bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dispersal, fruit utilization and seed predation ofDysoxylum gaudichaudianumin early successional rainforest, Krakatau, Indonesia
Authors: Whittaker Robert J. , Turner Bryan D. 
Published: July 2009

ABSTRACTDysoxylum gaudichaudianumis an important canopy tree on the Krakatau Islands, and its ecology is of significance to an understanding of successional dynamics. It is abundant on Panjang and Sertung, but only locally common on Rakata. A study was undertaken of three aspects of its seed ecology in July/August 1992. The chief dispersers ofD. gaudichaudianumare suggested here to be birds, with two species of pigeon and a bulbul prominent as fruit feeders over a short observation period. Bird activity dislodges large numbers of fruits and seeds which fall to the ground where they form a resource available to other animals. It was observed that seeds ofD. gaudichaudianumsuffer varying levels of attrition on the forest floor, with 40% of the total sample lost over a 12-day period, compared with 23% which had germinated. When mature, opening fruits develop a fishy aroma, which is attractive to insects. They hasten the decay process and release the seeds. The soft, rotting tissues of fallen fruits support a small, short-lived successional insect community. After about five days on the forest floor only the seeds and the outer fruit coat remain. Despite the abundance of fruit of this species during the dry season and its obvious attraction tó frugivorous birds,D. gaudichaudianumhas still colonized only a small fraction of the near-coastal lowlands of Rakata.
Evaluation of regression models for above-ground biomass determination in Amazon rainforest
Authors: Overman Johannes Petrus Maria , Witte Hendrik Johannes Louis , Saldarriaga Juan Guillermo 
Published: July 2009

ABSTRACTIn a mature lowland ‘terra firme’ forest near Araracuara in Colombia, a study was conducted to determine the above-ground biomass by means of regression analysis. Dry weight, DBH (i.e. stem diameter at 1.3 m above ground level, or just above buttresses if these surpassed 1.3 m in height), total height and specific wood density were measured on 54 harvested trees, chosen in a ‘selected random’ manner. Nine different regression models were evaluated for statistical correctness, accuracy of the estimates and for practical use. The logarithmically transformed models with DBH2, and DBH2 × height as independent variables appeared to be the only models meeting the above criteria, the latter being the most accurate.The exclusion of big trees (DBH >45 cm) from the regression did not result in significant changes of the regression coefficients.
Nitrogen cycling in a Venezuelan tropical seasonally flooded forest: soil nitrogen mineralization and nitrification
Authors: Barrios E.  , Herrera R.  
Published: July 2009

ABSTRACTSeasonally flooded forests represent a transition between terrestrial and aquatic ecosystems. The Mapire river, a tributary of the Orinoco river, floods its surrounding forests during the wet season (May–December). The soils are very acid and the total nitrogen concentration (0.1%) is only half that found in nearby soils flooded by Orinoco waters. Ammonium-nitrogen predominates in the soil during the flooded period while nitrate-nitrogen concentrations are higher in the dry period. Wide fluctuations in the inorganic nitrogen fractions did not considerably affect the annual course of soil nitrogen.The predominance of mineralization versus nitrification (56 and 5 μgsoil month−1respectively) and possibly the synchronization of nitrogen availability with plant demand could be considered as nitrogen conserving mechanisms.In synchrony with the hydrologic cycle, the seasonally flooded forest studied shows a nitrogencycle where inputs and accumulation are maximized when the system is under minimum stress (dry season). During flooding, the system enters a period of dormancy making minimal use of nutrient and energy to avoid or tolerate anaerobiosis.
Pollination biology and breeding systems of six Vochysia species (Vochysiaceae) in Central Brazil
Authors: Oliveira Paulo , Gibbs Peter 
Published: July 2009

ABSTRACTSix Vochysia species occurring in cerrado vegetation or gallery forest in central Brazil were studied for their pollination biology and breeding system. The species showed rather different flowering phenologies, but presented a relatively uniform floral morphology and attracted a mostly similar spectrum of visitors. Principal pollinators were large Anthophoridae bees, but three species were also visited by sphingid moths while hummingbirds were opportunistic visitors to all species. Some observations indicated that the slight differences in flower size or habitat between species may have influenced the relative importance of bees versus hummingbirds or sphingids as effective pollinators. All six species were found to be self-incompatible with self-pollen tube rejection, usually accompanied by callose deposition, occurring in the mid-style.
Growth ring characteristics of some AfricanAcaciaspecies
Authors: Gourlay Ian D. 
Published: July 2009

ABSTRACTThe age of most temperate tree species can be estimated accurately by counting the annual rings revealed by concentric changes in their wood anatomy. In the tropics and sub-tropics, this growth periodicity is seldom clearly and unambiguously defined. This research investigates whether a wood anatomical feature is present that delimits annual periods in one of the most widely distributed genera in the semi-arid and arid areas of Africa,Acacia.Most research on this topic has been based on sample trees from natural stands, often the largest and putatively oldest trees. In contrast, the trees sampled for this study were actively sought from material of known age, particularly those for which the history of management was known. Several AfricanAcaciaspecies were examined for growth rings. These were apparent in most species as narrow bands of marginal parenchyma filled with long crystal chains. The crystals were sub-sequendy identified as calcium oxalate through the use of a scanning proton microprobe. The number of bands formed annually corresponded to the number of peaks in the annual rainfall distribution. Ring widths were highly correlated with total annual rainfall.
Post-dispersal seed and seedling mortality of tropical dry forest trees after shifting agriculture, Chiapas, Mexico
Authors: Hammond D. S. 
Published: July 2009

ABSTRACTVertebrate attack accounted for 98.4% of all seed loss during the two months following dispersal. This accounted for, across all habitat types, 94% ofBursera, 76% ofSpondias, 37% ofSwieteniaand 25% ofErythrinaseeds artificially dispersed.Bursera, SpondiasandSwieteniaseeds in early successional habitat suffered significantly greater predation than in either older abandoned (30 y) or mature forest plots.Erythrinashowed generally low loss to predation in all plots. Seeds attacked were more often removed from, rather than buried or eaten at, the dispersal site. In young secondary habitats, however, seeds ofBurseraandSpondiaswere more frequently eaten at the site. Seeds dispersed individually rather than in larger aggregations (5, 10) were more likely to survive in mature forest and late secondary habitat. This advantage was lost inBurseraandSwieteniawhen they were dispersed to younger successional habitats.At the early seedling stage, recruitment ofBurseraandSwieteniawas highest in the older secondary habitats. Seedlings ofErythrinashowed the lowest overall losses to any of the mortality factors identified during the first two months of establishment. Seeds of forest tree species arriving in secondary habitat were more vulnerable to attack by non-flying vertebrates than in mature forest. Survival of seedlings of these species was most closely related to the moisture-conserving status of the habitat.
Seed predators and the fruiting phenology of Pithecellobium pallens (Leguminosae) in thornscrub, north-eastern Mexico
Authors: Grimm Christoph 
Published: July 2009

ABSTRACTLife table studies were conducted on the flowers, pods and seeds of the tree Pithecellobium pallens to assess the extent of damage by the seed predators Stator limbatus and Merobruchus insolitus (Coleoptera: Bruchidae). Brachyacma palpigera (Lepidoptera: Gelechiidae) was also found to feed on the seeds of this tree. Seed predation and herbivore damage destroyed 41% of the seeds. Pods were taken to the laboratory and seed predators within were reared and identified. B. palpigera and M. insolitus were major causes of mortality, whereas damage by S. limbatus was slight. The growth ratio of pods to seeds did not indicate a rapid development of seeds as an evasive strategy against bruchid attack. Experiments showed no successful attack by bruchids on seeds exposed on the ground after dispersal from the tree.
Swimming ants and pitcher plants: a unique ant-plant interaction from Borneo
Authors: Clarke C. M. , Kitching R. L. 
Published: July 2009

ABSTRACTThe relationship betweenCamponotussp. ants and the carnivorous pitcher plant,Nepenthes bicalcarata, from Borneo were investigated. The ants nest in the hollow tendrils of the plant, and feed on large prey items caught by the pitchers. These are hauled from the pitcher fluid by the ants and consumed. When large prey items are absent, the ants feed upon mosquito larvae which inhabit the pitcher fluid. The accumulation of excess prey in pitchers can lead to putrefaction of the contents, and disruption of the pitcher's digestive system. Experiments on the possible benefits of the ants' behaviour to the plant showed that the accumulation of excess prey and the putrefaction of the pitcher contents were significantly reduced in the presence of the ants. The accumulation of ammonia in pitchers was unaffected by the presence of the ants when small prey were added to pitchers, but was reduced significantly in the presence of ants when large prey were added. It is suggested thatCamponotussp. andN. bicalcaratahave a mutualistic association, from which the ants obtain food and nesting sites and, in return, prevent damaging accumulation of excess prey in the pitchers.
Tactics of reproduction and reproductive allocation in four species of woodlice from southern Africa
Authors: Dangerfield J. Mark , Telford S. R. 
Published: July 2009

ABSTRACTMeasurements of reproductive allocation, fertility and iteroparity were made on females of four species of woodlice (Isopoda: Oniscidae) from southern Africa. In three of the species between-population comparisons were made. The average body mass of reproductive females was smaller than in temperate woodlice and because of a positive scaling between body mass and fertility: brood sizes were rarely larger than 30 young and usually between 5 and 20. Reproductive allocation ranged from 16 to 27% of female pre-birth live mass and differed significantly between species. Associations between reproductive allocation and body mass were all positive although only significant in two of the populations. A small number of females produced more than one brood during the study and iteroparity appears the most likely reproductive tactic in these species.In woodlice a restriction on body size results in lower fecundity as brood size is ultimately determined by the size of the marsupium. It is postulated that a tactic of repeated reproduction, with a relatively conservative allocation of resources to each reproductive event to enhance survival probabilities, would be favoured, particularly in an environment where juvenile mortality and the chance of complete brood failure is high.
Effects of heat and fire on the germination of Acacia sieberiana D.C. and Acacia gerrardii Benth. in Uganda
Authors: Mucunguzi Patrick , Oryem-Origa Hannington 
Published: July 2009

ABSTRACTThe effects of heat treatment and fire on seed germination of Acacia sieberiana D.C. and Acacia gerrardii Benth. were studied. Dry heat and fire were studied separately. Seeds treated with dry heat were set to germinate in petri-dishes under laboratory conditions. Other seeds were planted in plots at the Uganda Institute of Ecology, Mweya, which were then burnt, and subsequent seedling emergence was monitored. The effect of heat treatment on seed germination depended on heat intensity and duration of exposure. Higher intensities reduced the germination capacity of Acacia seeds. Short exposure of seeds stimulated germination but prolonged exposure rapidly reduced seed viability. A. sieberiana had a higher heat resistance than A. gerrardii. The survival and germination of seeds after fire increased with depth of burial and A. sieberiana survived better than A. gerrardii. The germinability of seeds of A. gerrardii was not significantly increased by fire.
Tents and harems: apparent defence of foliage roosts by tent-making bats
Authors: Kunz Thomas H. , McCracken Gary F. 
Published: July 2009

ABSTRACTPalmate umbrella tents used by tent-making bats in Trinidad, West Indies, were observed in three species of Neotropical palms, Sabal mauritiiformis, Coccothrinax barbadensis and Mauritia flexuosa. Tents were most common in palm leaves that have supporting petioles angled at 50–70° above the horizontal. The shape and volume of tents is influenced mostly by leaf morphology (leaf width and leaflet length) and age of the tent. Tent-crowns varied from being heart-shaped in S. mauritiiformis, oval or round in C. barbadensis and spade-shaped in M. flexuosa. Leaves in which tents were constructed were most often beneath overhanging vegetation, and were generally free of vegetation below, allowing bats to enter and depart from tents without being impeded by the clutter of adjacent vegetation.Singles and small apparent harem groups of two bat species, Artibeus jamaicensis and Uroderma bilobatum, were captured and observed in tents made from the leaves of S. mauritiiformis and C. barbadensis. No bats were observed in tents constructed in leaves of M. flexuosa. The apparent harem social organization in these and other tent-making bat species suggests that leaves modified into tents may provide critical and defendable resources that promote the evolution of polygyny. This hypothesis is based on the observed patchy distribution of suitable palm trees, the inappropriateness of many palm leaves as potential tents and the resultant architecture provided by palmate umbrella tents. We suggest that tent-making is an adult male behaviour.
Structure and floristic composition of a tropical evergreen forest in south-west India
Authors: Pascal Jean-Pierre , Pelissier Raphael 
Published: July 2009

ABSTRACTA permanent plot of 28 ha was established in a dense wet evergreen forest in the Western Ghats of India to study the functioning of the ecosystem. Since April 1990, 1981 trees of ≥30 cm gbh have been enumerated in a systematic sampling of five strips totalling 3.12 ha. This paper describes the main structural and floristic characteristics of the plot.The density (635 trees ≥30 cm gbh per hectare) and basal area (39.7 m2 ha−1) are high. Despite the high diversity (Simpson's D = 0.92 and Shannon's H' = 4.56), four species are distinctly, dominant in terms of an importance value index (relative density + relative basal area). Each of these four species occupies a different layer in the ecosystem: Humboldtia brunonis Wall. (Fabaceae) dominates the undergrowth, Myristica dactyloïdes Gaertn. (Myristicaceae) the intermediate strata, Valeria indica L. (Dipterocarpaceae) the higher canopy level and Dipterocarpus indicus Bedd. (Dipterocarpaceae) the emergents. This pronounced species hierarchy is one of the most important characteristics of the evergreen forests of the Western Ghats. The two dipterocarps account for 20.1% of the total number of trees and contribute 40.9% to the total basal area. This formation can, therefore, be considered as the westernmost lowland dipterocarp forest of Asia.Analysis of the spatial variations in the floristic composition and in the structure of the main species populations shows that two kinds of mature phases can be identified: where the topography is raised and gently sloping, the vertical structure of the stand is discontinuous, with Dipterocarpus indicus and Vateria indica forming an emergent layer above a dense undergrowth; on slopes, the stand is lower, vertically continuous and saturated with Valeria indica and Myristica dactyloïdes. The link between the structure of the stand and dynamic processes is discussed.
Ant recolonization of rehabilitated bauxite mines at Trombetas, Pará, Brazil
Authors: Majer Jonathan D. 
Published: July 2009

ABSTRACTAnt species were sampled in three rainforest and 10 rehabilitated bauxite mine plots at Trombetas, in the tropical monsoonal region of Brazil. Rehabilitation ranged from 0 to 11 years in age and was mainly performed by planting mixed native forest tree species. One plot supported single-species blocks of Australian Eucalyptus and Acacia species. Two hundred and six ant species were recorded, of which 82 were exclusively found in the native vegetation, 54 were confined to the rehabilitation and 70 were found in both situations. In contrast with other studies, ant species richness in the Eucalyptus/Acacia plantation was as great as in the areas rehabilitated with native vegetation. The overall rate of return of ant species was considerably greater than in mines situated within subtropical regions of Brazil, Africa and Australia. However, if the greater richness of ants in the native vegetation at Trombetas was accounted for, the proportional return of the original ant fauna was not particularly rapid. The return of ant species slowed as the rehabilitated areas aged. In comparison with forest, the rehabilitation was characterized by proportionately more generalist species and fewer specialists, especially from the soil and litter layers. The full range of habitat requirements for the ant community has not been restored by the eleventh year of rehabilitation and further management may be required to enhance the degree of colonization. It is suggested that the findings for ants may apply to other components of the biota as well.
Frugivory and the fate of dispersed and non-dispersed seeds of six African tree species
Authors: Chapman Colin A. , Chapman Lauren J. 
Published: July 2009

ABSTRACTThe relationship between seedling recruitment (under and away from parent trees) and the behaviour of seed dispersers and predators, was explored in a three-year study in Kibale National Park, Uganda. On the basis of 1261 hours of observation, the foraging activity of the diurnal frugivores which fed on fruit from six tree species was quantified. The fate of dispersed and non-dispersed seeds and seedlings was examined experimentally. The findings suggest that a trade-off exists between factors that promote seedling growth in areas with high seedling density and factors that promote dispersal by frugivores. For example, dispersal ofMimusops bagshaweiincreases both seed and seedling survival; seeds placed away from adult conspecifics had a 8% lower probability of disappearing than seeds placed under adults and seedlings away from adults had a 30% greater probability of surviving than seedlings grown under adults. In contrast, forUvariopsis congensis, dispersed seeds had a 56% greater probability of disappearing than seeds directly under a parent tree, while the survival of dispersed and non-dispersed seedlings was similar. Non-dispersed seed and seedling disappearance were correlated with the percentage of the fruit crop removed from focal trees, suggesting that the ability to survive under an adult maybe related to other aspects of the tree's life history.
Stand dynamics in Mpanga Research Forest Reserve, Uganda, 1968–1993
Authors: Taylor David M. , Hamilton Alan C. , Whyatt J. Duncan , Mucunguzi Patrick , Bukenya-Ziraba R. 
Published: July 2009

ABSTRACTChanges in the composition and structure of mid-altitude, semi-deciduous tropical forest in Mpanga Research Forest Reserve, Uganda are described for a 25-year period between 1968 and 1993. Three surveys of a 0.64 ha (80 m × 80 m) permanent plot were carried out in 1968, 1982 and 1993, during which a total of 397 trees with a dbh≥9.5 cm were identified. Forty-nine species were identified in total, representing 19 families. Eight individuals remain unidentified. Dbh measurements were recorded for 359 non-buttressed trees, whilst the equivalent measurement for 38 buttressed trees was the diameter of the trunk immediately above the buttress. Basal area, diversity and density of trees increased within the plot during the survey period by, respectively, 8% (from 39.2 to 42.2 m2 ha−1). 7% (from 44 to 47 species) and 11% (459 to 508 trees ha−1). The main compositional changes were increases in understorey trees and a decline in serai taxa. Growth rates (productivity) and turnover were lower during the period 1982 to 1993 than the period 1968 to 1982. Rates of growth and mortality were generally highest in serai species and lowest in main canopy taxa. Mortality rates were also highest amongst the smallest trees enumerated (dbh <30 cm). Changes in composition and structure over the survey period are believed to reflect forest recovery after low intensity pit-sawing was curtailed from 1951. Forest recovery also may have caused the reduced growth rates and turnover recorded for the most recent survey period, by restricting the opportunities for light-demanding, faster-growing and relatively productive serai taxa, and to have outweighed any effects of externally-driven processes, such as changes in atmospheric conditions.
Changes in light below the canopy of a Jamaican montane rainforest after a hurricane
Authors: Bellingham P. J. , Tanner E. V. J. , Rich P. M. , Goodland T. C. R. 
Published: July 2009

ABSTRACTHurricane Gilbert caused disturbance to Jamaican montane rainforests in 1988. This study provides a detailed characterization of landscape-level changes in light below the canopy of these forests after the hurricane. Hemispherical photographs were taken below the forest canopy at four sites at permanent points 1 m above the ground between 7 and 33 mo after the hurricane. For each photograph photosynthetically active radiation (PAR) was computed. PAR declined exponentially in all sites during the period of measurement. During the first 24 mo after the hurricane, PAR beneath the canopy was significantly greater in sites that had been defoliated during the hurricane than in sites where few trees had been defoliated. By 28 mo after the hurricane there was no significant difference in PAR beneath the canopy among the four sites. By 33 mo after the hurricane canopy recovery was nearly complete and PAR was only slightly higher than measurements made before the hurricane. Our results were compared with studies of changes in light environment resulting from treefall gaps and under deciduous canopies. PAR during the first 18 mo after the hurricane was similar to that recorded in small canopy gaps in other forests. Widespread defoliation caused by hurricanes can thus increase PAR beneath the canopy over large areas and consequently opportunities may arise for widespread recruitment of tree species in response to increased light levels.