bluuebunny/crossref_metadata_2025 huggingface dataset:
Aggregation and synecology of arboreal arthropods associated with an overstorey rain forest tree in Australia
Authors: Basset Yves
Published: July 2009

The 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

The 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

The ‘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

Density 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

This 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

A 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

In 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

We 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

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

Dysoxylum 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

In 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

Seasonally 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

Six 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

The 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

Vertebrate 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

Life 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

The 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

Measurements 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

The 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

Palmate 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

A 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

Ant 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

The 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

Changes 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

Hurricane 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.
Functional association between apogeotropic aerial roots, mycorrhizas and paper-barked stems in a lowland tropical rainforest in North Queensland
Authors: Reddell Paul , Hopkins Michael S. , Graham Andrew W.
Published: July 2009

The root and trunk characteristics of species in a complex, lowland, evergreen, tropical rainforest at a seasonally inundated, coastal site on siliceous sands were examined. Roots in the soil were predominantly colonized by arbuscular mycorrhizal fungi although ectomycorrhizas were found on four species which contributed almost 25% of total basal area. Surface root mats were not a characteristic of the study site. In contrast, the ability to produce apogeotropic (upwardly growing) aerial roots which grew on and within the bark on trunks and branches was a consistent feature of the dominant species of trees in this forest. Eleven species representing eight families and constituting more than 85% of the basal area at the site produced these roots. Most trunks with DBH greater than 20 cm supported apogeotropic aerial roots produced by a range of species including themselves. Apogeotropic roots were most frequently found on the basal 0.5 m of trunks; however, they did occur up to 5 m above the forest floor. Apogeotropic aerial roots originated both from epicormic buds under the bark and from soil, and they were frequently colonized by arbuscular mycorrhizal and ectomycorrhizal fungi. There was a strong association between the ability to support these upwardly growing roots and the occurrence of laminated papery and flaky bark. We postulate that production of apogeotropic roots may provide a mechanism for nutrient uptake and root respiration during periods of inundation, for intercepting nutrients in stemflow and/or for extracting nutrients from bark.
Specialization for canopy position by hemiepiphytic Ficus species in a Bornean rain forest
Authors: Laman Timothy G.
Published: July 2009

The growth habits of five species of hemiepiphytic fig trees (Ficus subgenus Urostigma) were compared to see if any species occupied distinct canopy positions or showed unique host preferences in lowland rain forest in Gunung Palung National Park, Indonesian Borneo. Highly significant differences among species were found in the height of establishment on hosts, the level at which fig crowns were deployed, and the size and taxa of host trees. Ficus stupenda, F. dubia, and F. subtecta all had mean establishment heights between 29 and 31m above the ground, had their crowns in the upper canopy, and predominantly occupied large trees in the Dipterocarpaceae. F. consociata and F. xylophylla established at significantly lower mean heights of 24 and 18 m respectively, had their crowns predominantly in lower canopy layers, and disproportionately occupied smaller non-dipterocarp trees. These patterns were consistent both within lowland forest on alluvial terraces, which was most intensively sampled, and when data were combined from three other contiguous lowland forest habitats. Ficus species appear to be specialized to some extent for distinct microhabitats within the canopy.
Aspects of the morphology and ecology of two Panamanian ant-plants,Hoffmannia vesciculifera(Rubiaceae) andBesleria formicaria(Gesneriaceae)
Authors: Windsor Donald M. , Jolivet Pierre
Published: July 2009

Two formicarial ant-plants endemic to Panama and adjacent areas of Costa Rica co-occur in mid-elevation cloud forest yet have distinctive modifications to house and feed small, retiring ants.Besleria formicaria(Gesneriaceae) hosts onlyPheidolesp. which harvest the oil-rich seeds of its host and other plants and insect parts.Hoffmannia vesciculifera(Rubiaceae) hosts onlySolenopsissp. ants which obtain lipid and possibly other nutrients from vescicular tissues. Judging by their abundance in refuse deposits, fern sporangia appear to be a plentiful and evenly distributed resource exploited by both ant species.
Leaf nutrient dynamics of two tree species and litter nutrient content in Southern Bakundu Forest Reserve, Cameroon
Authors: Songwe Nicholas C. , Fasehun F. E. , Okali D. U. U.
Published: July 2009

The variations in macronutrient concentrations of the leaves of Terminalia superba and Pycanthus angolensis were studied and the concentrations of nutrients in leaves before abscission were compared with those after abscission. The amounts of nutrients returned to the forest floor were also computed from litter fall data at the start of maximum annual fall in the Reserve. With the exception of potassium in Pycanthus angolensis, there were significant variations in the nutrient concentrations of the two species with the time of year. With increasing leaf age the concentration of nitrogen, phosphorus, potassium and magnesium declined in Terminalia superba while magnesium concentration decreased in Pycanthus angolensis leaves. Furthermore, calcium showed an increasing concentration in Terminalia superba with increase in leaf age. The concentrations of nitrogen, phosphorus and potassium decreased before leaf fall. Estimated losses in nitrogen phosphorus and potassium before abscission were 44, 53 and 50%, respectively, whereas generally there was an increase (40%) in the concentration of calcium at leaf fall. Magnesium did not follow a definite pattern. The return of calcium through litter fall to the forest floor was the greatest of all the major elements. The distribution and variation of foliar nutrient concentrations in the leaves of Terminalia superba and Pycanthus angolensis and the importance of the amount of litter and the concentration of the various nutrients in the influencing soil fertility are discussed.
Removal of black palm (Astrocaryum standleyanum) seeds by spiny rats (Proechimys semispinosus)
Authors: Hoch Gregory A. , Adler Gregory H.
Published: July 2009

A seed-removal experiment was conducted to assess the role ofProechimys semispinosus(Central American spiny rat) as potential predator and disperser ofAstrocaryum standleyanum(black palm) seeds. One hundred fresh ripeA. standleyanumfruits were placed in semipermeable cages on each of 14 small islands in Panama, and seed disappearance rates were calculated for each island. Spiny rat density and biomass were determined by live-trapping on each island for 5 consecutive days and 4 nights. Censuses of fruiting trees were conducted on each island to control for effects of food availability on removal of palm fruits. Disappearance rates were related positively to total spiny rat density, density of adult and subadult spiny rats, and spiny rat biomass, but the density of fruiting trees accounted for very little variation. Spiny rats evidently prey heavily onA. standleyanumseeds, based on the high removal rates and on feeding observations of captive individuals. Since spiny rats may scatterhoardA. standleyanumseeds, they may also function as effective seed dispersers if seeds are removed to favourable germination sites unavailable to other seed predators. Results indicate that spiny rats, because of their abundance and wide distribution, may be important but overlooked predators and dispersers ofA. standleyanumseeds and of other large-seeded tree species.
Leaf-cutting ants and early forest regeneration in central Amazonia: effects of herbivory on tree seedling establishment
Authors: Vasconcelos Heraldo L. , Cherrett J. Malcolm
Published: July 2009

The effects of herbivory by the leaf-cutting antAtta laevigataFr. Smith on the re-establishment of forest trees in an abandoned farm near Manaus, central Amazonia, were investigated. Experimental seedling transplants and observations on seedlings which emerged naturally in the study area showed that damage by leaf-cutting ants negatively affected tree seedling survival and growth. However, excluding leaf-cutting ants from experimental plots for 20 mo did not significantly increase tree seedling densities. The number of seedlings emerging varied considerably between plots and this obscured any effect the ants may have had on seedling survivorship. Taller seedlings, and seedlings attacked only once, suffered less mortality than smaller seedlings and seedlings attacked twice or more. In general, mortality was greater for those species preferred by the ants, indicating that selective herbivory by leaf-cutting ants affects tree species composition. The number of seedlings attacked byA. laevigataremained approximately constant throughout the period of this study in spite of the fact that the number available for attack increased. Thus, the chance of any individual seedling being attacked declined with time, suggesting that the effect ofAttaherbivory on tree establishment is stronger during the first few years of forest regeneration.
Seed damage tolerance and seedling resprouting ability of Prioria copaifera in Panamá
Authors: Dalling J. W. , Harms Kyle E. , Aizprúa Rafael
Published: July 2009

Germination and seedling resprouting capacity of the very large-seeded tree species Prioria copaifera Griseb. (Fabaceae) was studied in the seasonally moist forest of Barro Colorado Island, Panamá. Seeds with 60% of their cotyledonary mass removed did not suffer a reduced probability of germination compared to unmanipulated seeds and seeds infested with up to eight insect larvae germinated as well as uninfested seeds. Unmanipulated seeds were able to consecutively produce up to four functional resprout shoots after excision of the initial, and subsequent, fully expanded shoots. Even seeds with up to 60% of their reserves removed showed some capacity to resprout. Less than 10% of seeds we encountered in the field 2 mo after the end of the fruiting season were in a viable state, with the majority (55%) of mortality attributable to insect or pathogen damage. Of the 46 seeds that were viable, 30% had suffered partial removal of seed reserves similar to our manipulation treatments. These results indicate that P. copaifera seeds are capable of tolerating severe seed and shoot damage. The selective advantage conferred by damage tolerance may in part have contributed to the evolution of large seed size in this species.
Seed dispersal, spatial distribution and population structure of Brazilnut trees (Bertholletia excelsa) in southeastern Amazonia
Authors: Peres Carlos A. , Baider Claudia
Published: July 2009

Seeds of the Brazilnut tree (Bertholletia excelsaHumb. & Bonpl., Lecythidaceae) sustain one of the most important extractive industries in neotropical forests. Yet little is known about the demography and seed dispersal ecology ofBertholletia, particularly in natural stands which have not been previously harvested. This study presents data on the population density, spatial distribution, and seed dispersal ecology of Brazilnut trees at a pristine stand located within the Kayapó Indian Area of southeastern Amazonia, Pará, Brazil. Brazilnut trees were primarily found within groves (castanhais) of 75 to 149 trees, with a few isolated trees in between. Although the density of trees ≥ 10 cm in diameter at breast height (hereafter, dbh) at two groves was 4.8 to 5.1 trees ha–1, the overall density for the entire study area ofc.950 ha was estimated at 1.3 tree ha–1. Within-grove nearest neighbour distances averaged 21 m and were markedly skewed towards even shorter distances. Seed dispersal experiments using 709 marked seeds indicated that this pattern can be largely explained by the highly restricted seed shadows imparted by the main seed dispersal agents ofBertholletiaat this site, the red-rumped agouti (Dasyprocta leporina). Agoutis on average scatterhoardBertholletiaseeds to an average distance of 5 m, and rarely beyond 20 m, from seed stations. We suggest that, once edaphic and climatic conditions are suitable, the highly contagious spatial distribution ofBertholletiatrees at the landscape level can be largely accounted for by the quantitatively dominant effect of short-distance dispersal by caviomorph rodents, and rare events of long-distance dispersal provided by other vectors. This mechanism of grove formation need not resort to untested conjectures of human dispersal and intentional planting in prehistoric and historic times as it has often been suggested in the literature.