bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mangrove Distribution during the Holocene in Tribugí Gulf, Colombia1
Authors: Jaramillo Carlos , Bayona Germín 
Published: March 2006

ABSTRACTNeotropical mangrove ecosystems have undergone drastic changes in terms of extension and floristic composition during Plio–Pleistocene times. It is unclear if the northern Pacific coast of Colombia has been occupied continuously by mangroves during the last 5000 years, or if their presence is a recent phenomenon. Two basic questions were asked: (1) is the establishment of mangroves recent?; and (2) what were the dominant floral taxa during the late Holocene? In the Gulf of Tribugí, northern Colombian Pacific, 22 sediment cores were drilled to a maximum depth of 2 m in a diverse suite of mangrove substrates and positions relative to the shoreline. Data were gathered from sedimentological descriptions, palynological analyses, and radiocarbon dating of these cores. During the last 4500 years, mangroves in the southern area of the Tribugí Gulf have remained floristically stable and dominated by Rhizophora. The abundant presence of Acrostichum aureum is recent, probably related to human activities. In contrast, two areas in the northern part of the Gulf show a different history. In the first area, the establishment of mangrove has been relatively recent (ca 2600 yr), probably a result of local subsidence due to tectonic faulting; this mangrove forest was and is dominated by Pelliciem rhizophorae. In the second area, mangrove pollen was not found in sediments younger than 2500 years, suggesting that the scarce presence of mangrove in the area is a result of recent colonization, and not due to logging as previously thought.
Developmental Patterns of Tree Dimensions in a Neotropical Deciduous Forest1
Authors: Bullock Stephen H. 
Published: March 2006

ABSTRACTFor 26 tree species in very dry tropical forest in Mexico, the developmental trends of relationships among trunk diameter, tree height, and crown diameter were inferred from a one‐time measurement of dispersed individuals across the size range from saplings to large, mature trees. On hillside sites in this high diversity forest, maximum dimensions were usually <10‐m height, 4‐m crown diameter, and 0.3‐m trunk diameter. The relationship of height to trunk diameter was characterized by an asymptotic, three‐parameter model. Crown diameter was a linear function of trunk diameter. The parameter values for both models varied widely among the species. In general, the dispersion among species of the height–crown diameter relationship increased linearly with trunk diameter (up to 0.2 m). Arborescent cacti were distant from other species at all sizes, although they were well modeled using the same equations. Empirical and theoretical features and limitations of the present and previous models, including mechanical buckling and water‐stress theories, are considered.
Insights into the Witheringia solanacea (Solanaceae) Complex in Costa Rica. II. Insect Visitors and Pollination Biology of W. asterotricha and W. meiantha1
Authors: Bohs Lynn 
Published: March 2006

ABSTRACTIsolating mechanisms are important in maintaining the taxonomic integrity of closely related sympatric taxa. A previous study found strong post‐zygotic isolating barriers between two species, Witheringia asterotricha and W. meiantha, of the W. solanacea (Solanaceae) species complex in Costa Rica. This study examines the presence of pre‐zygotic barriers between the two species at La Selva Biological Station in Costa Rica. Both species offer pollen and nectar as floral rewards and are visited primarily by solitary or semi‐social bees, some of which sonicate (“buzz”) the anthers to discharge pollen. No evidence was found for phenological differences in flowering time between W. asterotricha and W meiantha, but pre‐zygotic factors, such as ethological isolation and possibly fine‐scale ecological or geographic barriers, may be responsible for restricting gene flow between the two species.
Relationship between Plant Size and Ant Associates in Two Amazonian Ant‐Plants1
Authors: Vasconcelos Heraldo L. , Davidson Diane W. 
Published: March 2006

ABSTRACTA survey of two Amazonian melastome ant‐plants,Maieta guianensisandTococa bullifera, revealed a significant difference in plant size according to the species of ant inhabiting the plant. Plants withCrematogaster laevis, on average, were smaller than those withPheidole minutula(inM. guianensis)and those withAztecasp. (inT. bullifera).There is no evidence that these patterns were due either to the deterministic replacement ofC. laevisby another ant species during host‐plant ontogeny or to a habitat effect on plant growth rates coupled with colony survival. More likely, the smaller size ofC. laevisplants can be explained by its effects on host‐plant performance. Plants withC. laevislost their associated ant colonies more frequently than plants withP. minutulaandAztecasp. Plants that lost theirC. laeviseither died, or more commonly, were severely defoliated. Defoliated plants, once sprouted, tended to become recolonized, but such recolonizations were not deterministic so as to favor one species over another. Plants withC. laevisshowed similar, or only slightly greater, standing levels of herbivory than plants withP. minutulaorAztecasp. This suggests that whenC. laevisis present, it confers some degree of protection to its hosts. It was found that early in colony development, queens ofC. laevismoved off their host plants to build satellite nests in dead twigs on the ground, a behavior not seen in the other two species and one that possibly renders colonies more vulnerable to mortality from predation, flooding, or nest decay. Comparable 815N values inC. laevisandP. minutulaindicate that the two species are equally dependent on food supplied by the host plant.
Ant Defense of Euphyonarthex phyllostoma (Homoptera: Tettigometridae) during Trophobiotic Associations1
Authors: Dejean A. , Bourgoin T. , Orivel J. 
Published: March 2006

ABSTRACTDuring a five‐year field study, we made observations and conducted experiments to demonstrate unequivocally thatEuphyonarthex phyllostoma(Fulgoromorpha: Tettigometridae) is a myrmecophile. Isolated adults and colonies always were found in association with ants. Colonies were associated only withCamponotus brutusorC. acvapimensis(For‐micinae), whereas isolated adults were attended by ants belonging to several species of Formicinae, Dolichoderinae, and Myrmicinae. The size of the planthopper colonies reached higher levels when attended byC. brutusthan byC. acvapimensis.Experiments using ant exclusion showed that both ant species protected egg masses against parasitic wasps, but egg masses were less parasitized on trees occupied byC. brutusthan on those occupied byC. acvapimensis (P =0.0052). The production of egg masses by female hoppers was recorded only whenC. brutus, C. acvapimensis, or the myrmicine antMyrmicaria opaciventrisattended the hopper. In both former cases, the presence of ants influenced the aggregation of the nymphs as they dispersed when ants were excluded. The aggregation of the nymphs ensured chat they were properly attended. Parental care by the females was reduced to their presence above or close to the egg masses. In fact, specialized workers of the attending ant species protected the egg masses as well as nymphs.
Densidad Poblacional y Disponibilidad de Híbitat de la Danta de Montaña (Tapirus pinchaque) en los Andes Centrales de Colombia1
Authors: Cavelier Diego J. Lizcano M. y Jaime 
Published: March 2006

RESUMENEn este estudió se estimó la densidad poblacional de Tapirus pinchaqueen un área de 7000 ha en el Parque Nacional Natural Los Nevados, Andes centrales de Colombia. Se midieron ocho variables (largo y ancho de la huella y largo y ancho de cada un de los dedos) en 110 huellas de la pata posterior izquierda de T: pinchaque. La información sobre huellas se analizó, mediante el método de agtupamiento UI'GMA y distancia Euclidiana de los “scores” obtenidos mediante un análisis de componentes priiicipales (ACP) con las ocho variables. La disponibilidad de hábitat se midió en un área de 147,000 ha documentada con fotografías aéreas de los años 50s y 80s. Los resultados del an4aAlisis de agrupamiento indicaron que en las 7000 ha habitan entre 11 y 15 individuos, con una densidad de un tapir par cada 551 ± 85 ha. Las mediciones de la cobertura boscosa dentro del área de 147000 ha mostraron que la superficie disponible para el tapir (bosques montanos y plantaciones forestales) aumentó en 18141 ha de 10s años 50s a los años 80s. El incremento del área, boscosa parece tener un efecto positivo sobre el tamaño de la población de T: pinchaque, ya qrie en antiguas áreas de pastizales hay existen bosques secundarios con abundantes hellas y excrementos de danta.
A Comparison of the Phyllostomid Bat Assemblages in Undisturbed Neotropical Forest and in Forest Fragments of a Slash‐and‐Burn Farming Mosaic in Petén, Guatemala1
Authors: Schulze Mark D. , Seavy Nathaniel E. , Whitacre David F. 
Published: March 2006

ABSTRACTUsing mist nets, we compared phyllostomid bat ensembles of continuous mature forest in Tikal National Park, Guatemala, and of forest fragments in the nearby farming landscape. Of 20 species captured, 13 were shared between treatments, 4 were unique to continuous forest, and 3 were unique to forest fragments. Dominance–diversity curves were similar for the two treatments except that Sturnira lilium comprised 43 percent of captures in the forest fragments, resulting in greater dominance there. Capture rates (and presumably relative abundance) differed significantly between continuous forest and forest fragments, both in terms of species and feeding guilds. Sturnia lilium and Dermanura sp. were captured significantly more often in forest fragments than in continuous forest, whereas Artibeus jamaicensis, A. lituratus, and Centurio senex were taken significantly more often in continuous forest. Large frugivores accounted for a higher proportion of total captures in continuous forest than in forest fragments, whereas small frugivores showed the opposite pattern. By their abundances, Carollia perspicillata and S. lilium are indicators of forest disturbance. The relative abundances of large frugivores, which feed on large fruits of mature forest trees, and small frugivores, which feed on small‐fruited plants occurring in early succession, are an indicator of forest disturbance. Other groups, such as large insect‐ and vertebrate‐eating bats, because of their low capture rates, are impractical as indicators for rapid assessment of forest disturbance based on mist netting, but may prove especially vulnerable to forest fragmentation.
Nutrient Dynamics of Soil Derived from Different Parent Material on Barro Colorado Island, Panama1
Authors: Yavitt Joseph B. 
Published: March 2006

ABSTRACTI compared the concentrations of N, P, and S in both litter and mineral soil (0–15 cm depth) from three old‐growth, tropical moist forests on Barro Colorado Island (BCI), Panama. Each site was on a different substrate (i.e., parent material), but otherwise had similar climate, vegetation, and topography. There were no site differences in concentrations of N and S for either litter or soil. Concentrations of litter P and soil‐extractable P were greater for the andesite (igneous rock) site than for two sites on different sedimentary rocks; however, concentrations of several other litter and soil P fractions did not differ among sites. Patterns in soil P fractions suggested advanced soil development to the point that parent material has little control of P dynamics. Litter samples from each site, leached in the laboratory, released similar amounts of N, P, and S to the soil, indicating no differences in rates of turnover in the litter and in fluxes from litter into the mineral soil among sites. I expected more site differences in soil nutrient dynamics given vastly different parent materials and soil types (i.e., Oxisol vs. Alfisol) and very shallow soil on BCI that brings the parent material close to the plant root zone. Erosion and soil mixing may explain the uniformity in soil nutrient dynamics across the sites.
Lack of Ecotypic Differentiation: Plant Response to Elevation, Population Origin, and Wind in the Luquillo Mountains, Puerto Rico1
Authors: Fetched Ned , Cordero Roberto A. , Voltzow Janice 
Published: March 2006

ABSTRACTHow important is ecotypic differentiation along elevational gradients in the tropics? Reciprocal transplants of two shrubs, Clibadium erosum (Asteraceae) and Psychotria berteriana (Rubiaceae), and a palm, Preitoea acuminata var. montana (Palmaceae), were used to test for the effect of environment and population origin on growth and physiology in the Luquillo Experimental Forest of Puerto Rico. Two sites were used, one at Pico del Este (1000 m in cloud forest) and one at El Verde (350 m in lower montane rain forest). At the cloud forest site, plastic barriers were erected around a subset of the plants to examine if protection from wind affected survival or biomass accumulation. Survival of C. erosum and P. berteriana was not affected by site, population origin, or the presence of barriers. For P. acuminata var. montana, survival was higher for plants with barriers, but not affected by site and population origin. Plants of C. erosum and P. berteriana at El Verde grew larger than at Pico del Este, but there was no effect of population origin or barrier treatment on biomass accumulation for these species. For P. acuminata var. montana, there was no effect of environment, population origin, or barrier treatment on biomass accumulation. Light‐saturated photosynthetic rate (Amax) of C. erosum, P. berteriana, and P. acuminata var. montana, as well as leaf anatomical characteristics of C. erosum, were unaffected by environment, population origin, and barrier treatment. On balance, there seems to be little evidence of ecotypic differentiation in these species along the gradient.
Post‐Hurricane Regeneration of Pioneer Plant Species in South Florida Subtropical Hardwood Hammocks1
Authors: Kwit Charles , Platt William J. , Slater Harold H. 
Published: March 2006

ABSTRACTAfter Hurricane Andrew crossed southern Florida (U.S.A.) on 24 August 1992, native and exotic pioneer species in subtropical hardwood forests (hammocks) regenerated from seed banks. Regeneration occurred in hammocks of metropolitan Dade County and the Long Pine Key region of Everglades National Park. The density of the native pioneer Trema micrantha was significantly higher in hammocks of Long Pine Key than in those of metropolitan Dade County. In contrast, the basal area of the exotic pioneer Carica papaya was greater in Dade County hammocks than Long Pine Key hammocks. Although T. micrantha tended to be restricted to areas of soil disturbance (tip‐up pits) formed by trees uprooted during Hurricane Andrew, especially in Long Pine Key, C. papaya was located throughout hammocks. These results suggest differences in the regeneration niches in which the native T. micrantha required more specific disruptions (i.e., both canopy and soil) than C. papaya (only removal of canopy) for establishment. A broad regeneration niche could in part account for the capability of an exotic species with a dormant seed bank to invade native subtropical forests following natural large‐scale disturbances.
Small Canopy Gaps Influence Plant Distributions in the Rain Forest Understory1
Authors: Svenning Jens–Christian 
Published: March 2006

ABSTRACTThis study tested three hypotheses regarding how plants respond to the spatial heterogeneity in light availability in the rain forest understory: (1) understory plants occur preferentially in the lighter parts of the understory; (2) under–story palms are more shade tolerant than other understory plants; (3) rain forest plants differ in their ontogenetic response to understory light conditions. The study was carried out in old–growth rain forest in the Yasuní National Park, Amazonian Ecuador. The hypotheses were tested by comparing the distributions of 20 plant species (1454 individuals) over microsites with differing degrees of exposure to canopy gaps to the background distribution of these microsites in the forest. The gap exposure of a given microsite was described by an index based on the number and size of gaps in the canopy to which the site was exposed. Two plant height classes were studied: 0.80–2.49 and 2.50–5 m. The first and third hypotheses were accepted, while the second hypothesis was rejected. The results for the individual species corresponded well with what is known from earlier studies about the ecology of these species or close relatives, suggesting that the patterns observed can be generalized for Neotropical rain forests. Notably, the most abundant species in the study represent several different life history strategies. Thus, abundance in the rain forest understory can be achieved by several different strategies. This suggests that niche differentiation in terms of response to small changes in understory light conditions may be an important factor in the maintenance of the high local plant species richness of tropical rain forests.
Seedling and Sapling Dynamics of Treefall Pits in Puerto Rico1
Authors: Walker Lawrence R. 
Published: March 2006

ABSTRACTSeedling and sapling dynamics in a Puerto Rican rain forest were compared between forest understory and soil pits created by the uprooting of 27 trees during Hurricane Hugo. Soil N and P, organic matter, and soil moisture were lower and bulk densities were higher in the disturbed mineral soils of the pits than in undisturbed forest soils ten months after the hurricane. No differences in N and P levels were found in pit or forest soils under two trees with N–fixing symbionts (Inga laurinaandOrmosia krugii) compared to soils under a tree species without N–fixing sym–bionts (Casearia arborea), but other soil variables (Al, Fe, K) did vary by tree species. Forest plots had greater species richness of seedlings (<10 cm tall) and saplings (10–100 cm tall) than plots in the soil pits (and greater sapling densities), but seedling densities were similar between plot types. Species richness and seedling densities did not vary among plots associated with the three tree species, but some saplings were more abundant under trees of the same species. Pit size did not affect species richness or seedling and sapling densities. Recruitment of youngCecropia schreberianatrees (>5 m tall) 45 months after the hurricane was entirely from the soil pits, with no tree recruitment from forest plots. Larger soil pits had more tree recruitment than smaller pits. Defoliation of the forest by the hurricane created a large but temporary increase in light availability. Recruitment ofC. schreberianato the canopy occurred in gaps created by the treefall pits that had lower soil nutrients but provided a longer–term increase in light availability. Treefall pits also significantly altered the recruitment and mortality of many understory species in the Puerto Rican rain forest but did not alter species richness.
Reproduction in an Orchid Can Be Resource‐Limited over its Lifetime1
Authors: Meléndez‐Ackerman Elvia J. , Ackerman James D. , Rodriguez‐Robles Javier A. 
Published: March 2006

ABSTRACTMost orchids studied thus far show long‐term resource adjustments to increases in fruit production within a flowering season, but none of these offers rewards to their potential pollinators. If nectar production is energetically expensive, then resources utilized to produce fruits and seeds may be even more limited in pollinator‐rewarding orchids than in non‐rewarding ones. Thus, resource adjustments may be more dramatic or entirely different in nectar producing plants. In this study, we performed artificial hand‐pollinations for two consecutive flowering seasons in die nectar producing orchid Comparettia falcata, and tested whether or not fruit set, seed set, and seed viability were limited by the quantity of pollinations or by resources. In addition, we compared mechanisms of short‐term (fruit abortion within seasons) and long‐term consequences (percent change in leaf length and change in flower number per plant between seasons, probability of shoot and inflorescence production, and mortality) between hand‐ pollinated and unmanipulated plants. The relationships among plant traits related to vegetative size and reproduction also were examined. Hand‐pollinations showed some negative effects. Fruit set was higher in hand‐pollinated plants in the first season but was similar to the controls in the second. Seed set was significantly lower and abortions were higher than in unmanipulated plants. On the other hand, some of our measurements were unaffected by die hand‐pollination treatment. Unexpectedly, there were no significant differences between groups in percent change in leaf length, change in flower number per plant between seasons, or die probability of shoot and inflorescence production. Although there was a strong correlation between leaf size and die number of flowers produced within a season, associations between leaf size and traits related to current or future reproduction were not consistent. Like other epiphytic orchids, pollination limitation occurred within a single season in C. falcata., but increases in fruit production also resulted in reduced lifetime fitness as estimated by a compounded fitness index. Contrary to all other epiphytic orchids studied, long‐term adjustments to increased fruit production in C. falcata through reduction in future growth or flower and inflorescence production were either minor or lacking. Our results suggest that the nature of plant strategies associated with resource constraints during sexual reproduction may be dependent on whether or not plants have evolved traits that are costly.
Dioecy in South American Deprea (Solanaceae)1
Authors: Sawyer Neil W. , Anderson Gregory J. 
Published: March 2006

ABSTRACTDioecy in the Solanaceae is rare, occurring in < 1 percent of the species worldwide and known in only two species from South America. We report the occurrence of cryptic dioecy in the Neotropical genus Deprea. Studying herbarium material of the Venezuelan endemic D. paneroi revealed morphological distinctions that tentatively served to divide collections into male and female morphs. This discovery prompted investigation of population structure, crossing studies, and morphometric analyses of 95 individuals from the largest known wild population and a small sample of greenhouse‐grown plants. About 60 percent of the population was reproductive, and of these, nearly equal numbers exhibited female or male characteristics. Plants that bore fruit and small sterile anthers were characterized as female; those that lacked fruit but produced pollen in large anthers were characterized as male. The morphology, receptivity, and developmental phenology of pistils were identical in both forms. Crossing studies revealed significant enlargement of the ovaries in open‐pollinated female flowers and female X male hand‐pollinations. The ovaries in open‐pollinated male flowers and male X male hand‐pollinations never enlarged. These results suggest that the only legitimate combination is female X male. Dioecy in the family and possible mechanisms for the evolution and maintenance of dioecy in D. paneroi are discussed.