Epiphyte Species Richness Research Articles

Vascular Epiphytes in Doshke and Kurpaye: A Comparative Study, Gamo Gofa, Ethiopia

Epiphytes comprise about 10% of the world’s total flora. However, the survival of these important elements of the global vegetation is recognized to be increasingly threatened, and surveys made to study them remain far from being complete. This study has focused on investigating the vascular epiphytes (true epiphytes, hemiepiphytes, and accidental epiphytes) in Doshke and Kurpaye forests of Gamo Gofa zone, southwest Ethiopia. A total of 40 (20 in each) 25 m × 25 m quadrats were established along four line transects for vegetation data collection. A total of 35 species of vascular epiphytes were recorded in the two sites (22 and 14 species from Doshke and Kurpaye, resp.). Drynaria volkensii was the only species to be recorded from the two sites. Doshke and Kurpaye forests also varied in the number of phorophytes (17 and 10 phorophytes species, resp.). The richest epiphyte family of Doshke is Orchidaceae (5 species) and that of Kurpaye is Polypodiaceae (3 species) while Orchidaceae dominate the combined flora being represented by 7 species. In terms of vertical distribution, most species were located at the canopy area. Most vascular epiphytes showed no preference for host trees except for a few species which exhibited higher occurrence rates on the host plant species Syzygium guineense, Schrebera alata, and Acacia tortilis. Vascular epiphyte abundance and species richness were both significantly positively correlated with host tree size. Vascular epiphytes of the studied forests are under a serious pressure, mainly due to anthropogenic activities, and this may lead to their local extinction.

A Pine Is a Pine and a Spruce Is a Spruce--The Effect of Tree Species and Stand Age on Epiphytic Lichen Communities.

With an increasing demand for forest-based products, there is a growing interest in introducing fast-growing non-native tree species in forest management. Such introductions often have unknown consequences for native forest biodiversity. In this study, we examine epiphytic lichen species richness and species composition on the trunks of non-native Pinus contorta and compare these to the native Pinus sylvestris and Picea abies in managed boreal forests in northern Sweden across a chronosequence of age classes. Overall, we recorded a total of 66,209 lichen occurrences belonging to 57 species in the 96 studied forest stands. We found no difference in species richness of lichens between stands of P. contorta and P. sylvestris, but stands of P. abies had higher total species richness. However, species richness of lichens in stands of P. abies decreased with increasing stand age, while no such age effect was detected for P. contorta and P. sylvestris. Lichen species composition progressively diverged with increasing stand age, and in 30-year-old stands all three tree species showed species-specific assemblages. Epiphytic lichen assemblages in stands of 30-year-old P. contorta were influenced by greater basal area, canopy closure, and average diameter at breast height, P. abies stands by higher branch density and canopy closure, and stands of P. sylvestris by greater bark crevice depth. Differences in lichen species richness and composition were mainly explained by canopy closure and habitat availability, and the greater canopy closure in mature P. abies stands promoted the colonization and growth of calicioid lichen species. Our results indicate that the non-native P. contorta have similar species richness as the native P. sylvestris. The main difference in lichen species richness and composition is between P. abies and Pinus spp. in managed forests of boreal Sweden.

Vascular epiphyte assemblages in a Brazilian Atlantic Forest fragment: investigating the effect of host tree features

This study investigates the relative importance of dispersal- and niche-related mechanisms structuring the assemblages of vascular epiphytes in a 10-ha secondary Atlantic Forest patch in Sao Paulo city, Brazil. We tested for the effect of characteristics of host trees (species, height, trunk diameter, presence of lianas, and distance to a near stream) and of space on epiphyte abundance, species richness, and species composition of vascular epiphytes. Inside a 0.2-ha plot, all 86 trees with diameter at breast height >13 cm (27 species) were recorded, as well as all epiphytes larger than 15 cm in length on those trees (380 individuals, 22 species). Twenty-eight trees (32.6 %) did not carry epiphytes. On individual trees, tree species showed a significant effect on epiphyte abundance, richness, and species composition. The bark-shedding Piptadenia gonoacantha carried less epiphytes than other tree species. Distance to the stream showed effects on abundance and species composition, with lower abundance farther from the stream. Tree height had a positive effect on abundance, richness, and species composition, but trunk diameter had none, supporting the importance of vertical stratification in controlling epiphyte richness. Variation partitioning analyses showed little or no effect of “pure space” on abundance, richness, and species composition (explaining 6.7, 4.5, and 0.7 % of variation, respectively), as compared to environmental effects (26, 30, and 14.5 %), generally supporting a higher importance of niche-based processes in structuring epiphytic assemblages on host trees in the plot.

Slow recovery of tropical old-field rainforest regrowth and the value and limitations of active restoration.

There is current debate about the potential for secondary regrowth to rescue tropical forests from an otherwise inevitable cascade of biodiversity loss due to land clearing and scant evidence to test how well active restoration may accelerate recovery. We used site chronosequences to compare developmental trajectories of vegetation between self-organized (i.e., spontaneous) forest regrowth and biodiversity plantings (established for ecological restoration, with many locally native tree species at high density) in the Australian wet tropics uplands. Across 28 regrowth sites aged 1-59 years, some structural attributes reached reference rainforest levels within 40 years, whereas wood volume and most tested components of native plant species richness (classified by species' origins, family, and ecological functions) reached less than 50% of reference rainforest values. Development of native tree and shrub richness was particularly slow among species that were wind dispersed or animal dispersed with large (>10 mm) seeds. Many species with animal-dispersed seeds were from near-basal evolutionary lineages that contribute to recognized World Heritage values of the study region. Faster recovery was recorded in 25 biodiversity plantings of 1-25 years in which wood volume developed more rapidly; native woody plant species richness reached values similar to reference rainforest and was better represented across all dispersal modes; and species from near-basal plant families were better (although incompletely) represented. Plantings and regrowth showed slow recovery in species richness of vines and epiphytes and in overall resemblance to forest in species composition. Our results can inform decision making about when and where to invest in active restoration and provide strong evidence that protecting old-growth forest is crucially important for sustaining tropical biodiversity.

Epiphyte community development throughout tree ontogeny: an island ontogeny framework

AbstractAimEpiphytes are a conspicuous feature of numerous forests, yet they are poorly understood compared with terrestrial plants. Theoretical frameworks have helped bridge this gap; however, important questions relating to epiphyte community development have yet to be answered. For example, at what point in tree ontogeny do epiphytes first establish? Do epiphyte communities develop uniformly, or is there variation among host trees?MethodsIn this study, we build upon Darwin's geological theory of island ontogeny to explore changes in epiphyte species richness throughout the life span of their respective host trees. Based on the general features of island ontogeny, we predict that there are three stages of epiphyte community development: (i) an initial stage where host trees are devoid of epiphytes because they lack sufficient architectural and physiological characteristics suitable for epiphyte establishment, (ii) a second stage where trees acquire epiphytes as adults and continue to do so into maturity, and (iii) a final stage where epiphyte communities progress through a period of species decline following host tree mortality. To test our model predictions, we censused epiphyte communities on 371 host trees from six New Zealand tree species. We first assessed the relationship between epiphyte species richness and host tree diameter. We then tested whether relationships between epiphyte species richness and host tree diameter varied between host species.Results and conclusionResults were consistent with model predictions. Our investigation found variation in the ontogenetic stage at which host trees become favourable for epiphyte establishment. Moreover, the rate at which epiphyte species richness increased with host tree diameter varied among host species. Our findings indicate that an island ontogeny framework is useful for guiding investigations on epiphyte community development.

Microhabitat associations of vascular epiphytes in a wet tropical forest canopy

Summary In tropical forests, vascular epiphyte diversity increases with tree size, which could result from an increase in area, time for colonization or an increase in microhabitat heterogeneity within‐tree crowns if vascular epiphyte species are specialized to particular microhabitats within the crown. The importance of microhabitats in structuring epiphyte communities has been hypothesized for more than 120 years but not yet confirmed. We tested the importance of microhabitats in structuring epiphyte communities by examining microhabitat heterogeneity and epiphyte communities within the crowns of different‐sized Virola koschnyi (Myristicaceae) emergent trees in a Costa Rican tropical wet forest. We tested the degree to which epiphyte species composition was associated with environmental conditions and resources (i.e. microhabitats) using multivariate analyses and a null model that compared the observed epiphyte assemblages amongst different‐sized trees and crown zones with assemblages generated randomly. This study is the first to rigorously examine the degree of microhabitat specialization in epiphyte communities. Microhabitat heterogeneity, epiphyte species richness and abundance increased with tree size. The largest trees had the highest microhabitat and epiphyte diversity and a unique inner crown microhabitat with canopy humus. The few epiphytes found on small trees were mostly bark ferns. Large trees had different epiphyte communities in different parts of the crown; the inner crown contained species not abundant in any other microhabitat (i.e. aroids, cyclanths and humus ferns), and the outer crown contained bark ferns and atmospheric bromeliads. Variation in species composition amongst tree size classes was significantly related to the mean daily maximum vapour pressure deficit and tree diameter, while variation within large tree crowns was significantly related to canopy humus cover. Microhabitat specialization of epiphyte species increased with tree size with 6% of species significantly associated with small trees and 57% significantly associated with large trees. Of the species present in large tree crowns, 23% were specialized to the unique inner crown microhabitat. Synthesis. The increase in microhabitat heterogeneity within tree crowns as trees grow contributes to changes in epiphyte community structure, which supports decades‐old hypotheses of the importance of microhabitat diversity and specialization in structuring tropical epiphyte communities.

Moss and vascular epiphyte distributions over host tree and elevation gradients in Australian subtropical rainforest

There is a lack of comprehensive studies on the ecology of epiphytic flora in Australia’s rainforests. Globally, rainforest epiphyte distribution is determined by three main factors: micro-climate within the host tree; landscape changes in macro-climate; and the characteristics of the host tree. We tested the influence of these factors on the species richness and composition of vascular and non-vascular epiphytes in the subtropical rainforest of the Border Ranges in New South Wales. Vascular epiphytes and mosses were recorded in situ from four height zones, with 10 trees sampled at five elevations between 300 and 1100 m above sea level (asl). Vascular epiphyte species richness was highest in the inner canopy (6.3 species), whereas mosses tended to have a uniform distribution over the height zones (3.8–5.0 species). We found that both moss and vascular epiphyte species richness peaked at mid-elevations (500–700 m), with moss richness at a slightly higher elevation than the vascular epiphytes. Host tree characteristics (bark roughness, host size) explained very little of the species composition or richness of epiphytes. Strong patterns in species richness and composition over host tree and elevation gradients suggest that moisture, temperature and light may be the major influences on epiphyte distributions in the Border Ranges.

Impacts of nitrogen deposition on herbaceous ground flora and epiphytic foliose lichen species in southern Ontario hardwood forests

In this study 70 sugar maple (Acer saccharum Marsh.) dominated plots in Ontario, Canada were sampled in the spring of 2009 and 2010 and herbaceous plant and epiphytic foliose lichen species data were compared against modeled N and S deposition data, climate parameters and measured soil and plant/lichen S and N concentration. Herbaceous plant species richness was positively correlated with temperature and indices of diversity (Shannon Weiner and Simpson's Index) were positively correlated with soil pH but not N or S deposition or standardized foliar N scores. Herbaceous community composition was strongly controlled by traditional factors, but there was a small and significant influence of atmospheric S and N deposition. Epiphytic lichen species richness exhibited a strong negative relationship with standardized foliar N score and only one lichen species (Phaeophyscia rubropulchra) was observed at sites with a standardized foliar N score of 0.76.

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.

Southern leaf blight disease severity is correlated with decreased maize leaf epiphytic bacterial species richness and the phyllosphere bacterial diversity decline is enhanced by nitrogen fertilization.

Plant leaves are inhabited by a diverse group of microorganisms that are important contributors to optimal growth. Biotic and abiotic effects on plant growth are usually studied in controlled settings examining response to variation in single factors and in field settings with large numbers of variables. Multi-factor experiments with combinations of stresses bridge this gap, increasing our understanding of the genotype-environment-phenotype functional map for the host plant and the affiliated epiphytic community. The maize inbred B73 was exposed to single and combination abiotic and the biotic stress treatments: low nitrogen fertilizer and high levels of infection with southern leaf blight (causal agent Cochliobolus heterostrophus). Microbial epiphyte samples were collected at the vegetative early-season phase and species composition was determined using 16S ribosomal intergenic spacer analysis. Plant traits and level of southern leaf blight disease were measured late-season. Bacterial diversity was different among stress treatment groups (P < 0.001). Lower species richness—alpha diversity—was correlated with increased severity of southern leaf blight disease when disease pressure was high. Nitrogen fertilization intensified the decline in bacterial alpha diversity. While no single bacterial ribotype was consistently associated with disease severity, small sets of ribotypes were good predictors of disease levels. Difference in leaf bacterial-epiphyte diversity early in the season were correlated with plant disease severity, supporting further tests of microbial epiphyte-disease correlations for use in predicting disease progression.

Bathymetric variation of epiphytic assemblages on Posidonia oceanica (L.) Delile leaves in relation to anthropogenic disturbance in the southeastern Mediterranean.

A survey of the epiphytic leaves of Posidonia oceanica was conducted along a depth transect at both the control station Attaya in the Kerkennah Islands and the disturbed Mahres station on the Sfax coast (Tunisia). Samples were collected by scuba divers at depths of 5, 10, 15, and 20m in July 2008. We evaluated whether the pattern of spatial variability of the macroepiphyte assemblages of leaves of Posidonia oceanica differed in relation to anthropogenic interference. The results indicate that the decrease in shoot density and leaf length according to depth was low at Mahres. The biomass of epiphytic leaves and the percentage cover of epiphytic assemblages decreased with depth for both stations and heavily at Mahres, this decline being related to anthropogenic disturbance. This study shows that the highest values of epifauna and epiflora were detected at the disturbed station Mahres. Macroalgae assemblages decreased with depth at both stations and were dominated by Rhodophyta, whereas the percentage cover of the epifauna leaf that decreases according to depth was dominated by Hydrozoa and Bryozoa. Changes in epiphyte assemblages, epiphytic biomass, percentage cover, and species richness in proportion to Heterokontophyta, Rhodophyta, Cyanobacteria, Hydrozoa, Porifera, and Tunicata between the two stations constitute promising tools for detecting environmental disturbance.

Preferences of epiphytic bryophytes for forest stand and substrate in North-East Latvia

Distribution of epiphytic bryophyte species was studied in Woodland Key Habitats (WKH) and in managed forest stands in the North-East Latvia (district Gulbene). In total, 32 epiphytic bryophyte species were found in six WKH stands. Five endangered/threatened bryophyte species (Anomodon longifolius, Homalia trichomanoides, Jamesoniella autumnalis, Lejeunea cavifolia, Neckera pennata), that are listed in the Red Data Book of Latvia were recorded. The relation between the total and endangered/threatened epiphytic bryophyte species richness and composition with substrate factors (phorophyte species, diameter at breast height (DBH), shading, and tree bark pH) was studied. The most important factors regarding epiphytic bryophyte species cover, composition and richness were found to be tree species, DBH, bark pH and forest shading. WKH indicator species richness showed significant relationship only with tree species. Tree species was one of the most important factors explaining epiphytic species distribution.

Floristic composition and spatial distribution of vascular epiphytes in the restingas of Maracanã, Brazil

Vascular epiphytes constitute a life form that is important to maintaining the biological diversity of forest ecosystems, because they provide food resources and specialized microenvironments for fauna in the forest canopy. This study aimed to describe the floristic composition and ecological aspects of vascular epiphytes occurring in the restingas (coastal woodlands) within the Algodoal-Maiandeua Environmentally Protected Area, located in the municipality of Maracanã, in the state of Pará, Brazil. We sampled five 50 × 50 m plots (three in dry restinga forest and two in floodplain restinga forest), the sampled area therefore totaling 1.25 ha. In the plots sampled, vascular epiphytes were identified and described according to their frequency, abundance, importance value (IV), functional group and vertical distribution (trunk, lower crown or upper crown of the host). For both forest types, we identified 477 individuals belonging to five families, nine genera and 11 species. The most species-rich families were Araceae and Orchidaceae. The species with the highest density, frequency and IV were the secondary hemiepiphytes Philodendron acutatum, Anthurium pentaphyllum and Philodendron muricatum, collectively accounting for 92.1% of all sampled individuals. The true epiphytes predominated. Epiphytic species richness and abundance was greater on the host trunk than in the lower or upper crown. The seasonal climate and structure of the forest favored greater abundance of secondary hemiepiphytes and a higher frequency of epiphytes on the trunks of their hosts.

A tangled web in tropical tree‐tops: effects of edaphic variation, neighbourhood phorophyte composition and bark characteristics on epiphytes in a central Amazonian forest

AbstractQuestionHow do soil fertility, neighbourhood host tree composition and bark characteristics influence community attributes of vascular epiphytes in a central Amazonian forest?LocationAdolpho Ducke Forest Reserve, Amazonas, Brazil.MethodsThe abundances of all species of vascular epiphytes were recorded from 300 host trees with DBH &gt;30 cm. Phorophytes were distributed among 30 sample plots established in lowland, slope and upland habitats, and bark characteristics were classified into five types (rough, peeling, fissured, smooth, rugose). The epiphytic species were also classified into three functional types (true epiphytes, hemi‐epiphytes and nomadic vines) for separate analyses in an effort to highlight differences in ecological constraints in relation to neighbourhood phorophyte composition and edaphic variation.ResultsMore than 21 000 individuals representing 122 species distributed in 66 genera and 20 families of vascular epiphytes were recorded from 300 phorophytes during the course of the study. Multiple regressions demonstrated that neighbourhood phorophyte composition and edaphic variables, nitrogen (N) and phosphorus (P), together explained 65% of the variation in epiphytic species composition. However, edaphic factors were the only significant predictors of epiphytic species richness, accounting for 70% of this variation. Nearly one‐third of the true epiphytes occurred only on phorophytes in soils with high P content. Null models demonstrate that a vast majority of the epiphyte species (76% in positive and 96% in negative associations) failed to exhibit a statistically significant preference for bark texture.ConclusionNeighbourhood phorophyte composition, in concert with N and P availability, accounts for the vast majority of the variation in vascular epiphyte composition and abundance in central Amazonian forests. However, only N and P were shown to be significant predictors of epiphyte richness. Such results suggest that both biotic and abiotic variables influence epiphyte community structure (composition, abundance and richness) at differing intensities. Weak associations between bark type and epiphyte taxa suggest that epiphyte community variation may also be influenced by other unmeasured physical and environmental factors such as phorophyte architecture or microclimatic differences. Nonetheless, these results corroborate with other studies which report significant changes in epiphyte composition and richness as a result of experimentally manipulated ground soil fertility.

Indirect effects of hiking trails on the community structure and diversity of trunk-epiphytic bryophytes in an old-growth fir forest

Forest hiking trails may influence local microclimate and biodiversity, but the effects on community structure and diversity of epiphytic bryophytes on trees are currently unknown. Epiphytic bryophytes on 82 Abies faxoniana Rehder & Wilson tree trunks (41 along the hiking trail edge and 41 controls in the forest interior) were investigated at four heights from the ground (10, 50, 120, and 180 cm). At each site, air temperature and humidity were monitored for 1 year. The light radiation levels and air temperature were higher, and the canopy leaf area index and air humidity lower at the trail edge, indicating deterioration in microclimate, resulting from the trail establishment. The epiphytic bryophyte species richness, community cover, and mean cover of dendroid and pendent growth forms on trunks were significantly lower at the trail edge than the control site, suggesting that trail construction caused these reductions. One marked effect of the presence of the trail was the increase in some sun-loving species and decrease in shade-tolerant species. Moreover, the trail also slightly influenced species richness and epiphytic bryophyte cover at both community and species population levels along the height gradient. Comprehensive analyses showed that microclimate deterioration was mainly driven by the trail establishment, and that the change in micro-climate along the trail, rather than any host traits, played an important role in the declining epiphytic bryophyte community structure and diversity at the trail edge, confirming the initial hypothesis that the presence of a raised boardwalk (hiking trail) indirectly influences epiphytic bryophyte community and diversity by altering the microclimate.

Lichen species richness on retained aspens increases with time since clear-cutting

In modern forestry, attempts to mitigate negative effects on biodiversity include the integration of conservation actions into forestry activities, e.g. by leaving trees at harvesting. This practice has been used on a large scale for more than two decades without solid scientific support of whether desirable effects are achieved or not. To increase the knowledge of changes in the lichen flora on retained aspen trees (Populus tremula) with time since clear-cutting we made a study in boreal Sweden where 720 retained aspens in 24 stands were surveyed. Twelve stands were clear-felled 0–4years and 12 where clear-felled 10–16years prior to the inventory. Total lichen species richness increased with time since clear-cutting, as did richness of aspen-dependent lichens and lichens adapted to open environments. There was no difference between the age classes regarding the number of cyanolichens. We show that retained aspens function as lifeboats for old-forest lichens and as a new habitat for lichens adapted to open, sun-exposed habitats. Our results indicate that epiphytic species richness on retained trees is higher after the logging, due to coexistence of remaining species and colonizing species. We suggest that the retention of old aspen and the promotion of aspen generation in the production forest would benefit epiphytic lichens and are thus important conservation measures.

Factors influencing epiphytic bryophyte and lichen species richness at different spatial scales in managed temperate forests

The effect of management related factors on species richness of epiphytic bryophytes and lichens was studied in managed deciduous-coniferous mixed forests in Western-Hungary. At the stand level, the potential explanatory variables were tree species composition, stand structure, microclimate and light conditions, landscape and historical variables; while at tree level host tree species, tree size and light were studied. Species richness of the two epiphyte groups was positively correlated. Both for lichen and bryophyte plot level richness, the composition and diversity of tree species and the abundance of shrub layer were the most influential positive factors. Besides, for bryophytes the presence of large trees, while for lichens amount and heterogeneity of light were important. Tree level richness was mainly determined by host tree species for both groups. For bryophytes oaks, while for lichens oaks and hornbeam turned out the most favourable hosts. Tree size generally increased tree level species richness, except on pine for bryophytes and on hornbeam for lichens. The key variables for epiphytic diversity of the region were directly influenced by recent forest management; historical and landscape variables were not influential. Forest management oriented to the conservation of epiphytes should focus on: (i) the maintenance of tree species diversity in mixed stands; (ii) increment the proportion of deciduous trees (mainly oaks); (iii) conserving large trees within the stands; (iv) providing the presence of shrub and regeneration layer; (v) creating heterogeneous light conditions. For these purposes tree selection and selective cutting management seem more appropriate than shelterwood system.

Palaeoecological evidence for changes over the past 200 years in chironomid communities of a shallow lake exposed to cyanobacterial toxins

In spite of the existence of a number of papers applying the biomarker approach using pigments or akinetes to discuss the impact of cyanobacteria on the functioning of lakes in the palaeoenvironmental context, their sedimentary imprint in the form of microcystins (MCs) has never been taken into consideration. Our objective was to reconstruct 200 years of the develop- ment of chironomid assemblages in a shallow Polish lake with notoriously blooming toxic cyanobacteria. A 50-cm long sediment core sampled from the central part of the lake was sliced every 1 cm, dated, and analysed for the subfossil remains of Chironomidae and concentrations of MCs. The fauna underwent four distinct stages in its recent history: three periods when the assemblages were typical of hypertrophic conditions (the first one compris- ing the entire nineteenth century, and the second and third one including approximately the last 30 years of the twentieth century), separated by a ''eutrophic'' assem- blage during the first 70 years of the twentieth century. The typical features of the ''eutrophic'' midge assemblage were high total densities and high values of taxonomic richness and diversity. This period coincided with relatively low concentrations of MCs in the sediments. Sediments from the hypertrophic periods were distinguished by taxonomic impoverishment of chironomids, low Shannon diversity index, a strong decrease in chironomid numbers, and high concentrations of MCs. Significant negative correlations with MCs along the sediment profile were observed for eurytopic chiron- omids. MC concentrations were also negatively but not significantly correlated with total density of chironomids, their benthic and epiphytic assemblages, species richness, and diversity index.

Tree and stand-scale factors affecting richness and composition of epiphytic bryophytes and lichens in deciduous woodland key habitats

Conservation and sustainable forestry are essential in a multi-functional landscape. In this respect, ecological studies on epiphytes are needed to determine abiotic and biotic factors associated with high diversity. The aim of the present study was to evaluate relative sensitivity of conservation targets (epiphytic bryophytes and lichens) in relation to contrasting environmental variables (tree species, tree diameter at breast height, bark crevice depth, pH, tree inclination, pH, forest stand age, area and type) in boreo-nemoral forests. The study was conducted in Latvian 34 woodland key habitat (WKH) boreo-nemoral forest stands. Generalized linear mixed models and canonical correspondence analysis showed that tree species and tree bark pH were the most important variables explaining epiphytic bryophyte and lichen composition and richness (total, Red-listed, WKH indicator species). Forest stand level factors, such as stand size and habitat type, had only minor influence on epiphytic species composition and richness. The results of the present study indicate a need to maintain the diversity of tree species and large trees, particularly Acer platanoides, Carpinus betulus, Fraxinus excelsior, Populus tremula, Tilia cordata, Ulmus glabra and Ulmus laevis in conservation of epiphytic bryophyte and lichen communities in the future.

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

AbstractSecondary 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.