bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Selective Logging on Populations of Two Tropical Understory Herbs in an Amazonian Forest1
Authors: Costa Flívia Regina Capellotto , Senna Cristina , Nakkazono Erika Matsuno 
Published: March 2006

ABSTRACTThis study examined the effects of (1) rime elapsed after logging and (2) logging intensity on the total, juvenile, and adult densities, and on reproduction of Calathea altissima and Ischnosiphon amuma (Matantaceae), two monocot herb species in the understory of Central Amazonian forests. Logging was carried out experimentally at various intensities in eight plots (4 ha each) during 1987 and three plots in 1993. Five plots were left as experimental controls. In 1998, total and adult densities of the two species were greater in the plots logged 11 years before than in controls. For I. arouma, total and adult densities were also higher in the plots logged 5 years before; however, juvenile densities were less affected. The intensity of logging influenced adult density of both species but not total or juvenile densities. Densities of reproductive individuals of both species were higher in the logged areas and increased with logging intensity. The effects of time after logging and logging intensity on reproduction were indirect due to the greater number of adult plants in those areas. The observed effects were probably mediated by changes in canopy cover in logged areas. Greater light intensities in logging gaps, roads, and their margins may lead to increased reproduction, recruitment, growth, and survival, which in turn can lead to increased plant density. These results indicate that logging has long–term effects on understory plant populations.
Tree Seed Fate in a Logged and Fragmented Forest Landscape, Northeastern Costa Rica1
Authors: Guariguata Manuel R. , Claire Harold Arias‐Le , Jones Gabriela 
Published: March 2006

ABSTRACTWe 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.
Flight Speeds, Lipid Reserves, and Predation of the Migratory Neotropical Moth Urania fulgens (Uraniidae)1
Authors: Dudley Robert , Srygley Robert B. , Oliveira Evandro G. , DeVries Phil J. 
Published: March 2006

ABSTRACTAerodynamic 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.
Habitat Use and Diet of Baird's Tapirs (Tapirus bairdii) in a Montane Cloud Forest of the Cordillera de Talamanca, Costa Rica1
Authors: Tobler Mathias W. 
Published: March 2006

ABSTRACTResults 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 to be eaten by tapirs.
Seed Dispersal by the Sloth Bear (Melursus ursinus) in South India1
Authors: Sreekumar P. G. , Balakrishnan M. 
Published: March 2006

ABSTRACTPrevious 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.
Nutrient Limitation to Primary Productivity in a Secondary Savanna in Venezuela1
Authors: Barger Nichole N. , D'Antonio Carla M. , Ghneim Thaura , Brink Keary , Cuevas Elvira 
Published: March 2006

ABSTRACTWe examined nutrient limitation to primary productivity in a secondary savanna in the interior branch of the Coastal Range of Venezuela, which was converted from forest to savanna more than 100 years ago. We manipulated soil nutrients by adding nitrogen (+N), phosphorus and potassium (+PK), and nitrogen, phosphorus, and potassium (+NPK) to intact savanna. Eleven months after fertilization, we measured aboveground biomass and belowground biomass as live fine roots in the top 20 cm of soil, and species and functional group composition in response to nutrient additions. Aboveground biomass was highest in the NPK treatment ([mean g/m2]; control = 402, +N = 718, +PK = 490, +NPK = 949). Aboveground production, however, appeared to be limited primarily by N. Aboveground biomass increased 78 percent when N was added alone but did not significantly respond to PK additions when compared to controls. In contrast to aboveground biomass, belowground biomass increased with PK additions but showed no significant increase with N (depth 0–20 cm; [mean g/m2]; control = 685, +N = 443, +PK = 827, +NPK = 832). There was also a 36 percent increase in root length with PK additions when compared to controls. Whole savanna shoot:root ratios were similar for control and +PK (0.6), while those for +N or +NPK fertilization were significantly higher (1.7 and 1.2, respectively). Total biomass response (above + belowground) to nutrient additions showed a strong N and PK co‐limitation ([mean g/m2]; control = 1073, +N = 1111, +PK = 1258, +NPK = 1713). Aboveground biomass of all monocots increased with N additions, whereas dicots showed no response to nutrient additions. Trachypogon spp. (T. plumosus+T. vestitus) and Axonopus canescens, the two dominant grasses, made up more than 89 percent of the total aboveground biomass in these sites. Trachypogon spp. responded to NPK, whereas A. canescens, sedges, and the remaining monocots only responded to N. Even though nutrient additions resulted in higher aboveground biomass in N and NPK fertilized plots, this had little effect on plant community composition. With the exception of sedges, which responded positively to N additions and increased from 4 to 8 percent of die plant community, no changes were observed in plant community composition after 11 months.
Elevational Variation of Leaf Traits in Montane Rain Forest Tree Species at La Chinantla, Southern México1
Authors: Velízquez‐Rosas Noé , Meave Jorge , Vízquez‐Santana Sonia 
Published: March 2006

ABSTRACTVariation in leaf traits of dominant tree species in six montane rain forest communities was analyzed along an elevational gradient ranging from 1220 to 2560 m within a single basin at La Chinantla, Oaxaca, México. Three groups of characters were used: morphological (leaf shape, margin, blade configuration, and phyllotaxy), morphometric (leaf area, leaf mass per area, stomatal density, and blade length/width ratio), and anatomical (thicknesses of blade, palisade [PP], and spongy [SP] parenchymae, PP/SP ratio, and epidermis and cuticle thicknesses). The variation of morphological characteristics was only evident at the highest elevations; in contrast, thickness of leaf blade, PP, SP, as well as leaf mass per area clearly increased along the gradient, whereas leaf area was the only variable that significantly decreased with elevation. Thicknesses of epidermis and of the two cuticles were not significantly correlated with elevation. A classification analysis based on a leaf trait matrix led to the distinction between low and high elevation communities, with an approximate limit between them at ca 2300 to 2400 m. The results are discussed in light of environmental changes occurring along elevational gradients. Leaf characteristics of montane rain forest plants offer important insights about the complex roles of abiotic factors operating in these environments and supplement the traditional physiognomic classification schemes for these communities.
Herbivore‐Free Time? Damage to New Leaves of Woody Plants after Hurricane Andrew1
Authors: Koptur Suzanne , Rodriguez M. Cristina , Oberbauer Steven F. , Weekley Carl , Herndon Alan 
Published: March 2006

ABSTRACTAll broadleaf woody plants of pinelands and hammocks (upland areas) in the northern parts of Everglades National Park were defoliated by the strong winds of Hurricane Andrew in August 1992. Most plants re‐leafed within two months of the storm, at which time we tagged newly produced leaves of eight species (five species in two hardwood hammocks and four in two pineland sites; one species was studied in both habitats), and monitored individual leaf area lost or damaged monthly for three months. We marked a second cohort of new leaves on the same individuals four months later and monitored these for three months. Herbivory rates in leaves of the first cohort were lower than observed in pre‐hurricane studies on two of the species, and lower in the first cohort than in the second cohort in six of the eight species studied, indicating that most insect herbivores were virtually absent for the first few months after the storm. Additionally, most species produced significantly larger leaves in the first cohort than the second cohort, and leaves of the second cohort were not significantly different in size from pre‐hurricane leaves in one species for which pre‐hurricane data were available. The large disturbance of the hurricane defoliated and reduced the above‐ground biomass of the plants, but apparently also eliminated most herbivores and competition for light, facilitating the recovery of the plants.
Spatial and Temporal Variation of Macroinvertebrate Drift in Two Neotropical Streams1
Authors: Boyero Luz , Bosch Jaime 
Published: March 2006

ABSTRACTThe detection of spatial variation in macroinvertebrate drift depends on the spatial scale of investigation in streams of the La Selva Biological Station, Costa Rica. Drift samples were taken in a spatially nested design, with two streams, two reaches per stream, two riffles per reach, and four replicate samples per riffle. Drift showed little variation among streams, but varied significantly at the scales of reach and riffle, with variation among samples also high. In addition, sampling took place at two temporal scales: diel and at two different periods that differed in rainfall conditions. Drift diel periodicity was a clear pattern, while only density of individuals varied among sampling periods. This is the first study of macroinvertebrate drift at multiple spatial scales, despite the recognition that multi‐scale studies are essential for a more complete understanding of community patterns and processes.
Discrimination among Fish Models by Hawaiian Eleotris sandwicensis (Eleotridae)1
Authors: Corkum Lynda D. 
Published: March 2006

ABSTRACTI examined behavioral responses of the benthic fish Eleotris sandwicensis to painted models (dummies) of fish that Eleotris typically encounter in Hawaii. Eleotris sandwicensis were associated with coarse substrates where their mean (±SE) density was 1.5 (±0.30) fish/m2. I hypothesised that Eleotris would retreat from all models in open areas, but not when they were present in shelters. The five models represented Stenogobius hawaiiensis, Awaous guamensis, E. sandwicensis (female coloration), a male E. sandwicensis in breeding colors (black), and a 12 cm block of wood (control). Whether or not Eleotris held its position or retreated was not a function of body size. Differences among the responses of Eleotris to models depended on whether or not the fish was hidden or exposed on substrates. More retreats in response to models occurred when Eleotris were exposed on substrates than when fish were hidden. There were no significant differences in the response of E. sandwicensis to models when fish were exposed on substrates. In contrast, responses of E. sandwicensis to the models were not random for fish that were hidden, indicating that Eleotris discriminated among the models. The basis for discrimination among models was most likely visual. Although Eleotris are typically secretive, their presence on exposed substrates at this study site may be attributed to die lack of benthivorous fishes and few avian predators. The ability of Eleotris to distinguish among fishes when hidden as well as their tendency to retreat in response to all intruders whenever exposed on substrate surfaces could reduce potential interactions between Eleotris and other native and nonindigenous fishes.
Staggered Flowering in Four Sympatric Varieties of Geonoma cuneata (Palmae)1
Authors: Borchsenius Finn 
Published: March 2006

ABSTRACTPhenology, flowering biology, and pollination were studied for one year in four sympatric varieties of the polymorphic palm Geonoma cuneata in Ecuador. Flowering seasons of the three most common varieties were significantly staggered resulting in minimal temporal overlap. No marked differences were found with respect to flowering biology or pollination. The implication of these findings for explaining the complicated morphological variation pattern found in G. cuneata and similar species complexes is discussed.
Strategies of Tree Occupation at a Local Scale in terra firme Forests in the Colombian Amazon
Authors: Duque Alvaro , Cavelier Jaime , Posada Alberto 
Published: March 2006

ABSTRACTThe goal of this study was to define differences in species richness and tree and liana species assemblages of three adjacent terra firme forests in the middle Rio Caquetá, Colombia. A vegetation survey of trees and lianas equal to or more than 10 cm diameter at breast height (DBH) was carried out along a single longitudinal transect (10 × 2160 m) passing through a low plain terrace, a high dissected terrace, and a high plain terrace. Species were classified as either locally abundant or locally rare. Abundant species were defined as “generalists” (in all environments), “intermediate” (in two environments), and “specialists” (in only one environment) using a 2 × 3 contingency table. There were 146 (39%) species classified as locally abundant and 231 (61%) as locally rare. Among the abundant species, 70 percent were generalists, 25 percent were specialists, and 5 percent were intermediate. Although there was a significant number of rare species, for those species with sufficient numbers to statistically test spatial distribution, the results suggest that many species are generalists and that beta diversity at the local scale (2.16 ha) is low. Larger data sets over larger geographical areas should be analyzed to determine the degree of species turnover in Amazonian forests.RESUMENEn el presente estudio, se evaluaron las diferencias en la riqueza de especies y los agrupamientos florísticos de árboles y lianas en tres unidades del paisaje de tierra firme en el río Caquetá, Colombia. Se llevó a cabo un inventario de los árboles y lianas con diámetro a la altura del pecho a 10 cm, a través de un transecto longitudinal (10 × 2160 m) pasando sobre una terraza plana baja, una terraza alta disectada y una terraza alta plana. Las especies fueron clasificadas como localmente abundantes y localmente raras. Las especies abundantes fueron definidas como “generalistas” (en todas las unidades de paisaje), “intermedias” (en dos unidades) y “especialistas” (en unicamente una unidad), usando tablas de contingencia de 2 × 3. En todo, 146 (39%) especies fueron clasificadas como localmente abundantes y 231 (61%) como localmente raras. Entre las especies abundantes, el 70 por ciento fueron generalistas, el 25 por ciento especialistas, y el 5 por ciento intermedias. Aunque hubo un gran número de especies raras, para aquellas especies con abundancia y frecuencia suficiente para que su distribución fuera analizada estadisticamente, los resultados sugieren que muchas especies son generalistas y que la diversidad beta a escala local (2.16 ha) es baja. Bases de datos mucho más grandes son necesarias para determinar el grado de recambio de las especies en los bosques amazónicos.
Red‐rumped Agouti (Dasyprocta leporina) Home Range Use in an Amazonian Forest: Implications for the Aggregated Distribution of Forest Trees
Authors: Silvius Kirsten M. , Fragoso Jose M. V 
Published: March 2006

ABSTRACTWe radio‐tracked five red‐rumped agoutis (Dasyprocta leporina) for two to nine months each at the Estacao Ecologica Ilha de Maraca in the northern Brazilian Amazon. Agoutis fed primarily on seeds and pulp but also ate cotyledons, leaves, flowers, and invertebrates. Three plant species made up 63 percent of the feeding observations. Home range size varied from 3 to 8.5 ha. High‐use areas and home range boundaries shifted from the season of high fruit availability to the season of low fruit availability as different individual trees became the focus of feeding activities. Agoutis foraged preferentially within conspecific patches of preferred fruit species and concentrated their feeding and scatterhoarding activities near individual fruiting trees. These results suggest that agoutis, as extremely short‐distance seed dispersers, may contribute to the aggregated dispersion pattern of large‐seeded tropical forest trees.RESUMONós seguimos cinco cutias‐vermhelhas (Dasyprocta leporina) marcados com tele‐transmissores por dois á nove mȩses cada um na Estação Ecologica Ilha de Maracá, localizada no n&#x006f;̧rte da Amazonia Brasileira. Os principals itens da dieta foram sementes e polpa de frutos, mas as cutias também consumiram cotiledones, folhas e invertebrados. Trȩs espécies de plantas foram responsáveis por 63 porcento das observanções de dieta. O tamanho da área de vida variou entre 3 e 8.5 ha. As áreas mais usadas e as bordas da área de vida variaram de acordo com as estações de maior e menor disponibilidade de frutos porque diferentes árvores foram procuradas em diferentes estações. As cutias preferiram forragear nas áreas onde as espécies de sementes preferidas eram mais abundantes, e concentraram a alimentação e atividades de armazenamento nas regiões próximas as árvores frutíferas. Estes resultados sugerem que o papel das cutias como dispersores de sementes de curta dista̧ncia podem contribuir para a dispersão agregada de árvores tropicais com sementes grandes.
Remote Sensing Research Priorities in Tropical Dry Forest Environments
Authors: Sánchez‐Azofeifa G. A. , Castro K. L. , Rivard B. , Kalascka M. R. , Harriss R. C. 
Published: March 2006

ABSTRACTSatellite multi– and hyper‐spectral sensors have evolved over the past three decades into powerful monitoring tools for ecosystem processes. Research in temperate environments, however, has tended to keep pace with new remote sensing technologies more so than in tropical environments. Here, we identify what we consider to be three priority areas for remote sensing research in Neotropical dry forests. The first priority is the use of improved sensor capabilities, which should allow for better characterization of tropical secondary forests than has been achieved. Secondary forests are of key interest due to their potential for sequestering carbon in relatively short periods of time. The second priority is the need to characterize leaf area index (LAI) and other biophysical variables by means of bidirectional reflectance function models. These biophysical parameters have importance linkages with net primary productivity and may be estimated through remote sensing. The third priority is to identify tree species using hyper‐spectral imagery, which represents an entirely new area of research for tropical forests that could have powerful applications in biodiversity conservation.RESUMENEn las últimas tres decadas, los sensores satelitales multi e hiper‐espectrales han evolucionado hasta convertirse en importantes herramientas para el monitoreo de los ecosistemas. La investigación en los ecosistemas templados y boreales ha seguido el paso de los avances en los sistemas de percepción remota, mientras que en los sistemas tropicales existe un desface significative. En este articulo identificamos y revisamos tres prioridades básicas en la investigación basada en sensores remotos de las regiones neotropicales del bosque seco. Estas prioridades están relacionadas con el monitoreo de bosques secundarios, el desarrollo de estudios relacionados con la cuantificación del área foliar por médio de métodos ópticos y finalmente el desarrollo de técnicas, que ligadas a información hiper‐espectral, puedan ser utilizadas para la identificación de especies de árboles en zonas tropicales. Esta última prioridad representa una nueva área de investigación en los bosques tropicales con importantes connotaciones para la conservación de la biodiversidad boilógica.