bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tree densities and sex ratios in breeding populations of dioecious Central Amazonian Myristicaceae
Authors: Ackerly David D. , Rankin-De-Merona Judy M. , Rodrigues William A. 
Published: July 2009

ABSTRACTThe densities of the breeding populations and the sex of all flowering individuals were recorded for five dioecious canopy tree species of Central Amazonian Myristicaceae, in 11 study areas of the Minimum Critical size of Ecosystems Project totalling 22.5 ha. Adult population densities were extremely low, ranging from 0.38 to 1.61 ha–1 for the five species studied. In a 10 ha study plot the mean distance to the nearest flowering conspecific ranged from 48 to 100 m, while the mean distance to the nearest opposite sex conspecific was 147 m. The two most abundant species, Iryanthera macrophylla and Virola calophylla, both showed male-biased sex ratios, of 23:9 and 20:6, respectively. The size class distribution of males, females and non-flowering individuals in V. calophylla suggests that earlier reproductive maturation of male plants may provide a partial explanation for this bias. In I. macrophylla, since 95% of the individuals were observed flowering, the observed ratio is representative of the population, and may be caused by sex shifts from male to female. The low reproductive densities, combined with the skewed sex ratios and overlapping generations of these species, create very small effective breeding populations, placing species such as these at great risk in the face of deforestation and habitat fragmentation.
Acclimation of seedlings of three Mexican tropical rain forest tree species to a change in light availability
Authors: Popma J. , Bongers F. 
Published: July 2009

ABSTRACTA comparison is made of the light acclimation potential of seedlings of three canopy species of the tropical rain forest of Los Tuxtlas, Mexico: Cordia megalantha, Lonchocarpus guatemalensis, and Omphalea oleifera. These species showed similar growth rates in a range of microhabitats. Gap dynamics were simulated by transferring plants between three environments: beneath a closed canopy, a small gap, and a large gap. Plants of all three species were able to adjust their morphology and growth rates in response to changes in light availability. Growth rates increased when plants were moved to a (larger) gap, and decreased when plants were moved to a more shaded environment. Shade-grown plants were able to acclimate faster to increasing light availability than sun-grown plants to decreasing light availability. Also, plants moved from shady to sunny conditions showed higher relative growth rates than sun control plants, whereas sun-grown plants when moved to the shade showed lower relative growth rates than shade control plants. Species differed in their response to gap dynamics. Omphalea could not acclimate morphologically to shading, but reacted faster than the other species in response to the occurrence of a large gap. Acclimation potential seemed to be related to plasticity in physiological rather than in morphological traits. Suppressed seedlings of all three species performed well in the shade, and were able to acclimate rapidly to gap-conditions.
Red crabs in rain forest, Christmas Island: removal and fate of fruits and seeds
Authors: O'Dowd Dennis J. , Lake P. S. 
Published: July 2009

ABSTRACTThe red land crab (Gecarcoidea nalalis) is the major collector of fruits and seeds from the rain forest Moor on Christmas Island, Indian Ocean. At three sites, they rapidly removed fruits and seeds of 17 species tested (usually within 12 h after placement) and most were taken to crab burrows. Direct observations of seed predation, and application of estimated chelar forces of red crabs indicated that seeds of many species, especially those with thin seed coats, are likely to be killed through handling. However, removal of some resistant seeds to burrows may be favourable for seedling establishment when canopy gaps occur. Fruit removal rates by crabs were positively related to nitrogen concentration in fruit tissues but negatively correlated with condensed tannins. These observations suggest that seed predation by land crabs may affect the success of colonization and the relative abundance of plants on oceanic islands.
Nitrogen mineralization and nitrification interra firmeforest and savanna soils on Ilha de Maracá, Roraima, Brazil
Authors: Marrs R. H. , Thompson J. , Scott D. , Proctor J. 
Published: July 2009

ABSTRACTSoil mineralization and nitrification rates were measured in (1) undisturbed and felled gaps of varying size interra firmeforest, and (2) along a forest – savanna transect, on Ilha de Maracá in northern Brazil. Both rates were similar to those found in studies of other forests with a marked seasonal rainfall pattern. However, rates were much lower than those of tropical forests where there is little seasonality in rainfall. A major finding was that the highest rates were during the transition between dry and wet seasons, implying that wetting and drying may be an important initiator of soil nitrogen flux. Felling had little effect on either process up to a gap size of 2500 m2. In the forest-savanna study, nitrogen mineralization was lower in the savanna in all seasons, but in the wet season when the savanna soils were water-logged NH4+-N was immobilized. Experimental additions of nutrients identified two important results; first that added NH4+-N was quickly immobilized rather than nitrified – this may be an important nutrient conservation mechanism, and second that soil calcium appeared to be a limiting factor, either directly or through a pH effect.
Germination ecology of the woody herb Uraria picta, from southern Nigeria
Authors: Okusanya O. T. , Lakanmi O. O. , Oyesiku O. O. 
Published: July 2009

ABSTRACTThe germination response of Uraria picta to five environmental factors was investigated. It germinated both in light and dark but germination in the light was significantly better than in the dark; there was further germination when seeds first placed in the dark were later brought into the light. It germinated well in the three soil types used but germination in humus and sand was significantly better than in red earth. There was an increase in germination with an increase in burial up to 1.5 cm, thereafter germination levelled off. There was no germination in water-logged conditions and there was an increase in germination as soil moisture decreased. Alternating temperatures of 31/21°C and 31/15°C favoured germination while 21/15°C inhibited germination. The results are discussed in relation to the phenology and distribution of the species.
Community structure of Auchenorrhyncha (Homoptera) in montane rain forest in Vietnam
Authors: Novotný Vojtěch 
Published: July 2009

ABSTRACTThe adult Auchenorrhyncha community within the understorey of a montane tropical forest in Vietnam is described A total of 1132 specimens representing 223 morphospecies and 16 families was found in a 4300-sweep sample None of the species exceeded the 5% dominance level More than half the species are represented by single individuals within the 309 ms of vegetation Spatial community pattern is mosaic like at a scale of hundreds of metres as the similarity of 100 sweep samples does not depend on their spatial distance Areas 1 5–3 km distant from one another differ markedly in their Auchenorrhyncha communities These between-site differences exceed the intra-site community heterogeneity Population density of Auchenorrhyncha species is not correlated with their body size The Auchenorrhyncha community within a forest markedly differs from the community of an adjacent ruderal area A transitional zone between these habitats is intermediate in Auchenorrhyncha species composition
Habitat and food preferences of Greylag and Barheaded Geese wintering in the Keoladeo National Park, India
Authors: Middleton Beth A 
Published: July 2009

ABSTRACTGreylag (Anscr anser) and Barheaded Geese (Anser indicus) wintering in the Keoladeo National Park, Bharatpur, India, have habitat and food preferences which are comparable to overwintering geese in other parts of the world These geese preferred to eat the dominant grass species in the Park, Paspalum distichum, as determined by a comparison of the mean proportion of Paspalum of the total food eaten by Greylag and Barheaded Geese (0 932 & 0 971, respectively) with the mean availability of Paspalum in the wetland (0 795) However, based on a habitat study at the end of their overwintering season in February 1986, both species of geese used sites with the same amount of Paspalum distichum cover (c 14%) as sites that they did not use (c 14%)The means of habitat characteristics of sites geese used versus sites they did not use, respectively, are given here in order of their relative preference based on rankings of their standardized means Greylags preferred sites which were grazed concurrently by other species of herbivores (frequency = 0 9 & 0 4), were farther from trees with Painted Stork nests (Mycteria leucocephala; 981 & 887 m) and from trees in general (49 & 26 m), or had deeper water 61 & 49 cm) However, Greylags did not prefer sites which were farther from open water (65 & 223 m), had been cut by hand (frequency = <0 1 & 0 1), were farther from vegetation dominated by Vetivcria zizanioides (668 & 842m), had been bulldozed (frequency = <0 1 & 0 1), or had any amount of cover of the exotic aquatic weed, Eichhornia crassipes (0 0 & 0 3%)Barheaded Geese preferred sites which were remote from the Park boundary (1156 & 757m), were farther from any road (423 & 235 m), had been grazed by geese in 1984 (0 3 & <0 1), had higher covers of droppings (0 4 & 0 1%), or had been burned in the previous summer (frequency = 02 & 0 1) They did not prefer sites which had deeper water (25 & 61 cm), had been grazed by geese in 1985 (frequency = 0 0 & 0 5), were farther from vegetation dominated by Vetivcria (511 & 733 m), had been bulldozed (frequency = 0 0 & 0 1), or were farther from open water (29 & 115 m) This information can be used to construct management plans for Greylag and Barheaded Geese overwintering in the Keoladeo National Park and other parts of northern India
Aggregation and synecology of arboreal arthropods associated with an overstorey rain forest tree in Australia
Authors: Basset Yves 
Published: July 2009

ABSTRACTThe cohesion of the arthropod community associated with the rain forest tree Argyrodendron actinophyllum was studied in a warm subtropical rain forest in Australia. The distribution of most arthropods was contagious on the foliage of A. actinophyllum. Chewers and phloem-feeders were more clumped than epiphyte grazers and parasitoids. Arthropod predator-prey ratios were high and relatively constant over time, as revealed by measures of their activity. However, similar ratios in abundance and species-richness of arthropods foraging on foliage showed high variability in space and no consistent trends. Species associations on the foliage were difficult to predict and did not constitute either a single, well-united community or well-delimited subcommunitics. Most of the data suggest that on the foliage of A. actinophyllum, the cohesion of the arthropod community is not extremely strong. Apart from methodological constraints, possible reasons for this include the influence of host-tree phenology, and the high arthropod-diversity of the rain forest environment.
Seasonal activity patterns and behaviour of juliform millipedes in south-eastern Botswana
Authors: Dangerfield J. Mark , Milner Alice E. , Matthews Reba 
Published: July 2009

ABSTRACTThe seasonal patterns of surface activity and behaviour were recorded for three species of juliform millipede in a savanna habitat in south-east Botswana. Initially, surface activity followed rainfall events but this association weakened as the season progressed and, although significant, the correlation between the magnitude of rainfall events and activity was weak. Activity also occurred on moist, relatively cool and cloudy days, particularly inAlloporus uncinatuswhich was much larger than the other species. The onset and duration of surface activity varied between species. Observations of feeding behaviour suggested that millipedes in semi-arid savannas did not subsist exclusively on tree leaf litter but appeared to select a range of food types. Mobility is necessary to obtain these patchy resources but differences between the sexes in patterns of behaviour are more likely related to the mating patterns of these species.
The vegetation of Brazilian ‘murundus’ – the island-effect on the plant community
Authors: De Oliveira-Filho Ary Teixeira 
Published: July 2009

ABSTRACTThe ‘campos de murundus’ (carthmound fields) are typical landscapes of the cerrado (savanna) region of Central Brazil and are characterized by many rounded earthmounds called ‘murundus’ which are scattered over a grassland surface. As these areas are normally liable to seasonal water-logging, the earthmounds are true habitat islands capable of bearing woody plants typical of the cerrado, which are normally very intolerant of root inundation. The vegetation of an area of murundus field at Cuiaba, in the State of Mato Grosso, Central Brazil, was surveyed for the purpose of evaluating the island-effect on the plant community growing on the mounds/islands. Two main aspects were considered: the influence of the size of the mound and the differences between the types of cerrado occurring on the mounds and on the areas surrounding the murundus field. Most plant species occurring on the mounds were also present in the flora of the surrounding cerrado. However, only a fraction of these species was able to colonize the mounds successfully. The number of species on the mounds was found to be significantly correlated with mound area. Speciesarea relationships were better described with the power model S = C(Az) than with the exponential model S = C + z (logA) (fitted with linear regression). The mound size also had a strong influence on the spatial distribution of the species on the surface of the mounds. The species were organized in an increasing number of concentric topographic belts corresponding to a gradient of soil depth above the Hooding level.
Density and biomass of large herbivores and other mammals in a dry tropical forest, western Thailand
Authors: Srikosamatara Sompoad 
Published: July 2009

ABSTRACTDensity and biomass of four ungulate species, elephant (Elephas maximus) and seven other mammal species were estimated in an area of about 50 km2in a dry tropical forest in Huai Kha Khaeng Wildlife Sanctuary, western Thailand. Density estimations employed line transects, using either direct sightings or indirect signs. Total biomass of these ungulates and elephant was 1450 kg km–2which was lower than that found in a well protected and managed area of similar forest, Nagarahole National Park, in India. This is due to the intensive poaching activity and the lack of wildlife management in this study site. Three species of ungulate, banteng (Bos javanicus), gaur (Bos gaurus) and sambar deer (Cervus unicolor), contributed over 70% of the estimated herbivore biomass. This situation is similar to that found in other parts of Asia. The high biomass of a subterranean mammal,Cannomys badius, has not been documented elsewhere in Asia; this species probably influences the forest dynamics and ecology of small carnivores in this area.
Ecological, behavioural and nutritional factors influencing use of palms as host plants by a Neotropical forest grasshopper
Authors: Braker Elizabeth , Chazdon Robin L. 
Published: July 2009

ABSTRACTThis study focused on relationships between a tropical forest grasshopper and a major group of its host plants. Microtylopteryx hebardi (Acrididae:Ommatolampinae) at La Selva Biological Station, Costa Rica, feeds on understorey palms as well as other understorey plants. We assessed leaf damage levels in populations of three geonomoid palm species (Geonoma cuneata, Geonama congcsta, Asterogyne martiana), investigated feeding response of M. hebardi to the three palms, and examined leaf characteristics presumed to be important to herbivores. In understorey and gapedge habitats, total leaf damage did not differ significantly between palm species. In the centre of small light gaps, where M. hebardi was most abundant, total leaf damage and total herbivory on G. cuneata was equal to that on the other species, but herbivory attributable to grasshoppers was significantly greater. Female M. hebardi showed strong preference for G. cuneata over the other palm species in laboratory feeding trials. Experiments to elucidate the proximate basis for this feeding preference showed that grasshoppers preferentially bit filter paper discs containing cuticular wax extract of G. cuneata. In consumption and digestibility experiments, grasshoppers consumed more fresh weight of G. cuneata and gained more weight per unit time spent feeding on this species. Leaves of G. cuneata had the highest percentage water content, highest fresh and dry mass per unit leaf area, and the lowest percentage crude lignin among the three palms studied. These factors may partially explain the preference of M. hebardi for G. cuneata, which was reflected in higher herbivory rates incurred by G. cuneata in sites where M. hebardi was locally abundant.
Structure and spatial organization of an Amazonian terra firme forest primate community
Authors: Peres Carlos A. 
Published: July 2009

ABSTRACTA high-diversity primate community consisting of 13 species was examined at an entirely undisturbed and remote terra firme forest near the headwaters of the Urucu River, Amazonas, Brazil. Twelve of these species used a 900-ha study plot, located 4 km or more inland from the river, and comprised a total group density of 16 groups km−2, an overall density of 146 individuals km−2, a crude community biomass of 381 kg km−2, and a metabolic biomass of 278 kg0.75km−2. These species were occasionally found together within small (≥1 km2) areas of forest, so long as they included the full complement of available forest types. More frequently, however, only half the species co-occurred in a single habitat type at any one time, reflecting a relatively consistent pattern of subcommunity spatial organization. Habitat generalist species making extensive, yearround use of the predominant habitat type (high forest), were common, whereas habitat specialists were uncommon to very rare, and confined to minor habitats. Those species coexisting throughout the year in high forest were found to segregate vertically from one another. These and other modal patterns of community structure were disrupted seasonally by long-distance, inland movements by two ‘igapó’ forest species living in large groups – squirrel monkeys and white-face capuchins – to high forest areas, which apparently resulted from a food bottleneck in their habitat. Another species found in large groups – woolly monkeys – also exercised seasonally vagrant movements within the high forest matrix, which coincided with periods of greatest scarcity of mature fleshy fruits.
Regeneration by sprouting in slash and burn rice cultivation, Taï rain forest, Côte d'Ivoire
Authors: de Rouw Anneke 
Published: July 2009

ABSTRACTIn 14 forest plots (36 m2) all terrestrial plant species were recorded before slashing and burning of the vegetation. During subsequent cultivation with rainfed rice all resprouting plants were registered in permanent plots (72 m2). The fields studied (one per forest) covered all combinations of forest type and soil usually cultivated on local farms. Forest plots (total 409 species) and field plots (358 species) had 226 species in common. Most resprouting plants were woody. Though nine forests in the sample were secondary, 70% of resprouting plants belonged to primary forest species and with three exceptions, these species did not regenerate by seed.Experiments in one field inlcuded: different intensities of initial burning, weeding (none, once, twice) and length of the rice cultivation period (1, 2, 3 y). Resprouting plants were monitored in permanent plots (108 m2) during 3 y of cultivation and 2 y of fallow. More plants resprouted after a mild initial burning (5.8 plants m−2) than after a burn of normal intensity (1.4 plants m−2). Weeding and prolonged cultivation strongly reduced species diversity but plant densities were less affected because some climbers and trees were apparently stimulated and expanded.Fields abandoned after one rice harvest had, within six months, a closed forest canopy of pioneer trees emerging from the pre-existing seed bank and from the growth of resprouting trees. Prolonged cultivation (3 y) destroyed the pre-existing seed bank but affected sprouting plants less, these being the only component in the vegetation able to shade out weeds and forbs such asChromolaena odorata.
A comparison of amphibian communities through time and from place to place in Bornean forests
Authors: Inger Robert F. , Voris Harold K. 
Published: July 2009

ABSTRACTWe sampled riparian frogs along 18 streams at eight localities in Borneo. At four of these sites we sampled during more than one year. Altogether 49 species were included in our study and total sample size was 13,249. We measured overlap in species occurrences and arrays of abundances within and among localities. Variation over the time span of our study was minor within communities. Overlaps between streams at a locality were generally higher than overlaps of pairs of streams from different localities. Environmental variation, particularly in stream width and gradient, had a clear effect on both intra-and inter-locality overlaps. Although rainfall varied between localities and within localities over time, that variation did not seem to affect overlaps among or within communities. Environmental factors did not account for all differences in overlaps between communities. Instead, regional processes, perhaps the timing of barriers or speciation events, appear to have been responsible for geographic restrictions of several species, leading to variation in overlap values.
Sandfly stratification on tree buttresses in a Costa Rican tropical rainforest
Authors: Memmott Jane , Sutton Stephen L. 
Published: July 2009

ABSTRACTIn humid forests tree buttresses and tree trunks are used as diurnal resting sites by phlebotomine sandflies (Diptera: Psychodidae). When several species are present on the same buttress, the sandfly species are spatially segregated resulting in a pattern of vertical stratification on the buttress within 100 cm of ground level. A change in the distribution of one species induces a change in the distribution of an adjacent species. This is demonstrated under both natural and experimental conditions. Observations of sandflies at dawn and dusk have revealed that the buttress is used as a swarming site; this behaviour provides our favoured explanation for the patterns of vertical stratification on tree buttresses.