Leaf Litter Decomposition and Monodominance in the Peltogyne Forest of Marac Island, Brazil
Dora M. Villela and John Proctor
(Click for Abstract)(Resumen Haga Clic Aquí)
Seasonal Foraging Activity and Bait Preferences of Ants on Barro Colorado Island, Panama
Daniel A. Hahn and Diana E. Wheeler
(Click for Abstract)(Resumen Haga Clic Aquí)
Variation in Species and Trophic Composition of Insect Communities in Puerto Rico
M. F. Barberena-Arias and T. M. Aide
(Click for Abstract)(Resumen Haga Clic Aquí)
The Structure of Ground Beetle Assemblages (Coleoptera: Carabidae) at Fruit Falls of Melastomataceae Trees in a Brazilian Terra Firme Rain Forest
Wilfried Paarmann, Burkhard Gutzmann, Philipp Stumpe, Hubertus Bolte, Steffen Kppers, Karsten Holzkamp, Clemens Niers, Joachim Adis, Nigel E. Stork, and Claudio R. V. da Fonseca
(Click for Abstract)
Temporal and Spatial Diversity and Distribution of Arboreal Carabidae (Coleoptera) in a Western Amazonian Rain Forest
Andrea Lucky, Terry L. Erwin, and Jon D. Witman
(Click for Abstract)(Resumen Haga Clic Aquí)
Flower Visitation by Bats in Cloud Forests of Western Ecuador
Nathan Muchhala and Pablo Jarrn-V.
(Click for Abstract)(Resumen Haga Clic Aquí)
Host Specialization among Wood-decay Polypore Fungi in a Caribbean Mangrove Forest
Gregory S. Gilbert and Wayne P. Sousa
(Click for Abstract)(Resumen Haga Clic Aquí)
Tree Seed Fate in a Logged and Fragmented Forest Landscape, Northeastern Costa Rica
Manuel R. Guariguata, Harold Arias-Le Claire, and Gabriela Jones
(Click for Abstract)(Resumen Haga Clic Aquí)
Abundance and Diversity of Euglossine Bees in the Fragmented Landscape of the Brazilian Atlantic Forest
Athayde Tonhasca Jr., Jacquelyn L. Blackmer, and Gilberto S. Albuquerque
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Range, Habitat Use, and Activity of Baird's Tapir in Costa Rica
Charles R. Foerster and Christpher Vaughan
(Click for Abstract)(Resumen Haga Clic Aquí)
Insect Pollination in the Cycad Genus Bowenia Hook. ex Hook. f. (Stangeriaceae)
Gary W. Wilson
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Postpollination Nectar Reabsorption and Its Implications for Fruit Quality in an Epiphytic Orchid
R. Luyt and S. D. Johnson
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Mutualistic Association between a Tiny Amazonian Stingless Bee and a Wax-Producing Scale Insect
Joo M. F. Camargo and Silvia R. M. Pedro
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Flight Speeds, Lipid Reserves, and Predation of the Migratory Neotropical Moth Urania fulgens (Uraniidae)
Robert Dudley, Robert B. Srygley, Evandro G. Oliveira, and Phil J. DeVries
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Low Density of Ant Lion Larva (Myrmeleon crudelis) in Ant-Acacia Clearings: High Predation Risk or Inadequate Substrate?
Mara Genoveva Gatti and Alejandro G. Farji-Brener
(Click for Abstract)(Resumen Haga Clic Aquí)
Effects Of Forest Fragmentation on the Colima Long-Nosed Bat (Musonycteris harrisoni) Foraging In Tropical Dry Forest of Jalisco, Mexico
Kathryn E. Stoner, Mauricio Quesada, Vctor Rosas-Guerrero, and Jorge A. Lobo
(Click for Abstract)(Resumen Haga Clic Aquí)
Habitat Use and Diet of Baird's Tapirs (Tapirus bairdii) in a Montane Cloud Forest of the Cordillera de Talamanca, Costa Rica
Mathias W. Tobler
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Seed Dispersal by Sloth Bears (Melursus ursinus) in South India
P.G. Sreekumar and M. Balakrishnan
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Leaf Litter Decomposition and Monodominance in the Peltogyne Forest of Marac Island, Brazil
Dora M. Villela (dora@uenf.br) and John Proctor
The forest type dominated by Peltogyne gracilipes (Caesalpiniaceae) on the riverine Marac Island is the least species-rich of any recorded for Brazilian Amazonia. Because the forest has high soil and foliar Mg concentrations, and Mg is known to be toxic to plant growth at high concentrations, this study tested the hypothesis that dominance by Peltogyne is related to Mg leaf litter amounts and decomposition. We predicted that decomposition of Peltogyne leaves would differ from that of other species, and that their decomposition would result in a pulse of Mg release. Three plots (50 X50 m) were established in each of three forest types: Peltogyne -rich forest (PRF; dominated by P. gracilipes), Peltogyne -poor forest (PPF), and forest without Peltogyne (FWP). Three leaf litter decomposition experiments tested if decomposition of mixed leaf litter in coarse-mesh (CM) litterbags differed among forests (experiment 1); whether or not decomposition and nutrient release of Ecclinusa guianensis, Lueheopsis duckeana, and Peltogyne in CM litterbags differed among forests and species (experiment 2); and using fine-mesh (FM) litterbags, investigated the differences in the influence of faunal activity on Ecclinusa and Peltogyne decomposition (experiment 3). Decomposition was independent of the presence and dominance of Peltogyne, since decomposition rates in both PRF and FWP were in general lower than in PPF. These differences appeared to be related to faunal activity. The decomposition of Peltogyne leaves was lower than that of the other species tested and was more affected by microbial and physical action. It is possible that the monodominance of Peltogyne is related to its deciduousness and faster decomposition in the dry season, which coincides with a large leaf fall. Magnesium was lost quickly from the Peltogyne leaves and the resultant pulses of Mg into the soil during the heavy rains at the beginning of the wet season may be deleterious for other species that are not adapted to high solution Mg concentrations. Results obtained were consistent with the hypothesis that Peltogyne dominance is related to the pattern of its leaf decomposition and the seasonal pulses of toxic Mg.
A floresta dominada por Peltogyne gracilipes (Caesalpiniaceae) na Ilha fluvial de Marac a mais pobre em espcies reportada para a Amaznia brasileira. Devido a esta floresta possuir altas concentraes de Mg no solo e nas folhas, e pelo fato de Mg ser conhecidamente txico para o crescimento das plantas quando em altas concentraes, este estudo testou a hiptese de que a dominncia de Peltogyne est relacionada com as quantidades de Mg e com a decomposio das folhas da serrapilheira. Esperou-se encontrar um padro de decomposio diferente para folhas de Peltogyne, e que as folhas de Peltogyne apresentassem um pulso de liberao de Mg. Trs parcelas (50 X 50 m) foram estabelecidas em cada um dos trs tipos florestais: floresta rica em Peltogyne (PRF; dominada por P. gracilipes), floresta pobre em Peltogyne (PPF) e floresta sem Peltogyne (FWP). Trs experimentos de decomposio de folhas da serrapilheira testaram se a decomposio de folhas mistas da serrapilheira em sacos de serrapilheira de malha grossa (CM) difere entre florestas (experimento 1), se a decomposio e a liberao de nutrientes de Ecclinusa guianensis, Lueheopsis duckeana, e Peltogyne em sacos de serrapilheira CM difere entre florestas e entre espcies (experimento 2), e usou sacos de serrapilheira de malha fina (FM) para investigar as diferenas na influncia da atividade da fauna na decomposio de e Peltogyne (experimento 3). A decomposio foi independente da presena e dominncia de Peltogyne, j que as taxas de decomposio em PRF e FWP foram em geral menores que em PPF. Estas diferenas parecem estar relacionadas atividade da fauna. A decomposio de folhas de Peltogyne foi menor que a das demais espcies testadas e foi mais afetada pela ao microbiolgica e fsica. possvel que a dominncia de Peltogyne esteja relacionada com a sua deciduidade e com a rpida decomposio na estao seca, a qual coincide com uma grande queda de folhas. Magnsio foi perdido rapidamente das folhas de Peltogyne e os pulsos resultantes de Mg no solo durante as fortes chuvas no incio da estao chuvosa podem ser deletrios para outras espcies que no esto adaptadas as altas concentraes deste on. Os resultados obtidos foram consistentes com a hiptese de que a dominncia de Peltogyne est relacionada com o padro de decomposio de suas folhas e com os pulsos sazonais de Mg txico.
Seasonal Foraging Activity and Bait Preferences of Ants on Barro Colorado Island, Panama
Daniel A. Hahn (dhahn@u.arizona.edu) and Diana E. Wheeler
A yearlong arboreal baiting survey of ants was conducted during 1983 on Barro Colorado Island, Panama. Because of a severe El Nio event, the 1983 dry season in Panama was exceptionally long and dry with a distinct boundary between the dry and wet seasons. Baits, located on tree trunks, attracted both terrestrial and arboreal ants, allowing comparisons between the two groups. Species composition at baits changed dramatically with season. Baits were primarily occupied by arboreal species during the dry season, while wet season baits were occupied mostly by terrestrial species. Arboreal and terrestrial ants differed markedly in their preferences for protein- or carbohydrate-based baits; arboreal ants preferred protein-based baits and terrestrial ants preferred carbohydrate-based baits. Foraging preference for protein suggests that protein resources were limiting for arboreal ants, particularly during the dry season, and that carbohydrate resources were limiting for terrestrial ants. Fundamental differences in arboreal and terrestrial habitats may promote the differences in foraging strategies observed during an annual cycle in a seasonal tropical forest.
Durante el ao de1983 se realiz un estudio mirmecolgico en la isla de Barro Colorado, Panam. Debido a que el fenmeno "El Nio" fue muy severo ese ao, la estacin seca fue excepcionalmente intensa y larga; adems, se observ una diferencia marcada entre la estacin seca y la hmeda. Se colocaron cebos en los troncos de los rboles que atrajeron hormigas terrestres y arbreas, lo que permiti la comparacin de estos dos grupos. La composicin de las especies atraidas por los cebos vari notablemente de acuerdo a la temporada; durante la estacin seca predominaron las especies arbreas, mientras que en la hmeda predominaron las terrestres. Las hormigas arbreas y las terrestres difirieron notablemente en su preferencias por cebos preparados con proteinas o carbohidratos. Las hormigas arbreas prefirieron las proteinas, mientras que las terrestres prefirieron los carbohidratos. La inclinacin por proteinas sugiere que stas son un recurso limitante para las hormigas arbreas, particularmente durante la estacin seca; mientras que los carbohidratos lo son para las hormigas terrestres. Las diferencias fundamentales entre los ambientes arbreo y terrestre puede promover diferencias en las estrategias de forrajeo observadas durante el ciclo anual del bosque tropical.
Variation in Species and Trophic Composition of Insect Communities in Puerto Rico
M. F. Barberena-Arias (mf_barberena@yahoo.com) and T. M. Aide
Insects are important participants in many ecosystem processes, but the effects of anthropogenic and natural disturbances on insect communities have been poorly studied. To describe how disturbances affect insect communities, we addressed two questions: Do insect communities return to a pre-hurricane composition? and How do insect communities change during succession? To answer these questions, we studied insect communities in a chronosequence of two abandoned pastures (5 yr and 32 yr) and a mature forest ( >80 yr) that were recently disturbed by two hurricanes (Hurricane Hugo, 1989; Hurricane Georges, 1998). Although insect abundance and richness fluctuated during the study, all sites returned to pre-hurricane (Hurricane Georges) abundance and richness in less than one year. All trophic categories present before Hurricane Georges were present after the hurricane, but richness within categories fluctuated greatly. Insect richness did not increase during succession; the 5 yr site had the highest richness, the >80 yr site had an intermediate richness, and the 32 yr site the lowest. Nevertheless, the species composition of the two forested sites was different in comparison to the 5 yr site. These results suggest that trophic structure varies little in time and space, but the species composition within each trophic category is highly variable.
Los insectos participan en muchos de los procesos de los ecosistemas, sin embargo pocos estudios se han enfocado en el efecto que tienen las perturbaciones naturales y antropognicas sobre las comunidades de insectos. Para describir cmo las perturbaciones afectan las comunidades de insectos, nos planteamos dos preguntas: Regresan las comunidades de insectos a la composicin existente antes del huracn? y Cmo cambian las comunidades de insectos durante la sucesin? Para contestar estas preguntas, estudiamos las comunidades de insectos en una cronosecuencia de dos pastizales abandonados (5 aos y 32 aos) y un bosque maduro (>80 aos) que fueron recientemente perturbados por dos huracanes (Huracn Hugo, 1989; Huracn Georges, 1998). Aunque la abundancia y riqueza de insectos fluctu durante el estudio, todos los sitios recuperaron los niveles prehuracn (Huracn Georges) en menos de un ao. Todas las categoras trficas presentes antes del Huracn Georges siguieron presentes despus del huracn, pero la riqueza dentro de las categoras fluctu ampliamente. La riqueza de insectos no aument durante la sucesin; el sitio de 5 aos tuvo la riqueza mas alta, el sitio de >80 aos tuvo una riqueza intermedia, y el sitio de 32 aos tuvo la riqueza mas baja. Sinembargo, la composicin de especies de los dos sitios de bosque fue diferente en comparacin al sitio de 5 aos. Estos resultados sugieren que la estructura trfica vara poco en tiempo y espacio, pero la composicin de especies de las categoras trficas es muy variable.
The Structure of Ground Beetle Assemblages (Coleoptera: Carabidae) at Fruit Falls of Melastomataceae Trees in a Brazilian Terra Firme Rain Forest
Wilfried Paarmann (Wilfried.Paarmann@FU.FH-Goettingen.de), Burkhard Gutzmann, Philipp Stumpe, Hubertus Bolte, Steffen Kppers, Karsten Holzkamp, Clemens Niers, and Claudio R. V. da Fonseca
Although most Carabidae are recognized as predacious, recent studies have shown that some tropical rain forest Carabidae use the small seeds of fallen fruit from some tree species as a key food resource (particularly figs [Moraceae] but also those from other families). Assemblages of carabid beetles (Coleoptera: Carabidae) at fruit falls of the Melastomataceae tree genera, Bellucia, Loreya, and Miconia, were studied in a terra firme rain forest near Manaus (Amazonia, Brazil) from February 1992 to August 1996. Of 5483 specimens of 14 carabid species collected at 53 fruit falls, 98.2 percent of the collected beetles represented the seed-feeding genus Notiobia. Four of the 7 Notiobia species were found to reproduce at Melastomataceae fruit falls. The most abundant species, N. glabrata, was found to be a Melastomataceae seed generalist, while N. maxima seemed to prefer the seeds of Bellucia, and N. aulica and N. umbrifera the seeds of Miconia. The presence of larvae indicated reproduction of N. glabrata at fruit falls of all three tree genera and reproduction of N. maxima at those of Bellucia. Fruit falls of different species and genera of Melastomataceae appeared to occur at different times of the year and not continuously throughout the year. The seed-feeding Notiobia species, which specialize on Melastomataceae, used fruit falls of figs as migratory "stepping stones" during periods when there were no Melastomataceae fruit falls. The comparable suite of fig seed-feeding specialist species of Notiobia did not appear to do the reverse and seemed to avoid Melastomataceae fruit falls. The carabid assemblage at fig fruit falls was more diverse than the assemblage at those of Melastomataceae. Among the Melastomataceae, carabid species richness was highest at Miconia fruit falls and lowest at Loreya fruit falls. The three most common predatory species caught at Ficus fruit falls were also caught at those of Melastomataceae and appearred to reproduce at both fruit fall types. The proportion of the carabid assemblage accounted by predatory species was much lower at Melastomataceae (1.8%) than at fig fruit falls (8%).
Temporal and Spatial Diversity and Distribution of Arboreal Carabidae (Coleoptera) in a Western Amazonian Rain Forest
Andrea Lucky (Andrea_Lucky@yahoo.com), Terry L. Erwin, and Jon D. Witman
Diversity of arboreal carabid beetles was sampled by fumigation in 100 3 X 3 m stations within a 100 X 1000 m terra firme forest plot in Ecuadorian Amazonia. Nine sampling dates from January 1994 to October 1996 yielded 2329 individuals belonging to 318 species of which more than 50 percent were undescribed species. A high percentage of the species sampled were rare; the proportion that occurred once per sampling date (singletons) ranged from 50.0 to 62.5 percent. Estimates of species richness were from 82 to 282 species of arboreal carabids in the study plot on a given sampling date. Most richness values were greater than 173 species. Species accumulation curves attained asymptotes for all but one sampling date, indicating that an adequate level of sampling effort was used to characterize the diversity of carabid fauna. Total accumulation curves based on pooled data failed to reach asymptotes. There was a high turnover in species composition between sampling dates; less than 50 percent of the species between the majority of sampling dates were shared, suggesting that the total species pool may be extremely large. Although species composition changed seasonally, species richness varied little. Spatial autocorrelation analysis revealed that the structure of this species assemblage was significantly patterned at distances below 280 m. Taken together, the large percentage of undescribed species, the failure of the overall species accumulation curves to level off, and the high turnover in species composition indicate that the species diversity of carabid beetles is far higher than previously thought.
La diversidad de carbidos arbreos en la Amazona del Ecuador se muestre mediante fumigacin en 100 sitios de 3 X 3 m dentro de un rea de 100 X 1000 m de bosque terra frme. En nueve fechas de muestreo, desde enero de 1994 hasta octubre de 1996, se observaron 2329 individuos de 318 especies. Ms del 50 por ciento del nmero total de especies no estaba descrito. Muchas de las especies encontradas son raras. Las proporciones de las especies que estuvieron representadas por un solo individuo por fecha (singletons) tuvieron un rango de 50.0 a 62.5 por ciento. La estimacin estadstica de la riqueza de especies indic la presencia de 82 a 282 especies en las fechas de muestreo. Las curvas de acumulacin de especies se estabilizaron en todas las fechas con excepcin de una. Estos resultados confirmaron que el nivel de esfuerzo de muestreo fue adecuado para caracterizar la diversidad de los carbidos. Las curvas de acumulacin total no se estabilizaron a lo largo de todo el estudio. Se observaron diferencias en la composicin de especies entre las fechas de muestreo, con menos de un 50 por ciento de especies compartidas entre la mayora de las fechas. Sin embargo, entre las estaciones se registr poca variacin en la riqueza de especies. El anlisis de autocorrelacin espacial revel que la estructura de este grupo taxonmico tiene patrones significativos a distancias menores de 280 m. En total, el alto porcentaje de especies no descritas, la falta de nivelacin de las curvas de acumulacin y la baja proporcin de especies compartidas entre fechas, indican que la diversidad de carbidos es mucho ms alta de lo pensado.
Flower Visitation by Bats in Cloud Forests of Western Ecuador
Nathan Muchhala (nmuchhal@fig.cox.miami.edu) and Pablo Jarrn-V.
The importance of bat pollination has been demonstrated for many plant species. Yet this mutualism has rarely been studied on a community-wide level. In this paper we present results of a yearlong study of a bat-flower community in cloud forests on the western slopes of the Ecuadoran Andes. Of eight plant-visiting bat species caught, only Anoura caudifera and A. geoffroyi were carrying pollen. These species of Anoura supplement their diets with insects. Unlike glossophagines in other environments, however, which switch completely to a frugivorous or insectivorous diet during certain seasons, they are nectarivorous year-round and were never found with seeds or fruit pulp in their feces. Of the 13 morphotypes of pollen carried by the bats, 11 were identified to genus and 7 to species. Floral characteristics of all of these plants fit the traditional chiropterophilous syndrome well. Our study represents the first direct evidence of bat pollination for those plants identified to species, including four species of Burmeistera (Campanulaceae), as well as the first record of bat pollination for a plant of the genus Meriania (Melastomataceae). While overlap in the diets of the two Anoura was high, significant differences in visitation frequencies to particular plant species were detected. The larger bat species (A. geoffroyi) preferred large flowers, whereas the smaller species (A. caudifera) preferred small flowers.
La importancia de los murcilagos en la polinizacin se ha demostrado para muchas especies de plantas; sin embargo, este mutualismo ha sido poco estudiado a nivel de comunidad. Presentamos los resultados provenientes de un estudio, de un ao de duracin, en una comunidad de murcilagos polinizadores y sus relaciones con las plantas en bosques nublados de las estribaciones occidentales de los Andes del Ecuador. De las ocho especies de murcilagos registradas, solo Anoura caudifera y A. geoffroyi transportaban polen. Estos Anoura complementan su dieta con insectos; no obstante, a diferencia de Glossophaginae en otros ambientes, que cambian su dieta exclusivamente a frutas o insectos estacionalmente, stos se alimentan de polen a lo largo del ao y nunca fueron encontrados con semillas o pulpa de fruta en sus heces. De los 13 morfotipos de polen transportado por los murcilagos, 11 fueron identificados hasta gnero y 7 hasta especie. Las caractersticas florales de todas estas plantas corresponden al sndrome quiropterolfilo. Nuestro estudio representa la primera evidencia directa de polinizacin por murcilagos para las plantas identificadas hasta especie, incluyendo cuatro especies de Burmeistera (Campanulaceae), as como el primer registro para el gnero Meriania (Melastomataceae). Aunque exista solapamiento en la dieta de los dos Anoura, se determin diferencias significativas en las frecuencias de visita a especies particulares. La especie ms grande (A. geoffroyi) mostraba preferencia por flores grandes, mientras que la pequea (A. caudifera) prefera flores de menor tamao.
Host Specialization among Wood-decay Polypore Fungi in a Caribbean Mangrove Forest
Gregory S. Gilbert (ggilbert@cats.ucsc.edu) and Wayne P. Sousa
Host specialization in highly diverse tropical forests may be limited by the low local abundance of suitable hosts. To address whether or not fungi in a low-diversity tropical forest were released from this restriction, fruiting bodies of polypore basidiomycete fungi were collected from three species of mangroves (Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle) in a Caribbean mangrove forest in Panama. Unlike other tropical forests, the polypore assemblage in this mangrove forest was strongly dominated by a few host-specialized species. Three fungal species, each with strong preference for a different mangrove host species, comprised 88 percent of all fungi collected.
En los bosques tropicales de alta diversidad, la especializacin por un hospedero particular puede verse limitada debido a la baja abundancia de hospederos apropiados. Para determinar si dicha limitacin de hospederos no ocurre en los hongos que crecen en bosques tropicales de baja diversidad, se recolectaron cuerpos fructferos de hongos basidiomicetos poliporoides presentes en tres especies de mangle (Avicennia germinans, Laguncularia racemosa, y Rhizophora mangle) en un manglar de la costa caribea de Panam. A diferencia de otros bosques tropicales, la comunidad de hongos poliporales en el manglar estudiado se encontraba dominada por pocas especies altamente especficas. Tres especies de hongos, cada una con una preferencia particular por un hospedero diferente, representaron el 88 por ciento de todos los hongos recolectados.
Tree Seed Fate in a Logged and Fragmented Forest Landscape, Northeastern Costa Rica
Manuel R. Guariguata (mguarigu@computo.catie.ac.cr), Harold Arias-Le Claire, and Gabriela Jones
We compared the seed fate of two animal-dispersed, large-seeded timber species (Dipteryx panamensis [Fabaceae] and Carapa guianensis [Meliaceae]) in logged and fragmented forests with that for continuous forest in northeastern Costa Rica. For both species, we quantified rates of seed removal (an index of vertebrate predation) and the fate of dispersed seeds (those carried away from their original location that either germinated or were not subsequently removed within three months). We predicted that (1) fewer seeds would be dispersed by vertebrates in fragmented forest than in continuous forest due to low population abundances after hunting and/or loss of suitable habitat, and (2) seed predation rates would be higher in forest fragments than in continuous forest due to high abundance of small-bodied seed consumers. We compared three forest fragments currently managed for timber (140-350 ha) and a large reserve of continuous forest (La Selva, 1500 ha and connected to a national park). An exclusion experiment was performed (seeds placed in the open vs. seeds within semipermeable wire cages; 5 cm mesh size) to evaluate the relative roles of large and small animals on seed removal. Seed germination capacity did not differ among all four sites for both species. Removal of Dipteryx seeds was higher in forest fragments (50% removal within 10 days and related to the activity of small rodents) compared to La Selva (50% removal after 50 days). Also, more Dipteryx seeds were dispersed at La Selva than in fragmented forests. Contrary to our predictions, removal of Carapa seeds was equally high among all four sites, and there was a trend for more seeds of Carapa to be dispersed in fragments than in La Selva. Our results suggest that fragmentation effects on tree seed fate may be specific to species in question and contingent on the animal biota involved, and that management strategies for timber production based on regeneration from seed may differ between forest patches and extensive forests.
En bosque continuo y en un paisaje de bosque fragmentado bajo manejo para produccin maderera y en el noreste de Costa Rica, se evalu el destino de las semillas de dos especies de rboles comerciales con semillas grandes que son dispersadas por animales (Dipteryx panamensis [Fabaceae] y Carapa guianensis [Meliaceae]). Se compararon las tasas de remocin (un indicador de la depredacin por vertebrados) como de dispersin (aquellas semillas removidas de su ubicacin original y que germinaron o no fueron removidas posteriormente durante tres meses) entre estas dos especies. Nuestras predicciones fueron que (1) los vertebrados dispersaran menos semillas en los fragmentos que en el bosque continuo y que (2) las tasas de depredacin seran mayores en los fragmentos que en el bosque contnuo debido a una alta abundancia de consumidores. Se compararon tres fragmentos de bosque manejados (140-350 ha) y una reserva de bosque continuo de gran tamao (La Selva, 1500 ha y conectada a un parque nacional). Se realiz un experimento de exclusin (semillas colocadas sobre el suelo vs. semillas dentro de jaulas semipermeables con una malla de 5 cm) para evaluar el impacto relativo de vertebrados grandes y pequeos en las tasas de remocin. La capacidad de germinacin de las semillas de ambas especies no vari entre los cuatro sitios de estudio. La tasa de remocin de las semillas de Dipteryx fue mucho ms alta en los tres fragmentos (50 % de remocin en 10 das relacionado con la actividad de roedores pequeos) que en La Selva (50% de remocin luego de 50 das). Adems, en comparacin con los fragmentos, un mayor nmero de semillas de Dipteryx fue dispersado en La Selva. Contrario a nuestras predicciones, la remocin de semillas de Carapa fue uniformemente alta en los cuatro sitios de estudio y hubo una tendencia en las semillas de Carapa a ser dispersadas con ms frecuencia en los fragmentos que en La Selva. Estos resultados sugieren que los efectos de la fragmentacin sobre el destino final de las semillas de rboles pueden ser especficos para cada especie y dependen de la biota animal involucrada en el proceso. Asimismo, las estrategias de manejo para la produccin de madera basadas en la regeneracin a partir de semillas pueden diferir entre los fragmentos de bosque y las reas boscosas extensas.
Abundance and Diversity of Euglossine Bees in the Fragmented Landscape of the Brazilian Atlantic Forest
Athayde Tonhasca Jr. (tonhasca@uenf.br), Jacquelyn L. Blackmer, and Gilberto S. Albuquerque
Male euglossine bees were sampled with chemical baits every two months from September 1997 to July 1999 at nine sites in the Desengano mountain range, Rio de Janeiro State, Brazil. Four sites were located in Atlantic Forest mature second growth, two sites in disturbed forest, and three sites in forest fragments of 200, 156, and 14 ha, respectively. We collected 3653 male euglossine bees from at least 21 species. Analyses of variance indicated no differences among the three habitat types for total number of bees, and 5 of the 6 dominant species. Bootstrapping indicated significant variation in species richness and diversity for some sites, but there was no clear indication of differences among habitats. Similarity as measured with the Morisita-Horn index was inversely related to distance between sites, but relatively high for most site combinations. These results suggest that the euglossine bee community in the three habitats was essentially the same. Although some species were associated with each habitat type, most appeared to respond to temporal local conditions. Our results do not support the hypothesis that forest fragmentation or habitat alteration reduces abundance and diversity of euglossine bees.
Home Range, Habitat Use, and Activity of Baird's Tapir in Costa Rica
Charles R. Foerster and Christopher Vaughan (cvaughan@students.wisc.edu)
Home range size, habitat utilization, and activity patterns of five adult Baird's tapirs (Tapirus bairdii) were studied via radiotelemetry from June 1995 to May 1996 in Corcovado National Park, Costa Rica. Estimates of 4153 animal locations were made. Home range sizes (95% minimum convex polygon) for the entire study period (wet season and dry season) averaged 125.0 ha (SD = 72.7), 94.9 ha (SD = 47.6), and 96.8 ha (SD = 51.2), respectively. Monthly home range sizes averaged 55.5 ha (SD = 32.1) and did not vary between seasons. Across the entire study, secondary forest, the most commonly used habitat type (61.3%) was utilized more than expected as predicted by availability (49.6%), while the second most used habitat, primary forest, was used (25.0%) less than expected (36.2%). The same general habitat selection pattern was observed in the dry season. Wet season habitat utilization values showed tapirs using both primary and secondary forest habitats in proportion to their availability. Diurnal and nocturnal activity levels were estimated at 20.2 and 80.4 percent, respectively. More diurnal and less nocturnal activity was observed during the wet season compared to the dry season.
El mbito hogareo, uso del hbitat y los patrones de actividad de cinco tapires centroamericanos (Tapirus bairdii) se estudiaron por medio de radiotelemetra desde junio de 1995 hasta mayo de 1996 en el Parque Nacional Corcovado (PNC), Costa Rica. Nuestras estimaciones se basan en 4153 ubicaciones. Los mbitos hogareos promedio (polgono convexo mmimo del 95%) para todo el periodo de estudio, estacin hmeda y seca fueron de 125.0 ha (DE 72.7), 94.9 ha (DE 47.6) y 96.8 ha (DE 51.2) respectivamente. El promedio mensual del ambito hogareo fue de 55.5 ha. (DE 32.1) y no vari entre las estaciones. Durante el periodo de estudio, el bosque secundario fue el hbitat ms utilizado (61.3%) a pesar de tener una menor disponibilidad (49.6%); en segundo trmino le sigui el bosque primario (25%) que fue utilizado menos de lo esperado (36.2%). El mismo patrn de seleccin de hbitat se observ durante la estacin de secas. Los valores de utilizacin en la estacin hmeda indican que los tapires usan el bosque primario y secundario de acuerdo a su disponibilidad. Los niveles de actividad diurna y nocturna fueron 20.2 y 80.4% respectivamente. Durante la temporada hmeda se observ una mayor actividad diurna y una disminucin en la nocturna.
Insect Pollination in the Cycad Genus Bowenia Hook. ex Hook. f. (Stangeriaceae)
Gary W. Wilson (Gary.Wilson@jcu.edu.au)
All confirmed records of entomophilic pollination in cycads are for species in the Zamiaceae. This paper presents details of entomophily in both species of Bowenia in the Stangeriaceae. Seed set in female cones from which wind and water-borne pollen, but not insects, was excluded, indicates that pollination is obligately entomophilous. The pollination vectors are Miltotranes weevils and the relationships are species-specific and possibly coevolutionary.
Postpollination Nectar Reabsorption and Its Implications for Fruit Quality in Epiphytic Orchid
R. Luyt and S. D. Johnson (JohnsonSD@nu.ac.za)
We present evidence that pollination triggers nectar reabsorption in flowers of the epiphytic orchid Mystacidium venosum. The amount of sugar in nectar of M. venosum decreased significantly by more than 50 percent within 72 hours of pollination. Hand-pollinatred flowers from which nectar was previously removed set significantly smaller fruits with a lower percentage of viable seeds than hand-polllinated flowers containing nectar, suggesting that resources reclaimed by nectar resorption are allocated to fruit production.
Mutualistic Association between a Tiny Amazonian Stingless Bee and a Wax-Producing Scale Insect
Joo M. F. Camargo (jmfdcma@usp.br) and Silvia R. M. Pedro
The Amazonian stingless bee Schwarzula sp. houses and attends, in its nest, soft scale insects, Cryptostigma sp. (Coccidae), from which obtains sweet secretions (honeydew) for their feeding and additional wax to build their nests. The bees nests in tunnels burrowed by moth larvae in branches of Campsiandra angustifolia, Caesalpiniaceae.
A abelha amaznica sem ferro Schwarzula sp. hospeda e cuida, em seu ninho, de cochonilhas, Cryptostigma sp. (Coccidae), das quais obtm secrees adocicadas para sua alimentao, e cera adicional para construir seus ninhos. As abelhas nidificam em tneis escavados por larvas de mariposa em ramos de Campsiandra angustifolia, Caesalpiniaceae.
Flight Speeds, Lipid Reserves, and Predation of the Migratory Neotropical Moth Urania fulgens (Uraniidae)
Robert Dudley (r_dudley@utxvms.cc.utexas.edu), Robert B. Srygley, Evandro G. Oliveira, and Phil J. DeVries
Aerodynamic theory predicts that migrant fliers should reduce their speed of flight as endogenous energy reserves are gradually consumed. This prediction was tested for Urania fulgens (Walker) moths migrating through central Panama in 1987 and again in 1998. Direct airspeed measurements together with chloroform:methanol extractions of abdominal lipids were used to determine that, contrary to theoretical predictions, the speed of flight among individuals was independent of both body mass and abdominal lipid mass.
Low Density of Ant Lion Larva (Myrmeleon crudelis) in Ant-Acacia Clearings: High Predation Risk or Inadequate Substrate?
Mara Genoveva Gatti and Alejandro G. Farji-Brener (alefarji@yahoo.com)
We experimentally determined whether the low density of antlion larvae found in ant-acacia clearings is due to high levels of ant predation or an inadequate substrate for pit-trap construction. Pit establishment was more affected by soil improvement than by the exclusion of ants, suggesting that soil condition is the main factor that affect antlions' density. The low density of this ant-predator in ant-acacia clearings may be considered as an indirect advantage of the ant's pruning behavior.
Determinamos experimentalmente si la baja densidad de larvas del "len de las hormigas" en los claros de Acacia producidos por hormigas es consecuencia de los altos niveles de depredacion por hormigas o de la condicion del suelo alrededor de las Acacias. El establecimiento de las trampas del "len de las hormigas" estuvo ms afectado por el mejoramiento del suelo que por la exclusin de hormigas, sugiriendo que la condicin del suelo es el factor ms importante que afecta la densidad del "len de las hormigas". La baja densidad de este depredador de hormigas en los claros de Acacia puede ser considerada como una ventaja indirecta de la actividad "limpiadora" de las hormigas.
Effects of Forest Fragmentation on the Colima Long-nosed Bat (Musonycteris harrisoni) Foraging in Tropical Dry Forest of Jalisco, Mexico
Kathryn E. Stoner (kstoner@oikos.unam.mx), Mauricio Quesada, Vctor Rosas-Guerrero, and Jorge A. Lobo
We determined the effect of forest fragmentation on the nectarivorous Colima long-nosed bat (Musonycteris harrisoni) by observing foraging behavior of this species in disturbed and undisturbed forests on the flowers of Ceiba grandiflora (Bombacaceae). The study was conducted in the area of the Chamela-Cuixmala Biosphere Reserve in Jalisco, Mxico. Musonycteris harrisoni was observed visiting flowers during six nights (88 visits), exclusively in undisturbed forest. This species feeds on the nectar and serves as a pollinator of C. grandiflora.
Determinamos el efecto de la fragmentacin del bosque sobre el murcilago trompudo de Harrison (Musonycteris harrisoni) observando el comportamiento de forrajeo de este especie en bosque perturbado y no perturbado en las flores de Ceiba grandiflora (Bombacaceae). Se realiz el estudio en la regin de la Reserva de la Biosfera Chamela-Cuixmala en Jalisco, Mexico. Se observ M. harrisoni visitando flores durante seis noches (88 visitas), exclusivamente en bosque no perturbado. Esta especie se alimenta del nctar y sirve como polinizador para C. grandiflora.
Habitat Use and Diet of Baird's Tapirs (Tapirus bairdii) in a Montane Cloud Forest of the Cordillera de Talamanca, Costa Rica
Mathias W. Tobler (matobler@gmx.net)
Results from 24 transects showed that tapirs were less abundant in areas with higher human presence. They also preferred less steep areas, especially as browsing sites. An analysis of feces showed that fibers were the largest component (40-55%) followed by leaves (10-30%) and twigs (15%). Bamboo (Chusquea spp.) was found in all samples and probably accounts for the high proportion of fibers. Twenty-seven plant species were identified as eaten by tapirs.
Estudios en 24 transectos sealan que las dantas son menos abundantes en sectores con mayor presencia humana. Las dantas resultaron ser ms abundantes en pendientes bajas utilizadas como reas de alimentacin. Anlisis adicionales de heces mostraron un contenido de 40-55% de fibras, 10-30% de hojas y 15% de ramitas. Todas las muestras contenan restos de bamb (Chusquea spp.) que probablemente corresponden al alto contenido de fibras. Finalmente se identificaron 27 especies de plantas que las dantas consumen.
Seed Dispersal by the Sloth Bear (Melursus ursinus) in South India
P. G. Sreekumar and M. Balakrishnan (balak21@rediffmail.com)
Previous studies have shown that sloth bears are mainly myrmecophagous, but in this study, 39 and 83 percent (wet and dry season, respectively) of scats surveyed in South India contained fruits. Seeds from three of six plant species collected from scats germinated faster than seeds not passing through bears; germination percentage was not higher in any of the six species. These results suggest that the sloth bear may play an important role in the population dynamics of fleshy-fruited species of the region.