IPCC predictions for Honduras indicate that temperature will increase by up to 3–6°C and precipitation will decrease by up to 7–13% by the year 2050. To better understand how fern and lycophyte communities might be affected by climate change, we comprehensively surveyed the community compositions of ferns and lycophytes at Celaque National Park, the highest mountain in Honduras. We surveyed a total of 80 20 × 20 m2 plots along an altitudinal gradient of 1249–2844 m a.s.l., identifying all species and estimating their abundances. We recorded a total of 11,098 individuals from 160 species and 61 genera. Community composition was strongly influenced by changes in altitude, precipitation and the abundance of bryophytes (a proxy for air humidity). Of the 160 species, 63 are expected, under a RCP2.6 scenario for the year 2050, to shift their range fully or partially above the maximum altitude of the mountain. Of these, 65.1% are epiphytes. We found that species with narrow altitudinal ranges at high altitudes were more at risk. Our study indicated that conservation efforts should prioritise higher altitudinal sites, focusing particularly on preserving the vulnerable epiphytic fern species, which are likely to be at greater risk.

Epiphytic lichens are sensitive to deteriorating air quality, but levels of nitrogen and especially sulphur deposition have been in decline over most of Europe in recent decades. We assessed the response of epiphytic lichens to this decline, using data from long-term monitoring sites in Sweden. We analyzed 20 years of data to investigate temporal trends in lichen communities’ sensitivity to sulphur, nitrogen preference, species richness and alpha and beta diversity. We found only limited and partial evidence of recovery in the area that previously had high levels of deposition, and a decline in mean sulphur sensitivity at a northern site with low deposition levels throughout the monitoring period. The slow recolonization of sensitive species, even where environmental conditions are now suitable, is probably a result of impoverished regional species pools and the inherent limited dispersal capacity of many lichen species. We suggest due consideration of these factors in the use of epiphytic lichens as environmental indicators in a period of improving air quality.

This study presents two years of characterization of a warm temperate rhodolith bed in order to analyse how certain environmental changes influence the community ecology. The biomass of rhodoliths and associated species were analysed during this period and in situ experiments were conducted to evaluate the primary production, calcification and respiration of the dominant species of rhodoliths and epiphytes. The highest total biomass of rhodoliths occurred during austral winter. Lithothamnion crispatum was the most abundant rhodolith species in austral summer. Epiphytic macroalgae occurred only in January 2015, with Padina gymnospora being the most abundant. Considering associated fauna, the biomass of Mollusca increased from February 2015 to February 2016. Population densities of key reef fish species inside and around the rhodolith beds showed significant variations in time. The densities of grouper (carnivores/piscivores) increased in time, especially from 2015 to 2016. On the other hand, grunts (macroinvertebrate feeders) had a modest decrease over time (from 2014 to 2016). Other parameters such as primary production and calcification of L. crispatum were higher under enhanced irradiance, yet decreased in the presence of P. gymnospora. Community structure and physiological responses can be explained by the interaction of abiotic and biotic factors, which are driven by environmental changes over time. Biomass changes can indicate that herbivores play a role in limiting the growth of epiphytes, and this is beneficial to the rhodoliths because it decreases competition for environmental resources with fleshy algae.

Mistletoes are considered keystone species on woodlands and savannas worldwide, providing a food resource for a diversified fauna, as well as a nutrient-enriched litter. Infections can be large (∼1–3 m) and, in some parts of the Amazonian savannas, parasitize up to 70% of hosts locally. Despite these facts, biomass of mistletoes is rarely investigated. Here we constructed allometric models to predict the biomass stock of the shrubby mistletoe Psittacanthus plagiophyllus in an Amazonian savanna. In addition, we determined whether host size could be used as a proxy for mistletoe biomass. Finally, we compared the biomass of mistletoes with that of trees, to evaluate their relative importance. We have shown that: (1) biomass of leaves (46.1% ± 13.5%) are as important as of stems (47.8% ± 13.5%), and relative contribution of stems increases as plant grows; (2) the model including width, breadth and vertical depth was the best (SE = 0.39, R2 = 0.9) for predicting individual mistletoe biomass; (3) mistletoe load and biomass per host had a positive, but weak (R2 = 0.11 and 0.09, respectively), relationship with host size, and thus such host information is a poor predictor of mistletoe biomass; and (4) in comparison with trees, mistletoes constituted less than 0.15% (0.5–22 kg ha−1) of the total above-ground biomass, suggesting that this life-form is irrelevant to the local biomass stock despite its unequivocal biological importance.

There are a number of studies describing the gross range of morpho-anatomical variability in epiphytic Tillandsia species, but the interspecific variation in seed traits remain largely unexplored, although these play an important role in determining dispersal and establishment success. In order to evaluate interspecific variation in seed morphology, anatomy and germination, we sampled six Tillandsia species from the Yucatan peninsula, Mexico, distributed along a precipitation gradient. We studied morpho-anatomical traits (seed length, seed mass, ratio of coma to seed, ratio of embryo to endosperm), seed terminal velocity in still air, and performed histochemical analyses and germination trials under controlled conditions. Tillandsia recurvata differs from the other five species in the structure of the plumose coma; it was the only species lacking an endosperm and showed distinct seedling development. Among the species, bigger seeds were related to longer comas, and had higher germinability. Overall, seed terminal velocity was invariably slow, compared with reports of other anemochorous species, suggesting a high dispersal potential. Taxonomical and ecological implications of our results are discussed.

Epiphytes represent keystone resources for many arthropod and vertebrate species, however their ecology remains poorly explored, especially within the palaeotropics. Several recent studies have examined relationships between epiphyte richness and characteristics of local habitats, although these have all focused on neotropical forests. Here, we aim to determine whether predictors of neotropical epiphyte richness are consistent at a palaeotropical site. A total of 44 host trees (dbh range 25–288 cm) were sampled at two study sites on Buton Island, Indonesia. For each tree, epiphyte richness and seven variables relating to characteristics of the host tree and surrounding habitats were recorded: site (a proxy value for disturbance level and water availability), host above-ground biomass (agb), altitude, bark texture, exposure, emergence and crown area. Gaussian GLM analyses indicated that the percentage deviance explained in epiphyte richness per host was greatest for agb (20.9%), crown area (19.6%) and site (15.5%); similar to previous findings from the neotropics. Results therefore suggest that high epiphyte diversity within palaeotropical forests is most likely to be found in large tracts of undisturbed forest, supporting large, broad-crowned trees.

Tropical tropical montane cloud forests (TMCFs) cover a small portion of the Earth, yet they are significant biodiversity hotspots and centres of endemism, and they provide important hydrological and biogeochemical functions that affect human livelihoods. Given their fundamental sensitivity to climate, TMCFs also serve as an early warning system for climate change impacts. This paper outlines a new international initiative, CloudNet, that aims to promote integrated research across TMCFs, and introduces a special issue that reviews emerging themes and topics in the ecology of TMCFs, highlighting knowledge gaps and suggesting new directions for research. CloudNet is helping coordinate several new research projects and protocols: (1) a global repository of TMCF data and meta-analyses across multiple sites; (2) a multi-site study of plant functional traits across TMCFs; (3) a multi-site study of decomposition processes across TMCFs; (4) a protocol for standardizing climate data collection across TMCFs. These studies are intended to evaluate the extent to which general patterns emerge, accounting for biogeographic, phylogenetic and environmental differences among sites. Common data collection across TMCFs should also allow better integration across disciplines, such as linking nutrient limitation, seed production and propagule recruitment, and enable cross-site comparisons of how TMCFs respond to drivers of global change, including rising cloud bases, increasing temperatures, altered disturbance regimes, biological invasions and extinction, and changing human land use.

Although it has long been acknowledged that seed characteristics are of major importance to the conquest of tree crowns by vascular epiphytes, there is surprisingly little quantitative evidence on the aerodynamic properties of their diaspores. We used a custom-built device to determine the terminal velocity (Vterm) of falling seeds, a parameter that has been shown to have high predictive power for the wind dispersal potential of diaspores under natural conditions. We determined Vterm of 45 species of epiphytic and terrestrial Orchidaceae, which almost doubles the currently available database for this family. Although varying by a factor of five with values of 0.09–0.4 m s−1, Vterm was invariably very slow compared to plants in general. For each species, we also took morphological data and determined seed mass. None of these parameters was linearly correlated with Vterm and neither did the average Vterm differ between species found in the two habitats, although seeds of terrestrial taxa were significantly larger and heavier. Finally, we demonstrate the potential of our device to measure Vterm of even smaller diaspores by successfully quantifying Vterm of fern spores. This tool has much potential for the quantitative study of dispersal of plants with tiny diaspores, particularly in a conservation context in fragmented landscapes.

The spatial heterogeneity of tropical forest epiphytes has rarely been quantified in terms of biomass. In particular, the effect of topographic variation on epiphyte biomass is poorly known, although forests on ridges and ravines can differ drastically in stature and exposure. In an Ecuadorian lower montane forest we quantified epiphytic biomass along two gradients: (1) the twig–branch–trunk trajectory, and (2) the ridge–ravine gradient. Twenty-one trees were sampled in each of three forest types (ridge, slope, ravine positions). Their epiphytic biomass was extrapolated to stand level based on basal area–epiphyte load relationships, with tree basal areas taken from six plots of 400 m2 each per forest type. Our results document the successional addition and partial replacement of lichens by bryophytes, angiosperms and finally dead organic matter along the twig–branch–trunk trajectory. Despite having the highest tree basal area, total epiphytic biomass (mean ± SD) of ravine forest was significantly lower (2.6 ± 0.7 Mg ha−1) than in mid-slope forest (6.3 ± 1.1 Mg ha−1) and ridge forest (4.4 ± 1.6 Mg ha−1), whereas maximum bryophyte water storage capacity was significantly higher. We attribute this pattern to differences in forest dynamics, stand structure and microclimate. Although our study could not differentiate between direct effects of slope position (nutrient availability, mesoclimate) and indirect effects (stand structure and dynamics), it provides evidence that fine-scale topography needs to be taken into account when extrapolating epiphytic biomass and related matter fluxes from stand-level data to the regional scale.

This study compares the success of vegetative diaspore establishment of the old forest lichens Lobaria pulmonaria and L. scrobiculata sown on Picea abies branches in boreal rainforests. The larger diaspores of L. pulmonaria (green algal photobiont) established more successfully, and showed a greater flexibility in ecological amplitude, than the smaller diaspores of L. scrobiculata (cyanobacterial photobiont). The establishment success apparently depended on species-specific differences in morphological and physiological traits of the diaspores. Both species established as well in young plantations as in old forests. Lobaria scrobiculata was most successful on short branches and small trees. In contrast, L. pulmonaria responded positively to trunk circumference in the old stands. The establishment success of both species decreases with increasing canopy openness, indicating that the soredia/isidioid soredia failed to establish on the most exposed branches. The probability of establishment did not change with bark-pH or with distance from the nearest stream. Despite a successful establishment in regeneration forests, the long-term survival in managed forests is still uncertain.

Gastropod abundance was quantified in forest litter around 33 trees harbouring Lobaria pulmonaria in southern Norway. In total, 1709 snails representing 28 species were found, and the number of snail species strongly increased with the total number of specimens found. Number of snail species, as well as snail abundance, was highest around trees on high pH soils. There was a positive relationship between number of snail specimens and cover of grazing traces on L. pulmonaria, presumably because calcareous soils facilitate both litter dwelling and climbing gastropods. The results suggest that gastropods may limit the distribution of L. pulmonaria in calcareous broad-leaved forests.

The crustose lichen Lecanora conizaeoides has declined markedly around London with progressively diminishing sulphur dioxide pollution of the air since the 1960s. To identify the immediate causes of its decline, we applied S in the form of bisulphite (0·2 & 2 mM) and sulphate (2 mM), and N as nitrate (2 mM) to relict colonies of the lichen on beech trunks in a plantation in Windsor Forest. Growth of the lichen was monitored by estimating changes in percentage cover. By the end of a 25-month period of two-weekly treatments, all the chemical treatments had resulted in significant decreases in cover of L. conizaeoides compared to distilled water controls, with the 2 mM bisulphite causing the greatest loss. Bark surface pH was also lowered by the chemical treatments, but most by the 2 mM bisulphite applications. Similar results were obtained in two laboratory experiments where the nutrient applications were repeated under a controlled environment and thallus area monitored photographically. No evidence was obtained to support the hypothesis that growth of L. conizaeoides is stimulated by an elevated sulphur supply. We conclude that the disappearance of the lichen is linked to gradual increase in bark pH caused by the combined effects of a marked reduction in SO2 emissions and rising emissions of NH3.

Photosynthetic responses of 12 species including six fern species (Neottopteris nidus, Microsorum punctatum, Pseudodrynaria coronans, Asplenium finlaysonianum, Paraleptochilus decurrens and Tectaria fauriei) and seedlings of six fig species (Ficus curtipes, F. gibbosa, F. altissima, F. auriculata, F. oligodon and F. hookeriana) in different life forms to lightfleck were investigated, to test whether epiphytes and hemiepiphytes display a slower response to lightfleck and fast induction loss after a lightfleck compared with their terrestrial counterparts, and whether ferns display a slower response to lightfleck and slower induction loss compared to figs. The measurements of functional traits and physiological parameters were determined in a screenhouse of 4% full sunlight. Epiphytic ferns and hemiepiphytic figs had thicker leaves compared with their terrestrial counterparts. Compared with figs, ferns had thicker fronds, larger stomata with a low density, and lower stomatal conductance and photosynthetic capacity; ferns had lower light compensation point and dark respiration rate, conferring a positive carbon gain under low diffuse light beneath the canopy. The induction time to reach 90% maximum net photosynthetic rate (T90) upon the exposure to a saturated light varied strongly among life forms. Epiphytic ferns had slower T90 than terrestrial ferns (19.9–26.3 vs 5.9–16.3 min, respectively), and hemiepiphytic figs had slower T90 than terrestrial figs (13.1–20.4 vs 5.2–7.8 min, respectively). Compared with figs, ferns showed a slower response to lightfleck. Across ferns and figs, the induction time was negatively correlated with initial stomatal conductance. No significant difference in induction loss was found between two life forms within ferns or figs, whereas ferns had a significantly slower induction loss compared with figs. These results showed that the inherent conservative water use strategy of the epiphytes and hemiepiphytes constrain their lightfleck utilization.

The habit, shade-tolerance and dispersal agent of 19 bromeliad species were studied in a rainforest community in order to relate specific traits to the spatial occurrence of the species. Highest density was found in riparian forest (RF), followed by restinga scrub (RE), rocky shore (RS) and dense canopy forest (DF). Terrestrial bromeliads occurred in open sites (RE and RS), epiphytes were absent in RS and facultative species occupied all four habitats. Bird-dispersed bromeliads occurred in the upper canopy, whereas those dispersed by mammals were low in the forest profile. Bromeliads which are dispersed by similar fauna fruit sequentially through the year. Differences in traits may allow the sharing of habitats and strata among species.

In comparing the population structure of epiphytic and saxicolous Tillandsia species I found no significant differences between polycarpic species. Epiphytic T. ionochroma populations had a higher seedling:adult ratio than saxicolous T. ionochroma populations, but the difference was not statistically significant. Tillandsia ultriculala, a monocarpic epiphyte, had a significantly higher seedling:adult ratio than the polycarpic species. T. utriculata's higher ratio may result from its greater seed production and lack of vegetative propagation. Unlike the polycarpic species, all adult-size rosettes grow from seeds in T. utriculata. Tillandsia sphaerocephala, an obligate saxicole, occurred in larger clusters (i.e. more rosettes per genet) than T. ionochroma. The increased tendency for vegetative reproduction in T. sphaerocephala suggests that spatial patchiness is less of a constraint than with epiphytes.

The chemistry of epiphytic lichens was determined in two Venezuelan cloud forests adjacent to the Caracas Valley at Altos de Pipe and El Avila National Park. This is the second component of a two-part study examining the chemistry of fogs and their effects on sensitive biota in these forests. The widespread lichen Parmotrema madagascariaceum was chosen as an indicator of trace metal input. Background lichen collections and transplant experiments were carried out to evaluate spatial trends in atmospheric depositon of trace metals at different altitudes and exposures of the two montane locations. Elevated concentratons of metals including Pb and Zn were seen in lichen tissue and associated bark. Lead levels in lichens reached 190 μg g-1 dry wt. Lichens transplanted from relatively ‘clean’ to more polluted sites showed significant increases of metals, particularly Pb. Increases of up to 6.3 μg Pb g-1 mo-1 after 6 and 10 months were recorded relative to background and in situ lichen material. In contrast, when lichsens were reciprocally transplanted in nylon net bags from less to more exposed sites there was a significant decrease in Pb and Zn concentrations after 6 and 10 months. With long-term exposure to elevated concentrations of these trace metals epiphytic lichens, as well as other sensitive cloud forest biota, may be at risk of decline.

Vascular epiphytes can be quite abundant in vegetation close to the ocean surf, where they are exposed to a more or less continuous input of salt spray. The ecophysiological basis of their occurrence, i.e. salt tolerance or avoidance, is unresolved, because all previous studies were observational and conclusions thus circumstantial. Here, the effect of varying concentrations of salt water on germination, and growth and survival of seedlings and established plants was investigated in a growth cabinet study under controlled conditions. Seeds (1500), seedlings (750) and small tank plants (336) were from four populations of Werauhia sanguinolenta that were growing either close to the sea or inland in Panama. Changes of Na+ and K+ concentrations in plant tissue were also determined. No differences in the sensitivity to salt were found among populations, nor among life stages. External concentrations (Cext) of up to 15% sea water (c. 0.5% Na+) allowed complete germination as well as positive growth and survival in both seedlings and established plants over short periods (8–10 wk). After longer exposure (12 wk) of established plants visible damage and increased mortality were observed at lower Cext, but critical tissue Na+ levels were similar: c. 50 mg gDW−1. It is concluded that this common epiphyte does not meet the definition of a halophyte, but still possesses a rather high tolerance to sodium.

Bird's nest ferns (Asplenium nidus complex) (Yatabe & Murakami 2003) are common epiphytes of the Old World tropics and house a high abundance of arthropods (Ellwood & Foster 2004). Through interception and retention of leaf litter (Paoletti et al. 1991, Piggott 1996, Richardson 1999), epiphytes interrupt litterfall dynamics (Clark et al. 1998, Nadkarni & Matelson 1991) and delay the return of nutrients to the forest floor (Nadkarni 1984). Precipitation percolating through the canopy as throughfall is enriched as nutrients are leached from plant surfaces (Levia & Frost 2006). Water flowing down the trunk of trees as stemflow is further enriched from prolonged contact and accumulated nutrient deposits on the trunk (Levia & Frost 2003, Liu et al. 2002). Epiphytes can alter stemflow nutrient concentrations by slowing water percolation and by nutrient uptake and release (Awasthi et al. 1995, Strigel et al. 1994).

Plethiandra (Melastomataceae–Melastomatoideae–Dissochaeteae) comprises seven species in Borneo and one (P. sessiliflora) in the southern part of Peninsular Malaysia and central Sumatra. Plethiandra is easily recognized by its polystaminate androecium, having 16–40 stamens with short, straight, inappendiculate anthers. The closely related Medinilla has a diplostemonous androecium with 8–12 stamens and variously appendaged anthers. Ontogenetic studies in P. hookeri show that the increase in stamen number in Plethiandra results from subdivision of the stamen primordia into three or more subprimordia.

This paper provides a key, genus and species descriptions including diagnostic characters, distribution maps and ecological notes. One species, P. tomentosa, is newly described. During field observations on P. hookeri and P. cuneata pollination by bees and dispersal by birds and squirrels were observed.

Animal-pollinated angiosperm plants that replenish removed nectar invest energy that can entail a reproductive cost. Here we investigated whether or not seed production is affected by replenishing nectar in hummingbird-pollinated Tillandsia multicaulis and T. deppeana (Bromeliaceae) in a montane cloud forest in eastern Mexico. These epiphytic plants respond strongly and positively to repeated nectar removal. The female reproductive cost was assessed in manually, cross-pollinated flowers with or without repeated nectar removal. Seed production from experimental flowers was then contrasted with those naturally exposed to pollination and nectar removal. Tillandsia deppeana set the same number of seeds of the same size regardless of whether or not it had to replenish nectar. Seeds were slightly smaller if the result of natural open pollination than from copious hand crossing. In contrast, T. multicaulis set about half as many seeds when it had to replenish than when it did not, indicating a substantial cost to replenishment. There was no difference in seed number of T. multicaulis between open and hand-augmented pollination. The contrasting results for plants that respond strongly and positively to repeated nectar removal suggest that the female reproductive costs of nectar replenishment can range from costly to beneficial, depending on the conditions of the plants and on the species.