bluuebunny/crossref_metadata_2025_split huggingface dataset:
Host specificity and seed dispersal of Psittacanthus robustus (Loranthaceae) in south-east Brazil
Authors: Monteiro Ricardo Ferreira , Martins Rogério Parentoni , Yamamoto Kikyo 
Published: July 2009

ABSTRACTPsittacanthus robustus (Loranthaceae) is a Neotropical mistletoe which grows mainly on species of Vochysiaceae in Brazilian ‘cerrado’ regions. Its parasitizing pattern involves: (a) the height and the aspect of the crown of the host-plants; (b) the presence of sticky substance in the fruits of the parasite; and (c) the feeding behaviour and habitat selection of the dispersal agent, the swallowtanager Tersina viridis viridis. The feeding behaviour of this bird on fruits of P. robustus facilitates seed release and seedling establishment; its foraging habit and habitat selection account for high concentrations of the parasites on their preferred host-plants.
Growth of tree seedlings in tropical rain forests of North Queensland, Australia
Authors: Osunkoya Olusegun O. , Ash Julian E. , Graham Andrew W. , Hopkins Mike S. 
Published: July 2009

ABSTRACTThe effects of forest habitat, canopy light condition, vertebrate herbivory and species mean seed size on growth of tree seedlings were evaluated for six widely different species of North Queensland tropical rain forests. Two forest localities differing in size and rainfall intensity were used for the trial. In each forest, seedlings were transplanted three weeks after germination into small to medium-sized canopy gaps and into the forest interiors, with half protected by cages and the other half unprotected. Growth measurements were made over a period of 16 months. All growth parameters examined differed significantly between the six species. At the end of the study period, for most species, forest site and protection from vertebrates did not affect seedling biomass. For all species, growth was higher in gaps than in forest interior, but most biomass allocation patterns did not differ between the two habitats. This was attributed to the small difference in photosynthetically active radiation (PAR) levels between the two habitats (interior, 0.48–2.53% PAR; gap, 3.58–7.09% PAR). Between species, seedling growth in the forest interior and sensitivity to increasing light were significantly correlated with initial mean seed size. The growth ability of the six species in and out of canopy gaps is discussed in terms of regeneration status of forest tree species.
Ecology of the Asian Elephant in lowland dry zone habitats of the Mahaweli River Basin, Sri Lanka
Authors: Ishwaran Natarajan 
Published: July 2009

ABSTRACTThe ecology of the Sri Lankan elephant in the Wasgomuwa Strict Nature Reserve and its environs is reported for the first time. Seasonal changes in the availability of grazing sites influenced changes in the home range of elephants. Availability of such sites in the wet season was limited by agricultural activities. Paddylands, after the harvest of the rice crop in the late wet season, became important dry season grazing sites. In the Reserve and areas outside its southern boundary on the left bank of the Mahaweli River, (a) female herds were seen more often than solitaries (b) female herds were larger and had a higher than expected number of juveniles in the dry than in the wet season (c) about 45% of the individuals were juveniles and (d) 7.4% of adult and sub-adult females had calves. Conflict between elephants and farmers will be most intense along the southern and eastern boundaries of the Wasgomuwa National Park, established in 1984 by the addition of new areas predominantly to the northern part of the Wasgomuwa Strict Nature Reserve.
Responses to shading of seedlings of savanna grasses (with different C4 photosynthetic pathways) in Botswana
Authors: Veenendaal E. M. , Shushu D. D. , Scurlock J. M. O. 
Published: July 2009

ABSTRACTDifferent C4 photosynthesis pathways may influence plant response to shade and/or moisture stress. In the savanna of south-eastern Botswana, seedlings of PCK C4 type grass species were frequently observed to emerge in shaded habitats. The speciesDigitaria erianthasubsp.pentzii, which shows the NADP-ME pathway, was also found to be associated with the tree canopy. Species emerging in habitats exposed to full sun often showed the NAD-ME C4 pathway. Seedlings orAristida congesla, Eragrostis rigidiorandTragus berteronianuswhich normally emerge in full light, showed higher relative growth rates and/or unit leaf rates compared with seedlings ofPanicum maximumandUrochloa panicoideswhich are associated with shaded habitats. Seedlings of the latter species, however, survived low light conditions. Relative growth rate of the seedlings appeared to be negatively related to caryopsis weight. Light response analysis of leaves ofDigitaria erianthasubsp.pentzii, grown under low light intensities, showed similar trends in light saturation to those reported for the PCK type inPanicum maximum. Mesophyll rather than stomatal limitations appeared to induce light saturation at higher light intensities in leaves grown under shade conditions.
Food habits of sympatric termite species (Isoptera, Macrotermitinae) as determined by stable carbon isotope analysis in a Guinean savanna (Lamto, Côte d'Ivoire)
Authors: Lepage Michel , Abbadie Luc , Mariotti Andre 
Published: July 2009

ABSTRACTThe food habits of four hypogeous Macrotermitinae species were studied using stable carbon isotope analysis in several biotopes of a humid savanna of West Africa (Lamto, Côte d'Ivoire). The proportion of woody and herbaceous material in the diet of the different species was determined by measuring the13C natural abundance in the fungus comb. The diet varied with season and biotope, especially tree density. The results confirm the flexibility of the food habits of the fungus-growing termites as a consequence of their exosymbiosis with the fungusTermitomycessp.
Ecosystem dynamics at disturbed and undisturbed sites in north Queensland wet tropical rain forest. II. Litterfall
Authors: Herbohn John L. , Congdon Robert A. 
Published: July 2009

ABSTRACTRates of litterfall over a period of 3 y at one undisturbed site and two sites disturbed by selective harvesting are reported for a tropical rain forest area in North Queensland, Australia. Litterfall over a period of 18 months is also reported for a further undisturbed site in the same area. No significant differences were found in annual litterfall between the sites, with annual litterfall rates ranging from 5.0 to 6.0 t ha−1 y−1. These rates are considerably lower than those reported for other rain forest areas in Australia, and are within the lower ranges recorded for other tropical rain forests. Litterfall was found to be strongly seasonal at all sites with the maximum falls occurring from the end of the dry season to the end of the wet season. The between year variability of the sites was quite low, with the ratio of maximum to minimum production ranging from 1.05 to 1.20. The average percentages of leaves, wood and reproductive material in litterfall were similar at each site. Leaves were the dominant component of litterfall with the average proportion of the total litterfall ranging from 72% to 76% over the study period at each of the four sites. At certain times, however, the fall of wood and reproductive material was quite significant, comprising as much as 71% and 34% of litterfall respectively. A strong negative correlation was found between the fall of leaves and wood at all sites.
Dynamics of herbivory in Belizean mangal
Authors: Farnsworth Elizabeth J. , Ellison Aaron M. 
Published: July 2009

ABSTRACTWe report long-term observations on leaf herbivory in the mangrovesRhizophora mangleandAvicennia germinans, on the Placencia Peninsula of Belize. We labelled and traced leaves and recorded the amount of damage appearing over a period of 310 days. Herbivores had damaged 1–4% of total mean leaf area within the first 10 days, but damage rates levelled off thereafter, to a final total of 4–10% damage. Herbivores did not concentrate on leaves of younger age classes.Rhizophora manglegrowing in the high tidal zone (HHW) exhibited the highest initial and total attack rates at all but the final sampling dates. We also documented the dynamics of injury expansion and necrosis following artificial injury to seedling and tree leaves. Artificial holes in leaves were associated with higher subsequent rates of herbivory that varied among leaf age classes, and particular damage types were more prevalent in previously injured leaves. Artificial holes expanded significantly more in young leaves of both species. Holes in young leaves of both species expanded by up to 45.1% in area over 50 days, consistent with a similar study in Australia. Substantial necrotic areas developed around the injury site; a secondary effect of damage not often considered in herbivory studies. We discuss the implications of hole expansion and necrosis in estimating error in herbivory measurements. Temporally dynamic studies of herbivory are especially needed in tropical systems that show non-deciduous phenologies and long-lived leaves.
Reproductive phenology of Hong Kong shrubland
Authors: Corlett Richard T. 
Published: July 2009

ABSTRACTHong Kong is on the northern edge of the tropics and near the boundary of the Paleotropical and Holarctic floral kingdoms. The phenological states of 105 plant species in secondary shrubland were recorded weekly for three years. Community patterns of reproductive phenology are highly seasonal and vary little between years. There is a flowering maximum in May and a fruiting maximum in December/January. The winter fruiting peak coincides with diet switching by resident omnivorous birds and the arrival of partially frugivorous migrants from the Eastern Palearctic. However, wind-dispersed species also have a fruiting maximum at the same time, suggesting that fruiting in winter has other advantages.
The basis of reproductive seasonally in Mastomys rats (Rodentia: Muridae) in Tanzania
Authors: Leirs Herwig , Verhagen Ron , Verheyen Walter 
Published: July 2009

ABSTRACTReproduction of the African murid genus Mastomys, multimammate rats, is seasonal, starting after the rains and extending well into the dry season. During a two-year study in Tanzania, we tested three hypotheses to investigate the proximal causes of this seasonality. Food availability was no limiting factor since food supply could not induce continuous breeding. Temperature was always high and thus not a restrictive climatic factor. Diet was probably always sufficiently varied and protein-rich to allow reproduction. This contradicts earlier hypotheses that consider Mastomys as an opportunistic breeder in which reproduction is seasonally limited by poor conditions; environmental predictors were believed not to be involved since the animals live in an unpredictably unstable environment. However, although the occurrence of rain may be unpredictable, it is highly predictable that heavy rainfall will be followed by good conditions. Laboratory experiments show that sprouting grass has a stimulatory effect on reproduction, suggesting that breeding is triggered by new vegetation.
Effects of habitat fragmentation on Amazonian termite communities
Authors: de Souza Og Francisco Fonseca , Brown Valerie K. 
Published: July 2009

ABSTRACTIntuitively, termites would seem to be a very suitable group to illustrate effects of ecosystem fragmentation. Being detritivores, they do not control directly the rate at which their resources are available, nor do they restrict the ability of the resources to regenerate. Consequently, termites do not mask the ecosystem depletion caused by fragmentation. With this in mind, we compared the communities of termites in undisturbed Amazonian forest with those of two isolated fragments nearby, aiming to show that the differences observed may have resulted from habitat fragmentation. Dissimilarities between communities in the undisturbed forest suggest natural patchiness in their distribution, which could lead to misinterpretation of the effects of fragmentation. Continuous forest had higher species richness and fewer rare species than the fragments. Guild structure in the forest was biased towards soil-feeding termites, which are subterranean and soft bodied, and therefore more sensitive to variation in microclimate. In the fragments, litterfeeders and species intermediate between soil-feeding and wood-feeding types were numerically more important. Habitats in the forest were more equally used than in the fragments, suggesting habitat unsuitability increased with fragmentation. It is suggested that the community composition of the fragments is a result of the intrinsic patchiness of the original forest and deterministic and stochastic extinctions caused by fragmentation. The need for manipulative experiments to test such ideas is discussed.
The response to salinity of a population of Dactyloctenium aegyptium from a saline habitat in southern Nigeria
Authors: Adu A. A. , Yeo A. R. , Okusanya O. T. 
Published: July 2009

ABSTRACTThe effects of salinity upon the growth, photosynthesis, ion and water contents of a population of Dactyloctenium aegyptium originating from a saline site in Nigeria were investigated. Growth was unaffected by a salinity of 10% artificial sea water, but was reduced by one third in 20% and by two thirds in 30% artificial sea water respectively. Initial adjustment to salinity was due both to increases in the concentrations of sodium and potassium per unit dry weight and to reduced hydration, the latter being the more important at higher salinities. The increase in ion concentration in the cell sap balanced the salinity of the medium at 10% artificial sea water, but was excessive at higher concentrations of sea water. Net photosynthesis was unaffected by 10% artificial sea water but declined at higher salinities. The potassium content of the plants did not fall below 200–250 mM, and the sodium to potassium ratio did not exceed three, even at the highest salinities. Variation in the concentration of nutrients (potassium, nitrate and sulphate) in the medium in the presence of 25% artificial sea water had significant effects upon growth, but these were small in relation to the inhibitory effect of the salinity.The reduction in growth could not be attributed to lack of osmotic adjustment or to nutrient deficiency, and was probably due to ion toxicity within the leaves. The tolerance to reduced hydration, combined with the ability to germinate in saline conditions previously observed, could enable D. aegyptium to establish in a saline soil. The population did not exhibit any halophytic characteristics but did survive with a low growth rate at salinities up to 50% artificial sea water. It is concluded that the species was able to colonize the saline site because of its inherent adaptability, rather than the possession of an ecotype adapted to saline conditions.
The effects of man made gaps on germination, early survival, and morphology ofChlorocardium rodieiseedlings in Guyana
Authors: Steege Hans Ter , Bokdam Carla , Boland Miranda , Dobbelsteen Jose , Verburg Ivo 
Published: July 2009

ABSTRACTGermination success ofChlorocardium rodieiis low in large gaps. High light levels, however are beneficial for the survival of seedlings. (Partial) removal of cotyledons has a large negative impact on survival especially under low light conditions. Seedlings from large gaps are larger but not taller than those from the understorey, due to differential internode growth. Although growth of seedlings is improved by higher light levels caused for example by logging, great care should be taken with logging intensity, which may increase seed mortality.
Patterns of fruit-fall phenology in the Lopé Reserve, Gabon
Authors: White Lee J. T. 
Published: July 2009

ABSTRACTPatterns of fruit production were monitored over a 1-year period, from June 1990–May 1991, by counting the numbers of freshly fallen ripe and unripe fruits on five 5-km line transects located within 35 km of one another, in lowland tropical rainforest in the Lopé Reserve, central Gabon. A total of 195 species of fruit were found, representing at least 45 taxonomic families. The majority of fruits came from trees. Fruits were assigned to one of six categories which reflected their dispersal syndrome: succulent, arillate, dehiscent, fleshy pods, wind-dispersed, others. About three-quarters of all species had fruits characteristic of those dispersed by animals. There was a marked seasonal pattern to fruit production, with both the diversity and number of ripe fruits available peaking in January, and lowest immediately before and during the major dry season. The only climatic variable that showed a significant statistical correlation with fruit production was insolation. Candidates for the role of keystone fruit species were identified from species which fruited during the major dry season, and patterns of fruit production compared with other areas.
Vegetation and gap dynamics of a tropical wet evergreen forest in the Western Ghats of Kerala, India
Authors: Chandrashekara U. M. , Ramakrishnan P. S. 
Published: July 2009

ABSTRACTThe wet evergreen forest of Nelliampathy in the Western Ghats of Kerala in India is a mixed forest with a high species diversity and basal cover. In this relatively undisturbed ecosystem, canopy gaps are largely formed through single tree fall, but gaps through branch fall, crown fall, standing dead trees or multiple tree fall also occur. Canopy gap formation is more (over 82% of the total gaps created) during the monsoon season. The mean number of gaps formed in this forest is 1.13 ha−1 y−1 and the turnover rate is 83 years. The majority of the gaps created (over 70%) are of smaller size (≥ 100 m2). In this forest, while some top canopy tree species (those capable of exceeding 25 m in height at maturity) such as Palaquium ellipticum and Mesua nagassarium are well represented in seedling, sapling and mature tree stages, others like Aglaia exstipulata and Mastixia arborea are observed only as saplings and/or mature trees with no seedling populations. The possible reasons for these two types of regeneration behaviour by top canopy tree species in the context of canopy gap size and seasonality in gap formation are discussed.
Population dynamics of two sympatric isopod species in a pine forest in central Java, Indonesia
Authors: Vink K. , Purwanti E. Sri 
Published: July 2009

ABSTRACTThe populations of two dominant isopod species in aPinus merkusiiforest on the southern slope of mount Ungaran in central Java, Indonesia, were periodically sampled during one year using Tullgren extractions from soil cores. The aim of the research was to collect more information about the life-cycles of tropical isopods by analysing size-class distributions of two sympatric isopod species, belonging to the genusBurmoniscus. Biomass of the populations was estimated from length-weight conversions established for each species in the laboratory. The efficiency of the Tullgren extraction method was estimated by comparison to hand sorting; no difference was found between these methods.The abundance of the two species differed significantly with time.BurmoniscusSp. A was more abundant during the wet season, whereas the population fluctuations ofBurmoniscusSp. B were more spread over the year. Reproduction of both species took place in the wet season.BurmoniscusSp. A had one generation per year, while forBurmoniscusSp. B the situation was unclear due to extensive overlap of size classes. Comparisons were made with isopod abundance in other tropical and temperate forests. The mean density of the two species found in this study was 258 m-2forBurmoniscusSp. A and 272 m-2forBurmoniscusSp. B, while biomass was 80.4 mg m-2and 37.6 mg m-2, respectively. The data suggest that densities of isopods in tropical pine forests may be considerably higher than in comparable temperate ecosystems.
Mineral nutrient status of coastal hill dipterocarp forest and adinandra belukar in Singapore: analysis of soil, leaves and litter
Authors: Grubb P. J. , Turner I. M. , Burslem D. F. R. P. 
Published: July 2009

ABSTRACTThe soil of remnant primary rainforest on granite in Singapore is very acidic (pH mostly 3.5–4.2 at 0–10 cm) and has unusually low total concentrations of nitrogen and phosphorus, but the mean concentrations of N and P in the living leaves and freshly fallen leaves of the more shade-tolerant species are within the ranges found for other lowland forests on infertile oxisols and ultisols. The concentration of Ca in freshly fallen leaves is very low. The soil under secondary forest (bselukar) on sandstone dominated by Adinandra dumosa (Theaceae) was degraded during use for agriculture. It has the same pH range but even lower values of total N and P. The mean concentrations of N, P, K, Ca and Mg in the living leaves are slightly higher than in leaves of the more shade-tolerant trees of primary forest, but lower than in the leaves of the species which require canopy gaps for establishment or early onward growth. The few species sampled in both primary forest and belukar show no consistent trend in foliar concentrations. The degraded soil has selected species with inherently lower foliar concentrations.
Mineral nutrient status of coastal hill dipterocarp forest and adinandra belukar in Singapore: bioassays of nutrient limitation
Authors: Burslem D. F. R. P. , Turner I. M. , Grubb P. J. 
Published: July 2009

ABSTRACTBioassays of nutrient limitation were carried out for Melastoma malabathricum growing on soil from primary lowland dipterocarp rainforest in Singapore, and for Dillenia suffruticosa on soil from adinandra belukar, a nutrient-poor secondary forest type dominated by Adinandra dumosa. Three questions were addressed. 1. What is the nutrient most limiting to growth in primary forest? 2. What is the nature of nutrient limitation under conditions of adequate P supply? 3. Is there a qualitative difference in the nature of nutrient limitation under primary forest and adinandra belukar? Results showed that there was a strong limitation by P availability in both primary forest and adinandra belukar under the experimental conditions used. Once plants had an adequate P supply, all other nutrients became limiting to growth in primary forest soil. These findings are interpreted as support for the hypothesis that P availability would limit the productivity of moist tropical forests in general in the absence of mycorrhizas; tentative conclusions are drawn on the assumption that most woody tropical plants are mycorrhizal. It is argued that limitation by major cations may be common on old, highly leached tropical rainforest soils.
Competition effects and responses to variable numbers of neighbours in two tropical savanna grasses in Venezuela
Authors: Raventós José , Silva Juan F. 
Published: July 2009

ABSTRACTIn a garden experiment we monitored tillering and flowering for target plants of two grass species, surrounded by one to five neighbours and compared them with control plants growing alone. We analysed the results using a non-linear regression. The species differed markedly in their seasonal patterns of growth but these differences faded when growing with two or more neighbours. The presence of neighbours had a significant depressing effect on both tillering and flowering in both species. Effects and responses were strongly asymmetrical concerning species and mode of growth. Andropogon semiberbis is in disadvantage against Trachypogon plumosus concerning vegetative growth. However, T. plumosus is strongly affected in its reproductive growth by competition not only from A. semiberbis but also from conspecific neighbours. We conclude that the complexity of interactions between effects and responses as well as vegetative and reproductive growth could have a net result of competitive equivalence or compensating competitive abilities of these two species.