Neotropical Montane Forest Research Articles

Arbutoid mycorrhizas of the genus Cortinarius from Costa Rica.

Arbutoid mycorrhizas of Comarostaphylis arbutoides (Arbutoidea, Ericaceae) from neotropical montane forests are rarely described. To date, only mycorrhizal associations with the fungal species Leccinum monticola, Leotia lubrica and Sebacina sp. are known from literature. The genus Cortinarius is one of the most species-rich ectomycorrhizal taxa with over 2000 assumed species. In this study, two sites in the Cordillera de Talamanca of Costa Rica were sampled, where Com. arbutoides is endemic and grows together with Quercus costaricensis. Using a combined method of rDNA sequence analysis and morphotyping, 33 sampled mycorrhizal systems of Cortinarius were assigned to the subgenera Dermocybe, Phlegmacium and Telamonia. Specific plant primers were used to identify the host plant. Here, we present the phylogenetic data of all found Cortinarii and describe four of the arbutoid mycorrhizal systems morphologically and anatomically.

Variation in ectomycorrhizal fungal communities associated with Oreomunnea mexicana (Juglandaceae) in a Neotropical montane forest.

Neotropical montane forests are often dominated by ectomycorrhizal (EM) tree species, yet the diversity of their EM fungal communities remains poorly explored. In lower montane forests in western Panama, the EM tree species Oreomunnea mexicana (Juglandaceae) forms locally dense populations in forest otherwise characterized by trees that form arbuscular mycorrhizal (AM) associations. The objective of this study was to compare the composition of EM fungal communities associated with Oreomunnea adults, saplings, and seedlings across sites differing in soil fertility and the amount and seasonality of rainfall. Analysis of fungal nrITS DNA (nuclear ribosomal internal transcribed spacers) revealed 115 EM fungi taxa from 234 EM root tips collected from adults, saplings, and seedlings in four sites. EM fungal communities were equally species-rich and diverse across Oreomunnea developmental stages and sites, regardless of soil conditions or rainfall patterns. However, ordination analysis revealed high compositional turnover between low and high fertility/rainfall sites located ca. 6km apart. The EM fungal community was dominated by Russula (ca. 36 taxa). Cortinarius, represented by 14 species and previously reported to extract nitrogen from organic sources under low nitrogen availability, was found only in low fertility/high rainfall sites. Phylogenetic diversity analyses of Russula revealed greater evolutionary distance among taxa found on sites with contrasting fertility and rainfall than was expected by chance, suggesting that environmental differences among sites may be important in structuring EM fungal communities. More research is needed to evaluate whether EM fungal taxa associated with Oreomunnea form mycorrhizal networks that might account for local dominance of this tree species in otherwise diverse forest communities.

Do Nearctic migrant birds compete with residents at army ant raids? A geographic and seasonal analysis

ABSTRACT Army ant swarm raids in Neotropical montane forest are attended by diverse flocks of foraging birds that can include residents year-round and overwintering Nearctic migrants. We asked whether migrants and residents affect each other's ability to forage at army ant raids. We quantified variation in raid attendance by three guilds of birds: wintering migrants, regular and obligate raid attending residents (ant-following residents), and facultative raid attending residents. To test whether wintering migrants and residents were negatively associated at raids, we collected data on raid attendance in four adjacent life zones in the Tilaran Mountains of Costa Rica and in different seasons (when migrants were present and absent). We first compared the guilds' raid attendance among life zones. There was little geographic overlap of migrants and ant-following residents at raids, and raid attendance frequencies were strongly correlated with the estimated local abundances of these bird guilds in each life zo...

Topography and edge effects are more important than elevation as drivers of vegetation patterns in a neotropical montane forest

AbstractAimsThe high plant species diversity of tropical mountain forests is coupled with high habitat heterogeneity along gradients in elevation and topography. We quantified the effects of elevation, topography and forest edge on habitat conditions and woody plant diversity of tropical montane forest fragments.LocationTropical montane forest fragments, ‘Yungas’, Bolivia.MethodsWe measured microclimate and sampled soil properties and woody vegetation at forest edges and in the forest interior on ridges and in gorges along an elevational gradient of 600 m. We analysed effects of elevation, topography and forest edge on habitat conditions (i.e. microclimate, soil properties and forest structure), species richness, evenness and composition with linear mixed effects models and detrended correspondence analysis (DCA).ResultsChanges in habitat conditions were weaker along the elevational gradient than between forest interior and forest edge and between different topographies. Species richness was not affected by any gradient, while species evenness was reduced at forest edges. All three gradients affected species composition, while effects of topography and forest edge were stronger than that of elevation.ConclusionsIn general, effects of the 600‐m elevational gradient were weak compared to effects of forest edge and topography. Edge effects shifted species composition towards pioneer species, while topographical heterogeneity is particularly important for generating high diversity in montane forests. These results underscore that edge effects have severe consequences in montane forest remnants and that small‐scale variation between topographical microhabitats should be considered in studies that predict monotonous upslope migrations of plant species in tropical montane forests due to global warming.

Patterns of growth, recruitment, mortality and biomass across an altitudinal gradient in a neotropical montane forest, Dominican Republic

Abstract:We examined stand dynamics and biomass along an altitudinal gradient in a tropical montane forest (TMF) in the disturbance-prone Cordillera Central, Dominican Republic. We tested the general hypothesis that chronic disturbance by fire, wind, floods and landslides results in a landscape of relatively low above-ground biomass with high rates of mortality, recruitment and growth as compared with other TMFs. We also expected above-ground biomass to decrease with altitude in part due to declines in growth and increased biomass losses from mortality with increasing altitude. We resurveyed 75 0.1-ha plots distributed across the altitudinal gradient (1100–3100 m asl) 8 y after they were established. Our observations provided mixed evidence on these hypotheses. Turnover rates were high (> 2% y−1) and significantly greater on windward slopes. Above-ground biomass (mean = 306 Mg ha−1, 95% CI = 193–456 Mg ha−1) was highly variable but comparable to other TMFs. Altitudinal patterns of declining biomass and above-ground growth matched observations for other TMFs, whereas mortality and recruitment exhibited no altitudinal trends. More quantitative studies in a variety of TMF settings are needed to better understand how natural disturbance, complex environmental gradients and species dynamics interact to regulate carbon storage, sequestration and turnover across altitudinal gradients in TMFs.

Vegetation Zonation in a Neotropical Montane Forest: Environment, Disturbance and Ecotones

Gradual changes in vegetation structure and composition are expected to result from continuous environmental change with increasing elevation on mountains. Hence, the occurrence of abrupt or discrete ecotones in vegetation patterns is intriguing and may suggest key controls on community assembly in montane forests. We review tropical montane forest (TMF) zonation patterns focusing on a case study from the Cordillera Central, Hispaniola where a striking discontinuity in forest composition occurs consistently at ∼2000 m elevation, with cloud forest below and monodominant pine forest above. We propose that a discontinuity in climatic factors (temperature, humidity) associated with the trade-wind inversion (TWI) is the primary cause of this and other ecotones in TMFs that occur at a generally consistent elevation. Low humidity, fires and occasional frost above the TWI favor pine over cloud forest species. Fires in the high-elevation pine forest have repeatedly burned down to the ecotone boundary and extinguished in the cloud forest owing to its low flammability, reinforced by high humidity, cloud immersion and epiphytic bryophyte cover. Small-scale fire patterns along the ecotone are influenced by topography and where forest structure is impacted by hurricanes and landslides. Analogous patterns are observed worldwide in other TMFs where the TWI is important, high-elevation fires are frequent, and the flora contains frost-tolerant species (often of temperate lineage). The response of this and other TMFs to anthropogenic climate change is highly uncertain owing to potentially countervailing effects of different climatic phenomena, including warming temperatures and decreased frost; changes in the TWI, high-elevation drought or cloudiness; and increased frequency or intensity of hurricanes and El Niño-Southern Oscillation events. En zonas de montaña es de esperar que el cambio continuo que tiene lugar en las condiciones ambientales con la altitud se traduzca en cambios similarmente graduales de la estructura y composición de la vegetación. Por tanto, resulta llamativa la existencia de ecotonos abruptos o discretos en los patrones de vegetación de algunas montañas, los cuales pueden sugerir la existencia de factores clave que controlen el ensamblaje de las comunidades en bosques de montaña. En este trabajo revisamos los patrones de zonación en bosques montanos tropicales (BMTs) centrándonos como caso de estudio en la Cordillera Central, Hispaniola donde tiene lugar una consistente discontinuidad en la composición del bosque a 2000 m de altitud, con bosques de niebla por debajo de dicha cota y pinares monoespecíficos a mayor altitud. Proponemos que la causa principal de este y otros ecotonos en BMTs a similar altitud es la existencia de una discontinuidad en los factores climáticos (temperatura, humedad) provocada por una inversión térmica. La existencia de baja humedad, fuegos y heladas ocasionales por encima de la cota de inversión térmica favorece a los pinos en comparación con las especies de bosque nublado. Los fuegos que tienen lugar repetidamente en los pinares se extienden hasta llegar al ecotono, donde se extinguen debido a la baja flamabilidad del bosque de niebla, a la elevada humedad y a la cobertura de briófitos epífitos. Los patrones a pequeña escala de los fuegos a lo largo del ecotono están influenciados por la topografía y por cambios en la estructura del bosque causados por huracanes y deslizamientos de tierra. Patrones similares han sido observados en todo el mundo en otros BTMs donde la inversión térmica es importante, los fuegos a cotas altas son frecuentes, y la flora contiene especies tolerantes de las heladas (frecuentemente de origen templado). La respuesta de éste y otros BTMs al cambio climático es incierta debido a efectos potencialmente opuestos de diferentes fenómenos climáticos, incluyendo el aumento de temperatura y disminución de heladas, cambios en las inversiones térmicas, sequías o nubes en cotas altas, e incremento de la frecuencia e intensidad de huracanes y fenómenos el Niño. FIGURE S1. Map of study area and permanent vegetation plots established in 1999–2000, Bermúdez and Ramírez National Parks, Cordillera Central, Dominican Republic. FIGURE S2. View of the pine-cloud forest ecotone on a windward slope in the Cordillera Central, Dominican Republic. Please note: Wiley-Blackwell Publishing is not responsible for the content or functionality of any supporting materials supplied by the authors. Any queries (other than missing material) should be directed to the corresponding author for the article. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Elevational and geographic variation in army ant swarm raid rates

Geographic and elevational variation in the local abundance of swarm-raiding army ants has implications for the population dynamics of their prey, as well as affecting the profitability of army-ant-following behavior for birds. Here, we analyze systematically collected data on E. burchellii and L. praedator raid rates from geographically and elevationally wide-ranging sites, from lowland to montane forests. We show that raids of each species, and of both species pooled, reach peak densities at intermediate (premontane) elevations. These patterns suggest that army ant swarm raids are relatively abundant in Neotropical montane forests. Therefore, a paucity of ant raids does not explain the absence of obligate ant-following bird species, particularly true antbirds (Thamnophilidae), from montane forests. As army ant raids are relatively common at middle elevations, opportunities exist for other montane bird taxa to exploit army ant raids as a food source.

Army Ant Raid Attendance and Bivouac-Checking Behavior by Neotropical Montane Forest Birds

Abstract We quantified resident and migrant bird attendance at army ant swarm raids (n = 48) in a neotropical montane forest. All observations were during seasons when Nearctic migrant birds are present. Bird species differed in army ant raid-attending behavior. Resident bird species attended 2 to 54% of raids, while migrants attended at lower maximum frequencies (2 to 21% of raids attended per species). Some resident and migrant bird species attended raids more frequently than expected based on capture rates in mist-net studies and point-count density surveys. Army ant raid attendance may be a regular element of foraging behavior for some resident species, and important in the wintering ecology of some Nearctic migrant species. The bird species that attended raids most frequently were predicted to show behavioral specializations for exploiting army ant swarms. Eight resident bird species (but no migrants) performed a specialized behavior, bivouac checking, by which birds sample army ant activity. Resid...

Availability of cavities for avian cavity nesters in selectively logged subtropical montane forests of the Andes

Tree cavities play a critical role in the life history of cavity-using species and thus are an important structural feature of forests. Furthermore, some common forest management practices can have a profound negative effect on cavity quantity and quality. This is the first study to address cavity resources in Neotropical montane forests and with this information we hope to develop approaches to sustainable forest management that will assure the conservation of cavity nesters. Our study design consisted of two treatments (control and harvested forest) in both piedmont and cloud forests of the subtropical montane forests of the Andes. This study indicates that cavities are an uncommon feature even in control sites with only 3% of the trees harboring cavities in both forest types. Even more uncommon are potentially usable cavities for avian cavity nesters: only 0.15% of the trees have a potentially usable cavity in the piedmont forest and only 0.42% in the cloud forest. In logged forests there is a significantly lower density of potentially usable cavities (4.12 vs. 0.51 cavities/ha in piedmont forest and 3.91 vs. 1.64 cavities/ha in the cloud forest). Furthermore, we documented a high loss rate of potentially usable cavities (from 23 to 40%/year) that differs between tree species and DBH classes. More specifically, in the piedmont forest, large, decaying Calycophyllum multiflorum have a relatively greater probability of having potentially usable cavities, while in the cloud forest potentially usable cavities are disproportionably found in large, decaying Blepharocalyx gigantea. In both forest types, snags are also very likely to harbor a potentially usable cavity. In order for harvested stands in the subtropical montane forest of the Andes to regain some of their ecological value, it is necessary to retain trees that have potentially usable cavities and also trees with the highest probability of becoming usable cavity trees.

IMPLICATIONS OF GENETIC DIFFERENTIATION IN NEOTROPICAL MONTANE FOREST BIRDS1

The complex geography of the Neotropical montane system is a natural laboratory for population divergence. Understanding which geographic barriers (lowland barriers, arid river valleys, and montane barriers above the tree line separate these regions of endemism) are instrumental in promoting and maintaining population divergence is an important step in preserving genetic diversity and endemism within the region. Here, I analyze patterns of genetic differentiation between 16 predefined regions of endemism for 43 co-distributed zoogeographic species complexes of Neotropical montane forest birds. The analysis shows that lowland barriers generate the highest levels of genetic differentiation, while barriers above the tree line in the Andes show the least. Within the Andes, arid river valleys promote population divergence to varying degrees. The Rio Maranon shows the greatest effect, but the Rio Apurimac and Rio Quinimari are also associated with extensive genetic differentiation, while genetic divergence across other river valleys is generally weak. Most barriers are associated with a wide span of divergence times, supporting a protracted history of dispersal postdating barrier formation. If the goal is to maintain genetic diversity, preservation of populations within each region of endemism would help to ensure the continued survival of evolutionarily distinct lineages within species. Considering the alarming rate of deforestation in Neotropical montane regions, preservation of suitable tracts of montane forest is needed within each region of endemism, with special emphasis placed on endemism regions separated by lowland barriers and by deep intermontane river valleys.

Identification of characteristic plant co-occurrences in neotropical secondary montane forests

Aims Inferring environmental conditions from characteristic patterns of plant co-occurrences can be crucial for the development of conservation strategiesconcerningsecondaryneotropicalforests.However,nomethodological agreement has been achieved so far regarding the identification and classification of characteristic groups of vascular plant species in the tropics. This study examines botanical and, in particular, statistical aspects to be considered in such analyses. Based on these, we propose a novel data-driven approach for the identification of characteristicplantco-occurrencesinneotropicalsecondarymountainforests. Methods Floristic inventory data were gathered in secondary tropical mountain forests in Ecuador. Vegetation classification was performed by coupling locally adaptive isometric feature mapping, a non-linear ordination method and fuzzy-c-means clustering. This approach was designed for dealing with underlying non-linearities and uncertainties in the inventory data.

Historical biogeography and speciation in the Neotropical highlands: Molecular phylogenetics of the jay genus Cyanolyca

Phylogenetic relationships were studied in the genus Cyanolyca, an assemblage of jays distributed from Mexico south to Bolivia. Given its fragmented distribution along the humid forests of the Neotropics, the genus Cyanolyca is a model group for exploring hypotheses on biogeography and speciation. Phylogenetic analyses were based on two mitochondrial and three nuclear loci; taxon sampling includes all species in the genus and most subspecies. Maximum parsimony, maximum likelihood, and Bayesian analyses produced trees that were congruent and highly robust at both terminal and deep nodes of the phylogeny. Cyanolyca comprises two major clades: one contains the Mesoamerican “dwarf” jays, and the other consists of two main groups— C. cucullata + C. pulchra and the “core” South American species. Prior hypotheses of relationships were explored statistically using Maximum Likelihood and Bayesian approaches. Dispersal-Vicariance analysis revealed the importance of the Northern Andes as a major center for biological diversification, and the effects of dispersal across the Panamanian Land Bridge in the composition of South American and Mesoamerican avifaunas. Phylogenetic patterns are highly congruent with an allopatric mode of speciation. Implications of these results are discussed in the context of the biogeography of Neotropical montane forests.

Fire and Vegetation Dynamics in High-elevation Neotropical Montane Forests of the Dominican Republic

In March and April 2005, severe fires burned over 1000 km2 of tropical montane forests in the Cordillera Central, Dominican Republic. The fire burned through our network of permanent vegetation plots, which were established in 1999 to examine interactions among environment, vegetation, and disturbance. We used QuickBird satellite imagery combined with field surveys to map the extent and severity of the fire across the landscape. The fire burned through 96% of the pine forest but quickly extinguished at the pine-cloud forest boundary along most of the ecotone. Topographic factors and fire severity had no influence on fire behavior at the ecotone. These observations support our original hypothesis that fire maintains the abrupt boundary between the pine and cloud forest vegetation in these mountains. Vegetation structure and composition played a direct role in regulating fire spread and behavior in this landscape.

Fragmentation and elevation effects on bird–army ant interactions in neotropical montane forest of Costa Rica

Army ants (Formicidae: Ecitoninae) are top predators in neotropical forests. Army ant raids support a community of diverse organisms, including birds that attend the raids to collect prey. While elevation and forest fragmentation influence army ant and insectivorous bird communities, their effects on the interaction between army ants and bird species is unknown. We studied the size and species composition of bird flocks attending army ant swarms in forest fragments and continuous forest across an elevational gradient (1100–1680 m asl) in a neotropical montane region (Monteverde, Costa Rica). We observed a total of 41 bird species attending army ant swarms. Neither the number of birds, nor the total body mass of birds, nor the number of bird species in attending bird flocks was related to elevation. However, we found a higher bird species richness, larger flock size and greater total body mass of birds attending army ant swarms in continuous forest. Continuous and fragmented forest shared many attending bird species in common, but there was elevational segregation of attending bird species. Some montane endemic birds, and neotropical migrants, attend swarms regularly and use army ant raids as a food source.

Accumulation of Current-Use Pesticides in Neotropical Montane Forests

In Central America, chemical-intensive tropical agriculture takes place in close proximity to highly valued and biologically diverse ecosystems, yet the potential for atmospheric transport of pesticides from plantations to national parks and other reserves is poorly characterized. The specific meteorological conditions of mountain ranges can lead to contaminant convergence at high altitudes, raising particular concern for montane forest ecosystems downwind from pesticide use areas. Here we show, based on a wide-ranging air and soil sampling campaign across Costa Rica, that soils in some neotropical montane forests indeed display much higher concentrations of currently used pesticides than soils elsewhere in the country. Specifically, elevated concentrations of the fungicide chlorothalonil, the herbicide dacthal, and the insecticide metabolite endosulfan sulfate on volcanoes Barva and Poas, lying directly downwind of the extensive banana plantations of the Caribbean lowland, indicate the occurrence of atmospheric transport and wet deposition of pesticides at high altitudes. Calculations with a contaminant fate model, designed for mountain regions and parametrized to the Costa Rican environment, show that chemicals with a log K(AW) between -3 and -5 have a greater potential for accumulation at high altitudes. This enrichment behavior is quantified by the Mountain Contamination Potential and is sensitive to contaminant degradability. The modeling work supports the hypothesis suggested by the field results that it is enhanced precipitation scavenging at high elevations (caused by lower temperatures and governed by K(AW)) that causes pesticides to accumulate in tropical montane areas. By providing for the first time evidence of significant transfer of currently used pesticides to Central American montane cloud forests, this study highlights the need to evaluate the risk that tropical agricultural practices place on the region's ecological reserves.

Effects of varying forest edge permeability on seed dispersal in a neotropical montane forest

Hard (high-contrast with pastures) and soft (low-contrast with old-fields) forest edges created by slash-and-burn agriculture have become common landscape features in regions dominated by neotropical montane forest. However, little is know about the impacts of such edge types on forest regeneration dynamics. The consequences of varying forest edge permeability for oak acorn dispersal were investigated in a forest mosaic in the Highlands of Chiapas, Mexico. Rates of acorn production and removal, as well as the abundance and composition of small mammal seed consumers, were monitored along these different edge types (hard vs. soft) at specific distances from forest edges into forest patches and adjacent grasslands during two consecutive years. Results show that acorn removal declined significantly only in grasslands of sites characterised by hard edges (Logistic regression, P < 0.05). Movements of metal-tagged acorns support the hypothesis that soft edges are more permeable to small mammals, with rodents moving acorns up to 15 m into grasslands of sites with soft edges. In sites with hard edges, higher rates of acorn dispersal were recorded from the forest edge towards the forest interior. Peromyscus spp. were the main acorn predators and/or dispersers of acorns present in our study sites. Rates of acorn removal during a non-masting year were greater than the subsequent mast-seeding year (85% removal within 138 days vs. 75% within 213 days), demonstrating that mast seeding may allow some seeds to escape predation. The implications of these results for oak dispersal and regeneration along edges in fragmented tropical forest landscapes are discussed.

Microclimatic factors associated with elevational changes in army ant density in tropical montane forest

Abstract 1. The density (rate of encountering foraging raids) and species richness of army ants (Formicidae: Ecitoninae, and behaviourally convergent Ponerinae) was measured in montane tropical forest. Above‐ground and subterranean army ant raids were sampled using standard protocols at four sites across an elevational gradient (1200–1650 m above mean sea level) in and near cloud forest in the area of Monteverde, Costa Rica.2. Mean ambient temperature differed among sites, and decreased with elevation. For the above‐ground foraging army ant species, raid rates also declined with elevation. Surface army ant raid rates, however, were not affected by day to day weather variation within sites (temperature, cloud cover, or precipitation).3. For the underground foraging army ant species, raid rates did not vary directionally with elevation, and subterranean raid rates were not affected by day to day weather variation within sites.4. Army ant species richness was not directionally related to elevation, and species sharing among sites was generally high.5. Army ant community structure changes with elevation in Neotropical montane forest, and the results suggest that the strongest effects are of temperature regimes on the density of raids. These findings provide a baseline against which to detect changes in army ant communities that may accompany directional climate change in tropical cloud forests.

Effects of the type of montane forest edge on oak seedling establishment along forest–edge–exterior gradients

Recent studies have highlighted the importance of different edge types in the modulation of edge-related responses associated with habitat fragmentation. Hard (high contrast with pastures) and soft (low contrast with old-fields) forest edges created by slash-and-burn agriculture have become common landscape features in regions dominated by Neotropical montane forest. The growth and survival of seedlings of five oak species ( Quercus candicans, Quercus crassifolia, Quercus laurina, Quercus rugosa and Quercus segoviensis) was monitored experimentally by introducing seedlings across replicates of the forest–edge–exterior gradients (24, 12, 0, −12 and −24 m) typical for these two edge types (hard and soft) in the Chiapas Highlands, Mexico. Seedling survival and growth (measured in terms of basal area, new stem and leaf production, and defoliation) was generally greater in adjacent open habitats than in the forested portion of the gradient. However, seedling performance was optimal 12 m from the soft edges in the open habitat. Overall, Q. crassifolia had the lowest seedling survival, especially in the forested portion of hard forest edges, whereas Q. rugosa showed the highest growth rates and survival. This study shows that the edge effects detected along a forest–edge–exterior habitat gradient may depend in large part on the type of edge being studied. The implications of these results are discussed with respect to the influence of edge characteristics on forest patch dynamics in fragmented tropical montane landscapes.

Diversity and composition of Arctiidae moth ensembles along a successional gradient in the Ecuadorian Andes

ABSTRACTAndean montane rain forests are among the most species‐rich terrestrial habitats. Little is known about their insect communities and how these respond to anthropogenic habitat alteration. We investigated exceptionally speciose ensembles of nocturnal tiger moths (Arctiidae) at 15 anthropogenically disturbed sites, which together depict a gradient of forest recovery and six closed‐forest understorey sites in southern Ecuador. At weak light traps we sampled 9211 arctiids, representing 287 species. Arctiid abundance and diversity were highest at advanced succession sites, where secondary scrub or young forest had re‐established, followed by early succession sites, and were lowest, but still high, in mature forest understorey. The proportion of rare species showed the reverse pattern. We ordinated moth samples by non‐metric multidimensional scaling using the chord‐normalized expected species shared index (CNESS) index at various levels of the sample size parameter m. A distinct segregation of arctiid ensembles at succession sites from those in mature forest consistently emerged only at high m‐values. Segregation between ensembles of early vs. late succession stages was also clear at high m values only, and was rather weak. Rare species were responsible for much of the faunal difference along the succession gradient, whereas many common arctiid species occurred in all sites. Matrix correlation tests as well as exploration of relationships between ordination axes and environmental variables revealed the degree of habitat openness, and to a lesser extent, elevation, as best predictors of faunal dissimilarity. Faunal differences were not related to geographical distances between sampling sites. Our results suggest that many of the more common tiger moths of Neotropical montane forests have a substantial recolonization potential at the small spatial scale of our study and accordingly occur also in landscape mosaics surrounding nature reserves. These species contribute to the unexpectedly high diversity of arctiid ensembles at disturbed sites, whereas the proportion of rare species declines outside mature forest.

Rhodocollybia in neotropical montane forests

Traditional concepts of Collybia (Agaricales) have included a variety of morphologically disparate taxa. Reapplication of some characters used in circumscribing Collybia s.l. suggests realignment of well-known North American and European species into three genera, viz. Collybia s.s, Rhodocollybia, and Gymnopus. Rhodocollybia is recognized here at generic rank based on morphological characteristics and phylogenetic signaling. Seven new species epithets under Rhodocollybia, and a new combination under Gymnopus, are proposed. A key to species of Rhodocollybia found in neotropical montane forests is provided.