Significance of AI-assisted techniques for epiphyte plant monitoring and identification from drone images.

Monitoring forest canopies is vital for ecological studies, particularly for assessing epiphytes in rain forest ecosystems. Traditional methods for studying epiphytes, such as climbing trees and building observation structures, are labor, cost intensive and risky. Unmanned Aerial Vehicles (UAVs) have emerged as a valuable tool in this domain, offering botanists a safer and more cost-effective means to collect data. This study leverages AI-assisted techniques to enhance the identification and mapping of epiphytes using UAV imagery. The primary objective of this research is to evaluate the effectiveness of AI-assisted methods compared to traditional approaches in segmenting/identifying epiphytes from UAV images collected in a reserve forest in Costa Rica. Specifically, the study investigates whether Deep Learning (DL) models can accurately identify epiphytes during complex backgrounds, even with a limited dataset of varying image quality. Systematically, this study compares three traditional image segmentation methods Auto Cluster, Watershed, and Level Set with two DL-based segmentation networks: the UNet and the Vision Transformer-based TransUNet. Results obtained from this study indicate that traditional methods struggle with the complexity of vegetation backgrounds and variability in target characteristics. Epiphyte identification results were quantitatively evaluated using the Jaccard score. Among traditional methods, Watershed scored 0.10, Auto Cluster 0.13, and Level Set failed to identify the target. In contrast, AI-assisted models performed better, with UNet scoring 0.60 and TransUNet 0.65. These results highlight the potential of DL approaches to improve the accuracy and efficiency of epiphyte identification and mapping, advancing ecological research and conservation.

Aerial and terrestrial root habits influence the composition of the cell walls of Vanilla phaeantha (Orchidaceae).

In response to the restrictions imposed by their epiphytic habit, orchids have developed structural traits that allow greater efficiency in water uptake and use, such as a complex adventitious root system with velamen. The composition of cell wall of this specialized epidermis can be altered according to the substrate to which it is fixed, influencing wall permeability, absorption, and storage of water in roots. The current study aimed to evaluate the cell wall composition of adventitious roots of Vanilla phaeantha (Orchidaceae) that grow attached to the phorophyte, fixed in the soil, or hung free. Immunocytochemical analyses were used to determine the protein, hemicellulose, and pectin composition of the cell walls of aerial and terrestrial roots. We observed that pectins are present in the different tissues of the aerial roots, while in the terrestrial roots, they are concentrated in the cortical parenchyma. The deposition of xyloglucans, extensins, and arabinogalactans was greater in the epidermis of the free side of the roots attached to the phorophyte. The strong labeling of pectins in aerial roots may be related to the influx of water and nutrients, which are generally scarce in this environment. The arrangement of hemicelluloses and proteins with the pectins may be associated with increased cell rigidity and sustainability, a feature of interest for the aerial roots. In summary, the habit of roots can interfere with the non-cellulosic composition of the cell walls of V. phaeantha, possibly related to changes in cell functionality.

Use of lichens as bioindicators of contamination by agrochemicals and metals.

The presence or absence of lichens serves as an indicator of the condition of an ecosystem and the degree to which it is contaminated by various agents, such as agrochemicals and metals. Evaluating the use of lichens as bioindicators of agrochemical contamination could provide a more comprehensive perspective of current contamination levels. Monitoring was conducted over a 4-month period in two study areas: one was a well-conserved area contaminated by metals, and the other was an area surrounded by agricultural crops contaminated by agrochemicals. Data on the presence and abundance of lichens in each study area were recorded at 10 monitoring points, a procedure that was repeated 16 times (every 15 days), and concentrations of heavy metals and "organophosphate" agrochemicals in the lichens collected were measured by means of Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-OES) and Gas Chromatography (GC), respectively. Generalized linear mixed models were used to assess abundance and richness, while general linear mixed models were used to attain Shannon diversity and Simpson dominance indices. Moreover, a multivariate analysis was performed in order to compare the lichen communities in both areas. The results indicated differences between the area contaminated by metals and that contaminated by agrochemicals in terms of abundance and Simpson's dominance index, while no differences were found in the case of the richness and diversity models. The PERMANOVA analysis additionally showed differences between the lichen communities in the two areas. The results also demonstrated that Canoparmelia caroliniana bioaccumulated metals in both areas. The levels of barium, cadmium, and sodium were higher in the area contaminated by metals, while concentrations of chromium and copper were higher in the area contaminated by agrochemicals. Finally, the concentrations of agrochemicals were higher in the area contaminated by agrochemicals and included toxic substances such as Methylparathion and Parathion, which are prohibited in Ecuador. In conclusion, this research underscores the importance of lichens as precise indicators of environmental health and contamination by agrochemicals and metals.

Actualización de la flora epífita del Perú / Update of the epiphytic flora of Peru

Resumen A pesar de la alta diversidad de epífitas vasculares (EV) reportadas en Perú, no existe un listado actualizado que esté acorde con las nuevas delimitaciones taxonómicas y los nuevos conceptos de epífitas. En este trabajo actualizamos el listado de EV de Perú, a partir de una búsqueda bibliográfica y visitas a herbarios locales. Se actualizaron los nombres de las especies según World Flora Online, se confirmó su presencia en la EpiList, su distribución altitudinal y por departamento, su categoría de riesgo y endemismo; y finalmente, se estimó el coeficiente epífito. Encontramos 2462 especies, pertenecientes a 18 órdenes, 25 familias y 249 géneros. Las familias con mayor riqueza fueron Orchidaceae (1606), Bromeliaceae (201) y Piperaceae (139 spp.); el 85 % de las especies estaban en la EpiList (2088 spp.). El departamento con mayor riqueza fue Amazonas (709) y los de menor fueron Ica y Tacna (2 spp.). El rango altitudinal con mayor riqueza se ubica entre los 1501 - 2000 m (649); 689 especies son endémicas y 220 se encuentran en alguna categoría de riesgo; el cociente epífito es de 13.12. Esta actualización representa un incremento aproximado del 40%, lo que posiciona a Perú como el tercer país con mayor diversidad de EV. Se obtuvo un listado más completo y acorde con el concepto de epifitismo; con lo que se hace evidente la necesidad de incluir 384 especies a la EpiList, lo que ayudaría a complementar el listado global de EV en el mundo.

Abstract Despite the high diversity of vascular epiphytes (VE) reported in Peru, there is no updated checklist that is in line with the new taxonomic delimitations and the new concepts of epiphytes. In this study, we update the list of VE in Peru, based on a bibliographic search and visits to local herbaria. Species names were updated according to the World Flora Online, their presence in the EpiList was confirmed, as well as their altitudinal distribution and distribution by department, risk category, and endemism. Finally, the epiphyte coefficient was estimated. We found 2462 species, belonging to 18 orders, 25 families, and 249 genera. The families with the highest richness were Orchidaceae (1606), Bromeliaceae (201), and Piperaceae (139 spp.); 85% of the species were in the EpiList (2088 spp.). The department with the highest richness was Amazonas (709) and the lowest were Ica and Tacna (2 spp.). The altitudinal range with the highest richness is between 1501 - 2000 m (649); 689 species are endemic and 220 are in some risk category; the epiphyte quotient is 13.12. This update represents an approximate 40% increase, positioning Peru as the third country with the highest VE diversity. A more comprehensive list was obtained, in line with the concept of epiphytism, highlighting the need to include 384 species in the EpiList, which would help complement the global list of VE worldwide.

Basic ecology of ant gardens in a dry-premontane transitional forest / Ecología básica de jardines de hormigas en un bosque transicional seco-premontano

Abstract 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 distribution, building, diversity, demography and phenology of ant gardens in dry tropical forest. Methods: In January and February, 2018, we identified 170 ant gardens on a 100x5 m transect on the banks of the Quesada River, Colombia, and in adjacent secondary dry premontane transitional forest; we monitored changes, for gardens and plants, in 28 of them, every two weeks (March 2018-February 2019). Results: The gardens, built by Azteca ulei, were aggregated near water bodies; had 10 species of epiphytes and were on 13 tree species. Larger gardens had more epiphyte species. Some epiphytes had a bimodal phenological pattern. Less seedlings become established in the dry season, and less adults remain in the gardens. Garden characteristics benefit both epiphytes and ants. Conclusions: The gardens built by A. ulei have ecological characteristics that favor the germination, establishment, and reproduction of diverse epiphytes in this dry tropical ecosystem, including aggregation near water flows.

Resumen Introducción: Los "jardines de hormigas'' son nidos de hormigas en árboles, que se localizan a diferentes alturas, sobre los que germinan plantas epífitas vasculares que han sido transportadas y sembradas previamente por hormigas. Aunque esta relación mutualista ha sido estudiada en ecosistemas húmedos tropicales, la información en otros ecosistemas tropicales y en Colombia, es escasa. Objetivo: Caracterizar la distribución, construcción, diversidad, demografía y fenología de los hormigueros en bosque tropical seco. Métodos: En enero y febrero de 2018, identificamos 170 hormigueros en un transecto de 100x5 m a orillas del río Quesada, Colombia, y en el bosque secundario premontano seco de transición adyacente; monitoreamos cambios, para jardines y plantas, en 28 de ellos, cada dos semanas (marzo 2018-febrero 2019). Resultados: Los jardines, construidos por Azteca ulei, se agregaron cerca de cuerpos de agua; tenían 10 especies de epífitas y estaban sobre 13 especies arbóreas. Los jardines más grandes tenían más especies epífitas. Algunas epífitas tuvieron un patrón fenológico bimodal. Se establecen menos plántulas en la estación seca y quedan menos adultos en los jardines. Las características del jardín benefician tanto a las epífitas como a las hormigas. Conclusiones: Los jardines construidos por A. ulei tienen características ecológicas que favorecen la germinación, establecimiento y reproducción de diversas epífitas en este ecosistema tropical seco, incluyendo la agregación cerca de cursos de agua.

New Proposal of Epiphytic Bromeliaceae Functional Groups to Include Nebulophytes and Shallow Tanks.

The Bromeliaceae family has been used as a model to study adaptive radiation due to its terrestrial, epilithic, and epiphytic habits with wide morpho-physiological variation. Functional groups described by Pittendrigh in 1948 have been an integral part of ecophysiological studies. In the current study, we revisited the functional groups of epiphytic bromeliads using a 204 species trait database sampled throughout the Americas. Our objective was to define epiphytic functional groups within bromeliads based on unsupervised classification, including species from the dry to the wet end of the Neotropics. We performed a hierarchical cluster analysis with 16 functional traits and a discriminant analysis, to test for the separation between these groups. Herbarium records were used to map species distributions and to analyze the climate and ecosystems inhabited. The clustering supported five groups, C3 tank and CAM tank bromeliads with deep tanks, while the atmospheric group (according to Pittendrigh) was divided into nebulophytes, bromeliads with shallow tanks, and bromeliads with pseudobulbs. The two former groups showed distinct traits related to resource (water) acquisition, such as fog (nebulophytes) and dew (shallow tanks). We discuss how the functional traits relate to the ecosystems inhabited and the relevance of acknowledging the new functional groups.

Diversity and putative metabolic function of prokaryotic communities in tank bromeliads along an elevation gradient in tropical Mexico.

Tank bromeliads are unique canopy microhabitats that offer freshwater and organic nutrient-rich substrates in the Neotropics. In them it is possible to thoroughly characterize environmental factors and species composition of terrestrial and aquatic biota. Therefore, these plants have been used as natural models to study how communities are distributed and assembled. Here we used amplicon sequencing of the 16S rRNA gene and their functional annotations to study the diversity and metabolic potential of prokaryotic communities in tank bromeliads in five different forests along an elevation gradient in tropical Mexico. Furthermore, we analyzed the effects of vegetation type and environmental factors inside the tanks on prokaryotic composition. We found a high prokaryotic diversity in tank bromeliads along the elevation gradient. Prokaryotes commonly observed in acidic environments rich in organic carbon, and the potential pathogen Pasteurella multocida, were present in all samples, but few amplicon sequence variants were shared between forests. The prokaryotic composition was affected by forest type, and comparisons against null models suggest that it was shaped by non-neutral processes. Furthermore, prokaryotic community changes significantly covaried with tank water temperature, pH, and inorganic carbon. We found a high diversity of putative metabolic groups dominated by chemoheterotrophs and fermenters, but taxonomic groups involved in nitrogen and sulfur cycling were also present in all samples. These results suggest that tank bromeliads promote taxonomic and metabolic diversity of the prokaryotic community at a local and regional scale and play an important role in the biogeochemistry of forest canopies in the Neotropics.

Phylogenetic endemism of the orchids of Megamexico reveals complementary areas for conservation.

Orchid diversity provides a unique opportunity to further our understanding of biotic and abiotic factors linked to patterns of richness, endemism, and phylogenetic endemism in many regions. However, orchid diversity is consistently threatened by illegal trade and habitat transformation. Here, we identified areas critical for orchid conservation in the biogeographic province of Megamexico. For this purpose, we evaluated orchid endemism, phylogenetic diversity, and phylogenetic endemism within Megamexico and characterized orchid life forms. Our results indicate that the majority of the regions with the highest estimates of endemism and phylogenetic endemism are in southern Mexico and northern Central America, mostly located on the Pacific side of Megamexico. Among the most important orchid lineages, several belong to epiphytic lineages such as Pleurothallidinae, Laeliinae and Oncidiinae. We also found that species from diverse and distantly related lineages converge in montane forests where suitable substrates for epiphytes abound. Furthermore, the southernmost areas of phylogenetic diversity and endemism of Megamexico are in unprotected areas. Thus, we conclude that the most critical areas for orchid conservation in Megamexico are located in southern Mexico and northern Central America. We recommend that these areas should be given priority by the Mexican system of natural protected areas as complementary conservation areas.

Fungal diversity in shade-coffee plantations in Soconusco, Mexico.

Background: As forested natural habitats disappear in the world, traditional, shade-coffee plantations offer an opportunity to conserve biodiversity and ecosystem services. Traditional coffee plantations maintain a diversity of tree species that provide shade for coffee bushes and, at the same time, are important repositories for plants and animals that inhabited the original cloud forest. However, there is still little information about shade-coffee plantation's fungal diversity despite their relevance for ecosystem functioning as decomposers, symbionts and pathogens. Specifically, it is unknown if and what mycorrhizae-forming fungi can be found on the branches and trunks of coffee bushes and trees, which hold a diversity of epiphytes. Here, we evaluate fungal communities on specific plant microsites on both coffee bushes and shade trees. We investigate the ecological roles played by this diversity, with a special focus on mycorrhizae-forming fungi that may enable the establishment and development of epiphytic plants. Methods: We collected 48 bark samples from coffee bushes and shade trees (coffee; tree), from four plant microsites (upper and lower trunks, branches and twigs), in two shade-coffee plantations in the Soconusco region in southern Mexico, at different altitudes. We obtained ITS amplicon sequences that served to estimate alpha and beta diversity, to assign taxonomy and to infer the potential ecological role played by the detected taxa. Results: The bark of shade trees and coffee bushes supported high fungal diversity (3,783 amplicon sequence variants). There were no strong associations between community species richness and collection site, plant type or microsite. However, we detected differences in beta diversity between collection sites. All trophic modes defined by FUNGuild database were represented in both plant types. However, when looking into guilds that involve mycorrhizae formation, the CLAM test suggests that coffee bushes are more likely to host taxa that may function as mycorrhizae. Discussion: We detected high fungal diversity in shade-coffee plantations in Soconusco, Chiapas, possibly remnants of the original cloud forest ecosystem. Several mycorrhiza forming fungi guilds occur on the bark of coffee bushes and shade trees in this agroecosystem, with the potential of supporting epiphyte establishment and development. Thus, traditional coffee cultivation could be part of an integrated strategy for restoration and conservation of epiphytic populations. This is particularly relevant for conservation of threatened species of Orchidaceae that are highly dependent on mycorrhizae formation.

Local drivers of heterogeneity in a tropical forest: epiphytic tank bromeliads affect the availability of soil resources and conditions and indirectly affect the structure of seedling communities.

Environmental heterogeneity is a key component in explaining the megadiversity of tropical forests. Despite its importance, knowledge about local drivers of environmental heterogeneity remains a challenge for ecologists. In Neotropical forests, epiphytic tank bromeliads store large amounts of water and nutrients in the tree canopy, and their tank overflow may create nutrient-rich patches in the soil. However, the effects of this nutrient flux on environmental heterogeneity and plant community structure in the understory remain unexplored. In a Brazilian coastal sandy forest, we investigated the effects of the presence of epiphytic tank bromeliads on throughfall chemistry, soil chemistry, soil litter biomass, light, and seedling community structure. In the presence of epiphytic tank bromeliads, the throughfall nitrogen concentration increased twofold, the throughfall phosphorus concentration increased threefold, and the soil patches had a 3.96% higher pH, a 50% higher calcium concentration, and 11.88% less light. By altering the availability of soil resources and conditions, the presence of bromeliads partially shifted the available niche spaces for plant species and indirectly affected the structure of the seedling communities, decreasing their diversity, density, and biomass. For the first time, we showed that the presence of tank bromeliads in the canopy can create characteristic soil patches in the understory, affecting the structure of seedling communities via fertilization. Our results reveal a novel local driver of environmental heterogeneity, reinforcing and expanding the key role of tank bromeliads both in nutrient cycling and plant community structuring of Neotropical coastal sandy forests.

Fungal communities in feces of the frugivorous bat Ectophylla alba and its highly specialized Ficus colubrinae diet.

BACKGROUND: Bats are important long-distance dispersers of many tropical plants, yet, by consuming fruits, they may disperse not only the plant's seeds, but also the mycobiota within those fruits. We characterized the culture-dependent and independent fungal communities in fruits of Ficus colubrinae and feces of Ectophylla alba to determine if passage through the digestive tract of bats affected the total mycobiota. RESULTS: Using presence/absence and normalized abundance data from fruits and feces, we demonstrate that the fungal communities were significantly different, even though there was an overlap of ca. 38% of Amplicon Sequence Variants (ASVs). We show that some of the fungi from fruits were also present and grew from fecal samples. Fecal fungal communities were dominated by Agaricomycetes, followed by Dothideomycetes, Sordariomycetes, Eurotiomycetes, and Malasseziomycetes, while fruit samples were dominated by Dothideomycetes, followed by Sordariomycetes, Agaricomycetes, Eurotiomycetes, and Laboulbeniomycetes. Linear discriminant analyses (LDA) show that, for bat feces, the indicator taxa include Basidiomycota (i.e., Agaricomycetes: Polyporales and Agaricales), and the ascomycetous class Eurotiomycetes (i.e., Eurotiales, Aspergillaceae). For fruits, indicator taxa are in the Ascomycota (i.e., Dothideomycetes: Botryosphaeriales; Laboulbeniomycetes: Pyxidiophorales; and Sordariomycetes: Glomerellales). In our study, the differences in fungal species composition between the two communities (fruits vs. feces) reflected on the changes in the functional diversity. For example, the core community in bat feces is constituted by saprobes and animal commensals, while that of fruits is composed mostly of phytopathogens and arthropod-associated fungi. CONCLUSIONS: Our study provides the groundwork to continue disentangling the direct and indirect symbiotic relationships in an ecological network that has not received enough attention: fungi-plants-bats. Findings also suggest that the role of frugivores in plant-animal mutualistic networks may extend beyond seed dispersal: they may also promote the dispersal of potentially beneficial microbial symbionts while, for example, hindering those that can cause plant disease.

Leaf structure of Tillandsia species (Tillandsioideae: Bromeliaceae) by light microscopy and scanning electron microscopy.

Tillandsia L. is the largest genus of the family Bromeliaceae, containing 755 species and seven subgenera. Morphoanatomical studies of leaves provide useful characteristics to phylogenetic, taxonomic, and ecological analyses. This study aims to characterize and compare the leaves of 24 species of the four subgenera of Tillandsia that occur in Bahia and also perform adaptative inferences to environmental responses. The results of the species' morphoanatomical studies were compared through dissimilarity analysis. The species have rosulate leaves with varying lengths and widths. The peltate trichomes present variation in the indument density and the length of their wing and central disk. The stomata are longitudinally distributed in one or both sides of the limb. The mesophyll is dorsiventral and presents aquiferous and chlorophyllic parenchymas. The vascular bundles are collateral and partially covered by fibers, except for Tillandsia linearis. Based on the dissimilarity analysis, it was possible to identify the formation of five groups. Group G1 was composed of T. linearis, which diverged from the other species of the subgenus. Group G2 was formed by the remaining species of the subgenus Phytarrhiza. G3 and G4 presented the species of the subgenus Diaphoranthema and Tillandsia, respectively. Group G5 gathered 11 species of the subgenus Anoplophytum and presented higher variability than the other subgenera. Based on the results, the morphoanatomical characteristics can be used to characterize and group Tillandsia species, besides confirming the morphological variability of these species to the epiphyte habit in different environments, especially xeric ones.

Biovera-Epi: A new database on species diversity, community composition and leaf functional traits of vascular epiphytes along gradients of elevation and forest-use intensity in Mexico.

BACKGROUND: This data paper describes a new, comprehensive database (BIOVERA-Epi) on species distributions and leaf functional traits of vascular epiphytes, a poorly studied plant group, along gradients of elevation and forest-use intensity in the central part of Veracruz State, Mexico. The distribution data include frequencies of 271 vascular epiphyte species belonging to 92 genera and 23 families across 120 20 m × 20 m forest plots at eight study sites along an elevational gradient from sea level to 3500 m a.s.l. In addition, BIOVERA-Epi provides information on 1595 measurements of nine morphological and chemical leaf traits from 474 individuals and 102 species. For morphological leaf traits, we provide data on each sampled leaf. For chemical leaf traits, we provide data at the species level per site and land-use type. We also provide complementary information for each of the sampled plots and host trees. BIOVERA-Epi contributes to an emerging body of synthetic epiphytes studies combining functional traits and community composition. NEW INFORMATION: BIOVERA-Epi includes data on species frequency and leaf traits from 120 forest plots distributed along an elevational gradient, including six different forest types and three levels of forest-use intensity. It will expand the breadth of studies on epiphyte diversity, conservation and functional plant ecology in the Neotropics and will contribute to future synthetic studies on the ecology and diversity of tropical epiphyte assemblages.

Variación en la fenología de floración de una bromelia epífita a lo largo de un gradiente de elevación / Variation in the flowering phenology of an epiphytic bromeliad along an elevational gradient

ABSTRACT Elevational patterns in flowering phenology have been reported for trees, shrubs and herbs. However, for vascular epiphytes that rely on atmospheric sources for humidity and nutrients, and depend on phorophyte microhabitat, elevational patterns of variation are unknown. In this study, we described the flowering phenology of Tillandsia carlos-hankii, an epiphytic bromeliad, along an elevational gradient in Capulálpam de Méndez, Oaxaca. We analyzed the onset, seasonality and duration of flowering along and within different elevation zones, and we evaluated the effect of phorophyte features (tree height, DBH and canopy diameter) on flowering start date and duration. From June 2016 to May 2017, we periodically recorded phenological data from six populations along three elevation zones ("low": 2151 to 2283 m. a. s. l., "medium": 2284 to 2416 m. a. s. l. and "high": 2417 to 2548 m. a. s. l.), monitoring two population per zone. Start of flowering occurred between December and January, beginning six to 16 days earlier at low elevations than in the other zones, although this difference was not statistically significant. We observed marked flowering seasonality at all the elevation zones, with differences between zones (W≥18.49, p≤0.0001) and between the populations at medium and high elevations (W≥8.57, p≤0.05). Flowering duration spanned from December to May. Phorophyte features were not related to the onset or duration of flowering (t≤-1.47, p≥0.14, in all cases). Our results suggest that vascular epiphytes follow the same elevational patterns in phenology as other life forms, and that populations in the same elevation range can vary. The causes of such intra-elevational variation merit further investigation.

RESUMEN Se han reportado los patrones altitudinales en la fenología de floración para árboles, arbustos y hierbas. Sin embargo, para epífitas vasculares, que dependen de fuentes atmosféricas para la humedad y los nutrientes, y del microhábitat del forofito, los patrones de variación en gradientes de elevación se desconocen. Se describe la fenología de floración de Tillandsia carlos-hankii, una bromelia epífita, en un gradiente de elevación en Capulálpam de Méndez, Oaxaca. Se analiza el inicio, estacionalidad y duración de su floración entre y dentro de diferentes elevaciones y se evalúa también el efecto del forofito (altura, DAP y diámetro de copa) sobre el inicio y la duración de la floración. De junio de 2016 a mayo de 2017, se monitorearon individuos localizados en seis poblaciones en tres elevaciones (bajo: 2151-2283 m. s. n. m., medio: 2284-2416 m. s. n. m., alto: 2417-2548 m. s. n. m.), dos poblaciones por zona. El inicio de la floración ocurrió entre diciembre y enero, empezando de seis a 16 días antes en la elevación baja que en las otras, aunque estas diferencias no fueron significativas. Hubo una marcada estacionalidad en todas las zonas de elevación, con diferencias entre elevaciones (W≥18,49, p≤0,0001) y entre poblaciones de media y alta elevación (W≥8,57, p≤0,05). La floración duró de diciembre a mayo. Las características del forofito no estuvieron relacionadas con el inicio ni la duración de la floración (t≤-1,47, p≥0,14, en todos los casos). Los resultados sugieren que las epífitas vasculares siguen el mismo patrón fenológico altitudinal de otras formas de vida, y que las poblaciones en un misma elevación altitudinal pueden variar. Las causas de tal variación intra-altitudinal merecen mayor investigación.

Bryophyte and lichen biomass and nitrogen fixation in a high elevation cloud forest in Cerro de La Muerte, Costa Rica.

Cloud forests have been found to lose more nitrogen in stream discharge than they gain from atmospheric deposition. They also support a large diversity and biomass of tree epiphytes, predominately composed of cryptogams. Since cryptogam epiphytes harbor nitrogen fixing cyanobacteria, they may help make up for the nitrogen loss from ecosystems. We assessed cryptogam biomass on the ground, boles and branches in Quercus costaricensis dominated stands near the tree line in the Cordillera de Talamanca, Costa Rica. Nitrogen fixation was assayed using 15N2 uptake. Total cryptogam biomass was 2 977 kg ha-1, with 67% being found on the lower branches. Bryophytes and chlorolichens made up 53% and 44%, respectively, of the biomass. Half of the bryophyte mass was composed of the liverwort Plagiochila heterophylla, and 66% of the chlorolichen of Lobariella pallida. There were no significant differences in nitrogen fixation rates between the cryptogam species, with a mean rate of 5.04 µg N g-1 day-1 during the predominantly wet condition in the forest. The overall nitrogen input from fixation was 6.1 kg N ha-1 year-1, of which 78% came from bryophytes, 18% from chlorolichens, and 4% from cyanolichens. Only 2.0% of the fixation occurred in cryptogams on the ground, whereas 67%, 24%, and 7% occurred on the lower branches, boles, and upper branches, respectively. These results show that tree epiphytes constitute a significant source of nitrogen for these forests, due to the trees' large surface area, and can make up for the nitrogen lost from these ecosystems.

Briófitos en los troncos de árboles como indicadores de la alteración en bosques montanos de Panamá / Bryophytes on tree trunks as indicators of montane forest disturbance in Panama

Introducción: Los bosques montanos tropicales se caracterizan por una alta riqueza y endemismo de briófitos. Sin embargo, la diversidad es altamente sensible a cambios microclimáticos relacionados con alteraciones antrópicas. Objetivo: En este estudio, se evaluó la riqueza y composición de briófitos epífitos en los troncos de árboles de bosques montanos alterados y bosques no alterados ubicados en la ladera occidental del Parque Nacional Volcán Barú. Métodos: Los bosques no alterados mostraron alta humedad, mientras que los bosques alterados mostraron altos niveles de luz y temperatura. En cada árbol evaluamos la presencia y cobertura de briófitos epífitos en 160 cuadrantes de 20 × 30 cm. Resultados: Se registraron un total de 86 especies (49 hepáticas y 37 musgos). La riqueza fue positivamente influenciada por la alteración antrópica, donde los bosques alterados presentaron un mayor número de epífitos de sol. La composición de las comunidades difiere entre los dos tipos de bosques, donde las epífitas de sombra fueron restringidas a bosques no alterados, mientras que las epífitas de sol a zonas alteradas. Conclusiones: Las comunidades de briófitos fueron indicadores efectivos de la alteración de los bosques montanos del Parque Nacional Volcán Barú. Por lo tanto, la conservación de los bosques no alterados garantizará la conservación de una rica y diversa comunidad de briófitos epífitos.

Introduction: Tropical montane forests are characterized by high species richness and endemism of bryophytes. However, this diversity is highly sensitive to microclimatic changes related to anthropogenic disturbance. Objective: In this study, we assessed the richness and composition of epiphytic bryophytes on the trunks of trees in undisturbed and disturbed montane forests on the Western slope of the Baru Volcano National Park. Methods: Undisturbed forests were highly humid, while disturbed forests showed high light levels and temperature. In each tree we measured the presence and cover of epiphytic bryophytes in 160 quadrants of 20 × 30 cm. Results: In total, we recorded 86 species (49 liverworts and 37 mosses). Bryophytes richness was positively influenced by disturbance, with disturbed forests showing a high number of sun epiphytes. Bryophyte community composition was different in each forest type, with shade epiphytes confined to primary forests and sun epiphytes restricted to disturbed sites. Conclusions: Bryophyte communities were effective indicators of montane forests disturbance on the Baru Volcano. Thus, protection of the undisturbed forests remnants might help to preserve a rich and diverse community of epiphytic bryophytes.

Inducción de organogénesis in vitro con 6-bencilaminopurina en Cattleya trianae Linden & Rchb.f / Induction of organogenesis in vitro with 6-benzylaminopurine in Cattleya trianae Linden & Rchb.f

RESUMEN La orquídea Cattleya trianae Linden & Rchb.f. es reconocida como flor nacional de Colombia y se encuentra en peligro crítico, al presentar una reducción estimada mayor al 80% en los últimos 100 años, debido a la disminución en la calidad del hábitat y niveles altos de explotación o recolección. La familia Orchidaceae es una de las que mayor número de especies posee en el reino Plantae, con aproximadamente 900 géneros, de los cuales, el 38% es endémico de Colombia, concentrado en la región Andina, con 87,2%. Esta investigación buscó profundizar en el tema de la propagación como mecanismo de conservación, para lo cual, se determinó el efecto de la 6-Bencilaminopurina (6-BAP), sobre el desarrollo in vitro, en Fusagasugá (Cundinamarca), en un diseño de bloques completamente al azar, con 3 repeticiones. Cuerpos protocórmicos provenientes de semillas recolectadas en Pacho (Cundinamarca) fueron sembrados en medio básico Murashige & Skoog, enriquecido con 4 concentraciones de 6-BAP. Los resultados mostraron respuestas diferenciales a la adición de la citoquinina, ya que, con la concentración más alta, se obtuvo el mayor porcentaje de callos, con la de 0,05mg.L-1, el mayor porcentaje de brotes y sin la aplicación del regulador de crecimiento, el mayor porcentaje de raíz.

ABSTRACT The orchid Cattleya trianae Linden & Rchb.f. is recognized as the national flower of Colombia, the species is in a critical danger, presenting an estimated reduction of more than 80% in the last 100 years due to the decrease in habitat quality and high levels of exploitation or harvesting. The Orchidaceae family is one of the largest number of species in the Plant Kingdom, with approximately 900 genera, of which 38% are endemic in Colombia, concentrated in the Andean region with 87.2%. This research sought to deepen in the topic of the propagation as mechanism of protection for their conservation, for which the effect of cytokinin 6-benzylaminopurine (6-BAP) on development was determined in vitro in Fusagasugá (Cundinamarca), in a completely randomized block design with 3 replicates. The protocorm-like bodies from seeds collected in Pacho (Cundinamarca) were sown in a basic medium Murashige and Skoog enriched with 4 concentrations of 6-BAP. The results showed differential responses to the addition of cytokinin, as the highest concentration was obtained the highest percentage of callus, with the 0.05mg. L-1, the highest percentage of shoots and without the application of the growth regulator, the highest root percentage.

Functional composition of epiphyte communities in the Colombian Andes.

We identify changes in the functional composition of vascular epiphytes along a tropical elevational gradient with the aim of quantifying the role of climate in determining the assembly of epiphyte communities. We measured seven leaf functional traits (leaf area, specific leaf area, leaf dry-matter content, leaf thickness, force to punch, stomatal density, and potential conductance index) in the 163 most abundant epiphyte species recorded across 10 sites located along an elevational gradient between 60 and 2,900 m above sea level in the Colombian Andes. We grouped the epiphyte species into seven hierarchical functional groups according to their most characteristic leaf traits. Along the elevational gradient, the two main independent leaf trait dimensions that distinguished community assemblages were defined primarily by leaf area-photosynthetic (LAPS) and mass-carbon (LMCS) gradients. Mean annual temperature was the main determinant of species position along LAPS. In contrast, local changes in specific leaf area due to variation in the epiphytes' relative height of attachment was the main determinant of their position along the LMCS. Our findings indicate that epiphytic plant leaves have evolved to optimize and enhance photosynthesis through a leaf area-based strategy and carbon acquisition through investments in construction costs of leaf area per unit of biomass that aim to regulate light capture and tissue development. Given that most studies of plant functional traits neglect vascular epiphytes, our quantification of the multiple dimensions of epiphyte leaf traits greatly augments our understanding of vascular plant function and adaptation to changing environments.

Microbialite-like structures in Cladophora sp. (Ulvophyceae) mats from a subtropical Andean basin: ecological implications / Estructuras de tipo microbialito en Cladophora sp. (Ulvophyceae) de una cuenca andina subtropical: implicaciones ecológicas

Abstract The solubility equilibrium of calcite is influenced by physicochemical, climatic and biological factors. Annual cycles of exceptionally prolonged drought, in conjunction with naturally occurring diffuse organic pollution, generate the unique conditions for the precipitation of lithified carbonate structures (microbialites). The aim of this article is to analyze the possible implications of calcite precipitation produced in mats of Cladophora sp. in an Andean subtropical basin, considering it is the first time this phenomenon is described for the region. We collected samples from selected sites at the Lules River Basin, in four sampling dates between the years 2003 and 2004, within a monitoring work of 15 years. Samples were analyzed using an electron microscope and X-ray diffraction analysis. We found that Gomphonema sp. attached to Cladophora sp. contributes to precipitation of calcite and formation of microbialite like structures, in the studied area. This work presents an initial discussion of the discovery of microbialites-like structures attached to Cladophora sp. mats in a subtropical Andean stream and the environmental conditions that lead to their production, as well as the possible ecological implications of these microbialites.(AU)

Resumen La fase sólida de las sales de los cuerpos de agua juega un papel importante en la concentración de los elementos mayoritarios. El equilibrio de solubilidad de la calcita está influenciado por factores fisicoquímicos, climáticos y biológicos. Los ciclos anuales de sequía excepcionalmente prolongada, junto con la contaminación orgánica difusa de origen natural, generan condiciones únicas para la precipitación de estructuras de carbonato litificado (microbialitos). El objetivo de este artículo es analizar las posibles implicaciones de la precipitación de calcita producida en Cladophora sp. en una cuenca subtropical andina, considerando que es la primera vez que se describe este fenómeno para la región. Recolectamos muestras en sitios seleccionados en la Cuenca del Río Lules, en cuatro fechas de muestreo entre 2003 y 2004, en el marco de un trabajo de monitoreo de quince años. Usamos red Surber para realizar los muestreos. Las muestras de algas, una vez libres de macroinvertebrados, se secaron y pesaron. Analizamos utilizando microscopía electrónica y difracción de rayos X. Encontramos que Gomphonema sp. unido a Cladophora contribuye a la precipitación de calcita y la formación de estructuras similares a microbialitos, en el área estudiada. Este trabajo presenta una discusión inicial sobre el descubrimiento de estructuras similares a microbialitos unidas a filamentos de Cladophora sp. en una cuenca andina subtropical y las condiciones ambientales que conducen a su producción, así como las posibles implicaciones ecológicas de lo mencionado anteriormente.(AU)