Bee colonies in lowland forest in Panama were monitored for pollen and nectar harvest, pollen species utilization and nectar quality and quantity per returning forager. Despite sharing most pollen resources and nectar of the same quality with 20 introduced colonies of the African honey bee (Apis mellifera), native stingless bees of 12 species were largely unaffected by its activity. Pollen and nectar harvested by the honey bees were 10–200 times that procured by 17 stingless bee colonies. This discrepancy in total harvest and general lack of competitive effect is explained by a honey bee foraging area over 10 times that of the native bees, and apparent foraging shifts to escape competition with honey bees, thus reduced potential overlap in foraging sites.

Seven cases of direct resource competition for pollen or nectar were documented, out of 31 tests. Rare periods of intensive harvest were diminished by competing African honey bees. Such harvest peaks lasted for only a few hours in 13 days of observation. Despite average duration of 4% foraging time for each species, peaks included as much as 51% total harvest. Calculations based upon colony populations, food stores and flight range show that if African honey bees persist at a density of 1 colony per km2, colonies of some stingless bee species may disappear after 10 years. Their chances of escaping food competition by taxonomic specialization on flowers seem slight.

Community structure, macrohabitat selection, and patterns of species co-occurrence were examined during a 14-month study of small mammals in the Cerrado Province of central Brazil. Data were collected from mark-recapture grids in brejo and gallery forest, and from live-trapping and specimen collection in all habitat types within cerrado (campo limpo, campo sujo, cerrado [s.s.], cerradão, brejo, valley-side wet campo, and gallery forest). Gallery forest supported the highest species richness, most complex vertical distribution of species, highest level of trophic diversity, and highest macroniche diversity. Degree of habitat selection varied widely. All habitat types supported both rodents and marsupials, although marsupials tended to be much less common in the grasslands (campos) than in woodlands (cerrado) and forests (cerradão, gallery forest). Some species, such as Didelphis albiventris, occurred in all habitat types, while others were much more restricted. Oryzomys bicolor, for example, ocur-red only in gallery forest. No habitat type had a completely distinct fauna: overlap in species composition always occurred with at least one other habitat type. Because of the great variability of habitats, and the fact that subsets of the mammal fauna were frequently habitat specific, the overall species richness of any portion of mixed cerrado vegetation is remarkably high.

A study of the benthic leaf litter community of the Tarumazinho, a central Amazonian stream (03° S, 60° W) is presented. This small tributary of the Rio Negro is of the blackwater type with a very low nutrient content. The sampling stations were towards the mouth of the tributary where it flowed through annually inundated forest and the work was carried out during the low water season. Previous studies concluded that these acid waters were of very low productivity and held impoverished faunas. However, this study showed that leaf litter banks held a diverse aquatic community of unexpectedly high biomass. This was because the banks supplied food and shelter and were available during the low water period when other habitats had dried out. The macrofauna was dominated by fish and shrimps. From an examination of gut contents a food web was produced. Primary consumers were found to take mainly detritus and fungi and it was concluded that allochthonous inputs were the main source of energy and nutrients. No feeding specialists were found and all the predators took prey from more than one trophic level.

Samples of 29 distinct larval forms of anurans were collected in streams flowing through primary rain forest at Nanga Tekalit, Sarawak, at three periods spaced over 22 years. This assemblage of tadpoles lives in torrents, riffles, shingle areas, open pools, leaf drifts, protected side pools, potholes in rocky banks, bank seepages, and pools of small intermittent streams. Positive associations of species in types of microhabitats and co-occurrence within sites lead to recognition of four taxonomically heterogeneous groups: one concentrated in leaf drifts; one using riffles, shingle areas, and open pools; one concentrated in potholes; and one using side pools and potholes. Most pairs of larval forms having strong negative association are characterized by differences in morphology and feeding behaviour; they show little evidence of competitive relations. Between-sites variation in species composition differs among the types of microhabitats, leaf drifts showing the least amount of variation. Species composition within a site shows less change over intervals of 1–5 days than over intervals of 13–18 days. Variation in species composition is greater between sites than within sites over intervals of 9–31 days. Organization in this community seems to be effected by three factors: reproductive behaviour of adults and morphological and behavioural adaptations of tadpoles.

Tropical rain forest is described as a mosaic of ecologically uniform patches. A method is proposed to recognize and inventory the patches and to draw mosaic maps, based on the size and architecture of canopy trees. Mosaic maps from three different forest localities in Indonesia are compared in terms of the relative area occupied by each kind of patch, and the surface range and number of constituent patches. The comparison shows that the mosaic patterns are specific to the sites and can be used for the characterization of patch dynamics in different forest types. Possible implications for forest management are discussed in the light of the mosaic maps.

Campos de murundus (earthmound fields) are common throughout the cerrado (savanna) in Brazil. They have a clearly defined distribution particularly where they are associated with ground water. There is a distinctive woody vegetation on the discrete mounds contrasting with surrounding grass-covered depressions.

After a reconnaissance ground and air-photograph survey of the nature and distribution of mounds within the Federal District, four one-hectare plots were chosen for detailed study within the ecological reserve of the University of Brasília. Measurements were made of the size, shape and frequency of mounds. Numbers varied from 26 to 61 ha-1 with a uniform distribution occupying 10–50% of the plots. Heights ranged from 0.05 to over 2 m. The generally semi-elliptical shape in ground plan had an average size of 7 by 5.5 m with no evidence of preferred orientation although water scouring from runoff partly influences the morphology. Volumes varied from 0.01 m3 to 141.5 m3. The soils of the murundus differed from those of surrounding depressions by being better drained, with bright colours and strong cohesive structures; they were more argillic with lower base saturation and pH values. Such sites favour colonization both by cerrado plants and by termites. A classification of the murundus is postulated. Although this paper does not consider the origins of murundus, they appear to relate more closely to drainage and differential erosion than to termite activity.

Fleshy fruits collected from abundant woody plants on the Accra Plains, Ghana, were fed to frugivorous species common in the area. Seeds of each plant species were retrieved from each frugivore species for germination trials, and ingested seeds compared to fresh seeds in germination percentage and rapidity. Altogether 85 plant X animal feeding combinations were attempted. In 73% of trials, ingestion did not affect germination percentage; the remain-ing trials were about equally divided between significant increases and decreases. Ingested seeds had significantly faster germination in 12%, and significantly slower germination in 8%, of the trials. Germination percentages in all samples of fresh seeds ( = 37%) did not differ signifi-cantly from those ingested seeds ( = 31%).

There was a significant association between the effect of ingestion on both germination rapidity and percentage (significantly increased, decreased, or neither) and the plant species involved; there was no such association between the effect of ingestion and the animal species. Animals had inconsistent and frequently negligible effects on germination. Two-way analyses of variance (plants X animals) of germination percentage and of germination improvement showed that plant species were a significant source of variation and animal species were not. The fleshy-fruited plants of this assemblage are not generally dependent upon animals for successful germination of their seeds.

Concentration of CO2, above and below the soil surface and δ13C values of plant tissues, soil litter and organic matter were measured in a caatinga forest of the upper Rio Negro basin in southern Venezuela. CO2, concentrations near the forest floor were consistently higher than in the atmosphere. CO2, gradient in the soil was very steep probably because of the poor aeration in this flood-prone forest. δ13C values of plant tissues showed a clear pattern with lower values in the ground herbaceous plants and under-canopy trees. Tree seedlings showed δ13C values similar to the upper-canopy trees indicating their dependence on reserves carried in the seed from the mother tree. Decomposing litter and soil organic matter also showed δ13C values similar to the upper-canopy trees. It is suggested that lower δ13C values of the shade flora result primarily from the assimilation of CO2, depleted in δ13C originating from soil respiration. Probable effects of low light intensity and physiological factors are discussed.

The rates of water loss and humidity preference of carabids from dry tropical habitats have been studied and compared with corresponding data from temperate carabids and tropical tenebrionids. Within each group of beetles the rate of relative water loss decreases with increasing body size. Carabids from dry tropical areas have rates of water loss which are lower than those of temperate species, but considerably higher than the values for tenebrionids from dry tropical habitats. Small temperate carabids can stay in dry air for only a few hours, whereas large tropical tenebrionids may survive for weeks without becoming critically dehydrated. Given the choice between a dry and a humid atmosphere, well hydrated beetles of all groups will initially choose the dry atmosphere. Most temperate carabids will switch to humid atmosphere after a few hours and tropical carabids after 1–3 days, whereas tropical tenebrionids may remain in dry air for almost 3 weeks. The temperate carabids are very sensitive to dehydration and will shift to a humid atmosphere when dehydrated by only 2–5%. Tropical carabids and tenebrionids will shift first when they are dehydrated by 7–20% of their body weight in a hydrated state, implying that these beetles are considerably less sensitive to water loss than temperate carabids.

Phenological observations were made in a Sumatran rain forest during three years (1980–1982). Phenological changes followed a consistent seasonal pattern. The abundance of young leaves and the fall of leaf litter peaked between December and February (first dry season); flowers were most abundant between January and April (first dry and first wet sea son), and ripe fruits in July-August (the second dry season). The fruit of strangling fig trees showed peaks in April and October, both wet season months. Within the study area there was variation in both the phase and the amplitude of the phenological cycles. One year, 1981, displayed mast flowering and fruiting. The observations indicate that the conditions for production were better during the mast year, a finding that facilitates our understanding of the evolution of mast fruiting.

East African tenebrionid beetles of the species Zophosis congesta are active on sun-exposed surfaces in dry habitats during the hottest part of the day, when most other animals have retreated to protected areas. They remain on the surface at ambient temperatures up to 65°C which is 15°C above their highest tolerated body temperature. The beetles appear to regulate their body temperature behaviourally. They frequently rest and cool in the shade, and after each cooling period they remain on the sun-exposed surface until the heat influx from the environment has caused the body temperature to rise close to the lethal level. They have relatively low rates of transpiratory water loss, and appear unable to depress their body temperature by means of evaporative heat loss. The rate of metabolic production of water amounts to only about 20% of the rate of transpiratory water loss. Thus, the beetles depend strongly on water intake from dietary sources. The advantage of this type of activity pattern is probably avoidance of predators.

Plant and soil samples collected from four tropical forest areas were used to examine the correlation between the chemical abundances in soil and vegetation. On fertile soils in Panama and Colombia soil concentrations of copper, manganese, cobalt and zinc were correlated with plant concentrations. Calcium, caesium, iron, lead, magnesium, phosphorus, potassium, sodium and strontium-concentrations were not correlated. Factor analysis of plant chemistry at nine sites showed very little commonality between sites, even of vegetation belonging to the same plant association. A copper, manganese, cobalt, zinc factor was not recognized except in one case. A similar study of plant soil correlation in Colombia supported the conclusions from Panama; for most elements there was little evidence for significant correlation between plant and soil concentrations.

Analysis of plant-soil relationships on very infertile latosols with terra firme forest in the Amazon at San Carlos de Rio Negro, Venezuela and Manaus, Brazil revealed a soil effect on the statistical distributions of the elements in the plant biomass. This effect was strongest on the least fertile site at Manaus and was strongest for essential elements. The pattern of chemical distributions appears to be due to the fact that some species are capable of concentrating high levels of elements even under conditions of very low supply in the substrate.

Praying mantids (Insecta: Dictyoptera, Mantodea) attracted to light at a savanna site in Ghana (Legon) were studied over 34 months. 1771 insects of 26 species were recorded, most of which were males. There was a gradual decline in numbers during the study, which was probably due to habitat deterioration. Significantly more mantids were attracted to light on new moon nights than when the moon was full. For the second commonest species, Sphodromantis lineola, a significant correlation was found between mantid numbers and rainfall per month. Some species appear to have two peaks of abundance per year, others only one, while the commonest species, Miomantis paykullii, shows no clear seasonal pattern, but longer term studies are required to confirm these tentative conclusions.

Three measures of diversity are calculated and compared with mantid data from elsewhere in the tropics. Diversity at Legon was found to be very similar to that at Lamto, Côte d'lvoire, despite different methods of collecting the insects, but the mantid fauna of Panama is less diverse than at the two African sites. Suggestions to account for this result are presented.

Diurnal and nocturnal censuses were conducted on animal visitors at a single strangler Ficus aff. cotinifolia (H.B.K.) tree during the entire period of ripe fruit availability. Fruit fall to the ground was measured with fruit traps, and chemical analyses were conducted on the figs. Fourteen species of birds, four species of nonvolant mammals and two species of bats consumed the figs. Of the total number of ripe figs accounted for during the sampling period (N= 1.9 X 105), 42% fell to the ground, 45% were removed by mammals and 13% by birds. Frugivores such as the howling monkey Alouatta palliata, the cacomistle Bassariscus sumichrasti, the keel-billed toucan Ramphastos sulphuratus and fruit-eating bats removed the largest amounts of figs from the tree and deposited seeds of 13 plant species other than figs below the tree crown.