Bird species inventory in secondary tropical montane cloud forest at Cloudbridge Nature Reserve, Talamanca Mountains, Costa Rica

The tropical montane cloud forests (TMCF) of the Talamanca Mountains of Costa Rica are a unique and understudied habitat that is home to a high number of endemic bird species. Cloudbridge Nature Reserve is a TMCF reforestation reserve lying on the Pacific slope of Cerro Chirripó in the cantón of Pérez Zeledón. Here, we synthesize data collected at Cloudbridge between March 2016 and May 2020 from multi-year point count, walking, call-playback, and camera trap surveys along with photographs collected from February 2007 to April 2021 to present a bird species inventory of the reserve. In total, 204 bird species from 40 families, including 40 endemic species, were identified, and monthly presence summarized for each species. We discuss the implications of our findings for understanding TMCF avian communities, as well as the importance of year-round surveys using a variety of techniques to better capture overall avian diversity.

Measurement report: Impact of African aerosol particles on cloud evolution in a tropical montane cloud forest in the Caribbean

African aerosol particles, traveling thousands of kilometers before reaching the Americas and the Caribbean, directly scatter and absorb solar radiation and indirectly impact climate by serving as cloud condensation nuclei (CCN) or ice-nucleating particles (INPs) that form clouds. These particles can also affect the water budget by altering precipitation patterns that subsequently affect ecosystems. As part of the NSF-funded Luquillo Critical Zone Observatory, field campaigns were conducted during the summers of 2013 (23 d), 2014 (11 d), and 2015 (92 d) at Pico del Este, a site in a tropical montane cloud forest on the Caribbean Island of Puerto Rico. Cloud microphysical properties, which included liquid water content, droplet number concentration, and droplet size, were measured. Using products from models and satellites, as well as in situ measurements of aerosol optical properties, periods of high- and low-dust influence were identified. The results from this study suggest that meteorology and air mass history have a more important effect on cloud processes than aerosols transported from Africa. In contrast, air masses that arrived after passing over the inhabited islands to the southeast led to clouds with much higher droplet concentrations, presumably due to aerosols formed from anthropogenic emissions.

Ascomycetes from the relic forest of Oreomunnea mexicana, Oaxaca, Mexico

La Esperanza is an Oaxacan relic area of the Tertiary, dominated by the big tree Oreomunnea mexicana (Juglandaceae). The forest is part of the priority region for the conservation of La Chinantla and constitutes one of the most conserved Mexican tropical montane cloud forests. We studied the Ascomycetes fungi and found 63 species, of which 32 are new records for Oaxaca. Ascocoryne inflata, Calyculosphaeria macrospora, Cercophora costaricensis, Chaetosphaeria ellisii, Coccomyces limitatus, Lasiosphaeria ovina, Leptogidium dendriscum, Marthamyces quadrifidus, Stereocaulon didymicum and Thelonectria lucida are new records for Mexico. Xylaria was the most diverse genus with 12 species. The most abundant species were Xylaria arbuscula and Lachnum apalum. The main growth habit was lignicolous. The tropical montane cloud forest of La Esperanza has unique characteristics allowing great taxonomic diversity of Ascomycetes.

Influence of Pleistocene climatic oscillations on the phylogeography and demographic history of endemic vulnerable trees (section Magnolia) of the Tropical Montane Cloud Forest in Mexico

The Tropical Montane Cloud Forest (TMCF) is a highly dynamic ecosystem that has undergone frequent spatial changes in response to the interglacial-glacial cycles of the Pleistocene. These climatic fluctuations between cold and warm cycles have led to species range shifts and contractions-expansions, resulting in complex patterns of genetic structure and lineage divergence in forest tree species. In this study, we sequenced four regions of the chloroplast DNA (trnT-trnL, trnK5-matk, rpl32-trnL, trnS-trnG) for 20 populations and 96 individuals to evaluate the phylogeography, historical demography, and paleodistributions of vulnerable endemic TMCF trees in Mexico: Magnolia pedrazae (north-region), M. schiedeana (central-region), and M. schiedeana population Oaxaca (south-region). Our data recovered 49 haplotypes that showed a significant phylogeographic structure in three regions: north, central, and south. Bayesian Phylogeographic and Ecological Clustering (BPEC) analysis also supported the divergence in three lineages and highlighted the role of environmental factors (temperature and precipitation) in genetic differentiation. Our historical demography analyses revealed demographic expansions predating the Last Interglacial (LIG, ~125,000 years ago), while Approximate Bayesian Computation (ABC) simulations equally supported two contrasting demographic scenarios. The BPEC and haplotype network analyses suggested that ancestral haplotypes were geographically found in central Veracruz. Our paleodistributions modeling showed evidence of range shifts and expansions-contractions from the LIG to the present, which suggested the complex evolutionary dynamics associated to the climatic oscillations of the Pleistocene. Habitat management of remnant forest fragments where large and genetically diverse populations occur in the three TMCF regions analyzed would be key for the conservation of these magnolia populations.

Bidirectional Turbulent Fluxes of Fog at a Subtropical Montane Cloud Forest Covering a Wide Size Range of Droplets

Size-resolved turbulent fluxes of fog droplets are investigated above a subtropical montane cloud forest in Taiwan. By integrating an aerosol spectrometer into an eddy-covariance set-up, we measure droplet number fluxes and liquid water fluxes in a size range of aerosol particles and droplets with diameters ranging from 0.25 $${\upmu }\!\mathrm{m}$$ μ m to 17.3 $${\upmu }\!\mathrm{m}$$ μ m . We find two flux-direction changes within this size range: a downward flux occurs for accumulation-mode aerosols of diameters between 0.25 $${\upmu }\!\mathrm{m}$$ μ m and 0.83 $${\upmu }\!\mathrm{m}$$ μ m , an upward flux occurs for hydrated aerosols with diameters between 1.1 $${\upmu }\!\mathrm{m}$$ μ m and 2.4 $${\upmu }\!\mathrm{m}$$ μ m , and a downward flux occurs again for activated fog droplets between diameters of 3 $${\upmu }\!\mathrm{m}$$ μ m and 17.3 $${\upmu }\!\mathrm{m}$$ μ m . The droplet size distributions can be modelled by a trimodal log-normal distribution, and the modes correlate with the different flux directions. The formation of the three modes and the establishment of the respective flux directions can be explained by combining the Köhler theory on the basis of measured ion concentrations in fog with the turbulent transport of droplets. Finally, from the combined analysis of droplet fluxes and size distributions, we infer relevant processes of droplet development and dissolving during various phases of the life cycles of the fog events.

First Locality Record of Melanistic Oncilla (Leopardus tigrinus) in Monteverde, Costa Rica

The persistence of the coat color polymorphism melanism has been reported for several tropical felids, but its evolutionary advantages remain an active area of research. Few publications have explored melanism in the elusive species, oncilla (Leopardus tigrinus) within the Neotropical part of their range in Costa Rica. Herein, I present the first record of a melanistic oncilla within the montane cloud forest of Monteverde, Costa Rica. Recent studies have found support for theories (e.g. Temporal Segregation Hypothesis and Gloger’s Rule) explaining the ecological advantages driving melanism in oncilla and tropical felid populations. However, it is unclear what is driving melanism in this Monteverde oncilla population due to the singular observation. Further research investigating whether melanism is occurring at a higher frequency in other individuals in the region is critical to better understanding the occurrence of melanism in local populations of this cryptic species. The montane cloud forest in Monteverde provides critical habitat to this vulnerable species within the small Neotropical part of their range. Melanistic individuals may be particularly threatened by land-use change and increasing human pressure if theories for the evolutionary advantages and ecological conditions motivating melanism are supported.