Atmospheric gains and hydrologic losses of calcium, magnesium, potassium, phosphorus and nitrogen for 25 tropical forest sites on a variety of geological substrates are reviewed. The data set comprised 19 lowland and six montane sites. Twenty studies were subjected to further analysis after initial quality control. These were subdivided into forests on (1) very infertile soils (N = 5), (2) (moderately) infertile soils (N = 5), (3) moderately fertile soils (N = 4) and (4) fertile soils (N = 4). Two studies pertaining to large river basins were treated separately. Although variation in nutrient fluxes was large, reflecting both natural and methodological factors, scatter plots of annual calcium, magnesium and potassium losses v. annual runoff for small catchment areas revealed four groups with characteristic nutrient export patterns that corresponded closely with soil fertility levels. Element losses from the two large basins were much higher than those recorded for small basins in the same areas and were interpreted in terms of depths of weathering front, river incision and root network. Phosphorus accumulated in virtually all cases, reflecting the low mobility of the element. Nitrogen budgets were generally very incomplete. There is a need for more and careful studies of tropical forest nutrient budgets, especially for nitrogen. Standardization of methodology is essential if comparability of results is to be improved.

In May and June of 1989 data on elephant (Loxodonta africana) dung density were collected in the main forested areas of the Central African Republic. A total of 147.0 km of line transects (N = 14 transects, = 10.50 km, SD = 3.79) was completed. Dung was recorded in 37.4% of the 294 sectors of 0.5 km each. The overall dung density was estimated to be 266 piles km-2 (= 382, SD = 383.7). The highest dung density was found in the proposed Dzanga-Sangha Reserve in the extreme south-west with 1166 piles km-2 (N = 12 sectors of 0.5 km). The south-eastern forests were found to have an intermediate dung density of 336 piles km-2 (N = 215 sectors of 0.5 km, = 419, SD = 308). In the eastern section of the south-western forests no dung was recorded along survey transects (N = 67 sectors of 0.5 km). These data indicate that elephant populations are still relatively high in the forests of south-western and south-eastern Central African Republic, while the population in the eastern section of the south-western forests has diminished to a very low level.

An assessment of carnivore species richness and food habits was carried out in a 100 km2 area of dry tropical forest in Huai Kha Khaeng Wildlife Sanctuary, Thailand. Twenty-one carnivore species of five families were found to be feeding on at least 34 mammal species, as well as birds, lizards, snakes, crabs, fish, insects, and fruits. Forty-four percent of the prey identified in faeces of larger carnivores, primarily leopards, consisted of barking deer, Muntiacus muntjak. Sambar deer, macaques, wild boar, porcupine, and hog badger were important secondary prey items. In faeces from small carnivores (< 10kg), murid rodents accounted for 33% of identified food items. The two most frequently encountered mammalian prey species were the yellow rajah rat, Maxomys surifer, and the bay bamboo rat, Cannomys badius. Non-mammal prey accounted for 21.3%, and fruit seeds for 12.4%, of all food items found in small carnivore faeces.

Nanophyes shoreae is a pre-dispersal fruit-predator of several species of Dipterocarpaceae. The timing of oviposition of this weevil was monitored in six trees in Pasoh Forest Reserve, West Malaysia from September 1986 to February 1987. A flowering event occurred during this period. Oviposition started within 12 days after peak anthesis, and continued within any one tree for 11–39 days. Host trees of N. shoreae flowered over a 75 day period. Intra-specific flowering synchrony was high but different species flowered sequentially. The behaviour of N. shoreae and the period of the oviposition ‘window’ strongly suggest that this pre-dispersal fruit-predator ‘tracks’ the sequence of flowering shown by its host species. The implications for predator satiation through mass-flowering of the Dipterocarpaceae are discussed.

Carollia perspicillata and Sturnira lilium are two species of abundant and widely distributed phyllostomid bats. Both are frugivorous and frequently found coexisting in the same areas. A study on feeding habits and morphology of C. perspicillata and S. lilium was conducted at Serra do Japi, Sấo Paulo, south-eastern Brazil, investigating the mechanisms associated with their coexistence. The two species are fairly similar in morphology and feeding habits. Analysis of faeces produced by captured bats revealed that there is a significant difference in diet between the two species. C. perspicillata tends to specialize in fruits of the genus Piper and S. lilium specializes in Solarium fruits. The fruiting periods of the four species of Piper eaten by bats at the study site are successive, with little overlap and high productivity. The species of Solarium have long and overlapping fruiting periods, with very low productivity. Piper and Solarium provide food resources almost all year, allowing the food specialization that may be an important mechanism of resource partitioning between C. perspicillata and S. lilium.

In Iropical seasonal forests, mass seedling death may incidentally occur early in the rainy season following untimely germination provoked by an isolated heavy rainfall. We hypothesized that, in a soil with little moisture retention capacity, irregular rainfall patterns would result in large fluctuations of water supply and, in the early wet season, drought episodes could cause seedling death. This hypothesis was tested in a seasonal tropical forest in Mexico where seedling density is low and the soil consists of almost pure sand with a low water retention capacity. Various patterns of simulated rainfall were applied in the forest to seeds and seedlings of three common tree species. Overall very little difference in germination and seedling survival was observed between the various rainfall treatments. The results showed that rainfall patterns and the soil texture may interact in a much more complex way than was initially hypothesized, and that water availability to seeds and seedlings is not necessarily predictable. The absence of seedlings of the three tree species might be better explained by high seed predation and low light level in the understorey.

A comparison is made of the light acclimation potential of seedlings of three canopy species of the tropical rain forest of Los Tuxtlas, Mexico: Cordia megalantha, Lonchocarpus guatemalensis, and Omphalea oleifera. These species showed similar growth rates in a range of microhabitats. Gap dynamics were simulated by transferring plants between three environments: beneath a closed canopy, a small gap, and a large gap. Plants of all three species were able to adjust their morphology and growth rates in response to changes in light availability. Growth rates increased when plants were moved to a (larger) gap, and decreased when plants were moved to a more shaded environment. Shade-grown plants were able to acclimate faster to increasing light availability than sun-grown plants to decreasing light availability. Also, plants moved from shady to sunny conditions showed higher relative growth rates than sun control plants, whereas sun-grown plants when moved to the shade showed lower relative growth rates than shade control plants. Species differed in their response to gap dynamics. Omphalea could not acclimate morphologically to shading, but reacted faster than the other species in response to the occurrence of a large gap. Acclimation potential seemed to be related to plasticity in physiological rather than in morphological traits. Suppressed seedlings of all three species performed well in the shade, and were able to acclimate rapidly to gap-conditions.

Ant species in the genera Chelaner, Meranoplus and Pheidole were found to be seed-harvesters in a tropical savanna woodland in northern Australia. Despite the availability of other seed types (legume seeds in particular were abundant), all five seed-harvesting species studied are specialists in that they store only grass seeds. Depot experiments, in which seeds were placed along foraging trails, also indicate a preference for grass seeds over legume seeds. At least for some ant species the handling efficiency of legume seeds may be less than that of grass seeds. Marked differences in seed composition of granaries were observed among different seed-harvesting ant species and among colonies of the same species at different sites. All ant species studied, except Pheidole sp. 1, stored only one type of grass seed in granaries at any site despite the availability of other seed types. This contrasts with studies conducted elsewhere in Australia in which generalist foraging by seed-harvesters was found to be common. With the possible exception of Pheidole, dietary specialization docs not appear to arise from a low diversity or abundance of seed supplies. In addition to differences in seed preferences, species of seed-harvesting ants also exhibited some differences in temporal foraging behaviour and some partitioning of resources may be occurring among these co-occurring species. Temporal overlap in foraging, however, was much greater than dietary overlap. The viability of granary seeds was very low for three ant species suggesting that seeds stored by these ants were largely predated rather than dispersed.

The red land crab (Gecarcoidea nalalis) is the major collector of fruits and seeds from the rain forest Moor on Christmas Island, Indian Ocean. At three sites, they rapidly removed fruits and seeds of 17 species tested (usually within 12 h after placement) and most were taken to crab burrows. Direct observations of seed predation, and application of estimated chelar forces of red crabs indicated that seeds of many species, especially those with thin seed coats, are likely to be killed through handling. However, removal of some resistant seeds to burrows may be favourable for seedling establishment when canopy gaps occur. Fruit removal rates by crabs were positively related to nitrogen concentration in fruit tissues but negatively correlated with condensed tannins. These observations suggest that seed predation by land crabs may affect the success of colonization and the relative abundance of plants on oceanic islands.

Soil mineralization and nitrification rates were measured in (1) undisturbed and felled gaps of varying size in terra firme forest, and (2) along a forest – savanna transect, on Ilha de Maracá in northern Brazil. Both rates were similar to those found in studies of other forests with a marked seasonal rainfall pattern. However, rates were much lower than those of tropical forests where there is little seasonality in rainfall. A major finding was that the highest rates were during the transition between dry and wet seasons, implying that wetting and drying may be an important initiator of soil nitrogen flux. Felling had little effect on either process up to a gap size of 2500 m2. In the forest-savanna study, nitrogen mineralization was lower in the savanna in all seasons, but in the wet season when the savanna soils were water-logged NH4+-N was immobilized. Experimental additions of nutrients identified two important results; first that added NH4+-N was quickly immobilized rather than nitrified – this may be an important nutrient conservation mechanism, and second that soil calcium appeared to be a limiting factor, either directly or through a pH effect.

The germination response of Uraria picta to five environmental factors was investigated. It germinated both in light and dark but germination in the light was significantly better than in the dark; there was further germination when seeds first placed in the dark were later brought into the light. It germinated well in the three soil types used but germination in humus and sand was significantly better than in red earth. There was an increase in germination with an increase in burial up to 1.5 cm, thereafter germination levelled off. There was no germination in water-logged conditions and there was an increase in germination as soil moisture decreased. Alternating temperatures of 31/21°C and 31/15°C favoured germination while 21/15°C inhibited germination. The results are discussed in relation to the phenology and distribution of the species.