The variations in macronutrient concentrations of the leaves of Terminalia superba and Pycanthus angolensis were studied and the concentrations of nutrients in leaves before abscission were compared with those after abscission. The amounts of nutrients returned to the forest floor were also computed from litter fall data at the start of maximum annual fall in the Reserve. With the exception of potassium in Pycanthus angolensis, there were significant variations in the nutrient concentrations of the two species with the time of year. With increasing leaf age the concentration of nitrogen, phosphorus, potassium and magnesium declined in Terminalia superba while magnesium concentration decreased in Pycanthus angolensis leaves. Furthermore, calcium showed an increasing concentration in Terminalia superba with increase in leaf age. The concentrations of nitrogen, phosphorus and potassium decreased before leaf fall. Estimated losses in nitrogen phosphorus and potassium before abscission were 44, 53 and 50%, respectively, whereas generally there was an increase (40%) in the concentration of calcium at leaf fall. Magnesium did not follow a definite pattern. The return of calcium through litter fall to the forest floor was the greatest of all the major elements. The distribution and variation of foliar nutrient concentrations in the leaves of Terminalia superba and Pycanthus angolensis and the importance of the amount of litter and the concentration of the various nutrients in the influencing soil fertility are discussed.

The red crab Gecarcoidea natalis is the most abundant land crab on Christmas Island, Indian Ocean, and is found wherever native rain forest is still intact. The largest crabs grow to > 120 mm carapace width and reach > 500 g in mass. Red crabs are diurnally active, and moisture appears to be the most important factor governing surface activity – activity was nil below 77% RH, relatively low at 87% RH, and high above 95% RH. The crabs retreat to the interior of their burrows during dry periods, but emerge rapidly in response to rain. Because of their dependence on moisture for surface activity, red crabs show greater levels of activity during the wet season. Annual breeding migrations and moulting activity decreased the density of surface-active crabs at the main study sites for several weeks at the start of the wet season, and fruit and leaf fall caused dramatic local increases in the density of active red crabs. Density and biomass at the main study sites averaged 1.3 crabs m-2 and 1454 kg ha-1, respectively, and 1.2 crabs m-2 and 1137 kg ha-1 at a total of five sites across the island. Rough calculations suggest that the island-wide population is at least 100 million individuals. Red crabs are the dominant consumer on the forest floor, and consume seeds, seedlings and leaf litter. Because they are both abundant and widespread, these animals have the potential to be the most important determinant of pattern and process in rain forest on Christmas Island.

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

A seed-removal experiment was conducted to assess the role of Proechimys semispinosus (Central American spiny rat) as potential predator and disperser of Astrocaryum standleyanum (black palm) seeds. One hundred fresh ripe A. standleyanum fruits were placed in semipermeable cages on each of 14 small islands in Panama, and seed disappearance rates were calculated for each island. Spiny rat density and biomass were determined by live-trapping on each island for 5 consecutive days and 4 nights. Censuses of fruiting trees were conducted on each island to control for effects of food availability on removal of palm fruits. Disappearance rates were related positively to total spiny rat density, density of adult and subadult spiny rats, and spiny rat biomass, but the density of fruiting trees accounted for very little variation. Spiny rats evidently prey heavily on A. standleyanum seeds, based on the high removal rates and on feeding observations of captive individuals. Since spiny rats may scatterhoard A. standleyanum seeds, they may also function as effective seed dispersers if seeds are removed to favourable germination sites unavailable to other seed predators. Results indicate that spiny rats, because of their abundance and wide distribution, may be important but overlooked predators and dispersers of A. standleyanum seeds and of other large-seeded tree species.

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

The effects of escape distance to parental trees and tree clusters on the removal of Brazil-nut seeds (Bertholletia excelsa, Lecythidaceae) by vertebrate seed predators were examined in an entirely undisturbed stand of Brazil-nut trees of eastern Amazonia. Population density estimates, based on line-transect censuses, are also presented for Bertholletia trees and agoutis (Dasyprocta leporina), the most important scatterhoarder and seed predator of Brazil-nuts at this site. Seed removal experiments were conducted within and outside a natural Bertholletia tree cluster (castanhal) during both the wet and dry seasons. While there were no within-cluster effects of escape distance from parent trees on seed removal rates, overall seed removal within the cluster was significantly greater than that well outside the cluster. Moreover, removal rates in the wet season were consistently higher than those in the dry season both within and outside the tree cluster. Results suggest that the probability of early seed survival for Bertholletia, in relation to distance to seed sources, operates on different spatial scales, and that seed predators allocate greater foraging effort to scattered seeds during the fruitfall (wet) season, when buried seed stocks are being cached by agoutis.

The fate of seeds of eight tree species was followed during 4 y of storage in the soil of an Afromontane forest at Gara Ades in the eastern highlands of Ethiopia. Seeds were enclosed in nylon mesh bags and buried at 5 cm soil depth. The bags were exhumed at intervals and the viability of the seeds was assessed by germination and cutting tests. Seeds of Bersama abyssinica and Ekebergia capensis germinated in the soil almost completely within a year after burial. The seeds of Juniperus procera, Olea europaea and Podocarpus falcatus also germinated to a substantial degree in the soil but with a distribution over several years, and some seeds of these species remained viable at the end of the 4-y period. Germination in the soil was very low in seeds of Acacia abyssinica and Croton macrostachyus throughout the whole burial period and the seeds kept their viability. In C. macrostachyus fresh seeds were highly dormant, but after 3 y or more in the soil they germinated readily in the laboratory suggesting an altered dormancy with time in the soil. Dormancy in seeds of A. abyssinica and Indigofera rothii was not altered throughout the study period as evidenced by marginal or no germination during incubation in the laboratory. The differential seed behaviour observed during storage in the soil can be an indicator of the regeneration strategy of the species studied. B. abyssinica, E. capensis, J. procera, O. europaea and P. falcatus form seedling banks on the forest floor and lack persistent soil seed reserves in contrast to A. abyssinica, C. macrostachyus and I. rothii which accumulate reserves of long-lived seeds in the soil. The generally high levels of dormancy and somewhat extended viability in the soil, even in several of the species producing seedlings in undisturbed forest, may have been selected for under a climate of seasonal drought and unreliable rainfall that characterizes this region.

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

The change of mound structure of the fungus growing termite, Macrotermes gilvus, which has no clear air passage system in the mound, was examined in relation to the mound growth in a rubber plantation of southern Thailand. The nest proper consisted of the hive with a royal chamber and nursery, and diffused chambers with fungus combs. The location of the hive became higher with the growth of the mound. Therefore, colonies with a very large mound utilize only the upper mound part and this may be due to the lack of air passage systems in this species. A colony with a very large mound is not in reality commensurately large in colony size and this may be the reason why the density of huge mounds of M. gilvus in Thailand is much higher than that of Macrotermes in Africa.