Epiphytic Richness Research Articles

Exploring Co-Occurrence Patterns to Understand Epiphyte-Liana Interactions.

Although epiphytes and lianas share the same habitat, most research has treated these two groups independently. This study aimed to evaluate the co-occurrence of vascular epiphytes and lianas in the subtropical montane forests of northwestern Argentina. We recorded epiphyte cover and liana basal area on trees ≥ 10-cm-dbh in 120 20 × 20 m plots in the Sierra de San Javier (Tucumán, Argentina). Of the 2111 trees sampled, 727 (34%) hosted lianas, and 1095 (52%) hosted epiphytes. Both plant groups were found together on 20% of the sampled trees. The species richness of lianas and epiphytes, along with liana basal area and epiphyte cover, increased with tree diameter and reached higher values in mature forests compared to successional forests. Both groups colonized the same canopy tree species with larger diameters, whereas smaller trees were typically colonized by either lianas or epiphytes, but not both. Epiphyte species were more likely to co-occur with liana species with specialized climbing mechanisms. Tree size and forest type (mature vs. successional) emerged as key factors influencing the co-occurrence of lianas and epiphytes in these forests. This study establishes a basis for future research into the interactions between lianas and epiphytes, seeking to determine whether they co-occur in the same habitats.

Endemism Centres of the Five Richest Vascular Epiphyte Families in the Neotropics

ABSTRACTAimEndemic species, characterised by limited geographic ranges, face a high risk of extinction. The neotropical region harbours diverse ecosystems and a substantial number of endemic species, thus identifying areas of high endemism is crucial for protecting unique and threatened species and ecosystems. Vascular epiphytes—nonparasitic plants that grow on other plants without contact with the soil—exhibit remarkable diversity in the neotropics, with 63% of the global total of ca. 31,000 epiphyte species found in this region. This study aims to describe the endemism centres for the five most species‐rich families of vascular epiphytes.LocationNeotropics.TaxonTracheophyta.MethodsWe gathered information from free‐access web repositories, specific epiphytic plant databases and scientific and grey literature on epiphyte species of the families Araceae, Bromeliaceae, Orchidaceae, Piperaceae and Polypodiaceae within the neotropical realm as defined by Morrone et al. (2022). Geographical ranges were calculated using minimum convex polygons for 11,446 species, accounting for about 70% of all epiphyte species in the neotropics. Narrow endemic species were defined as those within the first quartile of the density distribution of geographic range sizes within each family and we identified endemism centres for epiphyte species of the five families.ResultsOur study identified endemism centres for vascular epiphyte species in several biogeographic provinces, including Paramo, Cauca, Guatuso‐Talamanca, Atlantic, Yungas and Puntarenas‐Chiriqui. Orchidaceae, accounting for most of the analysed species (71%), drove the overall distribution pattern; however, endemism patterns varied among families.Main ConclusionsRegions with high epiphyte richness exhibited a greater proportion of endemic species, though the composition of epiphyte species varied considerably among regions. The endemism centres identified in this study could be prioritised as conserved and protected areas.

Diverging Elevational Patterns of Tree vs. Epiphyte Species Density, Beta Diversity, and Biomass in a Tropical Dry Forest.

There is evidence to suggest that vascular epiphytes experience low competition for resources (light, water, and nutrients) compared to terrestrial plants. We tested the hypothesis that low resource competition may lead to higher nestedness among vascular epiphyte assemblages compared to trees. We studied the species composition and biomass of epiphytes and trees along an elevation gradient in a tropical dry forest in SW Ecuador. Both life-forms were inventoried on 25 plots of 400 m2 across five elevation levels (550-1250 m). Tree species density and total species richness increased with elevation, whereas basal area and biomass did not show significant trends. Epiphyte species density and richness both increased strongly with elevation, in parallel to biomass. Plot-level compositional changes were similarly strong for both life-forms. We attribute elevational increases in the species richness of trees and epiphytes to increasing humidity, i.e., more mesic growth conditions. We attribute the more pronounced elevational increase in epiphyte biomass, species density, and richness-the latter coupled with a higher degree of nestedness-to the greater moisture dependency of epiphytes and relatively low direct competition for resources. Our study provides a first comparison of elevational trends in epiphyte and tree diversity and biomass for a tropical dry forest.

Combining critical transition indicator to compare the stable structure of epiphyte–host networks

Networks have been widely used to describe a range of biotic interactions in ecosystems; topological indicators of ecological networks provide systematic way to characterize patterns of different interacting systems. However, it is hampered by sampling bias and detecting the true structures to compare the stability of ecological communities. In this context, we aimed to employ innovative approach of identifying critical transition indicator to compare stable network structure by simulating dynamics of network assembly. Four epiphyte–host networks were compiled, including two groups (epiphytic bryophyte and epiphytic vascular plant) of tropical rainforest (TRF) and subtropical forest (STF). The dynamics of three structure indictors, i.e. connectance, nestedness and modularity were simulated to explore what changes occurred as sampling effort increases. The critical transition indicator was detected to compare the structure of four networks at a stable state. Meanwhile, the variation dynamics of host size and epiphyte richness were fitted to analyze the underlying processes shaping the stable network structure. Using a dynamic simulation, the network structures showed the critical transition to stable state when sampling size approximated 30 hosts for epiphytic bryophytes and 100 hosts for epiphytic vascular plants. After critical transition, connectance and nestedness were higher in the STF than in the TRF. In contrast, modularity was higher in the TRF than in the STF. The coefficient of variations (CV) of host size and epiphyte richness tended to be stable at the same critical transition point; the distribution of host size and epiphyte richness could be the fundamental factors for the assembly of stable epiphyte–host network. Our study emphasized the importance of considering sampling effort while evaluating the network structure. Combining critical transition indicator with structure indicator dynamics could be a powerful method to compare the stable structure of different ecological networks.

Mutualistic and antagonistic phyllosphere fungi contribute to plant recruitment in natural communities

Abstract Phyllosphere fungal communities participate in multiple ecological functions (litter decomposition, disease‐causing, plant defence). However, there is a lack of knowledge on whether and how these functions contribute to plant community dynamics under natural conditions. One of the aspects of plant dynamics in which these fungi can most clearly affect is recruitment, since the success of newly germinated plants can be seriously compromised by pathogenic activity or the absence of mutualistic interactions. To determine the relationship between phyllosphere fungal communities and plant recruitment, we combined published information on the frequency of plant–plant recruitment interactions and phyllosphere fungal communities in 38 woody species from two mixed forests in southern Spain. Our results indicate that phyllosphere pathogens and saprotrophs have a negative effect on canopy–recruit interactions, while epiphytic fungi have a positive effect. Additionally, the presence of canopy species hosting high richness of epiphytes or counting with a high diversity of saprotrophic fungi favours the formation of an abundant sapling bank. Synthesis. Our results suggest that phyllosphere fungi play a relevant role in the assembly of the sapling bank in forest communities, thus, potentially influencing plant community dynamics. Beyond the well‐known negative effect of pathogenic fungi on recruitment, our results show the mutualistic effect of fungal epiphytes and a dual role of saprotrophs as antagonistic, decreasing recruitment of certain species, or mutualistic, enhancing recruitment in the sapling bank.

Vertical explorers: Unraveling vertical and horizontal patterns of vascular epiphyte diversity in a dwarf cloud forest

Vascular epiphytes are plants that grow on phorophytes, and their distribution may vary both horizontally and vertically. Understanding the factors shaping epiphyte distribution and their relationship with alpha and beta diversities is crucial for understanding richness and composition patterns. We investigated alpha and beta diversity variation in the vertical and horizontal stratification of epiphyte communities across different vegetation types in a dwarf cloud forest. Twenty-four 20 × 10 m plots were established in three vegetation types defined by distinct soil characteristics, different phorophyte height and differences in tree species composition in Parque Estadual do Ibitipoca, Minas Gerais, Brazil. Phorophytes were divided into four strata: (A) base of the trunk, (B) lower trunk, (C) inner canopy, and (D) outer canopy. Alpha and beta diversity analyses were performed for each site. We found a reduced stratification in the area, indicating minimal composition differences between the strata. However, the canopy exhibited greater species richness than the trunk. Vegetation types F1 and F2 displayed higher richness compared to F3. Orchidaceae was the richest family overall, while Bromeliaceae and Polypodiaceae were more frequent. Holoepiphytes were highly representative, demonstrating consistent patterns of richness, composition, and dispersion, with anemochorous species being the most abundant. This study highlights the unique patterns of epiphyte stratification, emphasizing the importance of biotic and abiotic characteristics in colonization processes. Despite the low canopy of the forest, the non-uniformity in stratification demonstrates that formation characteristics, such as height, play a significant role in shaping epiphyte richness and composition patterns.

Use of epiphyte by bird communities in IPB Dramaga campus

Epiphytes have a direct or indirect influence on terrestrial ecosystems. The presence of epiphytes can increase habitat complexity vertically and benefit animals, especially birds. The objectives of this study were to identify the species of epiphytes, their host trees, and the birds and to analyze how composition of epiphytes and host trees affects the diversity and abundance of birds. The research was conducted in seven sites within the IPB Dramaga Campus from December 2022 to February 2023. We collected biotic data (the number and type of epiphytes, host trees, and birds) and abiotic data (temperature and humidity) at each site. We used Paleontological Statisctic (PAST) to calculate the diversity index and R software to examine the correlation between birds and epiphytes. We found a significant positive correlation between the species richness of epiphytes, host trees, and birds. The sites with the highest diversity and abundance of trees, epiphytes, and birds were Conservation Park and Campus Forest Park. Sites with more diverse and abundant epiphytes had lower temperatures on average. We observed four bird species that used epiphytes: Pycnonotus aurigaster, Aegithina tiphia, Sitta frontalis, and Dicaeum trochileum. These species foraged for invertebrates on or near the Asplenium sp. epiphytes.

Differential Species Richness and Ecological Success of Epiphytes and Hemiepiphytes of Neotropical Araceae and Cyclanthaceae

Numerous plant functional traits of ecophysiology and morphology associated with an epiphytic life history have promoted relatively high rates of evolutionary diversification and ecological success in tropical families such as the Orchidaeae, Polypodiaceae, Bromeliaceae, and Cactaceae. Epiphytic life histories are relatively uncommon in the Araceae and rare in the Cyclanthaceae which lack key functional traits for epiphytism. Only two lineages of Neotropical Araceae, Anthurium and Philodendron, include examples of epiphyte life histories. The evolution of a hemiepiphytic life history represented an important development for tropical Araceae by providing functional traits that have greatly expanded opportunities for adaptive radiation and ecological success as indicated by species richness and frequency of occurrence. The key adaptive trait allowing the diversification of hemiepiphytic Araceae was the development of heteroblastic growth of leaves and stems. Although hemiepiphytic life histories are present in the Cyclanthaceae, the family has undergone only modest speciation and limited ecological success in both its epiphytes and hemiepiphytes. Extensive sampling of more than 4600 trees from primary forest on four soil groups in northeastern Costa Rica have found a modest diversity of 15 species of epiphytic Araceae but only two species of epiphytic Cyclanthaceae. In contrast, 38 species of hemiepiphytic Araceae and 5 species of hemiepiphytic Cyclanthaceae were sampled, indicating relatively limited adaptive radiation of hemiepiphytic Cyclanthaceae and lower ecological success. Using summed values of frequency of occurrence as a measure of ecological success, epiphytic Araceae were 18 to 42 times more frequent than epiphytic Cyclanthaceae in swamp, alluvial, and residual soil forests. Summed frequencies of occurrence of hemiepiphytic Araceae were 7 to 13 times higher than those of hemiepiphytic Cyclanthaceae. The four soil groups were similar in their floristic composition of epiphytic and hemiepiphytic Araceae and Cyclanthaceae, but the frequencies of occurrence of both epiphytes and hemiepiphytes were, with few exceptions, highest on swamp soil plots, with alluvial soil plots slightly less favorable.

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.

Plant life‐form distribution patterns in a tropical mountain region: Effect of climate, topography, and human disturbance

AbstractQuestionUnderstanding the specific distribution patterns of vascular plants on different spatial scales is central in ecology and conservation. We evaluate the distribution patterns of five plant life forms (climbers, epiphytes, herbs, shrubs, and trees) along the elevation gradient and geographic space of a mountain system, analyzing climate, topography, and human disturbance to explain variation in the richness of each life form, and determine the contribution of each life form to total richness along the elevation gradient.LocationSierra Madre of Chiapas, southeastern Mexico.MethodsWe used linear models to evaluate the elevational pattern of richness for each life form, as well as total richness, and analyzed the effects of climate (water–energy dynamics, thermal range), topography (topographic heterogeneity), and disturbance (Human Influence Index) on variation in total richness as well as of each life form using Generalized Linear Models (GLM). We used Non‐Metric Multidimensional (Distance) Scaling to determine variation in species composition along the elevation gradient. Finally, the contribution of each life form to total richness was evaluated using GLM.ResultsWe recorded 235 families, 1,439 genera, and 5,196 species. Total richness and the richness of each life form increased with increasing elevation. GLM explained a high proportion of the variation in the richness of each life form (34.3% for total richness; climbers 17.2%, epiphytes 44.9%, herbs 20.4%, shrubs 33.5%, and trees 24.9%). The proportion of richness of herbs and trees to total richness decreased, and the proportion of shrubs, epiphytes, and climbers increased with elevation. Climate largely determined species richness for all life forms, whereas disturbance was significant only for epiphyte richness.ConclusionsResults suggest that mechanisms driven by climatic variables (especially thermal range) contribute to maintaining the richness of each life form. However, human disturbance modifies distribution patterns and leads to a decrease in epiphyte richness. The differential contribution of each life form to total richness along the elevation gradient presents a challenge for designing conservation strategies applicable to all plant groups.

What makes a good phorophyte? Predicting occupancy, species richness and abundance of vascular epiphytes in a lowland seasonal tropical forest

Epiphytes typically exhibit clustered distribution patterns, but predicting the spatial variation of their distribution at fine scales has long been a challenge. Taking advantage of a canopy crane giving access to 1.1 ha of lowland seasonal rainforest in Yunnan (China), we assess here which factors promote the probability that a given tree hosts epiphytes, and the variation of species richness and abundance of epiphytic spermatophytes and ferns among trees. Variation in epiphyte species richness as a function of host tree size, characteristics of its surrounding environment, topography and microclimatic conditions, were analyzed by Random Forest. Epiphytic spermatophytes and ferns occupied 2.3 and 10.8% of the available host trees, respectively. Significant models predicting which trees are more likely to host epiphytes than others were obtained, indicating that host tree characteristics and their local environment play a significant role in determining which host tree is most likely to be colonized. These models, as well as models for species richness and abundance, however, exhibited a moderate to low accuracy (r2 0.28 and 0.24 and of 0.12 and 0.14 for spermatophyte and fern richness and abundance, respectively). The best predictor of the presence of epiphytes on a tree, of its epiphytic species richness and abundance, was its DBH. In ferns, however, two peaks of species richness were observed, representing shade-loving ferns on small trees and sun-loving ferns on large trees. Microclimatic conditions and light intensity were the second best factor accounting for variation in species richness and abundance among trees. The contribution of liana infestation, host tree identity, and characteristics of neighboring trees were marginal. Our inclusion of a large number of host-tree characteristics and their local environment did not allow for an apparent improvement of model accuracy over studies with a more limited number of predictors, pointing to the role of chance upon tree colonization. Our results confirm the utmost importance of large trees with emergent canopies for the conservation of the epiphytic flora, but also indicate that epiphytic diversity assessments in tropical forests must also include small understorey trees, which should be further considered for conservation. The importance of the micro-climatic conditions that prevail at the level of each individual host tree further points to the necessity of maintaining a buffer zone around large host trees targeted for conservation.

High species richness and turnover of vascular epiphytes is associated with water availability along the elevation gradient of Volcán Maderas, Nicaragua.

Research that has been conducted documenting species richness patterns on tropical mountains has resulted in conflicting observations: monotonic declines with increasing elevation, monotonic increases with increasing elevation, and a mid-elevation "bulge." Currently, it is unclear if these differences are due to environmental differences among study areas, the taxonomic groups or ecological groups (e.g., growth form) sampled, or the scale of study along elevation gradients. Because of the difficulty in sampling and identifying canopy-dwelling plants, the number of inventories quantifying tropical epiphytes is relatively limited and recent. In this study, we provide a detailed qualitative and quantitative assessment of the vascular epiphyte flora and its spatial distribution on Volcán Maderas, Isla de Ometepe, Nicaragua, including weather and environmental measurements along the entire elevation gradient of the volcano. We sampled epiphytes in five distinct forest types associated with increasing elevation as follows: dry forest, humid forest, wet forest, cloud forest, and elfin forest. Five weather stations were placed along the elevation gradient for us to relate observed patterns to environmental conditions. A mid-elevation peak in species richness was detected for all vascular epiphytes at approximately 1000 m in elevation (cloud forest), yet epiphyte abundance increased with increasing elevation. In total we identified 206 taxa of vascular epiphytes belonging to 26 families and 73 genera. The most species-rich family was the Orchidaceae with 55 species for the entire elevation gradient, followed by Bromeliaceae (29 species), Araceae (23), Polypodiaceae (25), Dryopteridaceae (16), and Piperaceae (11), with all other families represented by fewer than 10 species each. We found that richness patterns differ phylogenetically across epiphyte groups, possibly due to different adaptive strategies, and species for the most part appear to be narrowly distributed within specific habitat zones along the elevation gradient. Variables associated with moisture, precipitation, humidity, mist, or cloud cover are key to understanding the observed patterns.

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.

Basic ecology of ant gardens in a dry-premontane transitional forest

Introduction: Ant gardens are ant nests located at different heights on trees on which vascular epiphytic plants that have been transported and sown by ants have germinated. Although this mutualistic relationship has been studied in humid tropical ecosystems, information on other tropical and Colombian ecosystems is scarce. Objective: To characterize the spatial distribution, formation process, diversity, demography, and phenology of Ant gardens in a secondary dry premontane transitional forest in Colombia. Methods: We estimated the spatial distribution and formation process of ant gardens. Phenological and demographic monitoring of epiphytes plants of ant gardens was performed. The monitoring of the ant gardens was done in transects, every 15 days. Results: The ant gardens showed an aggregated distribution pattern relative to water bodies. The garden-forming ant species was identified as Azteca ulei. Ten species of epiphytes plants and 13 species of phorophytes trees related to ant gardens were identified. The behavior of A. ulei favored the formation and maintenance of the ant gardens. A positive relationship was found between epiphyte richness and ant garden size. Some epiphytes presented a bimodal phenological pattern. The demographic pattern of epiphytes suggests that in the dry season, the number of established seedlings is reduced, which reduces the number of adults that remain in ant gardens. Conclusions: Ant gardens are the microhabitat that allows the germination, establishment, and reproduction of diverse epiphytes in the studied dry-premontane transitional forest.

The Impact of Anthropogenic Disturbance to the Canopy Microclimate of Tropical Forests in the Southern Western Ghats, India

Anthropogenic disturbances are a pressing driver of forest degradation and are known to affect the microclimate within forests. Most organisms experience the microclimate and hence, associated changes may drive species communities in rainforests. However, such knowledge remains limited in the case of forest canopies, especially in south Asia. We aimed to identify differences in the temperature and light intensity, and beetles and vascular epiphytes in the canopy between old-growth and secondary forests. Using sensors, we recorded two key microclimatic variables, the air temperature, and light intensity, in the crowns of 36 Cullenia exarillata A. Robyns trees. We sampled beetles (morphospecies) and vascular epiphytes (genera) in the crowns. We provide evidence that canopies of secondary forest stands (intensively logged 60 years ago) (1) continue to show higher canopy air temperatures and light intensity, and (2) have higher beetle abundance (individuals), richness (morphospecies), and diversity but lower vascular epiphyte abundance (individuals), richness (genera), and diversity as compared to primary forest stands. We also show that the beetle communities differ (with greater beta diversity in the primary forest), but the vascular epiphyte communities were similar between the two forest types. We hope that this information begins to bridge the gap in understanding the role of microclimate in driving species communities and the ecology of human-modified forests.

Variation in vascular epiphytic assemblage along altitudinal zone in Temperate forest ecosystem

The focus of ongoing research in forest ecosystems is highly biased towards vascular epiphytes that grow non-parasitically on host trees and contribute substantially in shaping biodiversity. In this communication, an effort has been made to understand the vascular epiphytic assemblage and richness along the altitudinal gradients in temperate forests of Darjeeling Himalaya. Additionally, influence of environmental variables was also analyzed. Orchidaceae was the dominant family followed by Polypodiaceae and Ericaceae in terms of species abundance. The epiphytic richness and diversity were greater towards lower altitudinal tier compared to the higher. The epiphytic diversity was positively correlated with host tree CBH (circumference at breast height) and bark texture, while bark pH showed a negative correlation. The outcome of this study establishes a baseline of epiphytic characteristics with respect to elevational range and environmental variables in temperate Himalaya. However, a detailed study on population dynamics, habitat evaluation and geographic aspects with further development on monitoring and conservation effort is of utmost necessity.

Neglected epiphytism: Accidental epiphytes dominate epiphytic communities on tree ferns in the Atlantic Forest

AbstractVascular epiphytes and tree ferns constitute an important part of the Atlantic Forest structure. We characterized vascular epiphyte communities on two tree fern species (Alsophila setosa Kaulf. and Cyathea phalerata Mart.) including accidental epiphytes (i.e., species that are usually terrestrial, without necessarily completing their life cycle as an epiphyte), which have been overlooked in many previous studies. We aimed to understand epiphytism in terms of distribution, diversity, community composition, and host attributes that affect the richness and abundance of accidental epiphytes. Despite the great species richness of accidental epiphytes, they were—in contrast to true epiphytes—generally low in abundance and heavily represented by singletons and doubletons. We did not identify a difference in accidental epiphytic diversity and composition between host species, implying that both host species provide similar habitats for accidental epiphytes—although some epiphytic species showed a preference for a specific host species and/or stratum. Epiphyte richness and abundance were positively associated with a codependence of host surface area and moisture content, but only for accidental epiphytes. Our study illustrates the importance of two tree fern species as epiphyte hosts in the rainforest understory. It also shows that, although frequently overlooked, accidental epiphytism can be common in the understory of tropical forests and a phenomenon that merits further study in this region.Abstract in Portuguese is available with online material.

Relevance of Broad-Leaved Forest Stands for Maintaining Epiphytic Bryophyte Species and Functional Trait Diversity in Forest Landscape in Latvia

AbstractBroad-leaved trees play an important role in supporting epiphyte richness in deciduous forests. In this study we tested which broad-leaved forest stands in terms of tree composition best predicted biodiversity in regard to bryophyte species number and their functional traits. The bryoflora was surveyed in 70 stands differing in dominant broad-leaved tree species. One circular plot with diameter 30 meters was established in each stand situated in different parts of Latvia. Fifty-three of the plots were located in stands identified as protected habitats of the European Union. In total, 82 bryophyte species were recorded. At plot level the total number of species ranged between 6 and 38 species. Using principal component analysis (PCA), the ordination axes explained 41% of the variation in composition of bryophytes. The PCA axes were related to tree species composition. The presence of broad-leaved trees, especially ash, lime, and oak, was connected with higher species richness. Generalised linear models confirmed that epiphyte richness, both at the total and indicator species levels, was higher in ash stands. From the functional traits, all expected life-strategy and life-form categories were recorded. The most represented life-forms were smooth mats, tall turfs, and rough mats, while the dominant life-strategy was perennial stayers, followed by competitive perennials and long-lived shuttles. Functional trait richness was highest in Fraxinus excelsior, Tilia cordata, and Quercus robur forest stands.

Role of spatial and environmental factors in structuring vascular epiphyte communities in two neotropical ecosystems

The great heterogeneity of tropical systems challenges our understanding of how niche and neutral processes structure epiphyte communities. Dispersal, phorophyte identity and the environmental conditions created by phorophytes are the main determinants of vascular epiphyte structure and diversity. However, these forces comprise multiple causal factors that need to be decomposed to address the complex patterns of independent and confounded effects acting upon epiphyte communities. We tested the hypothesis that the environment created by phorophytes (size, bark characteristics, microenvironmental conditions, and substrate type) is more important than phorophyte species identity and space in determining the structure of epiphyte communities, with phorophyte size being a major determinant within the environmental component. We also expected larger phorophytes to exhibit greater epiphyte richness and diversity. The study was carried out on an inselberg within a semi-deciduous montane forest and a cloud forest in southeastern Brazil. Partial redundancy analysis was used to hierarchically decompose the relative abundances of vascular epiphytes into three components: association with particular phorophyte species, the environment created by phorophytes, and space (Moran’s eigenvector maps). Linear models were used to analyze the relationship between epiphytic diversity and richness with size descriptors. We show that neutral and niche-based processes act simultaneously on the dynamics of vascular epiphyte species, but distinctly on the inselberg and cloud forest. The potential for an epiphyte to occupy all favorable phorophytes was larger in the cloud forest due to the higher connectivity offered by trees. Abundance, richness and diversity of epiphytes increased with phorophyte size, probably due to an increase in the area, time of colonization or increase in microhabitat heterogeneity within phorophytes. Larger phorophytes are a major determinant of local environmental conditions and the spatial organization of epiphytes, as they promote their abundance and maintain their diversity in tropical systems.