bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of fire regimes on lizards in the wet-dry tropics of Australia
Authors: Braithwaite Richard W. 
Published: July 2009

ABSTRACTA quantitative analysis of the effect of fire regime on the abundance of common lizard species and genera and the species richness of two lizard groups in Kakadu National Park (12° S) is presented. A surprising range of relationships between species abundance and components of fire regimes was revealed. Carlia amax, Heteronotia binoei and Carlia gracilis appear to be fire-sensitive, Diporiphora bilineata and Carlia triacantha are favoured by early hot fires, Cryptoblepharus plagiocephalus seems relatively unaffected, Carlia foliorum seems very tolerant of fires, while Ctenotus and Sphenomorphus spp. are favoured by low intensity, patchy fires with high intensity spots.Lizard species experiencing the high-frequency fire regimes of the savannas and dry forests of the Australian wet-dry tropics are not able to select habitat at different stages of regeneration after fire but select habitat produced by fires of different types. The implication for management is that no one fire regime is optimal for the fauna as a whole. A range of fire regimes within a park should be maintained in order to retain the whole fauna.
Litterfall and productivity in a tropical rain forest, Southern Baakundu Forest Reserve, Cameroon
Authors: Songwe Nicholas C. , Fasehun F. E. , Okali D. U. U. 
Published: July 2009

ABSTRACTLitterfall was measured monthly in ten 1 m2traps in each of two 0.25 ha plots in the rain forest of Southern Bakundu Forest Reserve, Cameroon for 18 months from 1 July 1982 to 31 December 1983. Particular emphasis was placed on measuring species contributions and in relating litterfall to climatic factors; the litterfall data were also used in estimating leaf production. Annual litterfall ranged between 12.9 and 14.1 t ha−1and was partitioned to leaves (61–66%), branches (23–38%), fruits and flowers (8–12%) and ephiphytes (0.8%). Emergents and top canopy species likeDesbordesia glaucescens(evergreen) andCeiba pentandra(deciduous) contributed more litter than the numerically dominant lower storey species likeCola lepidotaandDiospyrosspp. Litter fell throughout the year but was greatest during the dry season (November to March); litterfall was thus strongly negatively correlated with environmental moisture variables and could be predicted from its linear regression on time of year, throughfall and relative humidity. By correcting the leaf fall data for leaf weight losses due to grazing and re-translocation, leaf production rates of 10.2 to 11.2 t ha−1yr−1were estimated for the forest.
Pioneer species distribution in treefall gaps in Neotropical rain forest; a gap definition and its consequences
Authors: Popma Jean , Bongers Frans , Martínez-Ramos Miguel , Veneklaas Erik 
Published: July 2009

ABSTRACTAn attempt was made to evaluate the consequences of applying a strict definition (Brokaw 1982a) to the delimitation of forest gaps in the field. The northernmost Neotropical rain forest, at Los Tuxtlas, Mexico, was searched for young (1–2 years old) single-event gaps that would meet the criteria of the definition. In 60 ha of rain forest, only 12 such gaps containing pioneer species could be found. Thirty-three pioneer species (shrubs and trees) were used as indicator species for gap conditions. Gap size, measured as projected canopy opening (sensu Brokaw 1982a), underestimated from 44 to 515% the size of the area colonized by pioneer species. On average the size of the colonized area was 3.4 times larger than the size of the projected canopy opening. The majority of the pioneer species showed a relative preference for gap borders, an area generally not included in the projected canopy opening. Pioneer plant abundance and density, and species richness and density, did not differ significantly between gap centres and gap borders. Floristical variation was not related to gap size or location in the gap. These findings can be explained if gap environment (to which pioneer plants respond) is seen as the result of many interacting factors, of which size of the canopy opening is only one. It is concluded that the definition for delimiting gaps in the field as proposed by Brokaw (1982a) cannot be regarded a generally applicable definition, and that its value as a comparative standard is doubtful.
Internal heterogeneity of gaps and species richness in Costa Rican tropical wet forest
Authors: Brandani Aldo , Hartshorn Gary S. , Orians Gordon H. 
Published: July 2009

ABSTRACTIn Costa Rican tropical wet forest the distribution of seedlings of most tree species colonizing 51 tree-fall gaps is clumped, probably because of differences in the proximity of gaps to fruiting trees. Different gap zones (root, bole and crown) are more similar to one another, in terms of their species composition, than they are to other zones in the same gap. This nonrandom pattern is established soon after gap formation, indicating that mortality of young seedlings is both high and related to gap zones. Some tree species are strongly positively associated with one of the gap zones, whereas others are associated with the age of the gap at the time the census was taken or the species of tree whose fall caused the gap. Root zones are dominated by fewer species than are bole or crown zones. Results are consistent with the assumption that an initial random distribution of seedlings is quickly changed to a strongly non-random pattern by selective mortality of seedlings of different tree species in the different gap zones. The internal heterogeneity of gaps is probably one of the factors helping to maintain the high tree species richness characteristic of tropical wet forests.
Jamaican limestone forests: floristics, structure and environment of three examples along a rainfall gradient
Authors: Kelly D. L. , Tanner E. V. J. , Kapos V. , Dickinson T. A. , Goodfriend G. A. , Fairbairn P. 
Published: July 2009

ABSTRACTWe describe forests from three areas of Jamaica, all on White Limestone but with markedly different rainfall regimes. The areas are Hog House Hill in the north-east with lower montane rain forest at c. 450 m altitude with a rainfall of c. 4000 mm yr−1; Broom Hall in the centre of the island with evergreen seasonal forest at c. 670 m altitude and with a rainfall of c. 1600 mm yr−1and a marked dry season; and Round Hill near the south coast with dry semi-evergreen forest at c. 300 m altitude with an irregularly distributed rainfall of c. 1000 mm yr−1. Species lists were made from c. 180 ha at Hog House Hill, c. 5 ha at Broom Hall and c. 50 ha at Round Hill, and detailed inventories made of five sample sites of c. 1000 m2, two at Hog House Hill, one at Broom Hall and two at Round Hill.At Hog House Hill we listed 280 vascular plant species, including 118 species of trees and larger shrubs; at Broom Hall 247 and 135; at Round Hill 129 and 81. Species-area and species-individuals curves confirm that Broom Hall was richer in tree species than Hog House Hill. The wetter forests contain high proportions of species endemic to Jamaica: 40% of the total flora at Hog House Hill and 36% at Broom Hall. Canopy height decreased from c. 26–28 m at Hog House Hill to c. 13–24 m at Broom Hall to c. 8–15 m at Round Hill. Predominant leaf size decreased from mesophyll at Hog House Hill to notophyll at Broom Hall to microphyll at Round Hill.Compared with forests on other Caribbean islands, the Jamaican forests appear to be as species-rich as any, but lower in stature than natural forest in Trinidad and Dominica. Continental Neotropical forests are both more species-rich and taller.
Dormancy, germination and seedling growth of two Kalaharian perennials of the genus Harpagophytum (Pedaliaceae)
Authors: Ernst W. H. O. , Tietema T. , Veenendaal E. M. , Masene R. 
Published: July 2009

ABSTRACTDormancy and germination ecology of two Harpagophytum species (Pedaliaceae) from an open Acacia savanna in Botswana were investigated. The maintenance of dormancy is governed partly by the seed coat but mainly by the endosperm and the embryo itself, as demonstrated by removal of the endosperm. Dissemination of the seed from the fruit can be delayed for several years without affecting the viability of the embryo, due to very low respiration rates.Germination can be enhanced slightly by high temperatures under natural conditions, and by gibberellic acid or removal of the endosperm under laboratory conditions. Relative growth rates for both Harpagophytum species are lower than for subtropical grasses and legumes, due to a strong investment in root and tuber biomass. Germination and seedling growth is discussed in relation to the drought avoidance syndrome and the animal disperser syndrome.
Crepuscular biting activity of mosquitoes at Peradeniya, Sri Lanka
Authors: Amerasinghe F. P. 
Published: July 2009

ABSTRACTThirty-four spedes of mosquitoes (Diptera: Culicidae) were collected at a series of human-bait catches designed to study evening crepuscular biting activity using the Nielsen crep unit, at a site at Peradeniya, Sri Lanka. Crepuscular biting profiles of seven species (Armigeres subalbatus, Aedes albopictus, Culex pseudovishnui, Cx. gelidus, Cx. fuscocephala, Cx. tritaeniorhynchus and Mansonia uniformis) were obtained. Modal periods for the onset of biting were analysed in six species: Cx. pseudovishnui, Cx. fuscocephala, Cx. gelidus, Cx. tritaeniorhynchus, Cx. quinquefasciatus and Ma. uniformis. Successions in the biting peaks and in modal onset of biting were seen in these species. Analysis of biting in Ar. subalbatus and Cx. pseudovishnui under high (clear sky) and low (cloud-overcast sky) light intensities showed earlier biting in both species under the latter conditions. The value of the Nielsen crep unit in making latitudinal comparisons is illustrated in Ma. uniformis, for which parallel data are available from Africa.
Litterfall in an Australian population of Mimosa pigra, an invasive tropical shrub
Authors: Lonsdale W. M. 
Published: July 2009

ABSTRACTAn investigation of seasonal changes in litterfall in a dense stand of the invasive tropical shrub Mimosa pigra was carried out in northern Australia between October 1984 and December 1986. Total annual litterfall averaged 758 g m−2, close to the value predicted for the latitude and altitude of the site. Leaf litter formed 56.6% of this total, woody material 22.7%, and reproductive material 20.7%. Total litterfall was strongly seasonal, at a maximum in the late wet season or early dry season, and at a minimum late in the dry season. A broadly similar pattern was shown by the various components of the litter, except for woody litterfall, which followed no strong seasonal trend. Variation in the amount of available soil moisture, as calculated from a simple water balance model, accounted for much of the variation in the components of litterfall.The proportion of all initiated flower heads which produce seeds was estimated to be between 2.1 and 4.5%. The mean annual seed fall was 9103 m−2, nearly two orders of magnitude higher than most native shrub populations, and it is argued that this is partly a result of the absence of natural enemies in the introduced range.
Effects of isolation on the water status of forest patches in the Brazilian Amazon
Authors: Kapos Valerie 
Published: July 2009

ABSTRACTPatterns of edge-related environmental changes and plant water relations were investigated in the isolated forest reserves of the INPA-WWF Minimum Critical Size of Eco-systems project near Manaus, Brazil early in the wet season.Air temperature was elevated and humidity reduced in the understorey within 40 m of the reserve margins, and air temperature and vapour pressure deficit (VPD) were higher in the interiors of 1 ha reserves than in 100 ha reserves. There was increased photosynthetically active radiation penetration to understorey level up to 40 m into a 100 ha reserve.Soil moisture was depleted in the outer 20 m of both small and large reserves, and surface soil water potentials fell below – 1.5 MPa at the margin of a 1 ha reserve.Studies of leaf relative water contents (RWCs) in understorey shrubs revealed no appreciable saturation deficits, though RWCs were sometimes lower at the reserve margins. Studies of leaf conductances revealed no evidence of restriction of water loss in these plants, and conductances of plants near the edges were significantly higher and higher for longer.The implications of these results for reserve design and for local and regional water budgets, as well as the possible role of water stress in increased tree mortality in isolated reserves are discussed.Padrōes de mudanças ambientais e hídricos de plantas relacionados a bordas de matas isoladas foram investigadas no início da estação seca nas reservas de floresta do Projeto Dinâmica Biológica de Fragmentos Florestais do INPA-WWF, proximo de Manaus, Brasil.No sub-bosque, até 40 m da borda da mata, a temperatura ambiental estava elevada e a umidade reduzida, e a temperatura do ar e o DPV estavam maiores nas reservas de 1 ha do que nas reservas de 100 ha. A penetração de radiaçao fotosintéticamente ativa no sub-bosque estava aumentada até 40 m da borda em reservas de 100 ha.A umidade do solo baixou consideravelmente nos 20 m periféricos de reservas grandes a pequenas, e o potencial hídrico na superficie do solo baixou para menos de −1.5 MPa na margem de uma reserva de 1 ha.Estudos do teor relativo de água (TRA) em folhas de arbustos de sub-bosque nӑo revelaram deficits de saturação apreciaveis apesar de que TRAs foram menores nas bordas das reservas. Estudos da conductancia foliar não revelaram evidência de restrições de perdas hídricas nessas plantas, e as conductancias de plantas próximas a bordas foram significativamente maiores durante um período mais longo.As impliçõtes desses resultados para o planejamento de reservas e para o balanço hídrico local e regional, assim como as possiveis funçoes de ‘stress’ hídrico na alta mortalidade de árvores em reservas isoladas são discutidas.
A study of the ecological history, vegetation and conservation management of Ile aux Aigrettes, Mauritius
Authors: Parnell John A. N. , Cronk Q. , Jackson P. Wyse , Strahm W. 
Published: July 2009

ABSTRACTMuch of the unique native vegetation of Mauritius has been destroyed. Coastal ebony (Diospyros egrettarum I.B.K. Richardson) forest forms an extreme type of Mauritian lowland forest which no longer exists on mainland Mauritius and only survives on one offshore islet, Ile aux Aigrettes. Undisturbed D. egrettarum forest is resistant to invasion by exotic plants, which have now invaded most relict patches of native lowland vegetation in Mauritius. Human disturbance however, has allowed many exotics (particularly Flacourtia indica (Burm. fil.) Merrill) to invade and form new vegetation types. Much of the disturbance was caused by illegal woodcutting up to 1985, prompted by an acute fuelwood shortage in Mauritius. On the basis of 132 4 X 4 m quadrats, we recognize 10 types of natural, semi-natural and exotic vegeta-tion. The conservation of the remaining natural ebony woodland vegetation requires the total cessation of woodcutting and the eradication of Tabebuia pallida (Lindl.) Miers (potentially the most damaging exotic species).
Environmental factors affecting physiognomic and floristic variation in an area of cerrado in central Brazil
Authors: Oliveira-Filho Ary Teixeira De , Shepherd George John , Martins Fernando Roberto , Stubblebine William Henry 
Published: July 2009

ABSTRACTCerrado is a species-rich savanna-like vegetation that covers a large area in central Brazil. Soil, and particularly soil fertility, is considered to be the major factor determining the wide and diverse physiognomic-floristic gradients encountered within cerrado vegetation. To describe the vegetational variations within a cerrado in southern Mato Grosso state (15° 21'S, 55° 49'W), a 1 ha transect was located to pass through an interfluvial cerrado and climb a steep talus slope. The vegetational and environmental variations are described by means of field classification, direct gradient analysis and reciprocal averaging ordination. The effects of differences in ground water regime in the interfluvial cerrado and differences in inclination with associated rockiness in the talus cerrado are related to the vegetational variations. As the soils are very similar in texture and in the majority of chemical properties, the role of the above environmental factors was more easily distinguished. In the interfluvial cerrado, the vegetation variations are probably related to the seasonal fluctuation in water table level.
Length-mass relationships among an assemblage of tropical snakes in Costa Rica
Authors: Guyer Craig , Donnelly Maureen A. 
Published: July 2009

ABSTRACTLength-mass relationships within an assemblage of tropical snakes are used to describe morphological groups. We report patterns of body size based on length and mass measurements of 603 individual snakes of 27 species captured at La Selva, Costa Rica from March 1982 through August 1984. This assemblage of snakes is composed of at least four morphological groups each of which consists of species with similar habitat preferences. These groups are heavy-bodied terrestrial forms, light-bodied arboreal forms, long-tailed leaf-litter forms, and forms of unextreme relative mass and tail length. This tropical snake assemblage is more diverse in species richness and morphological diversity than a temperate assemblage.
Assessment of permanence and stability in the territories of Kirk's dikdik (Rhynchotragus kirki) in Tanzania
Authors: Amubode Felix O. , Boshe John I. 
Published: July 2009

ABSTRACTThe permanence and stability of 20 territories of the dikdik Rhynchotragus kirki, were studied at Arusha National Park Tanzania. Response criteria included the structure, size and vegetation attributes of territories, density of dikdik, and spatial distances between neighbouring territories. Fourteen of the territories studied were spatially fixed and stable while six were unstable. Two of the unstable territories were completely abandoned. Mean territory size was 0.11 and 0.13 ha during the rainy and dry seasons, respectively. 14.2% of circular territories and 42.9% of elliptical and kidney-shaped territories were stable. The figure of 55 dikdik km−2 sighted during morning censuses was lower than that for evening censuses by 13.5%. Spatial distance between territories ranged from 4.5 m to 100 m, an indication that population density might be a function of the size of suitable habitat. Although shrub canopy cover within stable territories decreased by 44.6% between 1982 and 1987, and some territories were realigned with changes in rainfall pattern, pair-bond was maintained by dikdik in 70% of the territories studied.
Phenology, seed dispersal, and recruitment inCecropia peltata(Moraceae) in Costa Rican tropical dry forest
Authors: Fleming Theodore H. , Williams Charles F. 
Published: July 2009

ABSTRACTWe studied the seed dispersal ecology of the Neotropical pioneer treeCecropia peltataL. (Moraceae) in tropical dry forest by documenting its (1) fruiting phenology, (2) rates of visitation by vertebrate frugivores, and (3) rate of recruitment of juveniles in different habitats at Santa Rosa National Park in northwestern Costa Rica.At Santa Rosa,C. peltatais a common but patchily-distributed plant. Fruiting in females is seasonal, and fruit availability peaks in June through August (the early wet season). Females bear a few ripe fruit per day over a 4–5 month, fruiting period. At least 28 vertebrate species (15 diurnal and 13 nocturnal species) eatCecropiafruit; equal numbers of ripe fruit are removed during the night and day. Owing to their more gentle treatment of seeds in the gut, birds and bats probably are more effective dispersal agents than monkeys. The recruitment rate of juveniles into already established populations was about 0.8 ha−1y−1compared with a rate of 176 ha−1y−1during the colonization of a cleared roadside.
Nitrogen and phosphorus fertilization of Jamaican montane forest trees
Authors: Tanner E. V. J. , Kapos V. , Freskos S. , Healey J. R. , Theobald A. M. 
Published: July 2009

ABSTRACTPlots in the Jamaican montane forest were fertilized with nitrogen or with phosphorus to test the hypothesis that growth of trees in this natural forest is limited by the supply of N and P from the soil.Once a year from 1983 to 1986, urea was added to one plot (at 150 kg N ha−1 y−1) and triple superphosphate was added to another (at 50 kg P ha−1 y−1). In each of these plots and in two control plots, foliage of four common tree species was collected immediately before each fertilizer addition. Trunk growth was measured in 105 individuals.Foliar N concentrations were not significantly higher in trees fertilized with N compared to control trees. In Dendropanax cf. pendulus and Hedyosmum arborescens fertilization with N resulted in lower P concentrations but only after the third year of fertilization, possibly due to dilution by increased leaf production. Mean trunk diameter growth was significantly higher in the N-fertilized trees than in controls.Mean foliar P concentrations were higher in Podocarpus urbanii and Clethra occidentalis following fertilization with P, but only after two years of fertilization. Trunk diameter growth was greater in the P fertilized plot.Thus growth in some Jamaican montane forest trees was limited by the natural supplies of N and of P.