bluuebunny/crossref_metadata_2025_split huggingface dataset:
Profiles of CO2 concentration and δ13C values in tropical rain forests of the upper Rio Negro Basin, Venezuela
Authors: Medina Ernesto , Montes Gustavo , Cuevas Elvira , Rokzandic Zarko 
Published: July 2009

ABSTRACTConcentration of CO2, above and below the soil surface and δ13C values of plant tissues, soil litter and organic matter were measured in a caatinga forest of the upper Rio Negro basin in southern Venezuela. CO2, concentrations near the forest floor were consistently higher than in the atmosphere. CO2, gradient in the soil was very steep probably because of the poor aeration in this flood-prone forest. δ13C values of plant tissues showed a clear pattern with lower values in the ground herbaceous plants and under-canopy trees. Tree seedlings showed δ13C values similar to the upper-canopy trees indicating their dependence on reserves carried in the seed from the mother tree. Decomposing litter and soil organic matter also showed δ13C values similar to the upper-canopy trees. It is suggested that lower δ13C values of the shade flora result primarily from the assimilation of CO2, depleted in δ13C originating from soil respiration. Probable effects of low light intensity and physiological factors are discussed.
Studies of birds in a semi-arid area of Kenya. III The use of ‘Timed Species-counts’ for studying regional avifaunas
Authors: Pomeroy Derek , Tengecho Beatrice 
Published: July 2009

ABSTRACT‘Times Species-counts’ are a simple method of comparing the avifaunas of extensive areas by sampling representative habitats. The method has been evaluated in south central Kenya but could be applied to most terrestrial regions of tropical Africa. The essential feature is that the observers move anywhere within a sample site of about 1 km2, recording all of the species seen in a fixed time, e.g. 1 h.Counts are made in all seasons and at various times of day. Reasonable estimates of the total number of species in an area can be derived from a series of 15 counts, but such estimates tend to be low in non-forested habitats because ‘wanderers’ (non-resident species) continue to be recorded almost indefinitely. Open sites have far fewer species than well-wooded areas. The numbers of resident species in non-forested terrestrial habitats is related both to the amount of woody vegetation and to a measure of plant growth. However, total species numbers seem to depend solely on the amount of woody vegetation. Road counts, from a vehicle, were compared to those made on foot. They are less satisfactory, especially for cryptic species.
Soil nutrient availability, root symbioses and tree species composition in tropical Africa: a review
Authors: Högberg Peter 
Published: July 2009

ABSTRACTRelations between soil nutrient availability, the occurrence of root symbioses and tree species composition in tropical Africa are discussed in the light of new evidence. Transects from humid areas at the equator towards the deserts can be summarized as follows:High availability of nitrogen, low availability of phosphorus, low pH and aluminium toxicity probably restrict the competitiveness of nitrogen-fixing species in the forests on highly weathered and leached soils in humid west and central Africa. Ectomycorrhizal species attain dominance in species-poor forests on the soils poorest in phosphorus, while species with vesicular-arbuscular (VA) mycorrhiza form diverse forests on more fertile soils. Nitrogen-fixing species, which mostly are VA mycorrhizal, are more common in woodlands, where nitrogen is lost in grass fires, than in forests, which have a more closed nitrogen cycle. Low availability of phosphorus, however, limits the growth of nitrogen-fixing species in moist savannas. Ectomycorrhizal species are dominant, possibly because of a competitive advantage conferred by the large storage capacity of the fungal mantles under conditions of discontinuous nutrient supply. Nitrogen-fixing species become more abundant towards drier areas with an increase in soil phosphorus and a decline in soil nitrogen. These conditions culminate at the desert fringe, where nitrogen-fixing species reach their most conspicuous development.It is concluded that soil nutrient availability and root symbioses interact and strongly affect the composition of vegetation communities.
The freshwater lakes of Papua New Guinea: an inventory and limnological review
Authors: Chambers M. R. 
Published: July 2009

ABSTRACTA survey of the 1:100,000 topographic maps of Papua New Guinea revealed that there are about 5383 freshwater lakes in the country. They range in size up to 647 km2but the majority are less than 10 ha. They are found at all altitudes to over 4000 m but most are situated below 40 m in the floodplains of the Fly, Sepik and Aramia rivers. The majority of lakes are undoubtedly shallow but depths range up to 360 m. The lakes were formed in at least 20 different ways but the majority by fluviatile action. The few data on chemical and physical conditions suggest that most lakes are chemically poor with low light penetration and low pH values. With the possible exception of the macrophytes the fauna and flora of the lakes are virtually unstudied, particuarly from a quantitative aspect. Most lakes are probably polymictic.
Forest composition and inferred dynamics in Jengka Forest Reserve, Malaysia
Authors: Ho C. C. , Newbery D. McC. , Poore M. E. D. 
Published: July 2009

ABSTRACT1211 trees of 3 ft (0.91 m) girth or more were enumerated in 288 1-ch2(about 400 m2) quadrats forming a 11.7 ha plot on the mainly Segamat soil series, Jengka Forest Reserve, Peninsular Malaysia, in 1964. Of the 261 taxa, 84% were identified to species. Five per cent of the area was of the permanently wetter Akob soil series. The plot was topographically flat and lay about 3 km west of the plot on the Batu Anam soil series, described in an earlier paper. Data on the chemical composition of the three soils are summarized here from a survey in 1967.The vegetation on the Segamat series is of theShorea-Dipterocarpustype of lowland dipterocarp forest. It has an unusually high abundance of the Euphorbiaceae (25% of trees) and a clear dominant species,Elateriospermum tapos. E. tapos, which regenerates profusely in the shade, grows up in small gaps and is strongly clumped, and appears well suited to the very friable, relatively nutrient-rich soil of the Segamat series, with lower soil-water holding capacity especially in dry periods.Forest on the Segamat series is floristically very different from that on the Batu Anam series. This is most likely due to large differences in soil properties, the latter being of lower clay content, less nutrient-rich and, having a greater soil-water holding capacity at least in dry periods. It was dominated by Dipterocarpaceae.Classification of quadrats on the Segamat series highlighted four classes; vegetation of the mainE. tapos-dominated type on relatively dry soil (54% of plot area), vegetation on the wet Akob soil (21%), an association of shade-tolerant, mainly understorey trees beneath non-E. tapos-associated emergents (11%), and an association of long-lived, light-demanding pioneer trees of late-successional stages (11%); 3% of plot had no enumerated trees. Ordination showed that the plot was largely homogeneous with respect to edaphic factors but clearly displayed stages in forest succession.The possible dynamics of the Segamat forest are inferred in terms of species autecology. Two hypotheses are advanced to explain the composition of the Segamat forest: (a) a dynamic equilibirum, (b) a non-equilibrium recovery from a recent catastrophe. The latter was thought more likely. Compared with the more benign Batu Anam environment, where co-dominants might be ‘ecologically equivalent’, the more selective soil conditions on the Segamat leads to reduced equivalence, with accidents of regeneration playing a smaller role in the local distribution of the most abundant species.
A survey of food-plant utilization by Hemiptera (Insecta) in the understorey of primary lowland rain forest in Sulawesi, Indonesia
Authors: Hodkinson I. D. , Casson D. S. 
Published: July 2009

ABSTRACTThe study was conducted in tropical lowland forest in the Dumoga Bone National Park, Sulawesi, Indonesia. It sought (a) to establish the typical densities of sap-sucking Hemip tera, (b) to quantify the intensity of Hemiptera feeding on leaves, and (c) to investigate, using multivariate techniques, the relationships between Hemiptera density and/or feeding damage and a range of leaf or plant characteristics. Only 3% of shrubs examined had colonial Hemiptera feeding on growing shoots. Feeding punctures on leaves were common but the insects which produced them such as the Cicadellidae and various Heteroptera were scarce. Coccoidea and Aleyrodoidea were the dominant and ubiquitous Hemipterans, feeding primarily on the surface of the leaves. Psylloidea were relatively rare and Aphidoidea were not recorded. For the complete data set, which included all leaves examined, there were few significant correlations, either singly or in combination, between the various measures of insect abundance and the state of the 17 leaf characteristics recorded. However, when the data for young leaves were extracted there was evidence to suggest that the number of feeding punctures cm−2of leaf and the number of coccids cm−2of upper leaf surface increased rapidly to a maximum as the young leaf aged and certain characters changed accordingly. Other more stable leaf characteristics such as hairiness, spininess, glossiness, etc. explained only a small additional amount of the total variance in Hemiptera abundance.
Species structure in Zambian miombo woodland
Authors: Chidumayo E. N. 
Published: July 2009

ABSTRACTMiombo woodland in Zambia is divided into wetter and drier types by the 1100 mm mean rainfall isohyet. In the present study two wetter (Northern, Northwestern) and three drier (Central, Eastern, Western) miombo subtypes were recognized.A survey of the woody flora of 94 old-growth and 58 coppice stands in the five miombo subtypes revealed some significant differences in species diversity among them. The floristic differentiantion of miombo subtypes was best achieved by the use of the Shannon species diversity index (H′) and species density (number of species 0.1 ha−1 or 0.4 ha−1). H′ in miombo decreased from 2.247 in Northwestern to 2.136 in Northern, 2.052 in Eastern, 1.918 in Central and 1.824 in Western subtypes. Although species density was not significantly different between wetter miombo subtypes, this decreased in a similar fashion from 18.78 0.1 ha−1 in Northwestern to 18.30 in Northern, 16.65 in Eastern, 14.79 in Central and 12.29 in Western subtypes. The low species diversity in Western drier miombo was attributed to the combined effects of low soil fertility and rainfall.Although the mean number of species per 0.1 ha plot was higher in coppice samples, species richness (d) and index of diversity (H′) were lower than in old-growth samples. These results indicate lower species diversity in regenerating miombo. The dynamic aspects of species structure should therefore be considered in the future conservation of biological diversity in miombo woodland.
The seed bank ofEupatorium odoratumalong a successional gradient in a tropical rain forest in Ghana
Authors: Epp Gary A. 
Published: July 2009

ABSTRACTThe germinable seed bank of the colonizing weedEupatorium odoratumwas studied at the University of Ghana's Agricultural Research Station, near Kade. Five sites representing different successional stages were selected: a closed-canopy forest; intermittent-canopy forest; secondary forest; agricultural land; and a burnt forest. Twenty-five soil samples (each 500 cm3; 10×10×5 cm) were taken at random in each site, to be used for germination experiments. The secondary forest site had significantly more seeds ofEupatorium odoratum(8428 seeds per m2) than any of the other four sites. In this siteEupatorium odoratumconstituted 81% of the total seed bank and had significantly more rapid germination of seeds than any other species. The results indicate that the existence of a soil seed bank may depend on: (1) time allowed for seed accumulation; (2) habitat accessibility to dispersing seeds; (3) the type of disturbance that occurs in an area; (4) dispersal capabilities of colonizing species; and (5) the history of the species′ distribution in the area.
Survival, development and predatory effects of mosquito larvae in Venezuelan phytotelmata
Authors: Lounibos L. P. , Frank J. H. , Machado-Allison C. E. , Ocanto P. , Navarro J. C. 
Published: July 2009

ABSTRACTTo assess the influence of microhabitat and season on predator growth and survival and prey community structure, first instars of native Toxorhynchites haemorrhoidalis, a predatory mosquito, were released into Heliconia bracts, bamboo internodes, and the axils of two species of Aechmea bromeliads during wet and dry seasons in a lowland rain forest in eastern Venezuela. Experimental and control microhabitats were compared by complete censusing of macroscopic invertebrates 10 and 20 days after releases.Survival of T. haemorrhoidalis differed significantly among habitats and was reduced by desiccation in dry-season bamboos and in Aechmea nudicaulis and by the presence of a predatory damselfly (Odonata: Zygoptera) in bromeliads. Developmental rate differed among habitats in the wet but not in the dry season; rapid wet-season maturation was associated with increased prey abundance in Heliconia.Larvae of T. haemorrhoidalis consumed particular taxa and size categories of dipterous prey. Predation significantly reduced the abundance and skewed size-class distributions of Culicidae, Ceratopogonidae, Psychodidae, and pooled samples of Thaumaleidae plus Chironomidae. In bamboos, instar distributions of other mosquitoes were skewed in the presence of T. haemorrhoidalis even though a significant reduction in mosquito abundance was not detected. A decrease in species richness of aquatic Diptera was associated with intense predation by Toxorhynchites in Heliconia and A. nudicaulis.Toxorhynchites theobaldi was recognized as the naturally occurring predator in local bamboos, and released larvae caused significant reductions in abundance or size-class frequency shifts among three families of Diptera. Niche segregation between these sympatric Toxorhynchites is maintained by oviposition preferences: the larger species, T. theobaldi, oviposits in bamboos and the smaller T. haemorrhoidalis occurs in plant bracts and axils.
Stemonoporus(Dipterocarpaceae)-dominated montane forests in the Adam's Peak Wilderness, Sri Lanka
Authors: Greller A. M. , Gunatilleke I. A. U. N. , Jayasuriya A. H. M. , Gunatilleke C. V. S. , Balasubramaniam S. , Dassanayake M. D. 
Published: July 2009

ABSTRACTStemonoporusThw. (Dipterocarpaceae), a genus endemic to Sri Lanka, contains as many as 26 species, all but one confined to the perhumid forests of the island. Several species reach 1800 m, the highest altitude recorded for any dipterocarp species in Sri Lanka. We report the first quantitative data onStemonoporus-domirated stands in the montane zone (1500–1700 m).Stemonoporus cordifoliusand 5.rigidusshow clear single-species dominance of their respective stands.Stemonoporus gardneriis a co-dominant withPalaquium rubiginosumin its two stands. AllStemonoporusspecies appear to have a unique geographical and ecological range and no twoStemonoporusspecies co-exist in our stands.
Forest tree growth and dynamics at La Selva, Costa Rica (1969-1982)
Authors: Lieberman Diana , Lieberman Milton 
Published: July 2009

ABSTRACTPermanent plots totalling 12.4 hectares were established in 1969 in primary tropical wet forest at La Selva Biological Station, Costa Rica; all stems ≥10 cm diameter at breast height were tagged and measured. In 1982, the plots were again censused, and all live trees re-measured. Mortality over 13 years was 23.2%, or 2.03% per year based on a logarithmic mortality model. This suggests a stand half-life of around 34 years. Mortality was independent of size class in trees ≥10 cm diameter. Recruitment was equal to mortality. Tree growth curves and age-size relationships for 44 species were projected from 13-year diameter increments using a growth simulation procedure. Understorey trees grow slowly and consistently, and have short life spans; subcanopy trees also grow slowly, but live longer; shade-tolerant canopy trees show variable and often rapid growth and are long-lived; and shade-intolerant canopy trees grow rapidly, show little variation, and have short life spans. The longest imputed life span in our sample was around 440 years (years from 10 cm diameter to the maximum diameter); the shortest life span was around 50 years.
Oligochaetes in fire climax grassland and conifer plantations in Papua New Guinea
Authors: Standen Valerie 
Published: July 2009

ABSTRACTEarthworm populations in grassland and plantations in the area of Bulolo, Papua New Guinea were compared with populations in nearby undisturbed rain forest. The grasslands had been maintained by burning for many years. ThePinusplantation had been developed on a burned grassland site and theAraucariaplantation on a site which had been cleared of secondary forest.The grasslands and thePinusplantation supported moderate populations of exotic earthworms includingPontoscolex corethrurus, but no indigenous species. TheAraucariasite supported a native species,Amynthas zebrusonly, which was also found together with two other native species at very low density in rain forest.Exotic earthworm species widespread throughout the tropics, were present in disturbed soils and formed moderately high density populations in burned grasslands. There was no evidence that they displaced native Megascolecidae in rain forest.
Fish communities of a perturbed stream in Southern Nigeria
Authors: Victor Reginald , Tetteh Jacob Odenkey 
Published: July 2009

ABSTRACTFish communities of a fourth order stream impounded by a weir were studied in Southern Nigeria. Fifty-eight species were recorded of which 90% occurred upstream while reservoir and downstream accounted for 48% and 43% respectively. The distribution of some fish families indicated the effects of habitat alterations caused by reservoir and downstream conditions. The fauna upstream was different from that of reservoir and downstream. Relative abundance of non-cichlids common to reservoir and downstream showed 42% similarity. The longitudinal distribution of three non-cichlid populations was different in reservoir and downstream. Non-cichlid species richness was almost similar in reservoir and downstream, but its general diversity and evenness were higher in reservoir than its downstream. Fish community changes in this stream are discussed.
Vegetation damage in an oil field in the Niger Delta of Nigeria
Authors: Fagbami A. A. , Udo E. J. , Odu C. T. I. 
Published: July 2009

ABSTRACTAn investigation into the causes of massive destruction of the vegetation around Tsekelewu Oil Field in the Niger Delta was carried out. The 200 km2 area suffering varying degrees of damage was mapped and the damage quantified by photo interpretation of black and white aerial photographs. Soil, surface and ground water samples were taken from the various zones for chemical analyses which included the determination of pH, electrical conductivity and soluble salt analysis.The results showed that salt accumulation decreased from the sea inland-wards, with some upsurge in the saline-fresh water transitional zone where the greatest damage occurred. The electrical conductivity of the ground water varied from 45 dS m−1 in the area of greatest damage to less than 4 dS m−1 in the fresh water zone where there was no apparent damage. The salt-tolerant species along the coast were not affected, but in the transitional saline-fresh water zone in which the electrical conductivity of ground water was greater than 30 dS m−1, all the vegetation including the relatively salt-tolerant white mangrove (Avicennia africana) were killed. This destruction is attributed to high salinity caused by salt water incursion from the sea.
Tropical forests: much more than stocks of wood
Authors: Myers Norman 
Published: July 2009

ABSTRACTTropical forests offer many more products than the category for which they are best known, viz. wood products. They can supply a host of raw materials, such as resins, oils, fibres and fruits, which collectively represent a commercial value far higher than is generally recognized. In addition they provide an exceptional abundance and variety of genetic resources, which make substantial contributions to modern agriculture, medicine, industry and energy. On top of these materials, tropical forests supply significant environmental benefits, such as protection of the soil and safeguards for watershed systems. While it is sometimes difficult to quantify the economic values of these diverse goods and services, they are often to be reckoned as equal to, if not higher than, the marketplace values represented by the commercial hardwood timber. Yet when the forests are exploited for their hardwood timber, the process is usually so disruptive to forest ecosystems that the other outputs are severely reduced. By contrast, one may exploit the forests for their other outputs with virtually no disruption to forest ecosystems. The paper describes the main categories of non-wood products available from tropical forests, analyses their relative worth, and offers summarized proposals for an expanded approach to forest development in order to take integrative account of the full range of forest benefits.
Simulating forest shade to study the developmental ecology of tropical plants: juvenile growth in three vines in India
Authors: Lee David W. 
Published: July 2009

ABSTRACTBoth light quantity and quality affect the development and autoecology of plants under shade conditions, as in the understorey of tropical forests. However, little research has been directed towards the relative contributions of lowered photosynthetic photon flux density (PPFD) versus altered spectral distributions (as indicated by quantum ratios of 660 to 730 nm, or R:FR) of radiation underneath vegetation canopies. A method for constructing shade enclosures to study the contribution of these two variables is described. Three tropical leguminous vine species (Abrus precatonusL.,Caesalpinia bondicelaFleming andMucuna prunens(L.) DC) were grown in two shade enclosures with 3–4% of solar PPFD with either the R:FR of sunlight (1.10) or foliage shade (0.33), and compared to plants grown in sunlight. Most species treated with low R:FR differed from those treated with high R:FR in (1) percent allocation to dry leaf weight, (2) internode length, (3) dry stem weight/length, (4) specific leaf weight, (5) leaf size, and (6) chlorophyll a/b ratios. However, these plants did not differ in chlorophyll content per leaf dry weight or area. In most cases the effects of low R:FR and PPFD were additional to those of high R:FR and low PPFD. Growth patterns varied among the three species, but both low PPFD and diminished R:FR were important cues in their developmental responses to light environments. This shadehouse system should be useful in studying the effects of light on the developmental ecology of other tropical forest plants.
The post-nuptial moult of Quelea quelea in relation to breeding in Kenya
Authors: Thompson Jeremy John 
Published: July 2009

ABSTRACTDuring the unusually extended breeding season of 1984/85 in Tsavo-East National Park, Kenya, Quelea quelea were sampled and moult patterns recorded. Particular attention was paid to individuals with an interrupted moult pattern. These were further classified as either having their moult arrested or suspended. Apparently, post-nuptial moult begins earlier in males than in females. Although the majority of quelea bred and moulted sequentially, these activities overlapped in many individuals and moulting suspended after the replacement of a few feathers. The initiation of post-nuptial moult before the cessation of breeding, followed by moult interruption, is evidence for the physio-ecological drive in quelea to complete their moult as soon as possible to prepare for the next breeding opportunity.