bluuebunny/crossref_metadata_2025_split huggingface dataset:
Composition of spider communities in the canopies of rainforest trees in Borneo
Authors: Russell-Smith A. , Stork N. E. 
Published: July 2009

ABSTRACTSpiders from 10 rainforest tree canopies in Borneo were sampled by knockdown insecticide fogging. Spider density ranged from 2.0 to 10.1 m−2 on different trees, and species numbers ranged from 16 to 62; species diversity, as measured by William's α, ranged from 26 to 92. Similarity of the spider assemblages on individual trees was low, whether measured by the number of shared species or the Morisita-Horn index of similarity.The contribution of five descriptor variables of tree taxonomy and structure to the similarity of the spider assemblages on different trees was assessed using stepwise multiple regression. No variable made a significant contribution to the variation in similarity indices for the spider assemblages and it was concluded that either other factors were important in determining similarity or that the measurement of these variables was too imprecise. In particular, there was no evidence that taxonomic similarity between tree species influenced the similarity of spider assemblages.Results were compared with similar data from tropical and sub-tropical rainforests in Sulawesi and Australia. Species densities in Borneo and Sulawesi were similar but lower than in Australia. Species richness and diversity were markedly higher in the Bornean rainforest than in Sulawesi or Australia.
The anomaly of monodominant tropical rainforests: some preliminary observations in theNothofagus-dominated rainforests of New Caledonia
Authors: Read Jennifer , Hallam Patricia , Cherrier Jean-François 
Published: July 2009

ABSTRACTNothofagusspecies dominate small patches of rainforest on ultramafic soils in New Caledonia, forming an almost monospecific upper canopy on some sites. These stands are commonly bordered by rainforests of greater floristic and structural complexity, also on ultramafic soils. In two lowland stands, the population size structures ofNothofagus aequilateralisstems greater than 50 cm high had an approximately skewed bell-shaped distribution with a modal size class of 15–25 cm stem diameter, and with no evidence of old trees. This indicates that the establishment ofNothofagushas occurred over a limited time span, without sufficient recent regeneration to allow the future replacement of the existing canopy trees. The factors initiating the major period of regeneration are not certain, but large-scale disturbance is implicated and evidence of past wild-fire on both sites is consistent with this hypothesis. It is unlikely that significant regeneration ofNothofaguswill occur as the stands mature and canopy gaps are created by the death of old trees, since saplings of other species already occur at high densities in the understorey and will probably pre-empt the resources made available by canopy gaps. Two other study sites were situated above 900 m asl. At Dzumac, in an apparently older stand dominated byN. codonandra, there is some evidence of recent regeneration, predominantly confined to a single large canopy gap. The population size structure ofN. baumanniaeon the fourth site, on the summit of Mt Mou, shows a closer approximation to a reverse-J curve. Seedlings, however, are relatively uncommon on this site, and the numerous saplings may be suppressed rather than young.Analyses of topsoil provided no consistent evidence to suggest that mineral content is controlling the distribution ofNothofagusacross vegetation boundaries.The environmental factors promoting the formation of these monodominant canopies are uncertain, but appear to involve large-scale disturbance by windstorm or fire. The population size structures suggest that the canopies of the two lowland stands, at least, are likely to become more species-rich, with a progressive decline in the frequency ofNothofagus. Therefore, these lowland monodominant forests cannot be regarded as equilibrium communities, irrespective of whether more detailed studies reveal environmental differences across the community boundaries. The status of the two high altitude sites is less certain.
Variation in growth and reproduction of Bolomys lasiurus (Rodentia: Muridae) in an Amazonian savanna
Authors: Francisco Angelo De Lima , Magnusson William E. , Sanaiotti Tânia M. 
Published: July 2009

ABSTRACTReproduction by Bolomys lasiurus is strongly seasonal in the Amazonian savanna of Alter do Chāo, Pará, Brazil. No pregnant or lactating females were recorded during the early dry season (July-September). Relative growth rates showed a similar though less consistent pattern. These patterns do not appear to be due to a direct effect of rainfall as high reproduction and growth were recorded during the late dry season (October-November), even though rainfall and the availability of fruits of shrubs were low during that period. It is likely that reinitiation of reproduction during the dry season is due to an increase in the availability of invertebrates and/ or wind-dispersed seeds. Fire at the end of the dry season appears to affect the diet of the rats, causing an increase in the ingestion of invertebrates during the following wet season. However, our data do not indicate that fire affects individual reproductive output or growth.
Seed, seedling and sub-canopy survival in monodominant and mixed forests of the Ituri Forest, Africa
Authors: Hart Terese B. 
Published: July 2009

ABSTRACTThe central Ituri Forest of Zaïre is characterized by monodominant stands ofGilbert-iodendron dewevrei(mbau forest) within a matrix of mixed forest whereJulbernardia seretiiis subdominant. Both species produce supra-annual, synchronous (mast) seed crops. The relationship of mast seed production to monodominance for the two tree species was evaluated by investigating: (1) the relationship between seed density and seed survival, (2) the relative impact of mammal versus insect seed predators in high and low seed density areas, and (3) post-germination survival in the understorey. For the latter, tagged seedlings were monitored over 10 years and both species were censused in different understorey size classes. Percentage seed survival was significantly greater forJulbernardia(but not forGilbertiodendron) in areas of high conspecific seed density. Generalist fruit- and seed-eating mammals were the principal predators on seeds of both species when removed to areas without seed-fall. In mast areas high seed densities appeared to satiate mammalian seed predators but not the specialized beetle seed predators that were the major cause of seed destruction.Gilbertiodendronseedlings survived longer in the forest understorey than did seedlings ofJulbernardia. Furthermore,Gilbertiodendronmade up a greater proportion of the larger subcanopy size classes in monodominant forest than didJulbernardiain mixed forests. These results suggest that, irrespective of mortality to seeds, the ability to persist in the understorey may confer onGilbertiodendrona greater probability of reaching and dominating the canopy.
Structural characteristics and floristic composition of a Neotropical cloud forest, Monteverde, Costa Rica
Authors: Nadkarni Nalini M. , Matelson Teri J. , Haber William A. 
Published: July 2009

ABSTRACTThe Monteverde Cloud Forest Reserve protects a variety of primary montane forest communities on volcanic parent materials. We describe the structure and composition of the forest to provide background information for epiphyte and nutrient cycling studies and for comparison with other tropical montane forests. In a 4-ha study plot in leeward cloud forest, density of stems (2062 individuals ha−1 for stems >2 cm dbh, 555 individuals ha−1 for stems > 10cm dbh) and stem basal area (73.8 m2 ha−1 for stems >2 cm, 62.0 m2 ha−1 for stems >10 cm dbh) were high relative to other montane forests. Stems in a subset of the plot (c. 1/3 of the area) were identified and assigned to 47 families, 83 genera and 114 species, which is rich compared with other montane forests. Large stems had a higher spatial variability of structural and floristic characteristics than small stems.
The effects of the rainy season and irrigation on soil water and oxygen in a seasonal forest in Panama
Authors: Kursar Thomas A. , Wright S. Joseph , Radulovich Ricardo 
Published: July 2009

ABSTRACTThe effects of irrigation and the rainy season on soil gases, water and physical properties were studied in a lowland moist forest in Panama. Two control plots experienced a normal four-month dry season and two experimental plots were irrigated during the dry season.The forest soils were well aerated. The average soil oxygen content at 20 cm never dropped below 15%. Irrigation in the dry season resulted in treatment effects on soil oxygen and water that persisted throughout the rainy season. The late rainy season soil oxygen content at 20 cm was 18.2% in the control plots and 16.8% in the irrigated plots. The late rainy season soil water content at 0–10 cm was 0.34 m3 m-3 in the control plots and 0.36–0.37 m3 m-3 in the irrigated plots. In the control plots, in the absence of any experimental manipulation, the soil physical properties changed within a single rainy season. Specifically, soil oxygen dropped and soil water increased during the eight-month rainy season.The observed alterations in soil physical properties probably resulted from changes in soil structure and the abundance of large pores. The rainy season or irrigation may decrease soil porosity by dispersing aggregates of soil particles, whereas soil desiccation during the dry season may enhance the formation of aggregates and large pores. As a result, the irrigated soils held more water and were less permeable to gas and water than soils experiencing a normal dry season. We conclude that the dry season may play an important role in maintaining soil structure.
Effects of forest floor environment on germination and seedling establishment of two Bornean rainforest emergent species
Authors: Itoh Akira 
Published: July 2009

ABSTRACTSeeds of Dryobalanops aromatica and D. lanceolata (Dipterocarpaceae) were sown in gaps and understorey on a ridge and a valley in a Bornean rainforest. Germination rates were 92–100% regardless of site and species. On the ridge, the proportion of seedlings that opened primary leaves was larger in D. aromatica (19–30%) than in D. lanceolata (7–19%) due to higher root predation on D. lanceolata. In the valley, on the other hand, the proportion was larger in D. lanceolata (71–74%) than in D. aromatica (56%). After primary leaf production, seedlings of both species had higher survivorship in the gaps than in the understorey. Interactions between predators, soil conditions and light environment and their effects on seedling establishment are discussed.
Leaf and canopy CO2assimilation in a West African humid savanna during the early growing season
Authors: Le Roux X. , Mordelet P. 
Published: July 2009

ABSTRACTLeaf and grass canopy photosynthetic rates were measured in a West African humid savanna during several stages of the early growing season. The results obtained on the dominant grass speciesHyparrhenia diplandraand data published previously show that C4savanna grasses exhibit a remarkably high leaf photosynthetic capacity despite their low nitrogen content. A variation of leaf photosynthetic capacity in relation to leaf rank on stems is observed which is interpreted by ageing and shading effects within the canopy. Seasonal variations of the canopy CO2assimilation rate is explained in relation to variations of leaf area index and canopy nitrogen content. Despite low nitrogen content or low leaf area index, maximum canopy net photosynthesis was high (24 μmol CO2m-3s-1for LAI = 1.5). The high photosynthetic nitrogen use efficiency exhibited by leaves of humid savanna grass species is a major attribute explaining high photosynthetic rates of the grass canopy in this environment. This result sustains the emerging opinion that tropical savannas could be highly productive despite the generally low nutrient status they experience.
Windthrow in a tropical savanna in Kakadu National Park, northern Australia
Authors: Williams Richard J. , Douglas Michael 
Published: July 2009

ABSTRACTWindthrow was assessed following a convective storm in a stand of tropical savanna in Kakadu National Park, northern Australia. Over an area of 3 ha, 79 out of 810 trees (9.8%) were damaged; 27 of them were either uprooted or snapped off at the trunk. Logistic regression showed that both species and tree height were significant determinants of the probability of wind damage. Branch loss and either uprooting or trunk snapping was highest in the canopy sub-dominant Eucalyptus porrecta. Damage was lowest in the sub-dominant trees Erythrophleum chlorostachys, a species which is relatively resistant to termite damage, and Terminalia ferdinandiana, a deciduous species which is generally shorter than the main canopy dominants. Damage was intermediate in the two most common canopy dominants, Eucalyptus tetrodonta and E. miniata. Wind damage was greatest in trees taller than 9 m and relatively minor in trees below this height. Wind disturbs savanna trees in a manner opposite to that of fire, because wind damage is greatest in taller trees, whereas fire damage is greatest in smaller trees. This, coupled with significant within-patch variability in the extent of wind damage, may act to increase small-scale environmental heterogeneity in savannas.
Spatial organization of a bromeliad community in the Atlantic rainforest, south-eastern Brazil
Authors: Fischer Erich A. , Araujo Andrea C. 
Published: July 2009

ABSTRACTThe habit, shade-tolerance and dispersal agent of 19 bromeliad species were studied in a rainforest community in order to relate specific traits to the spatial occurrence of the species. Highest density was found in riparian forest (RF), followed by restinga scrub (RE), rocky shore (RS) and dense canopy forest (DF). Terrestrial bromeliads occurred in open sites (RE and RS), epiphytes were absent in RS and facultative species occupied all four habitats. Bird-dispersed bromeliads occurred in the upper canopy, whereas those dispersed by mammals were low in the forest profile. Bromeliads which are dispersed by similar fauna fruit sequentially through the year. Differences in traits may allow the sharing of habitats and strata among species.
Predation on marine snakes: a case for decapods supported by new observations from Thailand
Authors: Voris Harold K. , Jeffries William B. 
Published: July 2009

ABSTRACTScientific and commercial collecting have documented high levels of abundance among several species of marine snakes. Estimates of first-year mortality in populations of marine snakes range from 40 to 90%. The primary cause of this mortality is unknown. Storms, currents, sun exposure, dehydration and fire are abiotic factors that may control populations of marine and amphibious snakes. Disease, malnutrition and predation are biotic factors known to affect populations. In the literature there are isolated reports of predation by marine mammals, birds of prey, fish and invertebrates. Sharks in Australian waters are known to be predators on sea snakes. Our studies show that in the estuaries, intertidal mangrove creeks and mud flats of southeast Asia decapod crustaceans are important snake predators. Microhabitat overlap, exoskeleton armour and a respiratory advantage in an underwater standoff argue for their potential as potent predators. Field observations, a survey of crab stomach contents and encounters between snakes and crabs under laboratory conditions support this hypothesis. –
West Africa's last giraffes: the conflict between development and conservation
Authors: Ciofolo I. 
Published: July 2009

ABSTRACTThe distribution of the giraffe (Giraffa camelopardalis peralta Thomas 1898) has greatly diminished in West Africa, and now the last remaining population, reduced to less than 100 individuals, is found in Niger. These giraffes of West Africa are seriously threatened by extensive deforestation and clearing of their habitat. They live peacefully with humans and cattle and participate in an essential way in the dynamics of vegetation. Their disappearance would represent another step towards the impoverishment of the inheritance of Africa, a process already too far advanced. To save them, a fundamental rethinking of the connection between the environment and development on the one hand, and on the responsibilities of rural communities for the management of their natural resources on the other, has to be undertaken.
Elephants, selective logging and forest regeneration in the Kibale Forest, Uganda
Authors: Struhsaker Thomas T. , Lwanga Jeremiah S. , Kasenene John M. 
Published: July 2009

ABSTRACTThe Kibale Forest, western Uganda, is the only site where studies have compared the impact of elephants on rainforest regeneration in logged and unlogged control areas. Elephants used heavily logged areas more than lightly logged and unlogged areas. Forest gaps were used more by elephants than closed-canopy areas and large gaps more than small ones. Gaps were larger in logged than unlogged forest. There were lower densities of young trees (saplings and poles) and a higher incidence of elephant damage to them in heavily logged forest than in lightly logged and unlogged sites. Elephant use of an area and damage to young trees was inversely or unrelated to the density of young trees and directly related to the density of herbaceous tangle. Heavy logging resulted in large areas of herbaceous tangle, which attracted elephants who suppressed forest regeneration by damaging young trees and perpetuating the herbaceous tangle. The tangle directly competed with regeneration of young trees while also attracting elephants and rodents (seed and seedling predators) and facilitating increased windthrow of trees. Selective browsing of young trees by elephants affected rates of regeneration, growth form and species composition. Rather than remove elephants, a more effective and humane approach to long-term management of logging is to reduce logging offtake and incidental damage caused by timber extraction.
Phenology and flowering periodicity of Neotropical dry forest species: evidence from herbarium collections
Authors: Borchert Rolf 
Published: July 2009

ABSTRACTTo examine the potential contribution of herbarium material to the description and analysis of tropical tree phenology, flowering times and geographical distribution were graphed for 1673 flowering collections from 18 species native to Neotropical dry forests and phenological differences between species were analysed. These include the timing and duration of flowering as well as morphological differences such as flowering on leafless twigsvsflowering on shoots bearing old or new foliage. Species-specific flowering periods of herbarium collections are similar to those observed in phenological field studies, but are often longer because of the larger geographical and temporal sampling range. Conspecific collections of different geographical origin show distinct differences in flowering periodicity, which are correlated with differences in the timing and intensity of the dry season. Interspecific differences in the timing of phenology relative to the dry season indicate differences in the control of phenology by seasonal drought. Herbaria thus represent a large potential source of phenological information which can either supplement and extend phenological field studies or provide phenological information for dry forest species not studied in the field but well represented in herbarium collections.
Ungulate densities and biomass in the tropical dry deciduous forests of Gir, Gujarat, India
Authors: Khan Jamal A. , Chellam Ravi , Rodgers W. A. , Johnsingh A. J. T. 
Published: July 2009

ABSTRACTData on densities, biomass and ecological factors governing the distribution of various wild ungulate species in the difFerent management units of Gir forest from 1987 to 1989 were collected. Density of ungulates ranged from 50.8 km−2 to 0.42 km−2, the highest for chital (Axis axis), followed by chinkara (Gazella gazella), sambar (Cervus unicolor), nilgai (Boselaphus tragocamelus) and chowsingha (Tetracerus quadricornis). The density of chital did not vary significantly between different censuses and management units. The wild ungulate biomass ranged from 3290 kg km−2 in the National Park to 1900 kg km−2 in the Sanctuary East. Following the partial removal of people and livestock in the mid-1970s, there was an increase in the population of all wild ungulates except nilgai and wild pig (Sus scrofa). Concurrently, there was an increase in the proportion of wild ungulate prey in the lion's diet. Chital density has shown a 1320% increase. An increase in suitable habitats and a decrease in direct competition with livestock are the most likely factors to have triggered the eruption in chital population. These density estimates are discussed in relation to the prevailing ecological conditions in different management units of Gir.
Habitat, CO2 uptake and growth for the CAM epiphytic cactus Epiphyllum phyllanthus in a Panamanian tropical forest
Authors: Andrade Jose Luis , Nobel Park S. 
Published: July 2009

ABSTRACTIn the tropical forest of Barro Colorado Island, habitat characteristics, diel acidity changes, CO2 uptake and growth were investigated for the epiphytic cactus Epiphyllum phyllanthus (L.) Haw. It occurred most frequently in tree cavities with its roots in canopy soil and was especially abundant on two tree species: Platypodium elegans J. Vogel and Tabebuia guayacan (Seem.) Hemsl. Its maximum net CO2 uptake rates were low under natural conditions (1.4 μmol m−1) but were comparable to those of other CAM and C3 epiphytes under wet conditions in a screenhouse. Under both natural conditions and in the screenhouse, partial shade enhanced growth and CAM activity. When plants grew under a photosynthetic photon flux of c. 4 mol m−2 d−1, their nocturnal acidity increase and total net CO2 uptake were twice as much as for plants growing at lower (an average of 2.4 mol m−2 d−1) and higher (7.7 mol m−2 d−1) photosynthetic photon fluxes. Stem elongation was 27% greater at the intermediate photosynthetic photon flux. Seedlings of E. phyllanthus survived three months of drought and responded rapidly to rewetting, recovering fully within three days. Transpiration rates and nocturnal acidity increases also recovered to the values of well-watered plants a few days after rewetting, indicating that this species can take advantage of episodic rainfall during the dry season.