The present study reports on the exploitation of the nectar of Mabea fistulifera (Euphorbiaceae) by two platyrrhine primate species (Brachyteles arachnoides and Callithrix flaviceps) in the Atlantic Forest of south-east Brazil. Nectar-feeding by both primates was observed between late April and May, during which a peak in the floristic activity of M. fistulifera was recorded, in terms of both the number of trees flowering and the number of flowers available on each tree. Phenological records indicate, by contrast, that edible fruit was relatively scarce during this period, the early dry season at the study site. On the days when nectar was consumed, it accounted for 25% of records of plant feeding for B. arachnoides and 29% for C. flaviceps, although the former species was observed nectar feeding over a much longer period. The evidence indicates that M. fistulifera is a valuable, but not essential resource for both primates at a time of year when edible fruit is relatively difficult to obtain. M. fistulifera, in turn, can be seen as an opportunistic plant whose floral characteristics permit pollination by a wide range of volant and non-volant vertebrates, including primates.

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.

Soil-vegetation relationships were examined in a tabonuco forest community in eastern Puerto Rico using canonical correspondence analysis. Ca and pH were strongly correlated with the first ordination axis (r = 0.84 and 0.76, respectively), while Mg and Na were correlated with the second axis (r = 0.65 and 0.64, respectively); other soil variables were not significantly related to the first two axes. Four previously identified soil series corresponded well with the ordination, and statistically significant differences in soil variables were found among the soil series. Dominant canopy tree species Dacryodes excelsa and Manilkara bidentata were negatively associated with the first ordination axis and positively associated with dry soils having low concentrations of Ca and Mg and low pH. The palm Presloea montana was positively associated with the first axis and with wet soils having high concentrations of Ca and Mg and higher pH values. Another canopy species Sloanea bertenana was associated with the second ordination axis and with lower slope positions having higher concentrations of Mg.

A representative sample of waterways in Liberia was surveyed for crocodiles, and all three species of African crocodiles were observed. Contrary to previous reports, only Nile crocodiles inhabit the Monrovia mangrove swamps and brackish-water mouths of rivers; there are no slendersnouted or dwarf crocodiles in these habitats. There is partitioning of habitats among the three species in Liberia: Nile crocodiles in mangrove swamps and river mouths (brackish water); slendersnouted crocodiles in rivers through rain forest (freshwater); and dwarf crocodiles in small streams through rain forest (freshwater), some entering the adjacent river. Dwarf crocodiles utilize burrows in the stream banks.

Nowhere are crocodiles abundant, and there is an apparent absence of adults. Although 40% of Liberia is forested, deforestation is occurring rapidly by foreign timber companies and slash-and-burn agriculture practised by the largely rural population. Hunting with firearms, although illegal, is widespread, both for subsistence and commercially, without concern for depletion. Mangrove ecosystems near human population centres are being destroyed. The combination of the above factors has apparently depleted the crocodile populations in Liberia.

This study demonstrates that forest elephants (Loxodonta africana) play a key role as seed dispersal agents for the upper canopy forest tree, Balanites wilsoniana. Seed that passed through elephants had a much greater probability of germinating (50.7%) than seeds from fruits eollected directly from the tree (3%). Of 515 seeds that were collected from under parent trees, 89.1% were rotten at the time of collection, 2.6% had been eaten by forest pigs, 2.8% had been killed by squirrels, and 0.7% had been killed by insect damage. The remaining 4.8% of the seeds were still alive. In 150 hours of focal observations on B. wilsoniana trees, two fruits were seen to be destroyed by squirrels, no fruits were seen to be consumed by potential dispersers, and no evidence of scatter hoarding was found. Experimental seedling stations placed out under parent trees and away from parent trees indicated no significant effect of dispersal on seedling survival. Although elephants are not essential for the successful germination of B. wilsoniana seeds, they do greatly increase probability of germination and play a vital role in their dispersal, suggesting that this is a highly interdependent plant-animal seed dispersal system.

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 the S. eridania outbreak 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 of S. eridania were recorded for the first time in Puerto Rico.

The survival, height and leaf production of seedlings and juveniles of Aspidosperma fendleri and Richena grandis were measured monthly for three years after germination. During the first year, some seedlings and juveniles of Aspidosperma fendleri were collected and the number of rootlets, the primary root length and the shoot: root ratio were determined.

Both species show periodicity in growth but their relative growth rate differs between species. For Aspidosperma fendleri, the highest relative growth rate (0.313 y-1) was found for individuals grown under greenhouse conditions followed by individuals growing in an old forest gap (0.143 y-1) and finally individuals under the forest canopy (0.137 y-1). For Richeria grandis, the relative growth rate under the forest canopy was 0.261 y-1. Leaf production for Aspidosperma fendleri in the forest (natural conditions) was 4.39 total mean leaf number for five years and 5.46 total mean leaf number under greenhouse conditions. For Richeria grandis it was 5.34 mean leaf production for four years. The root: shoot ratio for Aspidosperma fendleri was constant during the observation year. Aspidosperma fendleri showed a lower number of rootlets than did Richeria grandis. There was an inverse relationship between growth and survival during the dry season. During this period, mortality was higher and the highest mortality occurred during the first year when the total relative growth rate was highest.

Slow growth is evident in both species. This mechanism may represent an adaptive advantage to remain dormant until there is an opening in the forest canopy. Since the seeds of Aspidosperma fendleri and Richeria grandis are highly vulnerable to predators and pathogens, slow growth as seedlings and juveniles allows them to survive, and contributes to regeneration in cloud forest.

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.

The cohesion of the arthropod community associated with the rain forest tree Argyrodendron actinophyllum was studied in a warm subtropical rain forest in Australia. The distribution of most arthropods was contagious on the foliage of A. actinophyllum. Chewers and phloem-feeders were more clumped than epiphyte grazers and parasitoids. Arthropod predator-prey ratios were high and relatively constant over time, as revealed by measures of their activity. However, similar ratios in abundance and species-richness of arthropods foraging on foliage showed high variability in space and no consistent trends. Species associations on the foliage were difficult to predict and did not constitute either a single, well-united community or well-delimited subcommunitics. Most of the data suggest that on the foliage of A. actinophyllum, the cohesion of the arthropod community is not extremely strong. Apart from methodological constraints, possible reasons for this include the influence of host-tree phenology, and the high arthropod-diversity of the rain forest environment.