Showing papers in "Biotropica in 2014"

Morphological and Spatio-Temporal Mismatches Shape a Neotropical Savanna Plant-Hummingbird Network

Abstract: Complex networks of species interactions might be determined by species traits but also by simple chance meetings governed by species abundances. Although the idea that species traits structure mutualistic networks is appealing, most studies have found abundance to be a major structuring mechanism underlying interaction frequencies. With a well-resolved plant–hummingbird interaction network from the Neotropical savanna in Brazil, we asked whether species morphology, phenology, nectar availability and habitat occupancy and/or abundance best predicted the frequency of interactions. For this, we constructed interaction probability matrices and compared them to the observed plant-hummingbird matrix through a likelihood approach. Furthermore, a recently proposed modularity algorithm for weighted bipartite networks was employed to evaluate whether these factors also scale-up to the formation of modules in the network. Interaction frequencies were best predicted by species morphology, phenology and habitat occupancy, while species abundances and nectar availability performed poorly. The plant–hummingbird network was modular, and modules were associated to morphological specialization and habitat occupancy. Our findings highlight the importance of traits as determinants of interaction frequencies and network structure, corroborating the results of a previous study on a plant–hummingbird network from the Brazilian Atlantic Forest. Thus, we propose that traits matter more in tropical plant–hummingbird networks than in less specialized systems. To test the generality of this hypothesis, future research could employ geographic or taxonomic cross-system comparisons contrasting networks with known differences in level of specialization.

The Multiple Impacts of Leaf‐Cutting Ants and Their Novel Ecological Role in Human‐Modified Neotropical Forests

Abstract: Herbivory has been identified as a potent evolutionary force, but its ecological impacts have been frequently underestimated. Leaf-cutting ants represent one of the most important herbivores of the Neotropics and offer an interesting opportunity to address the role played by herbivorous insects through a perspective that embraces population- to ecosystem-level effects. Here we: (1) qualitatively summarize the multiple ways leaf-cutting ants interact with food plants and their habitats and elucidate the ultimate outcome of such interactions at multiple organization levels; (2) update our understanding of leaf-cutting ant-promoted disturbance regimes; and (3) examine potential ecological roles by leaf-cutting ants within the context of human-modified landscapes to guide future research agendas. First, we find that leaf-cutting ants show that some herbivorous insects are able to generate ecologically important disturbance regimes via non-trophic activities. Second, impacts of leaf-cutting ants can be observed at multiple spatio-temporal scales and levels of biological organization. Third, ecosystem-level effects from leaf-cutting ants are ecosystem engineering capable not only of altering the abundance of other organisms, but also the successional trajectory of vegetation. Finally, effects of leaf-cutting ants are context-dependent, species-specific, and synergistically modulated by anthropogenic interferences. Future research should examine how leaf-cutting ants respond to deforestation and influence remaining vegetation in human-modified landscapes. By promoting either heterogeneity or homogeneity, leaf-cutting ants operate not only as agricultural pests but also as ecological key players.

Phyllostomid Bat Assemblage Structure in Amazonian Flooded and Unflooded Forests

Abstract: In Amazonia, the assemblages of several taxa differ significantly between upland terra firme and white-water flooded varzea forests, but little is known about the diversity and distribution of bats in these two forest types. We compare the spatio-temporal patterns of bat assemblage composition and structure in adjacent terra firme and varzea forests in the lower Purus River region of central Brazilian Amazonia. Bats were sampled using mist nets at five sites in each forest type during 40 nights (2400 net-hours). We captured 1069 bats representing 42 species and Phyllostomidae bats comprised 99.3 percent of all captures. The bat assemblages in varzea and terra firme forests were significantly different, mainly due to a marked dissimilarity in species composition and in the number of captures during high-water season. In addition, bat assemblages within forest types differed significantly between seasons for both terra firme and varzea. Frugivores dominated the bat assemblages in both forest types. Overall guild structure did not change between varzea and terra firme or between seasons, but frugivore and animalivore abundance increased significantly in varzea forest during the inundation. The difference in assemblage structure observed in the high-water season is probably caused by the annual varzea flooding, which provides an effective barrier to the persistence of many understory bats. We also hypothesize that some bat species may undertake seasonal movements between forest types in response to fruit abundance, and our results further underline the importance of floodplain habitats for the conservation of species in the Amazon.

Responses of Primates to Landscape Change in Amazonian Land‐bridge islands—a Multi‐scale Analysis

Abstract: Large hydroelectric dams are one of the current drivers of habitat loss across Amazonian forests. We investigated how the primate community at a hydroelectric dam in Brazilian Amazonia responded to changes in the landscape and local habitat structure of land-bridge islands after 21 yr of post-isolation history. The Balbina Dam, constructed in 1986, inundated 3129 km2 of primary forests and created more than 3500 variable-sized islands. We conducted primate and habitat structure surveys on 20 islands from 5 to 1815 ha, and extracted forest patch and landscape metrics for each island. The number of primate species per island varied between 0 and 7 species. Primate composition varied substantially according to both island area and forest cover remaining within the landscape, whereas island area alone was the most significant predictor of richness. Locally, tree density and vertical stratification were the most significant explanatory variables of primate composition and richness. A model containing area effects had the most explanatory power regarding site occupancy for most species. Individually, each species responded differently, with howler and brown capuchin monkeys showing greater tolerance to cope with habitat changes. Body size was also an important predictor of primate occupancy. We recommend protecting large fragments and enhancing the suitability of surrounding habitats to ensure primate conservation in most Neotropical fragmented landscapes. Given the flat topography of hydroelectric reservoirs, which mainly favors the formation of small islands, and the escalating hydropower development plans in Amazonia, our findings provide evidence for pervasive detrimental impacts of dams on primate communities. Resumo Mega hidreletricas representam atualmente um dos principais determinantes da perda de habitats em florestas amazonicas. Nos investigamos como a comunidade de primatas em uma Hidreletrica na Amazonia brasileira respondeu as mudancas na paisagem e estrutura local do habitat apos 21 anos de historia de isolamento. A Hidreletrica de Balbina, construida em 1986, inundou 3.129 km2 de florestas primaria e criou mais de 3.500 ilhas de tamanhos variados. Nos conduzimos amostragens de primatas e estrutura do habitat em 20 ilhas de 5 a 1815 ha, e extraimos metricas em escala local e de paisagem para cada ilha. O numero de especies de primatas por ilha variou entre 0 e 7 especies. A composicao de primatas variou substancialmente de acordo com a area da ilha e cobertura florestal remanescente dentro da paisagem, enquanto que area da ilha sozinha foi o preditor mais significativo da riqueza. Localmente, densidade de arvores com DAP >10 cm e numero de estratos verticais foram as variaveis explanatorias significativas de composicao e riqueza de primatas. O modelo contendo area apresentou o maior poder explicativo de ocupacao local para a maioria das especies. Individualmente, cada especie respondeu diferentemente, com guaribas e macacos-prego apresentando maior tolerância para lidar com alteracoes do habitat na paisagem de Balbina. Tamanho corporal foi tambem um importante preditor da ocupacao de primatas. Recomendamos proteger grandes fragmentos e melhorar a adequacao dos habitats circundantes a fim de garantir a conservacao de primatas na maioria das paisagens fragmentadas neotropicais. Considerando a topografia plana dos reservatorios hidreletricos, que favorece predominantemente a formacao de ilhas pequenas, e o avanco dos planos de energia hidreletrica na Amazonia, nossos resultados fornecem evidencias dos impactos negativos de hidreletricas sobre a comunidade de primatas.

Regional Variations in Biomass Distribution in Brazilian Savanna Woodland

Abstract: The Cerrado, the savanna biome in central Brazil, mostly comprised of woodland savanna, is experiencing intense and fast land use changes. To understand the changes in Cerrado carbon stocks, we present an overview of biomass distribution in different Cerrado vegetation types (i.e., grasslands, shrublands and forestlands). We surveyed 26 studies including 170 Cerrado sites. The grasslands presented mean total biomass of 24 Mg/ha, with 70 percent allocated in the belowground portion. In shrublands, the mean total biomass was 58 Mg/ha being 58 percent in the belowground portion. Finally, in forestlands the mean total biomass was 98 Mg/ha with 18 percent as belowground biomass. The surveyed studies presented 12 allometric equations for biomass estimate, most involving both diameter and height. Data on wood density for Cerrado shrubs and trees are not abundant and the average value was 0.66 g/cm3, similar to that found in the central portion of the Amazon Forest. We also examined the relationship between total precipitation and dry-season intensity with biomass variation in the Cerrado shrubland using data from tropical rainfall measurement mission (TRMM) for the period 2000–2010. Dry-season precipitation amount in cerrado areas in severe drought regions explained 29 percent of the variation in aboveground woody biomass. This finding is important in the face of the predictions of longer and more severe dry seasons in the region due to climate change.

Latitudinal Variation in Termite Species Richness and Abundance along the Brazilian Atlantic Forest Hotspot

Abstract: In this study, we investigated the termites of the Brazilian Atlantic Forest, one of the most threatened biodiversity hotspots in the world, in regularly spaced sites from 7° St o 27 ° S latitude. To our knowledge, this is the only report of a latitudinal survey of termites at species level performed with a standardized sampling protocol. We evaluate termite diversity and abundance, and describe patterns of species composition based on feeding groups along the latitudinal gradient. We also describe the relative contribution of environmental variables to explain diversity patterns. Termite assemblages were investigated by standardized surveys at 15 Atlantic Forest sites, on six transects divided into five sections of 10 m², with 30 sections per site (or 300 m²/site), which were investigated by one trained person for one hour. Observed species richness and abundance were negatively correlated with latitude. The influence of latitude was explained mainly by variables related to temperature, precipitation and ambient energy (potential evapotranspiration). Our results also suggest that temperature exerts a greater constraint on Atlantic Forest termites than productivity, because ambient productivity increases with latitude in this forest but termite diversity decreases. Termite species richness in the Atlantic Forest showed a different pattern than those described for other organisms, increasing in diversity where the coastal-forest strip narrows. Overall, our results indicate comparatively high termite species richness at northeastern sites and a significant impoverishment of termite assemblages in the southeastern and southern regions of the Atlantic Forest.

Species Richness, Forest Structure, and Functional Diversity During Succession in the New Guinea Lowlands

Abstract: Much of the world's tropical forests have been affected by anthropogenic disturbance. These forests are important biodiversity reservoirs whose diversity, structure and function must be characterized across the successional sequence. We examined changes in structure and diversity along a successional gradient in the lowlands of New Guinea. To do this, we measured and identified all stems =5 cm diameter in 19 0.25 ha plots ranging in age from 3 to >50 yr since disturbance. We also measured plant functional traits related to establishment, performance, and competitive ability. In addition, we examined change in forest structure, composition, species diversity, and functional diversity through succession. By using rarefaction to estimate functional diversity, we compared changes in functional diversity while controlling for associated differences in stem and species density. Basal area and species density increased with stand age while stem density was highest in intermediate secondary forests. Species composition differed strongly between mature and secondary forests. As forests increased in basal area, community-weighted mean wood density and foliar carbon increased, whereas specific leaf area and proportion of stems with exudate decreased. Foliar nitrogen peaked in medium-aged forests. Functional diversity was highest in mature forests, even after accounting for differences in stem and species diversity. Our study represents one of the first attempts to document successional changes in New Guinea's lowland forest. We found robust evidence that as succession proceeds, communities occupy a greater range of functional trait space even after controlling for stem and species density. High functional diversity is important for ecological resiliency in the face of global change.

Insect Herbivores and Leaf Damage along Successional and Vertical Gradients in a Tropical Dry Forest

Abstract: The availability and quality of resources for herbivores in tropical dry forests (TDFs) vary in time and space, affecting herbivore guilds differently across spatial scales (both horizontally and vertically), with consequences to the distribution of leaf damage in these forests We attempted to elucidate the distribution patterns of herbivorous insect guilds and leaf damage throughout the secondary succession and vertical stratification along the rainy season in a Brazilian TDF With the advance of the succession, a greater richness and abundance of herbivorous insects were found, resulting in higher leaf damage in intermediate and late stages This pattern, however, was not observed for the frequency of leaf miners At a smaller spatial scale, the host tree height positively affected the richness and abundance of insects The higher leaf damage was found in canopy, which also harbored a greater richness and abundance of chewing herbivores compared to the understory at both the beginning and the end of the rainy season Although for sap-sucking insects, this was only true at the beginning of the season We detected a decrease in insect richness and abundance at the end of the rainy season, probably due to a synchronization of insect activity with the availability of young, highly nutritious plant tissues These results are consistent with other studies that found a general trend of increasing richness and abundance of herbivorous insects and leaf damage throughout the secondary succession (early to late stages) and between vertical strata (understory to canopy), suggesting that forest complexity positively affects herbivores

Stable Isotope Evidence of Puma concolor (Felidae) Feeding Patterns in Agricultural Landscapes in Southeastern Brazil

Abstract: We evaluated puma (Puma concolor) feeding patterns in southeastern Brazilian agricultural landscapes using carbon and nitrogen stable isotope analyses of hair collected from fecal samples (N = 64). We classified the samples into three groups: feeding patterns based on forest remnants, on the agricultural matrix or both. We observed a predominance of consumption of C3 prey (~47% of individuals) in the area with the highest proportion of forest coverage. Conversely, C4 prey were highly consumed (~40% of individuals) where the agricultural matrix was predominant. The δ13C values for pumas in both areas indicated that their food resources come from both forest remnants and the agricultural matrix and that some individuals preferentially consumed C4 prey, indicating that food resources from the agricultural matrix make up most of their diet (~46% of prey individuals). The wide range of puma's δ15N values in both areas indicated a diet based on different types of prey. However, the C4 group had higher values, indicating that both pumas and their prey feed on enriched resources from the agricultural matrix. The results confirm the high behavioral plasticity of pumas in using highly anthropogenic habitats. The stable isotope analyses conducted in this study yielded new information on large carnivore trophic ecology that might be useful in the development of new conservation strategies in disturbed areas.

Shifts in Dominance and Species Assemblages over Two Decades in Alternative Successions in Central Amazonia

Abstract: Following perturbation, different assemblages that originate under the same abiotic conditions initiate successional pathways that may continue to diverge or converge toward an eventual climax. Forest regeneration in the Central Amazon begins with alternative successional pathways associated with prior land use. In a 12-yr study of secondary forests, initially ranging between 2 and 19 yrs after abandonment, we compared species compositions through time along two pathways, abandoned clear-cuts dominated by Cecropia and abandoned pastures dominated by Vismia; prior results at these sites have not directly evaluated species composition. At all ages, the Chao–Jaccard similarity index of species composition was highest comparing pasture transects to each other, lowest comparing pastures transects to clear-cut transects, and intermediate comparing clear-cut transects to each other. Through time, clear-cut transects became less similar to each other, as did pasture transects. Changes in similarity reflected declining dominance along both pathways, but Cecropia dominance of clear-cut transects declined more rapidly than Vismia dominance of pasture transects. A rich association of species replaced Cecropia in clear-cut transects, resulting in decreased similarity among them. In pasture transects one genus, Bellucia, replaced the lost Vismia, so similarity of Vismia transects was maintained despite some turnover in dominance. Overall, even with turnover of individuals and decline of the dominant pioneers, the alternative pathways exhibited strikingly different species assemblies after two decades of succession, suggesting that the effect of land use persists well beyond initial floristic composition. Resumo Apos um disturbio, diferentes comunidades de plantas com origem sob as mesmas condicoes abioticas iniciam trajetorias sucessionais que podem ou nao convergir em direcao a um eventual estadio climax. Na Amazonia Central, a regeneracao da floresta segue trajetorias sucessionais alternativas em funcao do historico de uso da area. Baseado em 12 anos de monitoramento de florestas secundarias com tempo de abandono inicial entre 2-19 anos, comparamos a composicao de especies no decorrer dos anos entre duas trajetorias sucessionais: pastagens abandonadas dominadas inicialmente por Vismia, e areas sem historico de uso da terra e dominadas inicialmente por Cecropia. Trabalhos anteriores nao avaliaram diretamente a composicao de especies na area de estudo. Ao longo dos anos, o indice de similaridade de Chao–Jaccard baseado na composicao de especies da area de estudo foi mais alto entre os transectos estabelecidos nas antigas pastagens dominadas por Vismia; intermediario entre os transectos inicialmente dominados por Cecropia; e mais baixo entre as duas trajetorias sucessionais. No decorrer do tempo, os transectos inicialmente dominados por Cecropia tornaram-se menos similares entre si, de modo analogo aos transectos em antigas pastagens dominados por Vismia. Mudancas na similaridade entre os transectos refletiram o declinio na dominância de especies em ambas as trajetorias sucessionais, embora a dominância por Cecropia decline mais rapidamente que a de Vismia.nas respectivas trajetorias. Um rico conjunto de especies substituiu Cecropia nos transectos sem historico de uso da terra, resultando no declinio da similaridade entre essas areas. Por outro lado, um unico genero (Bellucia) substituiu os individuos de Vismia nas antigas pastagens, mantendo a similaridade entre esses transectos apesar da mudanca na composicao de especies. Em geral, mesmo com a substituicao de individuos e o declinio das especies pioneiras dominantes, ambas as trajetorias sucessionais exibem diferencas contundentes na composicao de especies mesmo apos duas decadas de sucessao, sugerindo que o efeito do historico de uso dessas areas sobre a sucessao persiste no tempo e vai alem da composicao floristica inicial dessas areas.

Differences in Survival and Growth Among Tropical Rain Forest Pioneer Tree Seedlings in Relation to Canopy Openness and Herbivory

Abstract: Although differences in canopy openness, herbivory and their interaction may promote species coexistence, how these factors affect pioneer tree species and potentially limit growth, and survival has been poorly studied, particularly in tropical South Asia. We monitored the effect of canopy openness and herbivore damage on seedling survival and growth of 960 individuals of six pioneer tree species: Dillenia triquetra, Macaranga indica, Macaranga peltata, Schumacheria castaneifolia, Trema orientalis, and Wendlandia bicuspidata. Seedlings were placed in four gap-understory positions—center, outer gap edge, inner forest edge, and understory—in four large, natural gaps within the Sinharaja World Heritage Reserve, Sri Lanka. Canopy openness positively affected survival probability beyond the 550-d experiment, while herbivory decreased survival and was highest in understory conditions. The relative order of species survival stayed fairly consistent between gap-understory positions and followed their known shade tolerance rankings. When averaged across all experimental conditions, T. orientalis had the lowest survival probability estimate beyond the 550-d experiment (0.05), but the greatest capacity for growth where it successfully established, while the species with highest averaged survival probability (0.79), D. triquetra, showed the lowest growth. One species, W. bicuspidata, responded positively to herbivory by re-sprouting. Coexistence of D. triquetra, T. orientalis, and W. bicuspidata can be explained by a trade-off among species in survival, growth, and response to herbivory. In addition to variation in canopy light environment, herbivory may be important in determining pioneer species distribution through fine-scale niche partitioning and should be carefully considered in reforestation efforts.

Futures of tropical forests (sensu lato).

Abstract: When net deforestation declines in the tropics, attention will be drawn to the composition and structure of the retained, restored, invaded, and created forests At that point, the seemingly inexorable trends toward increased intensities of exploitation and management will be recognized as having taken their tolls of biodiversity and other forest values Celebrations when a country passes this ‘forest transition’ will then be tempered by realization that what has been accepted as ‘forest’ spans the gamut from short-rotation mono-clonal stands of genetically engineered trees to fully protected old growth natural forest With management intensification, climate change, species introductions, landscape fragmentation, fire, and shifts in economics and governance, forests will vary along gradients of biodiversity, novelty of composition, stature, permanence, and the relative roles of natural and anthropogenic forces Management intensity will increase with the increased availability of financial capital associated with economic globalization, scarcity of wood and other forest products, demand for biofuels, improved governance (eg, security of property rights), improved accessibility, and technological innovations that lead to new markets for forest products In a few places, the trend toward land-use intensification will be counterbalanced by recognition of the many benefits of natural and semi-natural forests, especially where forest-fate determiners are compensated for revenues foregone from not intensifying management Land-use practices informed by research designed and conducted by embedded scientists will help minimize the tradeoffs between the financial profits from forest management and the benefits of retention of biodiversity and the full range of environmental services

Flower and fruit availability along a forest restoration gradient

Abstract: Frugivores and pollinators are two functional groups of animals that help ensure gene flow of plants among sites in landscapes under restoration and to accelerate restoration processes. Resource availability is postulated to be a key factor to structure animal communities using restoration sites, but it remains poorly studied. We expected that diverse forests with many plant growth forms that have less-seasonal phenological patterns will provide more resources for animals than forests with fewer plant growth forms and strongly seasonal phenological patterns. We studied forests where original plantings included high tree species diversity. We studied resource provision (richness and abundance of flowers and fruits) of all plant growth forms, in three restoration sites of different ages compared to a reference forest, investigating whether plant phenology changes with restoration process. We recorded phenological data for reproductive plant individuals (351 species) with monthly sampling over 2 years, and found that flower and fruit production have been recovered after one decade of restoration, indicating resource provision for fauna. Our data suggest that a wide range of plant growth forms provides resource complementarities to those of planted tree species. Different flower phenologies between trees and non-trees seem to be more evident in a forest with high non-tree species diversity. We recommend examples of ideal species for planting, both at the time of initial planting and post-planting during enrichment. These management actions can minimize shortage and periods of resource scarcity for frugivorous and nectarivorous fauna, increasing probability of restoring ecological processes and sustainability in restoration sites.

Butterfly Community Composition Across a Successional Gradient in a Human-disturbed Afro-tropical Rain Forest

Abstract: Knowledge of the recovery of insect communities after forest disturbance in tropical Africa is very limited. Here, fruit-feeding butterflies in a tropical rain forest at Kibale National Park, Uganda, were used as a model system to uncover how, and how fast, insect communities recover after forest disturbance. We trapped butterflies monthly along a successional gradient for one year. Traps were placed in intact primary forest compartments, heavily logged forest compartments with and without arboricide treatment approximately 43 years ago, and in conifer-clearcut compartments, ranging from 9 to 19 years of age. The species richness, total abundance, diversity, dominance, and similarity of the community composition of butterflies in the eight compartments were compared with uni- and multivariate statistics. A total of 16,728 individuals representing 88 species were trapped during the study. Butterfly species richness, abundance, and diversity did not show an increasing trend along the successional gradient but species richness and abundance peaked at intermediate stages. There was monthly variation in species richness, abundance, diversity and composition. Butterfly community structure differed significantly among the eight successional stages and only a marginal directional change along the successional gradient emerged. The greatest number of indicator species and intact forest interior specialists were found in one of the primary forests. Our results show that forest disturbance has a long-term impact on the recovery of butterfly species composition, emphasizing the value of intact primary forests for butterfly conservation.

Changes in Elephant Abundance Affect Forest Composition or Regeneration

Abstract: While overall numbers of African elephant have declined dramatically in recent times, some populations are now confined to protected areas and are locally overabundant—an undesirable situation for both biodiversity conservation and elephants. In forested protected areas, options to manage elephants are limited because it is difficult to safely approach animals, yet it is vital that these populations are managed because browsing by elephants can dramatically alter forest ecosystems. Using data collected over 50 yr in Kibale National Park, Uganda, we examine the prediction that increasing elephant numbers and associated changes in their foraging behavior have caused a shift in tree community composition. Although the relative abundance of elephants increased significantly between 1996 and 2010, the population structure of their preferred tree food species did not change, nor did tree community composition change in favor of species able to re-sprout after elephant damage. Furthermore, over the last 50 yr Kibale elephants have not become more selective foragers, as would be expected if more nutritious tree species were declining. However, elephants are more abundant in disturbed areas dominated by shrubs and grasses and appear to have arrested forest succession in these areas. At their current abundance, elephants have not selectively altered the composition of intact old growth forest, but they do inhibit the regeneration of disturbed areas. Resumen Aunque las cifras globales de elefantes africanos han disminuido drasticamente en los ultimos tiempos, algunas poblaciones estan ahora confinados a las areas protegidas y son localmente sobreabundantes siendo una situacion indeseable tanto para la conservacion de la biodiversidad como para los elefantes. En areas forestales protegidas, las opciones para el manejo de los elefantes estan limitadas debido a que es dificil acercarse a los animales de forma segura, sin embargo, es vital que estas poblaciones se manejan porque el ramoneo realizado por los elefantes puede alterar dramaticamente los ecosistemas forestales. Utilizando los datos recopilados a lo largo de 50 anos en el Parque Nacional Kibale, Uganda, examinamos la prediccion de que un creciente numero de elefantes y los cambios asociados en su comportamiento de forrajeo han provocado un cambio en la composicion de la comunidad de arboles. Aunque la abundancia relativa de los elefantes aumento significativamente entre 1996 y 2010, la estructura poblacional de las especies arboreas preferidas como alimento y la composicion de la comunidad de arboles no cambio; por ejemplo, a favor de las especies capaces de rebrotar despues de un dano hecho por los elefantes. Ademas, en los ultimos 50 anos los elefantes en Kibale no se han convertido en forrajeros mas selectivos, como se esperaria si las especies de arboles mas nutritivos estuviesen disminuyendo. Sin embargo, los elefantes son mas abundantes en areas perturbadas dominadas por arbustos y hierbas, y parecen haber detenido la sucesion forestal en estas areas. En su abundancia actual, los elefantes no han alterado selectivamente la composicion de bosques intactos de edad madura, pero si inhiben la regeneracion de areas perturbadas.

Diet and Geophagy Across a Western Amazonian Parrot Assemblage

Abstract: We identified species- and community-level dietary characteristics for a species-rich Amazonian parrot assemblage to determine relationships among dietary metrics and use of geophagy sites. Previous studies suggest that soil is consumed at geophagy sites in this region mainly to supplement dietary sodium. We accumulated 1400 feeding records for 16 parrot species over 2 yr and found that seeds, flowers, and fruit pulp featured prominently in diets, while bark, insects, and lichen were consumed in small quantities. Food availability across 1819 trees was measured, and we found that flower availability was highest in the dry season and fruit production peaked in the wet season, but that phenology patterns of the 20 most commonly foraged plant species suggest no serious food bottlenecks. Partitioning of available food resources among the 13 most commonly encountered parrots is suggested by an ordination analysis (DCA), which placed the large macaws (Ara) with the Amazona parrots at the ‘primary forest’ end of a dietary resource axis and four smaller species at the ‘successional forest’ end of the axis. Parrot species associated with successional forest also consumed less plant species overall. Furthermore, these parrot species consuming successional forest resources had higher claylick visitation rates than those consuming primary forest resources suggesting they derive the greatest benefits from soil consumption. Resumen Identificamos caracteristicas de dieta a nivel de especie y comunidad en una comunidad de loros con una alta riqueza especifica en la Amazonia para determinar las relaciones entre el uso de sitios de geofagia y la composicion dietetica. Estudios previos sugieren que la arcilla consumida en los sitios de geofagia en esta region tiene el proposito de proveer un suplemento adicional de sodio. Nosotros acumulamos 1400 avistamientos de forrajeo en 16 especies de loros a lo largo de dos anos y encontramos que la dieta de estas especies estaba principalmente conformada por semillas, flores y pulpa de fruta, mientras que corteza, insectos y liquenes fueron consumidos en cantidades pequenas. La disponibilidad de alimento fue medida en 1819 arboles y encontramos que la disponibilidad de flores fue mayor durante la temporada seca y la produccion de frutos alcanzo su pico durante la temporada humeda, pero que los patrones fenologicos de las especies de arboles mas consumidas no representaban cuellos de botella alimenticios serios. La particion de recursos alimenticios disponibles entre las 13 especies de loros encontrados con mayor frecuencia es sugerido por un analisis de ordenacion (DCA), el cual ubico a los guacamayos grandes (Ara) junto a los loros (Amazona) en el extremo de los “bosques primarios” del eje de recursos alimenticios y cuatro especies mas pequenas en el extremo de los “bosques de sucesion” del eje. Las especies de loros asociados a los recursos de los bosques de sucesion tenian una tasa de visita a las collpas mas alta que aquellos consumiendo recursos en los bosques primarios, lo que sugiere que los primeros obtienen los mayores beneficios del consumo de arcillas.

Factors Affecting Tropical Tree Damage and Survival after Catastrophic Wind Disturbance

Abstract: The structure and dynamics of cyclone-prone tropical forests are driven in part by variation in tree species resistance to and survival after wind-induced structural damage. We determined the factors associated with tree damage and 3-yr survival following Category 5 Cyclone Olaf on the Polynesian island of Ta’u, American Samoa. Despite sustaining a high rate of severe damage (34.6% of all trees snapped, 23.0% uprooted), system resilience was high with 74.3 percent stem survival overall and an annual mortality rate of 7.9 percent compared with 2.1 percent in nearby undisturbed late successional forest. Three-yr survival rate of trees sustaining severe damage was 63.1 percent, compared to about 89 percent for trees sustaining only branch loss or defoliation. Three-yr survival differed according to damage type, 78.5 percent after snapping vs. 38.4 percent after uprooting. Species differed widely in resistance to and survival after snapping and uprooting. Several species and individual traits were associated with the probability of snapping or uprooting; however, wood density was the only species trait consistently, and negatively, associated with the probability of sustaining either damage type. Survival after snapping was negatively associated with the proportion of the tree snapped off, which was determined by individual tree architecture. Species growth rate was negatively associated with survival after uprooting, indicating the importance of shade tolerance for survival after uprooting. Thus, whereas species traits seemed to exclusively underpin resistance to and survival after uprooting, they only partly accounted for snapping resistance, and did not determine the intensity of snap damage or survival after snapping. Our results highlight the importance of considering each damage type separately when considering ecological trade-offs.

Niche Conservatism and Future Changes in the Potential Area Coverage of Arundina graminifolia, an Invasive Orchid Species from Southeast Asia

Abstract: The Asian orchid, Arundina graminifolia, has been introduced to many locations over the last 50 yr, predominantly in South and Central America. A list of localities of A. graminifolia was compiled and used to model potential climatic niches based on the maximum entropy method. The differences are presented between niches occupied by native and invasive populations of A. graminifolia, and possible changes in the potential range of the species are discussed on the basis of various climate change scenarios. The coverage of habitats suitable for A. graminifolia will be reduced under future climate changes scenarios. The created niche distribution models indicated a more significant reduction in the potential ecological niches of the studied species in its invasive range. Nevertheless, areas with potentially suitable bioclimatic conditions for A. graminifolia should be monitored to prevent future uncontrolled invasion of the orchid into new habitats and to study its impact on the local ecosystems, as vast areas of its potential niche in the Americas are still unoccupied. Resumen El sujeto de este estudio fue la orquidea asiatica, Arundina graminifolia, la cual ha sido introducida durante los pasados 50 anos en distintas locaciones, predominantemente en Sudamerica y central America. Una compilacion de localidades donde se hace referencia a A. graminifolia, ha aportado las bases para el modelaje de potenciales nichos climaticos, basados en el metodo de maxima entropia. Las diferencias entre los nichos han sido clasificados en poblaciones nativas e invasivas. Posibles cambios en el potencial rango de las especies ha sido discutido en base a los distintos escenarios del cambio climatico. La cobertura de los habitats aptos para A. graminifolia seran reducidos deacuerdo a los distintos escenarios de los cambios climaticos. Los modelos de distribucion de nichos indican una reduccion significativa del potencial ecologico de los nichos, en especies con rango invasivo. Sin embargo, areas con condiciones bioclimaticas potencialmente aptas para A. graminifolia deberian ser monitoreadas para prevenir futuras incontrolables invasiones de la orquidea dentro de nuevos habitats y su impacto en los ecosistemas locales, esto debido a que vastas areas de America con alto potencial para la diseminacion aun se encuentran desocupadas.

El Niño, Host Plant Growth, and Migratory Butterfly Abundance in a Changing Climate

Abstract: In the wet forests of Panama, El Nino typically brings a more prolonged and severe dry season. Interestingly, many trees and lianas that comprise the wet forests increase their productivity as a response to El Nino. Here, we quantify the abundance of migrating Marpesia chiron butterflies over 17 yr and the production of new leaves of their hostplants over 9 yr to test the generality of the El Nino migration syndrome, i.e., whether increased abundance of migrating insects and productivity of their food plants are associated with El Nino and La Nina events. We find that the quantity of M. chiron migrating across the Panama Canal was directly proportional to the sea surface temperature (SST) anomaly of the Pacific Ocean, which characterizes El Nino and La Nina events. We also find that production of new leaves by its larval host trees, namely Brosimum alicastrum, Artocarpus altilis, and Ficus citrifolia, was directly proportional to the SST anomaly, with greater leaf flushing occurring during the period of the annual butterfly migration that followed an El Nino event. Combining these and our previously published results for the migratory butterfly Aphrissa statira and its host lianas, we conclude that dry season rainfall and photosynthetically active radiation can serve as primary drivers of larval food production and insect population outbreaks in Neotropical wet forests, with drier years resulting in enhanced plant productivity and herbivore abundance. Insect populations should closely track changes in both frequency and amplitude of the El Nino Southern Oscillation with climate change. Resumen En el bosque humedo de Panama el fenomeno de ‘El Nino’ se asocia, tipicamente, con una mayor duracion y severidad de la estacion seca. En respuesta a las condiciones durante ‘El Nino’, muchas especies de arboles y lianas aumentan su productividad. En este estudio presentamos una cuantificacion de la abundancia de la especies de mariposa migratoria Marpesia chiron durante 17 anos, asi como de la produccion de hojas nuevas de sus plantas hospederas nuevas durante 9 anos. Nuestro objetivo es evaluar la generalidad del sindrome migratorio de El Nino, de acuerdo al cual existe una asociacion entre el incremento en la abundancia de insectos migratorios, el incremento en la productividad de las plantas hospederas y los fenomenos de La Nina y el Nino. Nuestros analisis muestran que la cantidad de individuos de M. chiron que migran a traves del canal de Panama fue directamente proporcional a la anomalia de temperatura superficial del mar (ATSM) del oceano Pacifico, la cual caracteriza los episodios de El Nino y La Nina. Tambien encontramos que la produccion de hojas nuevas de las plantas hospederas Brosimum alicastrum, Artocarpus altilis y Ficus citrifolia fue directamente proporcional a la ATSM con una mayor produccion de hojas durante el periodo migratorio que siguio El Nino. Al combinar estos datos con nuestros resultados publicados anteriormente de la especie migratoria Aphrissa statira y sus lianas hospederas, concluimos que la lluvia durante la estacion seca y la radiacion fotosintetica activa pueden funcionar como los factores que determinan la produccion de comida para las larvas y la explosion de poblaciones de insectos en bosques humedos Neotropicales, conduciendo a incrementos en la productividad de las plantas y abundancia de herbivoros durante los anos de mayor sequia. Dados estos resultados se espera que las poblaciones de insectos sigan de cerca los cambios en frecuencia y amplitud de la ‘Oscilacion del Sur El Nino’ causados por el cambio climatico.

Fire Damage in Seasonally Flooded and Upland Forests of the Central Amazon

Abstract: Neighboring upland and nutrient-poor seasonally flooded Amazon forests were penetrated by a fire in 2009, providing a natural com-parative experiment of fire damage for these widespread forest types. In upland, only 16 10% ( 2 SEM) of stems and 21 8%of basal area were lost to fire, while seasonally flooded forest lost 59 13% of stems and 57 13% of basal area. Drier understorycontributes to greater flammability. Much of the area occupied by seasonally flooded woody vegetation (>11.5 percent of the Amazonregion) is vulnerable to fire due to high flammability and slow recovery.Abstract in Portuguese is available in the online version of this article. Key words: flammability; forest structure; igapo; litter layer; relative humidity; tropical forest. O VER 11.5 PERCENT OF THE AMAZON BASIN IS OCCUPIED BY SEASON-ALLY INUNDATED WOODY VEGETATION (Melack & Hess 2010).Seasonally flooded Amazon forests are home to a high diversityof trees (Wittmann et al. 2010), endemic invertebrates (Adis et al.2010) and frugivorous fish (Goulding et al. 1988, Correa et al.2007). Although inundated for much of the year, the litter layerof a low open-canopy floodplain forest of the upper Rio Negrocan ignite when relative humidity of the understory drops below65 percent (Uhl et al. 1988).Fire also penetrates closed-canopy floodplain forests of themiddle Rio Negro. Using field inventories and high-resolutionimages Flores et al. (2014) found average tree mortality of 90 per-cent from fires associated with droughts—much higher than themortality or percent of biomass loss reported after a first burn ofupland forests (Barbosa & Fearnside 1999, Cochrane et al. 1999,Barlow & Peres 2004). Amazon forests seasonally flooded bynutrient-poor waters have an aerated root mat and accumulationof leaf litter which together comprise a stock of fine, quick-dryingfuel two to three times larger than in nearby upland forest(Kauffmann et al. 1988, Dos Santos & Nelson 2013).These prior results suggest that flooded forest is less resistantto fire damage than upland forest. However, no experiment has yetbeen performed comparing fire resistance of these two widespreadforest types. The Rio Negro provides few situations to compareflammability; river channels act as fire breaks between the two for-est types and ignition sources differ (e.g., fishermen’s campfires aremore abundant in the floodplain). A report by Nelson (2001) com-pared fire damage between upland and floodplain forests in closeproximity and penetrated by the same fire, but relied only on visualinspection of satellite images and air photography.Here, we use a natural experiment to address the hypothesisthat given equal ignition opportunity and identical recent rainfallhistory, fire will cause greater damage to undisturbed nutrient-poor flooded forest than undisturbed upland forest (H1). Oursecond hypothesis examines cause: The unburned flooded forestunderstory has more prolonged periods of flammability than theunburned upland forest understory (H2).South of the central sector of the Amazon River are exten-sive terraces 15–20 m above the present local high water level.Irion et al. (2010) interpret these as paleo-floodplains depositedduring Pleistocene interglacial periods, such as 110,000 years ago,when the Amazon River was slightly above its present relativelevel. During the final Pleistocene low sea stand the paleo-flood-plains became upland and were weakly incised by erosion, form-ing dense dendritic networks of shallow valleys. Post-Pleistocenesea level rise back-flooded the Amazon main stem and theseshallow incised valleys. Currently, they are seasonally inundatedby a 10 m amplitude annual flood pulse and are colonized bytrees tolerant to periodic inundation. Between the seasonallyflooded valleys, the paleo-floodplain terrace forms flat narrowinterfluves covered by flood intolerant upland tree species.For three reasons, fires on this landscape provide the idealnatural experiment to address H1. First, tree cover is continuousbetween the two forest types, with no intervening open water orerosional scarp to impede passage of fire. Second, the two foresttypes are spatially intercalated because of the dense network ofseasonally flooded valleys, allowing placement of all plots in closeproximity. As a result, sites can have identical pre-burn rainfalland equal ignition opportunity when fires course through the sea-sonally flooded valley forest (Fig. S1). Finally, because ignitionsources for both forest types (swidden fields and pastures) wereabsent over much of the area until recent decades, it is easy tofind forest that has burned only once.

Spatial Variability in Litterfall, Litter Standing Crop and Litter Quality in a Tropical Rain Forest Region

Abstract: Understanding the spatial variability in plant litter processes is essential for accurate comprehension of biogeochemical cycles and ecosystem function. We assessed spatial patterns in litter processes from local to regional scales, at sites throughout the wet tropical rain forests of northern Australia. We aimed to determine the controls (e.g., climate, soil, plant community composition) on annual litter standing crop, annual litterfall rate and in situ leaf litter decomposability. The level of spatial variance in these components, and leaf litter N, P, Ca, lignin, α-cellulose and total phenolics, was determined from within the scale of subregion, to site (1 km transects) to local/plot (~30 m2). Overall, standing crop was modeled with litterfall and its chemical composition, in situ decomposability, soil Na, and topography (r2 = 0.69, 36 plots). Litterfall was most closely aligned with plant species richness and stem density (negative correlation); leaf decomposability with leaf-P and lignin, soil Na, and dry season moisture (r2 = 0.89, 40 plots). The predominant scale of variability in litterfall rates was local (plot), while litter standing crop and α-cellulose variability was more evenly distributed across spatial scales. Litter decomposability, N, P and phenolics were more aligned with subregional differences. Leaf litter C, lignin and Ca varied most at the site level, suggesting more local controls. We show that variability in litter quality and decomposability are more easily accounted for spatially than litterfall rates, which vary widely over short distances possibly in response to idiosyncratic patterns of disturbance.

Cascading Effects of Climate Change: Do Hurricane‐damaged Forests Increase Risk of Exposure to Parasites?

Abstract: Financial sup-port for this research was received from the Natural Sciences andEngineering Research Council of Canada (NSERC), NationalGeographic, The Inter national Primatological Society, Sigma Xi,and The Depar tment of Anthropology, Faculty of Social Sciencesand Faculty of Graduate Studies at the University of Calgary.

Canopy Openness Enhances Diversity of Ant–Plant Interactions in the Brazilian Amazon Rain Forest

Abstract: In closed-canopy tropical forest understory, light availability is a significant determinant of habitat diversity because canopy structure is highly variable in most tropical forests. Consequently, variation in canopy cover affects the composition and distribution of plant species via creating variable light environments. Nevertheless, little is known about how variation in canopy openness structures patterns of plant–animal interactions. Because of the great diversity and dominance of ants in tropical environments, we used ant–plant interactions as a focal network to evaluate how variation in canopy cover influences patterns of plant–insect interactions in the Brazilian Amazon rain forest. We observed that small increases in canopy openness are associated with increased diversity of ant–plant interactions in our study area, and this change is independent of plant or ant species richness. Additionally, we found smaller niche overlap for both ants and plants associated with greater canopy openness. We hypothesize that enhanced light availability increases the breadth of ant foraging sources because variation in light availability gives rise to plant resources of different quality and amounts. Moreover, greater light availability promotes vegetative growth in plants, creating ant foraging ‘bridges’ between plants. In sum, our results highlight the importance of environmental heterogeneity as a determinant of ant–plant interaction diversity in tropical environments. Resumo No interior do sub–bosque de densas florestas tropicais, a disponibilidade de luz e um fator que determina a diversidade de habitats, principalmente porque a estrutura do dossel e altamente variavel na maioria das florestas tropicais. Consequentemente, a variacao na cobertura do dossel afeta a composicao e distribuicao das especies de plantas, criando ambientes com diferentes niveis de luz. No entanto, pouco e o conhecimento de como a variacao na abertura do dossel estrutura os padroes de interacoes planta–animal. Devido a grande diversidade e dominância de formigas nos ambientes tropicais, nos usamos como modelo de estudo as interacoes formiga–planta em uma floresta tropical na Amazonia brasileira. Nos observamos que pequenas mudancas na abertura do dossel esta associada com o aumento da diversidade das interacoes formiga–planta na nossa area de estudo, e essa mudanca e independente da riqueza de formigas ou de plantas. Adicionalmente, nos encontramos baixa sobreposicao de nicho tanto para formigas quanto de plantas em ambientes com maior abertura do dossel. Nos hipotetizamos que a disponibilidade de luz aumenta a possibilidade de forrageamento das formigas, uma vez que, a variacao na disponibilidade de luz fornece diferentes quantidades e qualidades de recurso disponivel nas plantas. Alem disso, a maior disponibilidade de luz promove o crescimento vegetativo das plantas, criando “pontes” entre as plantas para o forrageamento das formigas. Em resumo, nossos resultados destacam a importância da heterogeneidade ambiental como um fator que determina a diversidade das interacoes formiga–planta em ambientes tropicais.

Local Hydrological Conditions Explain Floristic Composition in Lowland Amazonian Forests

Abstract: Amazonian forests harbor a large variety of understory herbs adapted to areas with different hydrological conditions, ranging from well-drained to seasonally flooded forests. The presence versus absence of flooding forms the extremes of a hydrological gradient, with various intermediate conditions, such as seasonal soil waterlogged areas, in between. We investigated the relationship between understory herbs and hydrological conditions in Central Amazonian forests using eighty-eight 250 × 2 m plots distributed along a 600-km transect. Hydrological conditions were determined regionally by precipitation and locally by topographic conditions based on drainage potential, flooding height and soil permeability (sand content). Soil cation concentration was used as a proxy for soil fertility. The floristic dissimilarities among plots were visualized by Nonmetric Multidimensional Scaling, and simple and multiple regressions were used to identify the best predictor of herb species composition. Local drainage potential was more important in determining herb species composition than soil fertility or precipitation at non-flooded and flooded sites. Flooded sites comprised a very distinctive herb species composition even when the flood height was low (0.3 m). We conclude that hydrological conditions are the primary constraint of herb distribution within this flat regional landscape with moderate amounts of soil fertility variation (0.09–2.280 cmol(+)/kg). Hydrological models that consider local water conditions explained the largest part of herb species composition. Therefore, predictions of species distribution based on large-scale climatic variables may underestimate the favorable area for understory herbs if the variation on local hydrological conditions is not considered. Resumo Florestas Amazonicas abrigam uma grande variedade de plantas de sub-bosque adaptadas a diferentes condicoes hidrologicas, que incluem areas bem-drenadas ate areas sazonalmente alagadas. A presenca versus ausencia de alagamentos sao extremos do gradiente hidrologico enquanto algumas areas, como areas encharcadas, sao intermediarias desse gradiente. Nos investigamos a relacao entre plantas herbaceas e condicoes hidrologicas na Amazonia Central em 88 parcelas de 250 × 2 m em um transecto de ca 600 km. Condicoes hidrologicas foram determinadas regionalmente pela precipitacao e localmente pelas condicoes topograficas, dadas pela permeabilidade do solo (teores de areia), potencial de drenagem e profundidade do alagamento. A fertilidade do solo foi medida pela concentracao de cations do solo. As dissimilaridades floristicas entre as parcelas foram visualizada pelo uso de escalonamento multidimensional nao-metrico e regressoes simples e multiplas foram usadas para identificar os melhores preditores da composicao floristica. O potencial de drenagem local foi mais importante como preditor da composicao de ervas do que precipitacao e a fertilidade, tanto em areas alagaveis como nas nao alagaveis. A composicao de ervas em areas alagaveis foi bastante distinta, mesmo com o alagamento superfical (0.3 m). Nos concluimos que condicoes hidrologicas sao limitantes da composicao de ervas em areas com variacao moderada nos valores de fertilidade do solo (0.09–2.280 cmol(+)/kg). Modelos hidrologicos que consideram as condicoes hidrologicas locais explicaram a maior parte da composicao de ervas. Portanto, previsoes sobre a distribuicao de especies considerando apenas dados climaticos podem subestimar areas favoraveis para ervas caso as condicoes hidrologicas locais nao sejam consideradas.

Tree Species Distribution along Environmental Gradients in an Area Affected by a Hydroelectric Dam in Southern Amazonia

Abstract: We describe the patterns of composition and abundance of tree species and their relationships to environmental factors in an area affected by the Jirau hydroelectric dam on the Madeira River in the Brazilian state of Rondonia. Trees were sampled in 20 1-ha forest plots distributed among areas affected and unaffected by the hydroelectric reservoir. Predictors of species distribution included in the analyses were soil fertility (sum of bases) and texture, slope, and the vertical distance from the nearest drainage. We sampled 8504 individuals belonging to 909 species/morphospecies. Floristic differences occurred throughout the reservoir area and between the sides of the river, and were strongly associated with edaphic and geological factors. The predictor with the greatest effect on the floristic changes was the sum of bases, coupled with the vertical distance from the nearest drainage, the latter reflecting the influence of the riparian zone. The forests sampled were heterogeneous and included transitional formations between unflooded terra firme and seasonally inundated (varzea, campinarana) forests. Although a considerable number of species (253) were restricted to plots affected by the reservoir, most of these species have a widespread distribution in the Amazon region. However, conservation measures are required in order to preserve species associations and ecosystems processes similar to those most affected by the reservoir such as the river floodplains. Our study reinforces the need to consider the heterogeneity of habitats affected by reservoirs when making decisions concerning the building of hydroelectric dams in the Amazon. Resumo Discutimos os padroes de composicao e abundância das especies arboreas e suas relacoes com fatores ambientais na area que estara sujeita ao impacto decorrente da instalacao da hidreletrica de Jirau no rio Madeira, no estado de Rondonia, Brasil. As arvores foram amostradas em 20 parcelas de 1 hectare cada, distribuidas entre areas afetadas e nao afetadas pelo reservatorio da hidreletrica. Como preditores da distribuicao de especies incluimos dados de fertilidade (soma de bases) e textura do solo, topografia e distância vertical em relacao a drenagem mais proxima. Amostramos 8504 individuos pertencentes a 909 especies arboreas. Diferencas floristicas ocorreram ao longo da area do reservatorio e entre as margens do rio e foram fortemente associadas aos fatores geologicos e edaficos distintos. A soma de bases foi o preditor com maior efeito sobre a variacao floristica, alem da distância vertical em relacao a drenagem mais proxima, esta ultima caracterizando a influencia das zonas riparias. As florestas amostradas foram heterogeneas e incluiram formacoes transicionais entre florestas de terra firme e florestas de varzea e campinaranas, estas ultimas sazonalmente inundadas. Embora um consideravel numero de especies (253) tenha sido restrito as parcelas afetadas pelo reservatorio, a maioria das especies tem uma distribuicao ampla na regiao amazonica. Entretanto, medidas de conservacao sao necessarias para preservar associacoes de especies e processos dos ecossistemas similares aqueles mais afetados pelo resveratorio, como as planicies de inundacao. Nosso estudo reforca a necessidade de considerar a heterogeneidade de habitats afetados por reservatorios nos planejamentos relativos a construcao de hidreletricas na Amazonia.

Asymmetrical Dependence Between a Neotropical Mistletoe and its Avian Seed Disperser

Abstract: The degree of interdependence among interacting species has major implications for our understanding of the coevolutionary processand biodiversity maintenance. However, the mutualism strength among fruiting plants and their seed dispersers remains poorly under-stood in tropical ecosystems. We evaluated simultaneously the effectiveness of the avian seed dispersers of the mistletoe Struthanthus flexi-caulis (Loranthaceae) and the contribution of its fruits to their diets in a highland rocky savanna in southeastern Brazil. The mistletoefruits are small lipid-rich pseudoberries available throughout the year. Four passerine birds fed on fruits, but Elaenia cristata (Tyrannidae)was the most effective disperser, responsible for more than 96 percent of the dispersed seeds. This bird swallowed fruits whole, expel-ling and depositing undamaged seeds by regurgitation and bill wiping on perches. From 646 dispersed seeds, 56 percent were depositedon safe sites, thin live twigs of 38 susceptible host species. Elaenia cristata were predominantly frugivorous, feeding on typically ornithoc-oric fruits of at least 12 species, but also on arthropods. Although fruits represented 75 percent of the feeding bouts along the year, S.flexicaulis fruits represented only 34 percent of the E. cristata diet. Our results highlight the asymmetrical nature of this mutualistic inter-action, with the mistletoe life cycle locally linked to one highly effective seed disperser that is more weakly dependent on mistletoesfruits as a food source. We suggest that merging the seed dispersal effectiveness framework with diet assessment of seed dispersers isneeded to clarify the asymmetries in mutualistic pairwise interactions involving plants and their animal partners.Abstract in Portuguese is available in the online version of this article.

Do Bats Roost and Forage in Shade Coffee Plantations? A Perspective from the Frugivorous Bat Sturnira hondurensis

Abstract: Shade coffee plantations are considered important habitats for frugivorous bats. However, it is not known if bats use this agricultural habitat for shelter, food resources, or both. This study addresses these questions using the highland yellow-shouldered bat (Sturnira hondurensis) as an example. Twenty-six adult individuals of S. hondurensis were captured, 50 percent in tropical montane cloud forest (TMCF) and 50 percent in shade coffee plantations (SCP) in Veracruz, Mexico, and each was fitted with a radio transmitter for locating roosts and feeding areas. Data were obtained from 24 of them. The fieldwork was conducted between October 2010 and October 2011 covering all seasons. Twenty-two day roosts were located in the cavities of twelve different species of tree. Roosts located in TMCF differed significantly from those in SCP, having a smaller crown area and a greater species richness and density of plants around the roost. In SCP, both the average home range and the average core use area were smaller than in TMCF, but the differences were not statistically significant. Distances travelled by bats were generally longer and more variable in the SCP; the distance between capture site and foraging site was significantly greater in SCP than in TMCF. In SCP, there were fewer understory chiropterochorous plants, which are the main item in the diet of this bat and many other sympatric species of frugivorous bats. Although S. hondurensis does use roosts and foraging sites in the SCP, it is important to note that this species and others with similar requirements primarily depend on the preservation of intact forest adjacent to modified landscapes, where roosts and fruit are constantly available in abundance. Management practices should guarantee a greater density and diverse of trees and the preservation of understory plants with fruits in the coffee plantations that allow a long-term survival of frugivorous bats populations. Resumen Los cafetales con sombra son considerados habitats importantes para los murcielagos frugivoros. No obstante, se desconoce si estos cultivos estan ofreciendo a los murcielagos recursos de refugio, alimentacion o ambos. En este trabajo se intenta dar respuesta a esta pregunta utilizando a Sturnira hondurensis como ejemplo.Veintiseis individuos adultos de S. hondurensis fueron capturados en bosque mesofilo de montana (BMM) n = 13 y en cafetales bajo sombra (CBS) n = 13, en Veracruz, Mexico, y a cada uno se le coloco un radiotransmisor con el fin de localizar sus refugios y areas de forrajeo. Se localizaron 22 refugios diurnos en oquedades pertenecientes a 12 especies de arboles diferentes. Los refugios localizados en BMM difirieron significativamente de los de CBS en tener un tamano de copa mas pequeno y una mayor riqueza y densidad de plantas alrededor del arbol de refugio. En CBS, tanto el ambito hogareno, como el area de uso central fueron menores en promedio que en BMM; sin embargo, las diferencias no fueron estadisticamente significativas. Las distancias desplazadas por los murcielagos fueron generalmente mas largas y mas variables en CBS; la distancia entre el sitio de captura y el area de forrajeo fue significativamente mayor en CBS respecto a BMM. En CBS hubo una menor cantidad de plantas quiropterofilas en el sotobosque, las cuales constituyen el principal item en la dieta de esta y otras especies simpatricas de murcielagos frugivoros. Aunque se encontro que Sturnira hondurensis si usa refugios y sitios de alimentacion en los CBS, es importante senalar que esta y otras especies con requerimientos similares dependen realmente de la conservacion de bosque adyacente a los paisajes intervenidos, donde los refugios y frutos estan constantemente y en abundancia.

The Interplay of Habitat and Seed Type on Scatterhoarding Behavior in a Fragmented Afromontane Forest Landscape

Abstract: Scatterhoarding by rodents, whereby seeds are collected and stored for later consumption, can result in seed dispersal. Seeds may be covered in litter on the forest floor (cached) or buried. This is particularly so in the Neotropics for large, nutritious seeds, and where primary dispersers are rare or missing. In African forests, contemporary anthropogenic pressures such as hunting, forest degradation, and fragmentation are contributing toward major declines in large frugivores, yet the potential for scatterhoarding to mitigate this loss is largely unknown. In this study, we used thread-marked seed to explore the balance between seed predation and dispersal by rodents in Afromontane forest. We studied two tree species in three habitats: (1) continuous forest; (2) continuous forest edge, and (3) small, degraded riparian forest patches. We found that seed removal rates were high and almost the same in all three habitats for both tree species, but that the predation/dispersal balance differed among habitats. In continuous forest, more seeds of each species were scatterhoarded than depredated, and rates of scatterhoarding differed between the two species. In all habitats, burying seeds up to 2 cm belowground was more common than caching. Distances seeds were moved was approximately five times greater in continuous forest than in forest edge or riparian patches. We found strong evidence to suggest that the African pouched rat, Cricetomys sp. nov was responsible for the scatterhoarding.

Geographic and Temporal Trends in Amazonian Knowledge Production

Abstract: The presence of researchers from Western (i.e., developed world) institutions in Amazonia has frequently been contentious due to fears of ‘scientific imperialism’ or suspicions that they may be exerting undue influence over research agendas and knowledge production to the detriment of local researchers. Such negative perceptions are widespread, but not well substantiated. A more nuanced understanding of these issues requires information on who is conducting research in Amazonia and how knowledge production has changed over time. We performed a bibliometric analysis on Thomson Reuters’ISI Web of Science of all research articles about the Amazon published in three time periods: 1986–1989, 1996–1999, and 2006–2009. We found that the number of articles published and the diversity of countries involved in Amazonian research increased dramatically over the three time periods. The representation of several Amazonian countries—especially Brazil—increased, while the proportion of articles without a single author from an Amazonian country also increased. The results indicate that the research capacity of Amazonian countries has increased, but that leadership of high-impact projects may still largely reside with researchers from developed countries.

Differing Life History Characteristics Support Coexistence of Tree Soil Generalist and Specialist Species in Tropical Rain Forests

Abstract: Niche differentiation is a prominent mechanism for explaining tree species coexistence in tropical rain forests. Theory predicts that species that are specialized on a set of environmental conditions should competitively exclude generalists in those conditions, and that environmental heterogeneity allows the coexistence of many different species based on niche specialization. Yet, many tropical tree species of the family Dipterocarpaceae have broadly similar habitat preferences, with some occurring widely across several soil types. These soil generalists clearly persist despite the presence of other dipterocarp species that show clear soil specialization. We evaluate comparative seedling performance (growth and survival) of six Shorea species (Dipterocarpaceae) which differ in their adult tree habitat associations within the Sepilok Forest Reserve (Borneo, Malaysia). We tested the hypothesis that seedlings of species associated with a particular soil type perform better on that soil type than seedlings of soil generalist species, with generalists in turn performing better than specialists on a different soil type. We conducted a reciprocal transplant experiment including two soil types (alluvial and mudstone) and two light treatments (gap and understory). The soils differed in soil acidity, Al and P concentration. Observed species-specific differences in seedling responses to soil, light, and occasional flooding events could partially explain observed adult distribution, although not all species could be fully differentiated along these axes. Other trade-offs, such as investment in defense against herbivores and tolerance to soil waterlogging, may play additional roles in explaining coexistence of these species. Abstrak Perbezaan nic adalah mekanisme penting untuk menjelaskan kewujudan bersama spesies-spesies pokok dalam hutan hujan tropika. Secara teorinya adalah diramalkan bahawa spesies spesialis kepada satu set keadaan persekitaran akan bersaing secara kompetitif dan menolak kewujudan spesies generalis dalam set keadaan persekitaran yang sama, dan kepelbagaian alam sekitar membolehkan kewujudan bersama kebanyakan spesies yang berbeza berdasarkan spesialisasi nic. Bagaimanapun, kebanyakan spesies pokok tropika dari famili Dipterocarpaceae mempunyai keutamaan pilihan habitat yang sama, dan ada beberapa spesies yang lain dijumpai secara meluas di beberapa jenis tanah. Pertumbuhan berterusan spesies generalis sangat jelas walaupun adanya kehadiran spesies dipterokarpa yang lain yang menunjukkan spesialisasi tanah yang jelas. Kami menilai perbandingan pertumbuhan anak benih (tumbesaran dan kemandirian) daripada enam spesies Shorea (Dipterocarpaceae) yang berbeza dalam taburan habitat pokok dewasa di dalam Hutan Simpan Sepilok (Borneo, Malaysia). Kami menguji hipotesis bahawa anak benih spesies yang berasiosasi dengan jenis tanah tertentu akan menunjukkan prestasi pertumbuhan yang lebih baik daripada benih spesies generalis, dan seterusnya spesies generalis menunjukkan prestasi pertumbuhan yang lebih baik daripada spesies spesialis di tanah yang berbeza. Kami telah menjalankan satu eksperimen pemindahan tanaman dua hala dengan melibatkan dua jenis tanah (aluvium dan batu-lumpur) dan dua rawatan cahaya (kawasan luang dan kanopi bawah). Kedua-dua tanah tersebut berbeza dalam nilai keasidan tanah, dan kepekatan Al dan P. Diperhatikan adanya perbezaan mengikut spesies-spesifik dalam tindakbalas anak benih dengan keadaan tanah, cahaya dan peristiwa banjir yang kadang-kadang berlaku, dan ini dapat menjelaskan sebahagian pemerhatian pengagihan taburan pokok dewasa, walaupun tidak semua spesies menunjukkan pembezaan yang nyata. Lain-lain proses keseimbangan, seperti keupayaan tumbuhan dalam mencegah impak haiwan perosak dan daya ketahanan ditenggelami oleh banjir boleh memainkan peranan tambahan dalam menjelaskan kewujudan bersama spesies-spesies berkenaan.