bluuebunny/crossref_metadata_2025_split huggingface dataset:
Survival and growth of juvenile Virola surinamensis in Panama: effects of herbivory and canopy closure
Authors: Howe Henry F. 
Published: July 2009

AbstractEffects of mammalian herbivory and seasonal drought were studied for Virola surinamensis (Myristicaceae) juveniles on Barro Colorado Island, Panama. Seedlings were planted at three months of age and the juveniles were monitored for two years; Treatments included: intact plants protected from mammals by cages, defoliated plants similarly protected, and unprotected plants, each planted in treefall gaps, on gap edges, and in the shaded understorey.Juveniles planted in treefall gaps survived seasonal drought far better than those planted on gap edges or in shaded understorey. Two years after establishment, juveniles protected from mammalian herbivory showed a 78% survival in gaps (mean 6.8% skylight), 50% survival on gap edges (mean 3.0% skylight), and 33% survival in shaded understorey (1.4% skylight). This advantage was due to accelerated growth in gaps. Juveniles in gaps increased 616% in height, 1075% in leaf number, and 1800% in total leaf area. Comparable numbers in edges were 247%, 378% and 690%; in understorey 33%, 222% and 289%. Accelerated growth in gaps permitted yearlings to survive drought that killed suppressed yearlings in understorey. Mean light differentials as small as 0.6% and 0.3% skylight significantly influenced survival on edges and in shaded understorey, respectively.Mammalian herbivory killed juveniles directly, and defoliation by mammals strongly accentuated drought mortality by suppressing root development. Natural defoliation was not attributable to gap conditions. Demographic projections from experimental data suggest that mammalian herbivory kills at least 48% of the juveniles of this species over two years, and contributes to the death of 32% more that actually die of drought stress. These projections suggest that 14% of the juveniles of this species die of drought mortality, independent of herbivory, during the first two years. Herbivory most strongly affects plants < 0.5 m in height, and is a continuing source of mortality among suppressed juveniles in the understorey. Steep slopes and large seed size each enhanced juvenile growth and survival in the intermediate conditions of gap edges, but not under the extreme conditions of gaps or shaded understorey.The context of establishment determines the ‘shade tolerance’ of this conspicuous canopy tree. Without serious mammalian herbivory or extreme dry seasons, V. surinamensis can easily recruit as a shade tolerant plant in the understorey. Under present conditions on Barro Colorado Island, it cannot. Persistence involves both the chances of arrival in different microhabitats, and survival therein. Projections that include both the forest area represented by gaps, gap edges, and understorey and the experimental results from this study indicate that juvenile V. surinamensis can survive for two years in gaps, edges, and understorey, but that the higher proportions of vigorous individuals survive in edges, gaps and understorey, respectively.
Root proliferation in recent and weathered sandy soils from Veracruz, Mexico
Authors: Kellman Martin 
Published: July 2009

ABSTRACTField observations and laboratory experiments on unweathered and weathered dune sand beneath a tropical deciduous forest in Veracruz, Mexico were used to test the hypothesis that temporary nutrient adsorption by more weathered soil facilitates more effective nutrient recycling through the stimulation of a superficial fine root system. An analysis of soil solution composition in the field indicated that K, P andwere being more effectively retained in weathered sand topsoil than in recent sand but, in a leaching experiment, onlywas more effectively adsorbed by this soil. Fine roots in weathered sand were more concentrated superficially than in recent sand, and a bioassay with seedlings ofCedrela odoratashowed more fine root proliferation in this medium than in recent sand. In combination, these data suggest that weathering of sand in this area promotes an increased nitrate adsorption capacity which may stimulate greater root proliferation in topsoils and lead to the entrainment of other nutrients in a more concentrated topsoil-vegetation cycle. If these results can be applied to the larger domain of tropical soils generally, they suggest that nitrate adsorption may play an important role in stimulating effective nutrient recycling by forests occupying weathered soils.
Trophic structure of bat communities in the understorey of lowland dipterocarp rain forest in Malaysia
Authors: Francis Charles M. 
Published: July 2009

ABSTRACTBat communities in the understorey of primary lowland dipterocarp forest in peninsular Malaysia and Sabah were sampled with mist nets and harp traps to estimate their trophic structure. Overall, 4 of 26 species (15%) at one site, and 6 of 33 species (18%) at the other site were frugivores, while the remainder were insectivores. In terms of individuals, 7–12% of all captures were frugivores. However, the true proportion of frugivores at both sites was probably closer to 1%, because the sampling procedures were strongly biased towards frugivores. In contrast, previously published studies indicate that frugivores comprise 34–48% of species, and up to 80% of individuals in bat communities in the understorey of Neotropical forest. These results support the hypothesis, developed from studies of bird communities, that the under-storey of Malaysian dipterocarp forest supports relatively few obligate frugivores, at least in non-masting years. However, further data are required on bats in the canopy, and on the foraging ranges of bats to compare the absolute densities of bats in Malaysian and Neotropical forests.
Mineral nutrient flow from an inselberg in south-western Nigeria
Authors: Isichei Augustine O. , Morton Alan J. , Ekeleme Friday 
Published: July 2009

ABSTRACTIn a study carried out to find out if inselbergs enrich their surroundings with nutrients via drainage, amounts of total nitrogen, nitrate-nitrogen and potassium in rainfall, drainage from bare rock patches and vegetation mats on an inselberg in south-western Nigeria were measured over one year. 43.3 kg ha−1total nitrogen, 4.8 kg ha−1nitrate-nitrogen and 10.7 kg ha−1potassium were recorded in rainfall for the year of study. The amount of total nitrogen in drainage from bare rock was 79% of that in rainfall whilst that in drainage from vegetation mats was 29% of the rainfall amount. The respective values for nitrate-nitrogen were 57% and 13%; for potassium they were 90% and 38%.It was assumed that the loss of nutrients as water drains through vegetation mats and over bare patches was due to absorption by plants and soil in the mats and lichens in the bare patches. It was therefore concluded that there was no net enrichment of rainwater with nutrrients as it flows over inselberg slopes. There is, however, a funelling of water along with contained nutrients from the inselberg to the surrounding areas. This funnelling is additional to the nutrients and rainfall incident on these surrounding areas and may account for the vegetation around inselbergs being more lush than vegetation in the same area but further away from the inselbergs.A simple modelling approach was used to assess potential nutrient outflow from inselbergs. The model shows that discharge of nutrients from the edges of inselbergs increases linearly with inselberg diameter. The model further shows that if nutrient funnelling only affects an area near to the edge of the inselberg then nutrient addition is several times higher than would be expected from rainfall deposition alone.
A case study of a plant-animal relationship: Cola lizae and lowland gorillas in the Lopé Reserve, Gabon
Authors: Tutin Caroline E. G. , Williamson Elizabeth A. , Rogers M. Elizabeth , Fernandez Michel 
Published: July 2009

ABSTRACTThe frails of Cola lizae, an endemic tree with a limited geographical distribution, have been a major food source for lowland gorillas in the Lopé Reserve during part of each year over a six-year period. Faecal analysis indicated that 11,000-18,000 Cola seeds km-2 were deposited by gorillas during the 4-month season in 1989. Gorillas are the only important dispersers of this species: other primates consume the succulent mesocarp, but do not swallow the large seed; elephants do not eat Cola fruits. Observations of Cola seeds in gorilla faeces showed a very high germination rate and, despite initial high mortality, 18% of seedlings still survived six months after deposition. Survival of seedlings was significantly better in faeces left at nest-sites than in other areas of the forest: 40% of seedlings were viable at nest-sites six months after deposition. This suggests that the open areas of forest, preferred by gorillas as nest-sites, are advantageous to the propagation of this species.
Leaf litter production by lianes and trees in a sub-tropical Australian rain forest
Authors: Hegarty Elwyn E. 
Published: July 2009

ABSTRACTLeaf litter production by lianes (=lianas) and trees was compared in an evergreen rain forest in subtropical Australia. Several successional stages were represented at the main site. Lianes contributed 2.2% of total basal area (69.6 m2 ha-1) of this site, but 24% of leaf litterfall (5.9–6.5 tha-1 y-2 over two years. Minor year-to-year variation in litterfall was attributed to incidence of severe storms, and drought. Lianes were responsible for about 17% of leaf litterfall in spring, 21% in the summerpeak, and 40% in autumn, more lianes than trees being deciduous. Leaf litter production by 23 individual species of liane, in relation to their basal area within the main site, was, on average, 15 times as great as that by 34 tree species, but declined more steeply between the species-groups of early and later succession. Tendrillar lianes, unlike twiners and scramblers, were confined to the ‘early’ successional group, and their foliage was spread across canopy surfaces, maximizing light interception. It was concluded that this contributed to greater production of leaf litter, per unit basal area, by tendrillar than by other climbers, and to the successional decline in leaf litterfall from lianes.
Comparative effects of Acacia albida and Kigelia africana trees on soil characteristics in Zambezi riverine woodlands
Authors: Dunham Kevin M. 
Published: July 2009

ABSTRACTSoil nutrient concentrations under Acacia albida and Kigelia africana trees growing in Zambezi riverine woodlands were compared with soils in the open, beyond tree canopies. Concentrations of N, C, P and K were higher under tree canopies. Concentrations of Ca and Mg were unchanged. Soils were slightly more acid under A. albida trees relative to open soil, but were less acid under K. africana. Soil P concentration was higher under K. africana than under A. albida. Otherwise, the two species had similar effects on soil fertility. Despite previous claims, A. albida is probably no more efficient at increasing soil fertility than other savanna trees.
Some aspects of the ecology of bagrid catfishes in a southern Nigerian river
Authors: Idodo-Umeh George , Victor Reginald 
Published: July 2009

ABSTRACTSome aspects of the ecology of bagrid catfishes in River Ase, southern Nigeria were studied for a period of two years. Nine species of Bagridae were recorded and these accounted for 15.0% of the number and 24.4% of the weight of all fish captured. Chrysichthys nigrodigitatus and Chrysichthys auratus longifilis were the principal species. C. nigrodigitatus was a rainy season species, while C. auratus longifilis was abundant in both dry and rainy seasons. Both species showed a major peak in catches between 0600 and 0900 h. C. nigrodigitatus exhibited a minor peak in catches between 1500 and 2100h, while C. auratus longifilis showed a minor peak between 1500 and 1800h. The spatial distribution of C. nigrodigitatus and C. auratus longifilis populations was heterogeneous. Bagrid fishes were an important component in the fish yield of the study river and its species composition has been compared with those of other Nigerian waters. The distribution and abundance of C. nigrodigitatus and C. auratus longifilis are discussed in detail.
Interactive ecology of two cohabiting characin fishes (Astyanax fasciatusandAstyanax bimaculatus) in an eutrophic Brazilian reservoir
Authors: Arcifa Marlene Sofia , Northcote Thomas Gordon , Froehlich Otávio 
Published: July 2009

ABSTRACTThe competitive interactions between two species of characins (Astyanax fasciatus and Astyanax bimaculatus) were investigated by studying their horizontal distribution, relative abundance and feeding habits in littoral and limnetic zones of Americana Reservoir, southern Brazil.Differences in horizontal distribution of the species mainly as adults led to their partial habitat segregation. Most adultA. bimaculatuswere littoral dwellers, whereasA. fasciatusadults were distributed from inshore to offshore waters, but with most in the latter region.Both are facultative zooplanktivores in the reservoir, feeding mostly on planktonic crustaceans, insects (chiefly chironomids), some higher plant material, detritus and even fish scales (A. bimaculatus). Food overlap coefficients, considering adult and juvenile stages of both species are large in dry as well as wet seasons, although in the dry season the overlaps are significantly reduced for juveniles of both species and for juveniles ofA. bimaculatusversus adults ofA. fasciatus. Both species prey more on cladocerans than on cyclopoid copepods, and the adults selectively take larger forms (Daphnia gessneriandMoina micrura) in the reservoir (as in previously reported enclosure experiments). Juveniles prey heavily onBosmina longirostris.These two formerly riverine species may reduce competition, in the reservoir, by partial habitat segregation in older stages, a mechanism to avoid competition, which may have existed in their previous interactive history in rivers.
Population dynamics and production of the rocky stream-dwelling fish Garra ceylonensis (Cyprinidae) in Sri Lanka
Authors: Silva K. H. G. M. De 
Published: July 2009

ABSTRACTA population of Garra ceylonensis in a rocky, hill stream was studied by monthly sampling over a period of two years. The monthly population density, which varied from 1.28 to 4.16 m-2 with a mean of 2.37 m-2, was negatively correlated with the water speed. Asymptotic length (L∞) and the growth constant (K) were found to be 180.5 mm total length and 0.62. Maximum size observed was 174 mm, which is attained in about five years, but 99% of the population had a life expectancy of less than 3.4 years. The overall male to female ratio of the population was 0.58. The sex ratio was 1.0 in smaller size classes but decreased steadily with increasing size. There was a major spawning season following the main rainy period in contrast to the trend of most tropical freshwater fish species, which show enhanced breeding during the rainy season. The mean length and age at sexual maturity in females appear to be 109 mm and eighteen months. Fecundity varied between 740 and 4390. Average longevity and natural mortality were 4.8 years and 1.86. The mean biomass, average annual production and turnover ratio of the population were about 23.7 gm-2 wet weight, 41.2gm-2 and 1.7, respectively.
Diversity of soil fauna in the canopy and forest floor of a Venezuelan cloud forest
Authors: Paoletti Maurizio G. , Taylor R. A. J. , Stinner Benjamin R. , Stinner Deborah H. , Benzing David H. 
Published: July 2009

ABSTRACTArboreal and terresterial soil and lilter were sampled for macro-and microinvertebrates at two locations in a Venezuelan cloud forest. Fauna were most abundant in forest floor soil and associated litter. However, media suspended in the canopy and particularly those trapped in bromeliad shoots were most densely populated, while the diversities of the arboreal and terrestrial soil fauna were indistinguishable. Rates of leaf litter decomposition in the arboreal and terrestrial soils were similar, but the arboreal soils contained higher concentrations of mineral nutrients and carbon. Implications of these findings for the definition of soil in humid tropical forests, and related differences between temperate and tropical forests are discussed. The similarities in diversity and differences in species composition between arboreal and terrestrial soil fauna raise questions concerning the evolution of tropical soil fauna, as well as the estimate of global biotic diversity.
Microbial biomass and relative contributions of bacteria and fungi in soil beneath tropical rain forest, Hainan Island, China
Authors: Yang Jia Cheng , Insam Heribert 
Published: July 2009

ABSTRACTSoil microbial biomass (Cmic.) and is relation with soil carbon and nutrient contents in a tropical rain forest (Bawangling Nature Reserve, Hainan Island, P.R. China) were studied. Cmic. was determined by the substrate induced respiration (Sir) method; bacterial and fungal fractions were measured using a selective inhibition technique. For the A horizon, Cmicranged between 350 and 700μgg-1soil in April (beginning of the rainy season) and 250–600μg g-1in October (end of the rainy season). Cmic. contents of the AB and B horizons were lower, ranging from 80 to 350 μg Cmicg-1soil. On average, 75% of the biomass was bacterial, in the AB and B horizon this was slightly higher than in the A horizon. Cmicwas closely correlated with Corgand N content. N and P contents as well as the respiratory response upon glucose addition indicated that towards the end of the rainy season compared with the start the soils were depleted in nutrients. These observations stress the importance of microbial biomass as a factor for nutrient retention in tropical forest ecosystems.
Population dynamics of pioneer (Macaranga) trees and understorey (Mallotus) trees (Euphorbiaceae) in primary and selectively logged Bornean rain forests
Authors: Primack Richard B. , Lee H. S. 
Published: July 2009

ABSTRACTUsing data from forest sites in Sarawak, East Malaysia, a demographic comparison is made of pioneer species in the genus Macaranga with understorey trees of the primary forest in the closely related genus Mallotus. In primary forest, saplings and trees of these genera arc uncommon and have low growth rates. For the six years following disturbance by logging, a Macaranga population was characterized by high rates of diameter growth and recruitment. Eleven years after disturbance, seedling and sapling abundance had declined sharply. In contrast, the Mallotus population was stable in size class distribution and increased slightly in total population size during the 11 years after logging. Growth rates of Mallotus trees increased after logging but were still much less than Macaranga trees.A morphological comparison shows that most Macaranga species, in contrast with Mallotus species, have large hollow twigs that are occupied by ants and have larger, hairier, thicker, more toothed leaves with longer petioles, axillary inflorescences with more flowers, infructescences with more fruit, fruits that are smaller in size and smaller seeds.
Ecological energetics of populations of four sympatric isopods in a Hong Kong forest
Authors: Lam Paul K. S , Dudgeon David , Ma Herbert H. T. 
Published: July 2009

ABSTRACTPopulation energy budgets of four sympatric isopods,Burmoniscus ocellatus, Burmoniscussp. (Philosciidae),Formosillo raffaelei and Orodillo maculatus(Armadillidac), were calculated at two sites in a Hong Kong mixed forest. Mean population standing stock of the four species ranged from 1.25 to 13.61 kj m-2. Mean total isopod biomass at the two sites was 0.85 and 1.85g m-2. Annual production of the four species varied from 4.24 to 30.43 kj m-2with 5.2–26.4% (energy content) allocated to reproduction. Annual production of the four species combined at the two sites was 23.22 and 50.15kJ m-2.ratios varied from 2.24 to 4.27. Annual population consumption on mixed litter by the four isopod species ranged from 28.4 to 183.0 kj m-2. Total annual consumption by all species at the two sites was 233.7 and 360.2 kj m-2(1.96 and 2.53% of annual litter fall). Isopod respiratory rales were proportional to body weight, with an exponent ranging from 0.68–0.78 at 23°C. The annual population metabolism of the four species varied from 14.62 to 86.11 kj m-2. Total annual isopod metabolism at the two sites was 116.33 and 185.95 kj m-2. These results are discussed with reference to the role of isopods in litter breakdown and energy flow in the Hong Kong forest.
The spatial distribution of rain forest butterflies at three sites in North Queensland, Australia
Authors: Hill Christopher J. , Gillison Andrew N. , Jones Rhondda E. 
Published: July 2009

ABSTRACTSurveys of the microhabitat distribution of adult butterfly species were undertaken at three rain forest sites in North Queensland, Australia, encompassing a range of rain forest vegetation types. These surveys found little evidence for a specialist canopy fauna. Most species recorded in the canopy were often seen close to the ground. At all sites, most species were observed at the edge of the rain forest habitat; within the rain forest, more species were observed near the ground than in the canopy.
Populations in nests of the termite Macrotermes jeanneli in Kenya
Authors: Darlington J. P. E. C. , Zimmerman P. R. , Wandiga S. O. 
Published: July 2009

ABSTRACTEstimates were made of the populations of seven nests ofMacrotermes jeanneliof different sizes in Kenya. Caste and instar composition were examined, and relationships of these to the dimensions of the mound were investigated. Survival of nests of different sizes was followed over four years.
Understorey light environments in a north-east Australian rain forest before and after a tropical cyclone
Authors: Turton S. M. 
Published: July 2009

ABSTRACTThis paper describes estimates of canopy openness and associated light availability in the understorey of a north-east Australian rain forest before and immediately after a tropical cyclone. On the basis of 20 hemispherical (fisheye) canopy photographs it was shown that direct, diffuse and total site factors increased significantly as a result of the slight-to-moderate canopy disturbance caused by the cyclone. In the understorey, median total site factors ranged from 2.5–3.4% before the cyclone and from 6.0–8.6% after the cyclone, representing a 2- to 3-fold increase in potential light availability. Following the cyclone, mean relative gap frequencies increased substantially at all altitudes but particularly at canopy positions more than 70° above the horizon. Cyclone-induced canopy disturbance not only reduced the complexity of the understorey light regime but may have also increased the seasonal variability of light within the understorey of the forest during the interval of canopy recovery. The implications of these results for the ecophysiology of understorey tree seedlings and saplings at several temporal scales are discussed.
Lepidoptera outbreaks in response to successional changes after the passage of Hurricane Hugo in Puerto Rico
Authors: Torres Juan A. 
Published: July 2009

ABSTRACTFifteen species of Lepidoptera occurred in large numbers in spring and early summer after the passage of Hurricane Hugo over the north-east of Puerto Rico.Spodoptera eridania(Noctuidae) was the most common of the larvae and fed on 56 plant species belonging to 31 families. All the Lepidoptera fed on early successional vegetation. Some of the plants represent new host plants for these species. The outbreaks appeared to be based on the flush of new foliage that developed in the Luquillo Mountains after the passage of the hurricane. The end of theS. eridaniaoutbreak was concurrent with the consumption of its preferred host plants and to an apparent increment in parasitism by ichneumonids (Hymenoptera). Parasitism by tachinids (Diptera) may have contributed to the reduction in abundance of other Lepidoptera species that were temporarily very abundant. Natural enemies ofS. eridaniawere recorded for the first time in Puerto Rico.