bluuebunny/crossref_metadata_2025 huggingface dataset:
Some aspects of the ecology of bagrid catfishes in a southern Nigerian river
Authors: Idodo-Umeh George , Victor Reginald
Published: July 2009

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

The competitive interactions between two species of characins (Astyanax fasciatus and Astyanax bimaculatus) were investigated by studying their horizontal distribution, relative abundance and feeding habits in littoral and limnetic zones of Americana Reservoir, southern Brazil.

Differences in horizontal distribution of the species mainly as adults led to their partial habitat segregation. Most adultA. bimaculatuswere littoral dwellers, whereasA. fasciatusadults were distributed from inshore to offshore waters, but with most in the latter region.

Both are facultative zooplanktivores in the reservoir, feeding mostly on planktonic crustaceans, insects (chiefly chironomids), some higher plant material, detritus and even fish scales (A. bimaculatus). Food overlap coefficients, considering adult and juvenile stages of both species are large in dry as well as wet seasons, although in the dry season the overlaps are significantly reduced for juveniles of both species and for juveniles ofA. bimaculatusversus adults ofA. fasciatus. Both species prey more on cladocerans than on cyclopoid copepods, and the adults selectively take larger forms (Daphnia gessneriandMoina micrura) in the reservoir (as in previously reported enclosure experiments). Juveniles prey heavily onBosmina longirostris.

These two formerly riverine species may reduce competition, in the reservoir, by partial habitat segregation in older stages, a mechanism to avoid competition, which may have existed in their previous interactive history in rivers.
Population dynamics and production of the rocky stream-dwelling fish Garra ceylonensis (Cyprinidae) in Sri Lanka
Authors: Silva K. H. G. M. De
Published: July 2009

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

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

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

Using data from forest sites in Sarawak, East Malaysia, a demographic comparison is made of pioneer species in the genus Macaranga with understorey trees of the primary forest in the closely related genus Mallotus. In primary forest, saplings and trees of these genera arc uncommon and have low growth rates. For the six years following disturbance by logging, a Macaranga population was characterized by high rates of diameter growth and recruitment. Eleven years after disturbance, seedling and sapling abundance had declined sharply. In contrast, the Mallotus population was stable in size class distribution and increased slightly in total population size during the 11 years after logging. Growth rates of Mallotus trees increased after logging but were still much less than Macaranga trees.

A morphological comparison shows that most Macaranga species, in contrast with Mallotus species, have large hollow twigs that are occupied by ants and have larger, hairier, thicker, more toothed leaves with longer petioles, axillary inflorescences with more flowers, infructescences with more fruit, fruits that are smaller in size and smaller seeds.
Ecological energetics of populations of four sympatric isopods in a Hong Kong forest
Authors: Lam Paul K. S , Dudgeon David , Ma Herbert H. T.
Published: July 2009

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

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

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

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

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

Psittacanthus 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

The 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

The 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

Different 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

The 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

Rates 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

We 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

Hong 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

Reproduction 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

Intuitively, 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

The 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

Germination 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

Patterns 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

The 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

The 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

The 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

Bioassays 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

In 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.
Growth, recruitment and mortality in the Gama gallery forest in central Brazil over a six-year period (1985–1991)
Authors: Felfili Jeanine Maria
Published: July 2009

Diameter increments, recruitment and mortality were studied over a six-year period in a 3.02 ha sample in an area of 64 ha of undisturbed gallery forest alongside the Gama stream. The study site is located in Fazenda Água Limpa in Brasília, Federal District, Brazil. Trees ≥ 31 cm gbh (10 cm dbh) were measured every three years from 1985 in 151 (10 m × 20 m) permanent plots in Gama forest.

The mean annual diameter increment for trees ≥ 10 cm dbh was 0.25 cm y-1. Variability was high with coefficients of variationc.100% or more. Light-demanding and large upper storey species tended to grow faster than shade-tolerant and lower storey species. Mean increments for the community increased with increasing diameter classes.

The mean annual mortality rate for the community was 3.5% y−1while the recruitment was 2.7%. The community was dynamic with 86% of all species either suffering mortality or gaining recruits or both during the six years. The net difference between recruitment and mortality was zero for 55 species. The recruitment compensated for the mortality of most of the abundant species.
Variation in propagule mass and its effect on carbon assimilation and seedling growth of red mangrove (Rhizophora mangle) in Florida, USA
Authors: Lin Guanghui , Sternberg Leonel Da S. L.
Published: July 2009

We investigated the intraspecific variation in propagule mass within red mangrove (Rhizophora mangle) and its effect on carbon assimilation and seedling growth. Propagule sizes of red mangrove varied considerably at all three study sites along the south-eastern coast of Florida, with propagule fresh mass from 3.9 to 20.7 g for the scrub form and from 5.3 to 35.8 g for the tall form. Highly significant correlations were observed between propagule length and fresh weight at all three study sites and for two growth forms. The scrub form had significantly smaller propagules than the tall form. A greenhouse study showed that CO2 assimilation rates were not correlated with propagule mass, but total leaf area per plant increased significantly with increasing initial propagule mass in all three family lines of both the scrub and tall forms. Consequently, total carbon fixation rate by each seedling increased significantly with increasing propagule fresh weight in all cases, and the biomass increment significantly increased with increasing mass. Relative growth rate, however, was not correlated with propagule mass. The differences in leaf areas and biomass accumulation among seedlings from different sizes of propagules seem to have resulted from the differences in maternal reserve of hypocotyls. The considerable intraspecific variation in propagule size observed for red mangrove may have a significant effect on seedling growth and competitive ability.
Home-range size and territoriality inBolomys lasiurus(Rodentia: Muridae) in an Amazonian savanna
Authors: Magnusson William E. , De Lima Francisco Angelo , Sanaiotti Tania M.
Published: July 2009

Bolomys lasiurusis the only species of rodent commonly found in the savanna of Alter do Chão, central Amazonia. Peak densities during 42 months were less than have been reported from the cerrado biome of central Brazil. However, the population at Alter do Chão appears to be more stable than those in other areas and we never recorded zero densities. Many animals were captured over periods greater than 7 months, indicating that either mortality or dispersal was less than in previous studies. Mean home-range size of females was inversely related to the proportion of females that were gravid or lactating. Female home ranges were mutually exclusive and averaged 35% (SD = 8.2%) of male home ranges. Male home ranges overlapped extensively. Indices of home-range size varied seasonally and among years.
Seedling survival and growth of four Shorea species in a Sri Lankan rainforest
Authors: Ashton P. Mark S. , Gunatilleke C. V. S.
Published: July 2009

In this study four species of the genus Shorea section Doom were investigated. All occur together as canopy trees in the Sinaraja rainforest of south-west Sri Lanka. Partitioning of the regeneration niche can be one explanation for the co-existence of ecologically similar canopy tree species within a forest. Seedlings were planted in plots located in five zones that represent a range of forest groundstorey microenvironments found adjacent to and across canopy openings of three sites – valley, midslope, ridgetop. Experiments were designed to monitor survíval and growth of planted seedlings for two years. At the end of two years percentage survival was calculated, height increment recorded and destructive samples taken to measure dry mass gain of root, stem and leaves. Comparisons were made of establishment and growth performance of seedlings planted in the different plots and sites. Results demonstrated clear differences in survival and growth among species. These differences appeared related to availability of soil moisture and groundstorey radiation regimes. Disturbance patterns that determine species co-existence are suggested.
Comparison of three fruit census methods in French Guiana
Authors: Zhang Shu-Yi , Wang Li-Xin
Published: July 2009

Three census methods for studying fruiting phenology and fruit production were compared: platform observation, fruit-trap collection and raked-ground survey. The estimation of fresh fruit mass varied greatly with the census method used. Moreover, the fruiting phenology recorded using the fruit-trap collection and raked-ground survey methods showed a delay of one to two months compared with the platform observation method. Any of the three methods can be used for the approximation of annual fruiting phenology, but that of fruit-trap collection is suited to measure the annual fruit production, and that of platform observation offers the best estimation of the quantity of fruit in tree crowns at a given time.
Litter decomposition and nutrient release in a tropical rainforest, Southern Bakundu Forest Reserve, Cameroon
Authors: Songwe Nicholas C. , Okali D. U. U. , Fasehun F. E.
Published: July 2009

Decomposition of litter on the forest floor and of leaves of five species,Celtis zenkeri, Cola lepidota, Desbordesia glaucescens, Ceiba pentandraandTerminalia superbain nylon mesh bags, as well as wood decay were studied in the tropical rainforest at Southern Bakundu Forest Reserve, Cameroon.

The rate of loss of dry matter was fastest inCeltis zenkeriwhich was significantly different from the other species, while potassium was the most rapidly released element from all species with more than 50% being released in the first two months of the experiment. Nitrogen and phosphorus showed initial increases in bagged leaf litter independent of dry weight losses and while nitrogen was later released phosphorus continued to increase reaching 2–3 times the initial concentration. Decomposition constant (k) of litter on the forest floor was found to be 2.23 whereas the mean decomposition constants of the different species were as follows:Celtis zenkeri4.18,Cola lepidota2.18,Desbordesia glaucescens1.60 andCeiba pentandra2.16 for the two experiments.

Termites were found to have a very great influence on the decay of the wood ofTerminalia superbawith decay due to micro-organisms being negligible.
Relationships between rainfall, nesting habitat and fecundity ofCaiman crocodilus yacarein the Pantanal, Brazil
Authors: Campos Zilca , Magnusson William
Published: July 2009

Differences in rainfall between years influenced the proportions of different types of nesting habitats ofCaiman crocodilus yacareavailable near water bodies in a region of intermittent rivers (Campo Dora Ranch). In contrast, rainfall had little effect on the proximity of nesting habitat to water bodies in a region of isolated lakes (Nhumirim Ranch). There was a strong positive correlation between female body size and clutch size Snout-vent lengths of females on Campo Dora Ranch were significantly larger than those from Nhumirim Ranch which probably accounts for the larger mean clutch size than in the region of isolated lakes. Hatchling size was correlated with egg size, but there was no relationship between egg size and female size or egg size and clutch size.
Leaf-cutting ants and forest groves in a tropical parkland savanna of Venezuela: facilitated succession?
Authors: Farji Brener Alejandro G. , Silva Juan F.
Published: July 2009

Some savanna areas in the Orinoco Llanos region in Venezuela are characterized by the abundance of small forest groves, resulting in a parkland landscape. We hypothesized that forest groves are the result of colonization of the open savanna by forest species, facilitated by the activity of leaf-cutting ants. In this paper we present results from a field study conducted on an ecotonal belt between a deciduous gallery forest and an open savanna in the western Llanos of Venezuela. In seven transects, trees, groves and leaf-cutting ant nests were counted, size parameters evaluated and distance from grove to forest measured. Soil chemical analysis and microclimatic measurements were performed in the forest, grassland and groves. Floristic composition of the woodland component of the savanna (scattered trees) was very dissimilar from that of the forest, but the composition of the groves was essentially a mixture of both woodland and forest species. Woodland trees were present in all groves, whereas forest trees were present only in larger groves. The size structures of populations of the two types of trees differed significandy according to the size of the grove; also, woodland tree population structure differed significantly between open savanna and groves. The frequency of groves withAtta laevigatanests increased with the size of the grove, and groves with forest trees were positively associated with the presence of nests.A. laevigatanests improved the soil of groves, increasing N, Mg, Ca and organic carbon, but other soil properties were not modified. Temperatures at ground level in the dry season were ameliorated in the groves compared with the grassland, and this effect increased with the size of the grove. We concluded that a dynamic process of grove formation is facilitated by the aggregation of a few woodland trees, followed by the successful invasion of forest trees and a leaf-cutting ant nest. The results did not show any clear sequence of arrival of the ants or the forest trees, but it seems clear that these two would act synergistically, improving conditions for each other.
Movement patterns of five species of small mammals in a Brazilian restinga
Authors: Gentile Rosana , Cerqueira Rui
Published: July 2009

During the course of a population study of small mammals in a Brazilian coastal shrubland we calculated the movements between successive captures, the residence time, the indices of aggregation and the kinds of movements of the five most common species of small mammal. A capture-mark-recapture study was undertaken over two years, quarterly.Philander opossum, Akodon cursorandProechimys iheringipresented low mobility, with a high proportion of restricted movements, long residence time and larger coefficients of aggregation.Didelphis auritaandMetachirus nudicaudatuspresented higher mobility and exploratory movements, short residence time and small coefficients of aggregation. The species with lower mobility had permanent populations within our sampling grid, while the species with higher mobility used areas outside the grid, presenting no local populations but occupying portions of regional metapopulations.