bluuebunny/crossref_metadata_2025_split huggingface dataset:
The water status of six woody species coexisting in the Sahel (Ferlo, Senegal)
Authors: Berger A. , Grouzis M. , Fournier C. 
Published: July 2009

ABSTRACTIn the Sahel during recent decades, anthropogenic disturbance and periods of drought have caused changes in woody species frequency. The internal water status of six coexisting species was analysed to estimate the importance of water constraints in this process. Predawn and midday xylem pressure potential and stomatal conductance were monitored monthly for two years. The relations between xylem pressure potential and transpiration made it possible to determine the hydraulic conductivity of the soil—plant system. Two types of results were obtained. First, there was considerable diversity in water status of the different species. Minimum predawn xylem pressure potentials (dry season) ranged from – 1.5 MPa to – 5 MPa depending on species, with interseasonal variation from 0.08 MPa to 2 MPa. Response to rainfall was very rapid (a few days) or very slow (several months). The three functioning types defined using these results were compared with the phytogeographical status of the species. Second, more specific phenomena were observed, (a) Some species (Balanites aegyptiaca and Boscia senegalensis) showed an imbalance between the predawn xylem pressure potential and the soil water status during the rainy season; (b) a sharp increase in xylem pressure potential was observed in deciduous species in the middle of the dry season; probably related to bud break; and (c) the water status was always favourable for Combrelum glutinosum. The few remaining individuals seem to benefit from very favourable subsoil water supply conditions.
Elevational and latitudinal changes in tree associations and diversity in the Eastern Arc mountains of Tanzania
Authors: Lovett Jon C. 
Published: July 2009

ABSTRACTA total of 200 variable-area plots covering 20.3 ha containing 4000 trees with a basal area of 921.4 m2 were assessed over a combined elevational range of 410–2180 m in the moist forests of three Tanzanian Eastern Arc mountains: West Usambara, Nguru and Udzungwa. Plot data were ordinated on the basis of species presence/absence, frequency and basal area. Axis 1 of ordinations based on species presence/absence are correlated with elevation. Axis 1 of the frequency-weighted ordination was correlated with elevation in the Nguru and Udzungwa mountains, but plots from the West Usambara showed a rainfall-related discontinuity. Axis 1 of the West Usambara basal area-weighted ordination showed evidence of long-term dynamics of Ocotea usambarensis and in the Udzungwa mountains was determined by presence of Parinari excclsa. Plot diversity was not correlated with elevation or latitude, but was lower in disturbed, low rainfall or more seasonal forest. Stem density was positively correlated with elevation and was greater on ridge tops than valley sides and valley bottoms.
Hurricane damage and forest structure in Guadeloupe, French West Indies
Authors: Imbert Daniel , Labbé Patrick , Rousteau Alain 
Published: July 2009

ABSTRACTA comparative study of the damage caused by Hurricane Hugo on the three main types of forest in the lesser Antilles was carried out in the mangrove forest, the semi-evergreen forest and the rainforests of Guadeloupe. Hurricane impact on these forests showed at first that high canopy trees generally prevented understorey trees from heavy direct damage (shield effect). In the species-poor, structurally homogeneous stands, in the mangrove forest, species' susceptibility was the major determinant in both intensity and type of damage. Damage was heavy in places and showed a certain spatial uniformity. In the rainforest, the high structural complexity of the vegetation generally induced a great variability in the spatial distribution of damage even at a small scale. Due to the presence of tall trees, indirect damage was locally very heavy. Clumps of large trees formed resistant structures which diminished lethal damage below the main canopy (cluster effect). In such a highly structured, species-rich forest, species' susceptibility was concealed at the local scale by the prevailing influence of vertical structure. Because of its relatively rich flora but low stature, the semi-deciduous forest exhibited intermediate patterns of damage. It was concluded that floristic composition and forest structure help to explain, and to predict, hurricane damage to forest cover.
Successional age and forest structure in a Costa Rican upper montaneQuercusforest
Authors: Kappelle Maarten , Geuze Thorwald , Leal Miguel E. , Cleef Antoine M. 
Published: July 2009

ABSTRACTChanges in structure of a Costa Rican upper montaneQuercusforest were studied in twelve 0.1 ha plots along a chronosequence including 8- to 20-year-old Early Secondary Forest (ESF), 25- to 32-year-old Late Secondary Forest (LSF) and mature Primary Forest (PF). In 1.2 ha 2854 stems ≥ 3.0 cm dbh belonging to 42 tree species were recorded. Tree species richness per 0.1 ha ranged from 15 to 30. Diversity indices did not change significantly during succession. Stem density did not differ significantly among successional phases, while basal area was significantly higher in PF than in ESF and LSF. Maximum canopy height and basal area increased linearly during the first three decades of recovery. Height and dbh showed a significant, logarithmic regression for all forest phases. A period of 84 y was estimated as the theoretically minimum time needed for structural recovery. The maximum canopy height and basal area recovered two to five times slower in upper montane than in lower montane or lowland Neotropical forests.
Removal of seeds ofCarapa procera(Meliaceae) by rodents and their fate in rainforest in French Guiana
Authors: Forget Pierre-Michel 
Published: July 2009

ABSTRACTExperiments were performed to investigate monthly variations in seed fate ofCarapa procera(Meliaceae), a rodent-dispersed subcanopy tree species in French Guiana. A total of 600 thread-marked seeds were placed on the ground in mature forest under 20 adult trees during different months (March, April and May 1991) of the species' fruiting season. In 1991 the seed crop reached 1536 seeds in the study area, with a majority of seeds being produced in March and May. On average, seed removal rate steadily increased from March (23%) to May (96%). Of the seeds removed, the proportion eached almost doubled between March (28%)-April (25%) and May (48%), whereas the proportion eaten (gnawed) steadily declined between March (43%) and May (9%). Approximately 75–100% seed removal was therefore associated with intense scatterhoarding and low seed predation, especially in May. Greater seed dispersal rates occurred during the late wet season when fruit diversity decreased but when overall fruit biomass peaked because of fruiting occurrence of large-seeded species. The seasonal hoarding behaviour of rodents is discussed.
Effects of canopy species dominance on understorey light availability in low-elevation secondary forest stands in Costa Rica
Authors: Kabakoff Randy P. , Chazdon Robin L. 
Published: July 2009

ABSTRACTThe effect of canopy species dominance on understorey light availability in secondary forests was examined for Pentaclethra macroloba and Goethalsia meiantha, two common tree species with contrasting canopy architecture at La Selva Biological Station in the Atlantic lowlands of Costa Rica. In each of six 12- to 16-year-old successional stands dominated by one of these species, relative abundance and basal area of the focal species were determined within a 20 m × 50 m plot. Light availability at 1 m height was measured within each plot using a Licor-2000 Plant Canopy Analyzer at 27 locations and by analysing hemispherical photographs taken at 10 locations. Across stands, mean LAI values were significantly negatively correlated with canopy openness. Understorey microsites beneath Pentaclethra had significantly higher light availability than microsites beneath Goethalsia. Across stands, however, light availability was not correlated with either total basal area or stem density of trees ≥10 cm DBH. These results indicate that basal area and stem density of trees in the upper levels of the forest canopy are poor predictors of light penetration to the understorey. One hypothesis suggested here is that dense subcanopy and understorey vegetation in tropical secondary forests can strongly influence understorey light levels. Alternatively, light transmittance characteristics of the upper forest canopy may be influenced by species-specific differences in canopy architecture or foliage density that vary independently from tree diameter and density.
Resource availability, diet and reproduction in Glossophaga longirostris (Mammalia: Chiroptera) in an arid zone of the Venezuelan Andes
Authors: Sosa Maricela , Soriano Pascual J. 
Published: July 2009

ABSTRACTSeasonal variation in the consumption of cactus fruit by the bat Glossophaga longirostris was related to the availability of this resource in the arid pocket of Lagunillas in the Venezuelan Andes. When fruits were scarce, G. longirostris ate items not preferred in other seasons. The intraspecific flowering periods of the most common cactus species, Stenocereus griseus and Subpilocereus repandus, were synchronized but the number of flowers open per night was low. S. griseus and S. repandus had separate flowering and fruiting periods, possibly to reduce competition for dispersers and pollinators while providing food resources for bats throughout the year. G. longirostris is bimodally polyestrous with extended reproductive periods, probably as a response to the continual availability of cactus flowers and fruits. A strong interdependence between columnar cacti and G. longirostris was demonstrated. Sexual reproduction of the cacti would be greatly reduced without the bats, which in turn could not live in the arid study area without the food sources provided by these cacti.
Characteristics of vertebrate-dispersed fruits in Hong Kong
Authors: Corlett Richard T. 
Published: July 2009

ABSTRACTHong Kong has a native angiosperm flora of approximately 1800 species, of which 27% (482 spp.) bear fleshy, presumably vertebrate-dispersed fruits, including 76% of the 337 tree and shrub species and 70% of the 103 climber species. Morphological characteristics were determined for 255 species and nutritional characteristics of the fruit pulp for 153 species. Most fruit species were black (45.1%) or red (24.3%) and 85.9% had a mean diameter <13 mm. Nutritional characteristics varied widely between species with ranges and median values as follows: pulp percentage (range 10.0–99.2%, median 69.2%), water content of pulp (11.1–94.0%, 78%), lipid (0–84.0%, 2.0%), soluble carbohydrate (4–88%, 53%), nitrogen (0.2–3.4%, 0.86%), neutral detergent fibre (1–44%, 14.3%). Fruit development time (50–360 d, 156 d) showed a negative correlation with lipid content, but no significant correlation with fruit or seed size. Principal components analysis of fruit characteristics was dominated by a trend from single-seeded fruits with a thin, lipid-rich pulp layer to multiple-seeded fruits with much, watery, carbohydrate-rich pulp. Birddispersed species cover the full range of fruit characteristics except those too large to swallow and too hard to peck bits from. Mammals (bats, civets and/or macaques) are known or suspected to consume most of the fruits too large for birds as well as many bird fruits but none with high-lipid content. Summer fruits (May—September) were significantly larger and had significantly higher seed size and carbohydrate content than winter fruits (November-March). Winter fruits took more than twice as long to develop as summer fruits.
Sepal and nut size ratio of fruits of Asian Dipterocarpaceae and its implications for dispersal
Authors: Suzuki Eizi , Ashton Peter S. 
Published: July 2009

ABSTRACTThe relationship between sepal and nut size of fruits was studied in fruit of 394 species of Dipterocarpaceae in Malesia and Sri Lanka. The fruits of many dipterocarps have long twisted sepals which have a role as blades for dispersal by gyration. But long sepals decrease resource allocation to other parts, and increase the chance of fruit being trapped in the canopy. The frequency distribution of the ratio of sepal length to nut length was bimodal. The gyrationdispersed group with longer sepals comprised 74% of Dipterocarpaceae studied. The group with short sepal mainly comprised understorey trees, but there were a few emergents. In both groups, sepal areas were expressed as a power function of nut volumes'. Because fruit weight per sepal area increases with fruit size, larger fruits fall more quickly than smaller fruits, and sepals of the former can not serve so effectively as propeller blades. This is consistent with the fact that a few emergent trees with large nuts have short sepals and are not dispersed by gyration. Therefore, the re-evolution of short fruit sepals appears to have been mainly due to two reasons: reduction of tree height and enlargement of nut size.
Comparison of root and mycorrhizal characteristics in primary and secondary rainforest on a metamorphic soil in North Queensland, Australia
Authors: Hopkins Michael S. , Reddell Paul , Hewett Robert K. , Graham Andrew W. 
Published: July 2009

ABSTRACTRoot biomass, root lengths, and mycorrhizal associations were compared in a series of primary and Acacia-dominated secondary rainforest stands on nutrient-poor, red podzolic soils developed from low grade Palaeozoic metasediments. Five soil cores to 200 mm depth were collected at random locations from each of 20 sites. Ten of these sites were in 20–25 m high closed secondary forest (30–40 y old) dominated by Acacia aulacocarpa and ten sites were located in primary, selectively-logged, rainforest (28–32 m tall). Arbuscular mycorrhizas were the only form of association found in the primary forest sites. Ectomycorrhizas dominated the secondary forest sites although arbuscular mycorrhizas were also present. The primary forest sites had significantly higher root biomass (34.4 ± 17.8 t ha-1) and root length (33,400 ± 3,200 km ha-1) than the secondary forests (11.6 ± 4.6 t ha-1 and 25,200 ± 4,800 km ha-1 respectively), and this was interpreted as a reflection of the greater allocation of biomass to roots necessary to support the greater above ground biomass. The specific root length in the secondary forest (340 ± 119 cm g-1) was twice that of the primary forest (154 ± 65 cm g-1) indicating that the trees in the secondary forests achieved a degree of soil exploration which was comparable to that in the primary forest with less than half the biomass allocation to roots. The dominance of ectomycorrhizas in the secondary forest was associated with the prevalence of Acacia aulacocarpa, and the results cannot be extended to other secondary forests in the region. The implications that the dominant ectomycorrhizal associations have for the patterns of successional development and the patterns of species colonization in these Acaria-dominated secondary forests are discussed.
Dispersion and abundance of Macrotermes michaelseni colonies: a limited role for intraspecific competition
Authors: Schuurman Gregor , Dangerfield J. Mark 
Published: July 2009

ABSTRACTThe position of Macrotermes michaelseni mounds were mapped in six areas of 1.5 to 31.0 ha in a range of habitats on the fringes of the Okavango delta. Abundance varied significantly between and within habitats with highest densities in relatively stable floodplain woodland. In all sites apparent overdispersion of active mounds was not statistically significant when edge effects were taken into account. When active and inactive mounds were combined some overdispersion was seen but due to the disturbance regime the probability of all mounds being active simultaneously was small. Intraspecific competition was, therefore, not considered likely. Our results and reanalyses of dispersion patterns in published accounts for Macrotermes species suggest that although mound dispersion can appear to be regular this is probably a result of historical precedence and chance events rather than any current density-dependent process.
Ecological correlates of trap response of a Neotropical forest rodent, Proechimys semispinosus
Authors: Adler Gregory H. , Lambert Thomas D. 
Published: July 2009

ABSTRACTPatterns of trap response in the Central American spiny rat (Proechimys semispinosus), a frugivorous forest rodent, were examined in relation to age, sex, density and resource abundance. Populations on four small islands (designated numbers 4, 8, 14, and 52) in Gatun Lake (central Panama) were sampled by live-trapping for four nights every month for four years. Trappability was calculated as the proportion of all individuals known to be alive that were actually captured. Mean body mass at first capture was within the range of subadult body masses and differed among islands but not between sexes. Trappabilities summed over the entire study were generally low and differed among islands and age classes (juveniles, subadults and adults) and between sexes. In general, adults were more trappable than juveniles and subadults, and females (particularly adults) were more trappable than males. Trappability and the number of captures per individual varied seasonally and were generally greatest during December and January. Monthly estimates of these two variables were examined for autocorrelation, and the order of the autoregressive error model was determined separately for each island population. The arcsine of trappability and the number of captures per individual were regressed on log10 densities of spiny rats and of fruiting trees and lianas after controlling for autocorrelation. Both trappability indices were negatively related to the density of fruiting trees and lianas on islands 8 and 14, indicating that spiny rats may be seasonally food-stressed. The number of captures per individual was related positively to the density of spiny rats on island 52 and negatively on island 8. Results indicate that spiny rat populations must be sampled with greater intensity and duration than temperate forest rodents.
Bird communities in Panamanian black mangroves: potential effects of physical and biotic factors
Authors: Lefebvre Gaëtan , Poulin Brigitte 
Published: July 2009

ABSTRACTIsolated in forest patches, mangrove stands often experience different physical conditions (rainfall, tide, salinity) despite similar floristic composition and structure. These abiotic factors are known to influence mangrove phenology but their potential effect on the local invertebrate and bird fauna have not been investigated. This study contrasts two sites of black mangrove (Avicennia germinans) located on the Caribbean and Pacific coasts of Panama. The two mangrove sites are characterized by different rainfall and tide patterns, and consequently ground inundation and salinity. These mangrove sites also differed in their plant phenology as well as invertebrate and bird composition. Although 95% of the bird species sampled occur on both coasts, the two mangrove sites shared only 34%. Moreover, each bird community was composed of a particular feeding guild assemblage consistent with the abundance distribution of their invertebrate-prey. Because floristically similar mangrove stands can support different invertebrate and bird faunas, conservation efforts should target mangrove patches submitted to different physical factors in order to preserve biodiversity.
Mound structure of the fungus-growing termite Macrotermes gilvus in Thailand
Authors: Inoue Tetsushi , Vijarnsorn Pisoot , Abe Takuya 
Published: July 2009

ABSTRACTThe change of mound structure of the fungus growing termite, Macrotermes gilvus, which has no clear air passage system in the mound, was examined in relation to the mound growth in a rubber plantation of southern Thailand. The nest proper consisted of the hive with a royal chamber and nursery, and diffused chambers with fungus combs. The location of the hive became higher with the growth of the mound. Therefore, colonies with a very large mound utilize only the upper mound part and this may be due to the lack of air passage systems in this species. A colony with a very large mound is not in reality commensurately large in colony size and this may be the reason why the density of huge mounds of M. gilvus in Thailand is much higher than that of Macrotermes in Africa.
Seed and seedling survival of the palmAstrocaryum murumuruand the legume treeDipteryx micranthain gaps in Amazonian forest
Authors: Cintra Renato , Horna Viviana 
Published: July 2009

ABSTRACTThe role of regeneration strategies in structuring tropical tree communities has been a recent focus of attention of tropical ecologists. Canopy discontinuities created by tree-falls are considered to be critical to many rain forest trees for establishing and completing their life cycles. It was investigated whether it is advantageous for two common large-seeded and shadetolerant Amazonian tree species, the palmAstrocaryum murumuruand the legume,Dipteryx micrantha, to have their seeds dispersed to gaps. The dispersal process was simulated by placing experimental seeds and seedlings in gaps and in the shaded understorey, and then following their performance. Seeds and seedlings from the two species were used. The Cox proportional hazard model was used to estimate the survival functions and compare survivorship curves. Survival ofAstrocaryumseeds, and ofDipteryxseeds and seedlings, was higher in two gap zones (crown and bole) than in the shaded understorey (both near and far away from a conspecific adult). A higher proportion of seedlings of both plant species survived within gaps than in the shaded understorey over an 18-wk period. One year after the seedlings had been transplanted into gaps these patterns still held. Naturally occurringAstrocaryumseeds survived better beneath conspecific adult trees located within 30 m of gaps than beneath trees located 100 m from gaps. Variation in gap size was significant forDipteryxseeds, but not forDipteryxseedlings andAstrocaryumseeds and seedlings.Dipteryxseeds survived longer in smaller than in larger gaps. By colonizing tree-fall gaps, these two species improved their chances of completing their life cycles.