The dispersal of seeds by howler monkeys (Alouatta seniculus) and the role of dung beetles in determining the fate of the dispersed seeds were studied at Nouragues Station, French Guiana, during three 2-mo periods (April–May, 1995–97). Howler monkeys were observed to disperse seeds of 47 plant species. Monkey dung attracted 57 species of dung beetles (Scarabaeidae), including tunnellers (maximum size 37 mm) and ball rollers (12.6 mm). The rate of seed burial was negatively correlated with seed size (10 plant species) and positively correlated with dung beetle size (six species of tunnellers). More than 80% of small seeds (< 5 mm) and 30% of large seeds (22 mm), were buried by the largest tunnellers. Dung beetles buried 13 to 23% of seeds ranging 8–13 mm in width. The maximum average depth of burial was 28 cm and varied according to the species of dung beetle. The rate of disappearance of large dung clumps varied during the day and was completed by nocturnal dung beetles. Seeds of Chrysophyllum lucentifolium (Sapotaceae) buried at 5 and 10 cm depths did not suffer predation, but showed low germination success compared to seeds left at the soil surface. Dung beetles affected the survival and distribution of a portion of the seeds dispersed by monkeys, and their relative importance in shaping seed fate depended on seed and beetle size.

Vegetative regeneration is an important component of forest recovery after disturbance. This study focused on the role of resprouting, both as root suckers and above-ground sprouts in comparison to seed regeneration (plants 30–130 cm tall), under different disturbance regimes, pattern with successional age and importance in mature forest. Differently aged forest fallows, a fire-degraded stand (Paraguay), differently aged logged stands (Venezuela) and mature forest in both sites were selected. In Paraguay, the percentage of resprouts declined from 76% in the young forest fallows (2–5-y old) to 48 and 14%, respectively, in the older forest fallows (10 and 15-y old) and mature forest. In Venezuela, by contrast, the proportion of resprouts from the youngest logged stand (5-y old) to the oldest logged stand (19-y old) and mature forest slightly increased from 10 to 16% and 17%, respectively. Root suckers were more common than above-ground sprouts in any of the sampled stands. In forest fallows, 38% of all species possessed both modes of regeneration, while 20 and 18%, respectively, were either found with above-ground sprouts or root suckers. In the fire-degraded stand, most resprouting species were observed with root suckers (28%), whereas species represented with either above-ground sprouts or both modes of vegetative regeneration were less common (7 and 14%, respectively). In logged stands, species reproducing by both means of vegetative regeneration were more frequent (20%) than the other groups (14 and 8%, respectively). In the mature stands in Paraguay and Venezuela, 42 and 14% of the species, respectively, were found with either or both modes of vegetative regeneration. In both sites, significant differences in the ability to resprout between growth forms were found. Of 301 resprouting individuals in Paraguay, 114 were found to be uncut stems, of these 108 produced root suckers andsix above-ground sprouts.

The energy budget of all fish populations was estimated in two small tributaries of the Paraná River (Paraná, Brazil). Total energy consumed by fish in the Caracu and the Agua do Rancho Rivers was 4.1 and 1.8 MJ m−2 y−1, and food items consumed were 2284 and 994.5 g wet weight m−2 y−1, respectively. The gross (K1) and net (K2) ecological efficiency coefficients were very low, but 43.2 and 59.6% of the total fish diet in these two streams, respectively, consisted of plant detritus. In both fish communities, omnivorous (opportunist) species dominated and specialists were rare. Although the Caracu River was more affected by human activity than was the Agua do Rancho, ecological efficiency coefficients calculated for the dominant fish populations were not significantly different.

Seed density and seed bank species composition were determined by germination trials on soils collected during the initial phase of deforestation in a Mexican tropical deciduous forest. The reference forest, pre-burn, 1-d post-burn, and 1-y post-burn soils contained 700, 1000, 70 and 3500 germinating seeds m−2, of 30, 30, 8 and 13 species, respectively. A total of 43 dicotyledonous species were identified. Percentages of herbs, vines, shrubs and small trees/shrubs were similar in reference forest, pre-burn, and 1-d post-burn soils; herbs were the most common growth form. Pasture conversion greatly altered seed bank species composition; 81% of the species that germinated from the seed bank before burning were absent from the seed bank 1 d after the fires. One-year post-burn soil was dominated by monocots; only 3% of the seedlings were herbs; no vines, small trees/shrubs or trees germinated. The reference forest and the pre-burn soils had 18 dicot species in common and the highest similarity index, 0.43; six of the shared species were herbs. One-day and 1-y post-burn soils had the lowest similarity index, 0.05. Burning the slashed forest and conversion to cattle pasture depleted the original seed bank, replacing it by one dominated by pasture grasses.

Examination of phenological patterns of tropical trees at different temporal and spatial scales can elucidate biotic and abiotic factors that correlate with fruiting, flowering and/or leaf set patterns. In this study, 3793 trees from 104 species in Kibale National Park, Uganda were monitored. The trees were selected from two sites (Kanyawara and Ngogo) separated by 10 km. Trees were monitored monthly to document community-wide and population-level fruiting and flowering patterns for a maximum of 76 mo. Analysis of two sites over a number of years permitted examination of generalities of patterns found on smaller spatial and temporal scales. Spectral analysis indicated that community-level flowering and fruiting at Kanyawara exhibited regular annual peaks, although the flowering peaks were of shorter duration. At Ngogo, community-level flowering also displayed regular annual peaks, but fruiting had an irregular pattern with no distinct peaks. The abundance of fruiting trees at Kanyawara was negatively related to the minimum temperature in the previous season (3–7 mo prior). Since fruiting tended to peak when the first wet season of the year was ending and the dry season was beginning, this suggests that the minimum temperature in the previous dry season is important in determining how many individuals fruit. Flowering at Kanyawara peaked immediately after the maximum annual period of high irradiance. Within-species synchronization was evident in the flowering for all species examined at Ngogo and for 64% of those at Kanyawara. Fruiting was synchronous within species for 64% of the species at both sites. Despite this general community-level synchronization, the months of peak fruiting and flowering for some species varied markedly among years. Furthermore, for a number of species the timing of fruiting or flowering events differed between Kanyawara and Ngogo. For some species, trends that were suggested from one year of data were not supported when additional years were considered. Although these two sites are close together, share many of the same species, and experience similar climatic regimes, many phenological patterns were site-dependent.

Plants potentially compete for seed dispersal. Selection may favour temporally segregated fruiting phenologies to minimize this competition and also to maintain resident populations of dispersal agents. Alternatively, selection may favour temporally aggregated fruiting phenologies when the effectiveness of seed dispersal agents varies seasonally or when large, synchronous fruit displays enhance dispersal. These evolutionary scenarios assume that plants share seed dispersal agents. This assumption and temporal overlap in fruiting phenologies were evaluated for the Miconia and Psychotria of central Panama. These two genera accounted for 18 and 27%, respectively, of 1096 fleshy fruits found in regurgitation or faecal samples taken from 2054 birds of 103 species netted in the forest understorey. Two species of manakins accounted for 62% (123/200) of all Miconia fruit taken. Three species of manakins and three species of migratory thrushes accounted for 97% (282/292) of all Psychotria fruits taken. There is a high potential for intrageneric competition for seed dispersal for both plant genera. Null model analyses showed that the fruiting phenologies of Miconia (14 species) are segregated in time, while fruiting of Psychotria (21 species) is highly aggregated. The Miconia were found in up to 24% of the diet samples for the two manakin species, suggesting that Miconia may be a critical resource for both species. The Psychotria fruited when the diversity of understorey fruits was greatest, suggesting a high potential for both intra- and extrageneric competition. The abundance and nomadism of the six bird species that consumed most Psychotria fruit peaked when the Psychotria fruited, supporting the enhancement hypothesis.