Our results show that F. bicolor must be considered in forest management practices to determine which trees must be logged, in order to preserve the viability of populations of these key organisms in the treetops of South-American temperate rainforests.

Vascular epiphytes on Pseudobombax (Malvaceae) in rocky outcrops (inselbergs) in Brazilian Atlantic Rainforest: basis for conservation of a threatened ecosystem

Abstract This study evaluated the richness of vascular epiphytes on Pseudobombax sp. nov. in three inselbergs in the Atlantic Forest Domain in state of Espírito Santo and evaluated the floristic similarity between the areas. We sampled 111 phorophytes in three regions in the southern of Espírito Santo state and identified 151 species, 77 genera and 21 families of vascular epiphytes, of which the families Orchidaceae and Bromeliaceae showed the highest richness. Non-parametric estimators (Chao 2, Jackknife 1) indicate that 90 and 95% of species richness of epiphytes was recorded. The most diversified ecological category was the characteristic holoepiphytes. The ratio of the number of epiphytes and number of phorophytes sampled in a montane inselberg, in this study, was greater than the richness of vascular epiphytes found in the rocky outcrops of quartzite, and, in general, different types of Atlantic Domain forests, but smaller in richness for some Dense Ombrophilous Forests of southern Brazil. The three inselberg areas had distinct floras. The high richness, the endemism found, and the number of endangered species of epiphytes demonstrate the important role of Pseudobombax sp. nov., because of its architecture and size, in the maintenance of biodiversity on the inselbergs in southeastern Brazil.

Assessing the completeness of inventories of vascular epiphytes and climbing plants in Chilean swamp forest remnants

ABSTRACTPlant species inventories provide the foundation for more complex analytical studies and are the basis of monitoring programmes; however, if they are to provide reliable information in the long term, their level of completeness needs to be estimated. This work assessed the completeness of inventories of climbing plants and vascular epiphytes in swamp forest remnants of the Araucanía region of south-central Chile, which has been severely disturbed by agroforestry expansion. We sampled 30 sites using transects, with observations from ground level to a height of 2.3 m up the trees. To assess the potential existence of unrecorded species we drew rarefaction curves based on sample trees and extrapolated them towards one of the most intensely sampled sites. We then calculated the asymptotic species richness with the Chao 1 estimator. The results showed: (1) a total richness of 16 species of epiphytes and 17 species of climbing plants; (2) the rarefaction curve differentiated only two categories of sampling effort (‘rich’ and ‘poor’ sites) as a result of the substantial overlap of the confidence limits at 95%; and (3) the maximum richness estimated by Chao 1 was similar to the richness observed in all the sites. We conclude that greater sampling effort is required to obtain tighter statistical confidence levels in the rarefaction curve; however, from a biological point of view, the sampling effort achieved adequate representation of the species richness at all the sites. Total richness of vascular epiphytes and climbing plants was only slightly below values reported for much larger areas of better-conserved forest in south-central Chile and adjacent areas of Argentina. Finally, we found evidence that forest fragmentation has more severe effects on species richness of vascular epiphytes than on that of climbing plants.

Distribution of vascular epiphytes along a tropical elevational gradient: disentangling abiotic and biotic determinants

Epiphytic vascular plants are common species in humid tropical forests. Epiphytes are influenced by abiotic and biotic variables, but little is known about the relative importance of direct and indirect effects on epiphyte distribution. We surveyed 70 transects (10 m × 50 m) along an elevation gradient (180 m–1521 m) and sampled all vascular epiphytes and trees in a typical tropical forest on Hainan Island, south China. The direct and indirect effects of abiotic factors (climatic and edaphic) and tree community characteristics on epiphytes species diversity were examined. The abundance and richness of vascular epiphytes generally showed a unimodal curve with elevation and reached maximum value at ca. 1300 m. The species composition in transects from high elevation (above 1200 m) showed a more similar assemblage. Climate explained the most variation in epiphytes species diversity followed by tree community characteristics and soil features. Overall, climate (relative humidity) and tree community characteristics (tree size represented by basal area) had the strongest direct effects on epiphyte diversity while soil variables (soil water content and available phosphorus) mainly had indirect effects. Our study suggests that air humidity is the most important abiotic while stand basal area is the most important biotic determinants of epiphyte diversity along the tropical elevational gradient.

Branchfall as a Demographic Filter for Epiphyte Communities: Lessons from Forest Floor-Based Sampling.

Local variation in the abundance and richness of vascular epiphytes is often attributed to environmental characteristics such as substrate and microclimate. Less is known, however, about the impacts of tree and branch turnover on epiphyte communities. To address this issue, we surveyed branches and epiphytes found on the forest floor in 96 transects in two forests (Atlantic rainforest in Brazil and Caribbean rainforest in Panama). In the Brazilian forest, we additionally distinguished between edge and core study sites. We quantified branch abundance, epiphyte abundance, richness and proportion of adults to investigate the trends of these variables over branch diameter. Branches <2 cm in diameter comprised >90% of all branches on the forest floor. Abundance and richness of fallen epiphytes per transect were highest in the Brazilian core transects and lowest in the Panamanian transects. The majority of epiphytes on the floor (c. 65%) were found attached to branches. At all three study sites, branch abundance and branch diameter were negatively correlated, whereas epiphyte abundance and richness per branch, as well as the proportion of adults were positively correlated with branch diameter. The relationship between branch diameter and absolute epiphyte abundance or richness differed between study sites, which might be explained by differences in forest structure and dynamics. In the Panamanian forest, epiphytes had been previously inventoried, allowing an evaluation of our surveying method by comparing canopy and forest floor samplings. Individuals found on the forest floor corresponded to 13% of all individuals on branches <10 cm in diameter (including crowns), with abundance, richness and composition trends on forest floor reflecting canopy trends. We argue that forest floor surveys provide useful floristic and, most notably, demographic information particularly on epiphytes occurring on the thinnest branches, which are least accessible. Here, branchfall acts as an important demographic filter structuring epiphyte communities.

Vascular epiphytes of the Atlantic Forest in the Sinos River basin, state of Rio Grande do Sul, Brazil: richness, floristic composition and community structure.

The Atlantic Forest, which has a vast epiphytic richness, is a priority area for preservation, listed as one of the five most important world hotspots. Vascular epiphyte richness, composition and community structure were studied in two fragments, one of the ombrophilous (29º43'42"S and 50º22'00"W) and the other of the seasonal (29º40'54"S and 51º06'56"W) forest, both belonging to the Atlantic Forest biome in the Sinos River basin, Rio Grande do Sul, Brazil. In each fragment, 40 trees, divided into four ecological zones, were analyzed. In each zone, the occurrence of the species was recorded, and the importance value of each species was calculated according to the frequency of phorophytes and intervals, and cover scores. The Shannon index was calculated for the two communities. In the fragment of the ombrophilous forest (F1), 30 epiphytic species were recorded, and in the seasonal forest (F2), 25. The highest importance value was found for Microgramma squamulosa (Kaulf.) de la Sota in both fragments. The diversity indexes for F1 (H'=2.72) and F2 (H'=2.55) were similar and reflected the subtropical location of the areas. The decrease in mean richness in both fragments in zone 3 (internal crown) to zone 4 (external crown) may be associated with time and space availability for epiphyte occupation and microclimate variations. Exclusive species were found in the areas, which suggest that a greater number of preserved fragments may result in a greater number of preserved epiphytic species in the Sinos River basin.

Epiphyte assemblages respond to host life-form independently of variation in microclimate in lower montane cloud forest in Panama

Abstract:We investigated the effects of host tree on epiphyte diversity, controlling for microclimate. We measured the light profiles of the lower trunks of 20 individuals, each from three host groups (tree ferns, dicots, palms) occupying the understorey in a tropical montane forest in Panama. The per cent cover and species richness of vascular and non-vascular epiphytes were surveyed on the lower trunks of each understorey host. Light varied considerably between trees (5–21% total transmitted light) but mean light level did not vary between types of host. Light was not significant as a covariate with host in any model. Tree ferns had higher covers than dicots and palms of filmy ferns (15%, 0.02% and 0.2%), other ferns (7%, 0% and 0.5%) and other vascular epiphytes (16%, 3% and 3.4%), and greater species richness of vascular epiphytes (filmy ferns: 3, 0.4 and 0.5; other ferns: 2, 0.2 and 0; other vascular: 7, 2 and 2). Dicots had a higher cover of liverworts (53%) than palms (18%) and tree ferns (27%). Palms and tree ferns were the compositional extremes. We conclude that the differences in species composition and cover between the three host groups relate better to physical differences between hosts than differences in light climate.

Regional and Elevational Patterns in Vascular Epiphyte Richness on an East Asian Island

AbstractThe distribution of species on mountains has been related to various predictor variables, especially temperature. Thermal specialization—presumed to be more pronounced on tropical mountains than on temperate mountains—accounts for the elevational pattern of species richness and varies between organisms and geographic areas. In this study, the elevational and regional distribution patterns of 331 epiphyte species in Taiwan were explored using 39,084 botanic collections, mostly from herbaria. Species richness showed a peak in elevation at 500–1500 m. This peak could not be explained by a null model, the mid‐domain effect, suggesting that environmental variables accounted mostly for the distribution of species on the mountains. Next, species distributions were modeled to assess epiphyte regional and elevational distribution patterns. The model results not only corroborated the position of the mid‐elevation peak in richness, but also identified two mountain areas on the island with exceptionally high species richness. These areas of high epiphyte diversity coincide with areas of high rainfall in relation to the direction of the prevailing winds. Moreover, a subsequent exploratory ordination analysis showed a varied thermal preference between epiphyte subcategories (hemiepiphytes, dicotyledons, orchids, and ferns). In contrast to predictions by the elevational Rapoport's rule, ordination analysis also showed that the degree of thermal specialization increased with elevation, suggesting that highland species may be especially vulnerable to global warming.

&lt;b&gt;Relações de epífitos vasculares com fatores ambientais nas florestas do Rio Tibagi, Paraná, Brasil&lt;/b&gt;&lt;br&gt;doi: 10.5007/2175-7925.2010v23n3p37

The aim of this work was to evaluate the relationships of vascular epiphyte richness with climatic, geomorphologic, pedologic and forest structural factors, that change along the Tibagi River. The floristic turnover of the 188 registered species was high, indicating the singularity and importance of the communities to the conservation of epiphytes in the river basin. The similarity was greater between geographically closer areas, which made possible the creation of three groups of epiphytic communities distributed along the river. The greatest richness of epiphytes was registered in the medium Tibagi, where the phytogeographic units are in liaison and the forests present the best conservation status. The increase of epiphytic richness is only significantly and positively related to the maximal diameter of trees, an important environmental factor of the enlargement of alpha diversity. The beta diversity results, probably, from environmental heterogeneity which is principally represented by distinctive geomorphologic patterns and climatic conditions between study areas and different environmental regions of the river.

A protocol for sampling vascular epiphyte richness and abundance

Abstract:The sampling of epiphytes is fraught with methodological difficulties. We present a protocol to sample and analyse vascular epiphyte richness and abundance in forests of different structure (SVERA). Epiphyte abundance is estimated as biomass by recording the number of plant components in a range of size cohorts. Epiphyte species biomass is estimated on 35 sample-trees, evenly distributed over six trunk diameter-size cohorts (10 trees with dbh &gt; 30 cm). Tree height, dbh and number of forks (diameter &gt; 5 cm) yield a dimensionless estimate of the size of the tree. Epiphyte dry weight and species richness between forests is compared with ANCOVA that controls for tree size. SChao1is used as an estimate of the total number of species at the sites. The relative dependence of the distribution of the epiphyte communities on environmental and spatial variables may be assessed using multivariate analysis and Mantel test. In a case study, we compared epiphyte vegetation of six Mexican oak forests and one Colombian oak forest at similar elevation. We found a strongly significant positive correlation between tree size and epiphyte richness or biomass at all sites. In forests with a higher diversity of host trees, more trees must be sampled. Epiphyte biomass at the Colombian site was lower than in any of the Mexican sites; without correction for tree size no significant differences in terms of epiphyte biomass could be detected. The occurrence of spatial dependence, at both the landscape level and at the tree level, shows that the inclusion of spatial descriptors in SVERA is justified.

Distribution and species richness of vascular epiphytes in an old-growth beech forest

Distribution and species richness of vascular epiphytes in an old-growth beech forest

Diversity patterns of vascular epiphytes along an elevational gradient in the Andes

AbstractAim To document the elevational pattern of epiphyte species richness at the local scale in the tropical Andes with a consistent methodology.Location The northern Bolivian Andes at 350–4000 m above sea level.Methods We surveyed epiphytic vascular plant assemblages in humid forests in (a) single trees located in (b) 90 subplots of 400 m2 each located in (c) 14 plots of 1 ha each. The plots were separated by 100–800 m along the elevational gradient.Results We recorded about 800 epiphyte species in total, with up to 83 species found on a single tree. Species richness peaked at c. 1500 m and declined by c. 65% to 350 m and by c. 99% to 4000 m, while forests on mountain ridges had richness values lowered by c. 30% relative to slope forests at the same elevations. The hump‐shaped richness pattern differed from a null‐model of random species distribution within a bounded domain (the mid‐domain effect) as well as from the pattern of mean annual precipitation by a shift of the diversity peak to lower elevations and by a more pronounced decline of species richness at higher elevations. With the exception of Araceae, which declined almost monotonically, all epiphyte taxa showed hump‐shaped curves, albeit with slightly differing shapes. Orchids and pteridophytes were the most species‐rich epiphytic taxa, but their relative contributions shifted with elevation from a predominance of orchids at low elevations to purely fern‐dominated epiphyte assemblages at 4000 m. Within the pteridophytes, the polygrammoid clade was conspicuously overrepresented in dry or cold environments. Orchids, various small groups (Cyclanthaceae, Ericaceae, Melastomataceae, etc.), and Bromeliaceae (below 1000 m) were mostly restricted to the forest canopy, while Araceae and Pteridophyta were well represented in the forest understorey.Main conclusions Our study confirms the hump‐shaped elevational pattern of vascular epiphyte richness, but the causes of this are still poorly understood. We hypothesize that the decline of richness at high elevations is a result of low temperatures, but the mechanism involved is unknown. The taxon‐specific patterns suggest that some taxa have a phylogenetically determined propensity for survival under extreme conditions (low temperatures, low humidity, and low light levels in the forest interior). The three spatial sampling scales show some different patterns, highlighting the influence of the sampling methodology.

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

AbstractAim 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.

Patterns in species richness and distribution of vascular epiphytes in Chiapas, Mexico

AbstractAim We aim to assess regional patterns in the distribution and species richness of vascular epiphytes with an emphasis on forests that differ in altitude and the amount of rainfall.Location Tropical America, in particularly the 75,000 km2 large state of Chiapas in southern Mexico at 14.5–18.0°N. Chiapas is diverse in habitats with forests from sea‐level to the tree‐line at c. 3800 m altitude and with annual amounts of rainfall ranging from 800 to over 5000 mm. It is also one of the botanical best‐explored regions in the tropics.Methods First we give an overview of epiphyte inventories to date. Such epiphyte surveys were mostly carried out on the basis of surface area or individual trees and we discuss their problematic comparison. Applying a different methodological approach, we then used 12,276 unique vascular epiphyte plant collections from Chiapas that are deposited in various botanical collections. The locality data were georeferenced and compiled in a relational data base that was analysed using a geographical information system. To compare the number of species between inventories that differed in the numbers of records, we estimated the total richness, SChao, at each.Results We recorded 1173 vascular epiphyte species in thirty‐nine families (twenty‐three angiosperms), comprising c. 14% of all confirmed plant species in the state. About half of all species were orchids (568). Ferns and bromeliads were the next species‐rich groups with 244 and 101 species, respectively. Most species were found in the Montane Rain Forest and in the Central Plateau. Trees of different forest formations, rainfall regimes, altitudes and physiographical regions supported a characteristic epiphyte flora.Main conclusions We were able to confirm the presumed presence of a belt of high diversity at mid‐elevations (500–2000 m) in neotropical mountains. In contrast to predictions, however, we observed a decrease in diversity when the annual amount of rainfall exceeded 2500 mm. The decrease is attributed to wind‐dispersed orchids, bromeliads and Pteridophyta that may find establishment problematical under frequent downpours. In the wet but seasonal forests in Chiapas, this decrease is not compensated by plants in the animal‐dispersed Araceae that are abundant elsewhere. We presume that in addition to the annual amount of rainfall, its distribution in time determines the composition of the epiphyte community.