bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and Composition of One Hectare of Central Amazonian Terra Firme Forest1
Authors: Milliken William 
Published: March 2006

ABSTRACTThe trees, vines, and stranglers ≥10 cm in diameter in 1 ha of terra firme forest in Amazonas State, Brazil, were measured and identified. The plot contained 645 trees representing 201 species, 95 genera, and 34 families (basal area ca 31 m2); 16 vines representing 14 species, 13 genera, and 8 families; and 1 strangler. The dominant families of trees present were the Leguminosae (sensu latu), Lecythidaceae, Sapotaceae, Burseraceae, and Moraceae; the dominant species were Clathrotropis macrocarpa (Leguminosae), Eschweilera coriacea (Lecythidaceae), and Protium hebetatum (Burseraceae). In terms of structure, diversity, and floristic composition, this plot is reasonably typical of the terra firme forests in the central Amazon, as far as this diverse biota can be typified.
Growth and Reproduction in Forest Trees of the Cactus Opuntia excelsa1
Authors: Bullock Stephen H. , Martijena Nora E. 
Published: March 2006

ABSTRACTIn southwestern México, the number of new cladodes on Opuntia excelsa was a skewed bell‐shaped function of size (“size” being the number of cladodes persisting from previous years). Fruit number was a sigmoidal function of size, but the number of seeds per fruit was independent of number of fruits per plant. The curves for production of new cladodes and of fruits both showed maximum increase for plants with 150–350 cladodes, when the crowns were reaching or in the canopy. New cladode production declined at about the size where reproduction plateaued; we suggest this was due to limitation of crown dimensions by mechanical and physiological factors.
The Fecundity, Seed, and Seedling Ecology of the Edible PalmEuterpe edulisin Southeastern Brazil1
Authors: Matos D. M. Silva , Watkinson A. R. 
Published: March 2006

ABSTRACTEuterpe edulisflowers at the beginning of the wet season and fruits over an extended period during the end of the wet season and the dry season. Reproductive plants produced an average ofca1500 fruits within a season. Five species of birds belonging to the family Turdidae were observed to feed on and disperse the fruits. Most seeds fell directly to the ground, where there was some subsequent local dispersal by water. The dispersion of seeds was highly clumped with most seeds being found in close proximity to adult plants; the distance of dispersal could be described by a negative power curve. Germination was higher on wetter soils. The probability of seedlings advancing to the next size class within a year was inversely related to the density of seedlings, and occurred optimally atca4 m from adult plants. The latter observation indicates that the survival and growth of seedlings are suppressed in the immediate vicinity of conspecific adults.
An Advantage of Large Seed Size: Tolerating Rather than Succumbing to Seed Predators1
Authors: Mack Andrew L. 
Published: March 2006

ABSTRACTAlthough large seeds might be more attractive and apparent to seed predators, large seed size could enable tolerance of seed predators. If seeds are large enough to sustain damage that would kill smaller seeds yet still produce viable seedlings, investment above the minimum by the maternal plant could be advantageous. I tested this hypothesis by removing 0–80 percent of the cotyledons of four large‐seeded (4–180 g) tree species from Papua New Guinea and monitoring germination and seedling growth for eight months. All species showed little negative effect on seedling size with up to 50 percent removal of cotyledons and the larger species showed a less serious effect on growth than smaller‐seeded species above 50 percent removal. Large‐seeded species clearly have more than the minimum‐required cotyledonary reserves. Observations of viable seedlings with heavily damaged cotyledons suggest that these species withstand attack by rodents and beetles by virtue of their large size.
Dictyostelid Cellular Slime Molds in Canopy Soils of Tropical Forests1
Authors: Stephenson Steven L. , Landolt John C. 
Published: March 2006

ABSTRACTThe occurrence and distribution of dictyostelid cellular slime molds (CSM) in the mantle of dead organic matter (literally a “canopy soil”) at the bases of large epiphytes were studied in the Luquillo Experimental Forest of north‐eastern Puerto Rico. CSM were isolated from 18 of 50 samples collected from this microhabitat, and four different species were recovered. Dictyostelium purpureum was the single most abundant species and represented almost half (48%) of all clones isolated during the study. Total densities (clones/g) averaged only 38 in the five forest types examined, but densities > 75 were recorded for two forest types. Relative abundance of CSM in canopy soils of the five forest types followed the same general pattern displayed by these organisms in forest floor litter, but a particular species was not necessarily common to both microhabitats in a given forest type.
Soil Characteristics and Vegetation Structure in a Heavily Deteriorated Mangrove Forest in the Caribbean Coast of Colombia
Authors: Cardona Pablo , Botero Leonor 
Published: March 2006

ABSTRACTMass mortality and biomass of mangrove trees are related to soil factors in the Caribbean Coast of Colombia. Soil properties measured were particle size distribution, bulk density, organic matter, total nitrogen, total phosphorus, pH, redox potential, salinity, and extractable nitrogen (NO2, NO3, NH4) and phosphorus (PO4). Sampling was performed at three locations along two 50 m transects at each site. Soil nutrient concentrations of either exchangeable nitrogen or phosphorus were comparable to other reported values. Redox potentials (Eh) were variable probably due to microtopographic conditions and to the amount of water and organic matter present in the soil. Hydrogen potentials (pH) are within the range reported as normal for mangrove soils. Locations with highest biomass had an average soil salinity of 35 with a range of 20 to 53. Sites with dead or dwarfed vegetation had an average soil salinity of 74 and minimum and maximum values observed were 52 and 100 respectively. Statistical analysis exhibited temporal and spatial differences in soil salinity and suggest that this parameter is most correlated to the development and distribution of mangrove vegetation in the area indicating that basal area and biomass volume are inversely correlated with soil salinity.
Cannibalistic Interactions Resulting from Indiscriminate Predatory Behavior in Tadpoles of Poison Frogs (Anura: Dendrobatidae)1
Authors: Caldwell Janalee P. , de Araújo Maria Carmozina 
Published: March 2006

ABSTRACTPoison frogs in the genusDendrobateshave very small clutch sizes (2–6 eggs among species for which there are data) and typically transport their tadpoles singly to small phytotelmata, such as bromeliad tanks, leaf axils, fallen fruit capsules, and treeholes. Tadpoles of many species are predaceous, consuming larvae of insects that use the same microhabitat for breeding, such as giant damselflies and mosquitoes. Previous studies and observations on the behavior of poison frog tadpoles led us to question whether tadpoles might be cannibalistic. We studied a population ofDendrobates castaneoticusin lowland rainforest in Pará, Brazil; additional data were collected onDendrobates auratusin Nicaragua. At the study site in Brazil, we established a grid of 40 Brazil nut capsules, the microhabitat used byD. castaneoticusfor tadpole deposition. Of 42 tadpoles deposited during the 55 days of the study, 20 were killed or died; 16 of these were presumably killed by conspecific tadpoles. Growth rate and time to metamorphosis was higher among tadpoles that consumed three or more tadpoles or relatively large larvae of the mosquitoTrichoprosopon digitatum, a colonist of newly opened Brazil nut capsules. We propose that selection has favored the development of predatory behavior in poison frog tadpoles primarily as a mechanism to eliminate predators from the small phytotelmata in which they develop and that cannibalism is a secondary outcome of this behavior. Predatory behavior also provides tadpoles with a source of food, which is frequently limited in these microhabitats. Additional studies of the biology of tadpoles of other species ofDendrobatesare needed to determine the evolution of predatory and cannibalistic behavior in the clade.
Patterns of Genetic Population Differentiation in Four Species of Amazonian Frogs: A Test of the Riverine Barrier Hypothesis1
Authors: Gascon Claude , Lougheed Stephen C. , Bogart James P. 
Published: March 2006

ABSTRACTPatterns and levels of allozyme variation among populations of Amazonian frogs were used to test the riverine barrier hypothesis of species differentiation. Two frog species were sampled from each of the two main forest habitats on both banks of the Juruá River in the southwestern Brazilian Amazon Basin at various points along its course to contrast different barrier strengths.Scarthyla ostinodactylaandScinax rubrawere sampled from flooded forest (varzea), andPhysalaemus petersiandEpipedobates femoralisfrom non‐flooded forest (terra firme). All species showed high levels of within‐population genetic variation. Average Nei's (1978) and Rogers’ (1972) genetic distances between sampled sites for all species were high indicating substantial among‐population differentiation. The observation of low gene flow between sampled sites within species was further substantiated with Slatkin's (1993) &#x004d;̂ analyses. Randomization tests suggested that there was some population structure at a few assayed polymorphic loci that was consistent with the riverine barrier hypothesis. However, it was apparent from the raw allozyme frequency data that these results were largely driven by substantial differentiation at one or a few collecting localities rather than by basin‐wide patterns of riverine differentiation. Phenograms using genetic distance matrices supported this interpretation. Patterns of geographic variation are probably more consistent with the idea of this region being a zone of secondary contact.
Biology of the Mongoose (Herpestes javanicus) in a Rain Forest of Puerto Rico1
Authors: Vilella Francisco J. 
Published: March 2006

ABSTRACTEcological aspects of the mongoose (Herpestes javanicus) were studied in the Luquillo Mountains, a rain forest region in eastern Puerto Rico. Information was obtained by removal trapping of mongoose from grids placed in tree plantations, colorado and tabonuco forests. Trapping efficiency was two mongoose per 100 trap‐days, suggesting mongoose abundance is low in wet montane forests of Puerto Rico. Sex ratio was biased (2.6:1) in favor of males. Body masses of male mongoose inhabiting rain forests of the Luquillo Mountains were larger than those in dry forests at Guánica (P < 0.0001). Stomach contents from 18 mongoose were examined, animal matter comprised 75 percent of the total food items encountered. Of these, 33 percent were from vertebrates. The food items most frequently encountered were lizards (Anolis spp.), centipedes (Scolopendra spp.), and cockroaches (Blatellidae).
Abundance and Distribution of Native and Alien Grasses in a “Cerrado” (Brazilian Savanna) Biological Reserve1
Authors: Pivello V. R. , Carvalho V. M. C. , Lopes P. F. , Peccinini A. A. , Rosso S. 
Published: March 2006

ABSTRACTSeveral species of African grasses brought to Brazil as cattle forage have spread widely, outcompeting native herb species. The open forms of Brazilian savanna (“campo cerrado” and “campo sujo”) are the most affected by such invasions, because their structure is open, permitting enough sunlight into the lower strata. The invasion of alien forage grasses occurs in almost every cerrado nature reserve. This study was carried out in the “Cerrado de Hmas Biological Reserve”, Pirassununga, São Paulo State, Brazil, with the following objectives: (a) to compare the abundance of native and alien grass species; (b) to verify the importance of such alien grasses in the community; (c) to identity distribution patterns for the alien grass species in a gradient from the edge (highly disturbed) to the center (less disturbed) of the reserve; and (d) to explore the distribution of native and alien grasses in the search for possible competitive interactions. Using the “point method,” a total of 260 points was sampled and 52 species were recorded. The four most frequent species (FA = absolute frequency) were two native (Echinolaena inflexa [Poir.J Chase [FA = 38.85%] and Diandrostachya chrysotrix [Nees] Jacues Felix [FA = 15.38%]) and two alien African species (Melinis minutiflora Beauv. [FA = 33.08%] and Brachiaria decumbens Stapf [FA = 13.85%]). M. minutiflora and E. inflexa had higher values of absolute vigor (67.69 and 59.62%, respectively), relative vigor (28.16 and 24.80%, respectively), and cover (100.77 and 98.47, respectively), indicating higher biomasses and densities and their dominance in the community. B. decumbens presented the highest number of contacts per point, showing the highest stratification. To detect possible edge–center distribution gradients, correspondence analysis was done, initially using all the recorded species and subsequently only the four more frequent grasses, with similar results: (a) the alien grasses, especially M. minutiflora, did not show a distinct distribution gradient from edge to center, but occurred over the whole reserve; (b) no distinct ecotonal band around the reserve (edge–belt) was detected, the whole reserve seeming to be “ecotonal”; and (c) E. inflexa and M. minutiflora showed similar phytosociological patterns, and spatial distribution; association between these two species was statistically significant.
Litter Interception on Astrocaryum mexicanum Liebm. (Palmae) in a Tropical Rain Forest1
Authors: Alvarez‐Sánchez J. , Guevara S. 
Published: March 2006

ABSTRACTThe goal of this study was to quantify litter interception onAstrocaryum mexicanumLiebm., an abundant and efficient litter–capturing palm. The study was done in a forest at Los Tuxtlas, Veracruz, on the Gulf of Mexico coast. Palms were randomly selected and total litter retention was quantified by determining dry weight over two years. Litter interception by palms was 4.4 and 27.1 Mg/ha/yr for the first and second years, respectively, and accounted for 47.9 and 239.4 percent of the reported annual litterfall in the same area. Results showed that litter interception by plants is related to litterfall and should therefore be added to total litterfall in order to calculate the net primary productivity.
Root Architecture and Root:Shoot Allocation of Shrubs and Saplings in Two Lowland Tropical Forests: Implications for Life‐Form Composition1
Authors: Becker Peter , Sharbini Norhartini , Yahya Razali 
Published: March 2006

ABSTRACTEntire root systems of saplings of five canopy species and of six shrub and treelet species growing in lowland mixed dipterocarp forest at Andulau, Brunei were excavated and measured. Referring to a prior study at Gigante, Panama, two‐way, fixed‐factor ANOVAs were used to compare life–forms and sites. Rooting depth and the proportion of root surface area in the upper 20 cm of soil did not differ significantly between life‐forms because some treelets/shrubs at Andulau were deep‐rooted; all saplings studied were deep‐rooted. The root:leaf area ratios of both saplings and treelets/ shrubs at Andulau were significantly higher than those at Gigante. We attribute this strong difference to the lower soil content of available nutrients at Andulau where rainfall shortage is less severe and regular than at Gigante. Available data on life‐form composition and mortality rates in large plots are consistent with our proposal that shallow‐rooted shrubs and treelets are more vulnerable to drought than deep‐rooted life‐forms. We suggest that future studies of water use partitioning, wood anatomy, leaf morphology, and associations with neighboring plants would benefit from an explicit examination of their relation to rooting depth.
Growth Ecology of Carapa nicaraguensis Aublet. (Meliaceae): Implications for Natural Forest Management1
Authors: Webb Edward L. 
Published: March 2006

ABSTRACTThe probability of achieving a sustainable tropical logging operation is increased if the growth of surviving trees is maximized after logging. This research examined the growth ecology of seedlings and trees of the Neotropical timber species, Carapa nicaraguensis (Meliaceae). Shadehouse experiments, field plantings, and growth rate analyses tested the hypothesis that Carapa seedlings and trees experience higher growth rates in high light levels (recently formed logging gaps or logged forest plots) than in low light levels (old logging gaps or undisturbed forest plots). Consistently poor seedling growth rates under low light conditions suggest that seedlings establishing in newly formed gaps will be more successful than those establishing in building‐phase gaps. Thus, the first year after logging is a critical time for gap recolonization by Carapa, and seed casting into gaps after logging is recommended. Growth of Carapa trees was significantly faster in logged forest than in undisturbed forest, and was positively associated with light availability. The results provide evidence that harvest models can be both diameter‐ and illumination‐based. Crown illumination was not significantly higher in logged forest than in undisturbed forest, indicating that the illumination scale for this study was not sensitive enough to detect increases in light availability brought about by selective logging. Potential silvicul‐tural methods (particularly poison‐girdling) that maintain adequate forest light levels in Carapa swamps without significantly altering long‐term tree diversity or allowing invasion of secondary species should be explored.
Litterfall Mass, Chemistry, and Nutrient Retranslocation in a Monodominant Forest on Maracá Island, Roraima, Brazil1
Authors: Villela Dora M. , Proctor John 
Published: March 2006

ABSTRACTMaracá Island is on the boundary of the Amazon rain forest and the Rio Branco‐Rupunini savanna. The annual rainfall is ca. 1800 mm, with a dry season from October‐March and a wet season from April‐September. A forest type dominated by Peltogyne gracilipes (Caesalpiniaceae) occurs on parts of the island and the adjacent mainland, the least species‐rich (for trees > 10 cm DBH) of any recorded in Brazilian Amazonia. The goal of this study was to test the hypothesis that the dominance by Peltogyne is associated with an unusual litterfall mass, nutrient concentrations, or retranslocation. Three plots (50 × 50 m) were set up in each of three forest types: (1) Peltogyne‐rich forest (PRFa), dominated by Peltogyne gracilipes; (2) Peltogyne‐poor forest (PPF), with a sparse occurrence of Peltogyne; and (3) forest without Peltogyne (FWPa). Litterfall was collected for 360 d at ca 15‐d intervals in 11 randomly positioned traps (0.32 m2) per plot. Mature Peltogyne leaves were collected at random from three randomly selected understory Peltogyne trees in each of the three PRFa plots during the early dry and early wet season. Additionally, young Peltogyne leaves were collected during the early wet season. Chemical analyses were made on bulked (on a 2‐mo basis) litterfall samples and young and mature Peltogyne leaves. The estimated annual litterfall was similar among PRFa (7.9 t/ha), PPF (9.1 t/ha) and FWPa (8.6 t/ha); however, PRFa was distinguished by its litterfall seasonality, because of the deciduous Peltogyne, and its higher concentrations of Ca (9.3 compared to 6.5 mg/g in FWPa) and Mg (3.2 compared to 1.9mg/g in FWPa). About 40–50 percent of N and P, 25–41 percenr of K, and 2–13 percent of Mg were rerranslocated from Peltogyne leaves.
Factors Limiting Tropical Rain Forest Regeneration in Abandoned Pasture: Seed Rain, Seed Germination, Microclimate, and Soil1
Authors: Holl Karen D. 
Published: March 2006

ABSTRACTVegetation, seed rain, seed germination, microclimate, and soil physical and chemical parameters were measured in a recently abandoned pasture and adjacent primary rain forest in southern Costa Rica. The goal of this study was to assess the importance of these factors in limiting forest regeneration in abandoned pastures. Seed rain of animal dispersed species decreased dramatically in the pasture >5 m from the forest/pasture edge; fewer wind dispersed seeds fell in the pasture than in the forest, but the difference was much less than for animal dispersed seeds. Percent seed germination of most species studied was similar in the forest and in pasture with grasses; seed germination was lower during the dry season in areas of pasture cleared of grasses. Air temperature, vapor pressure deficit (VPD), and photon flux density (PFD) were much higher in the pasture than in the forest at 1 m above the ground. VPD and PFD at ground level and soil temperature were similar in the pasture and the forest, indicating that pasture grasses strongly modify microclimatic conditions near the soil surface. The lowest gravimetric water content recorded in the pasture during the dry season was 0.5 and leaf relative water contents of the two species measured in the forest and pasture were identical, suggesting that plants in the pasture were not water stressed. Levels of most soil nutrients were lower in the pasture as compared to the forest; however, aboveground and root biomass for seedlings grown in pasture and forest soils did not differ significantly. Although a number of factors impede forest recovery in abandoned pastures, these results suggest that the most imporrant limitation is lack of seed dispersal.
Vegetative Life History of a Dominant Rain Forest Canopy Tree1
Authors: Gavin Daniel G. , Peart David R. 
Published: March 2006

ABSTRACT Tetramerista glabra has a remarkable combination of life history traits. It is a dense‐wooded, large, common canopy tree in primary peat swamp rain forest. Its seedlings, although shade tolerant, can grow rapidly in high light conditions, but frequently lack structural stability. Most juvenile stems (94% in the understory and 38% in canopy gaps) collapse under their own weight or from branchfalls. Fallen stems then ramify into vegetative sprouts, which in turn may collapse, perpetuating a vegetative juvenile cycle. Most recruitment is from sprouts rather than from seed. Structural analysis of stem dimensions shows that stems 2–8 cm DBH (diameter at breast height) are close to the theoretical buckling limit, especially for those dependent on neighboring vegetation to maintain vertical form. Trees > 4 cm DBH persisting as upright stems develop stilt root support and become structurally independent at ca 8 cm DBH. Eventually, as stems thicken, stilt roots anastamose and trees adopt the cylindrical growth form of mature canopy trees (up to 150 cm DBH). Thus, the vegetative life history strategy of the species is to: (i) regenerate a large “ramet bank” from the majority of juveniles that fail structurally while suppressed in the understoty, and (ii) to maximize height growth at the expense of diameter growth in high light conditions. The growth pattern and plastic form of T. glabra shows how a shade tolerant species may adapt to utilize the ephemeral light resource in canopy gaps. The growth strategy of this species allows it to circumvent the normal trade‐off between shade tolerance and rapid growth in canopy gaps.