Experiments were performed to investigate monthly variations in seed fate of Carapa procera (Meliaceae), a rodent-dispersed subcanopy tree species in French Guiana. A total of 600 thread-marked seeds were placed on the ground in mature forest under 20 adult trees during different months (March, April and May 1991) of the species' fruiting season. In 1991 the seed crop reached 1536 seeds in the study area, with a majority of seeds being produced in March and May. On average, seed removal rate steadily increased from March (23%) to May (96%). Of the seeds removed, the proportion eached almost doubled between March (28%)-April (25%) and May (48%), whereas the proportion eaten (gnawed) steadily declined between March (43%) and May (9%). Approximately 75–100% seed removal was therefore associated with intense scatterhoarding and low seed predation, especially in May. Greater seed dispersal rates occurred during the late wet season when fruit diversity decreased but when overall fruit biomass peaked because of fruiting occurrence of large-seeded species. The seasonal hoarding behaviour of rodents is discussed.

The root and trunk characteristics of species in a complex, lowland, evergreen, tropical rainforest at a seasonally inundated, coastal site on siliceous sands were examined. Roots in the soil were predominantly colonized by arbuscular mycorrhizal fungi although ectomycorrhizas were found on four species which contributed almost 25% of total basal area. Surface root mats were not a characteristic of the study site. In contrast, the ability to produce apogeotropic (upwardly growing) aerial roots which grew on and within the bark on trunks and branches was a consistent feature of the dominant species of trees in this forest. Eleven species representing eight families and constituting more than 85% of the basal area at the site produced these roots. Most trunks with DBH greater than 20 cm supported apogeotropic aerial roots produced by a range of species including themselves. Apogeotropic roots were most frequently found on the basal 0.5 m of trunks; however, they did occur up to 5 m above the forest floor. Apogeotropic aerial roots originated both from epicormic buds under the bark and from soil, and they were frequently colonized by arbuscular mycorrhizal and ectomycorrhizal fungi. There was a strong association between the ability to support these upwardly growing roots and the occurrence of laminated papery and flaky bark. We postulate that production of apogeotropic roots may provide a mechanism for nutrient uptake and root respiration during periods of inundation, for intercepting nutrients in stemflow and/or for extracting nutrients from bark.

The effect of canopy species dominance on understorey light availability in secondary forests was examined for Pentaclethra macroloba and Goethalsia meiantha, two common tree species with contrasting canopy architecture at La Selva Biological Station in the Atlantic lowlands of Costa Rica. In each of six 12- to 16-year-old successional stands dominated by one of these species, relative abundance and basal area of the focal species were determined within a 20 m × 50 m plot. Light availability at 1 m height was measured within each plot using a Licor-2000 Plant Canopy Analyzer at 27 locations and by analysing hemispherical photographs taken at 10 locations. Across stands, mean LAI values were significantly negatively correlated with canopy openness. Understorey microsites beneath Pentaclethra had significantly higher light availability than microsites beneath Goethalsia. Across stands, however, light availability was not correlated with either total basal area or stem density of trees ≥10 cm DBH. These results indicate that basal area and stem density of trees in the upper levels of the forest canopy are poor predictors of light penetration to the understorey. One hypothesis suggested here is that dense subcanopy and understorey vegetation in tropical secondary forests can strongly influence understorey light levels. Alternatively, light transmittance characteristics of the upper forest canopy may be influenced by species-specific differences in canopy architecture or foliage density that vary independently from tree diameter and density.

The growth habits of five species of hemiepiphytic fig trees (Ficus subgenus Urostigma) were compared to see if any species occupied distinct canopy positions or showed unique host preferences in lowland rain forest in Gunung Palung National Park, Indonesian Borneo. Highly significant differences among species were found in the height of establishment on hosts, the level at which fig crowns were deployed, and the size and taxa of host trees. Ficus stupenda, F. dubia, and F. subtecta all had mean establishment heights between 29 and 31m above the ground, had their crowns in the upper canopy, and predominantly occupied large trees in the Dipterocarpaceae. F. consociata and F. xylophylla established at significantly lower mean heights of 24 and 18 m respectively, had their crowns predominantly in lower canopy layers, and disproportionately occupied smaller non-dipterocarp trees. These patterns were consistent both within lowland forest on alluvial terraces, which was most intensively sampled, and when data were combined from three other contiguous lowland forest habitats. Ficus species appear to be specialized to some extent for distinct microhabitats within the canopy.

Seasonal variation in the consumption of cactus fruit by the bat Glossophaga longirostris was related to the availability of this resource in the arid pocket of Lagunillas in the Venezuelan Andes. When fruits were scarce, G. longirostris ate items not preferred in other seasons. The intraspecific flowering periods of the most common cactus species, Stenocereus griseus and Subpilocereus repandus, were synchronized but the number of flowers open per night was low. S. griseus and S. repandus had separate flowering and fruiting periods, possibly to reduce competition for dispersers and pollinators while providing food resources for bats throughout the year. G. longirostris is bimodally polyestrous with extended reproductive periods, probably as a response to the continual availability of cactus flowers and fruits. A strong interdependence between columnar cacti and G. longirostris was demonstrated. Sexual reproduction of the cacti would be greatly reduced without the bats, which in turn could not live in the arid study area without the food sources provided by these cacti.

Hong Kong has a native angiosperm flora of approximately 1800 species, of which 27% (482 spp.) bear fleshy, presumably vertebrate-dispersed fruits, including 76% of the 337 tree and shrub species and 70% of the 103 climber species. Morphological characteristics were determined for 255 species and nutritional characteristics of the fruit pulp for 153 species. Most fruit species were black (45.1%) or red (24.3%) and 85.9% had a mean diameter <13 mm. Nutritional characteristics varied widely between species with ranges and median values as follows: pulp percentage (range 10.0–99.2%, median 69.2%), water content of pulp (11.1–94.0%, 78%), lipid (0–84.0%, 2.0%), soluble carbohydrate (4–88%, 53%), nitrogen (0.2–3.4%, 0.86%), neutral detergent fibre (1–44%, 14.3%). Fruit development time (50–360 d, 156 d) showed a negative correlation with lipid content, but no significant correlation with fruit or seed size. Principal components analysis of fruit characteristics was dominated by a trend from single-seeded fruits with a thin, lipid-rich pulp layer to multiple-seeded fruits with much, watery, carbohydrate-rich pulp. Birddispersed species cover the full range of fruit characteristics except those too large to swallow and too hard to peck bits from. Mammals (bats, civets and/or macaques) are known or suspected to consume most of the fruits too large for birds as well as many bird fruits but none with high-lipid content. Summer fruits (May—September) were significantly larger and had significantly higher seed size and carbohydrate content than winter fruits (November-March). Winter fruits took more than twice as long to develop as summer fruits.

Two formicarial ant-plants endemic to Panama and adjacent areas of Costa Rica co-occur in mid-elevation cloud forest yet have distinctive modifications to house and feed small, retiring ants. Besleria formicaria (Gesneriaceae) hosts only Pheidole sp. which harvest the oil-rich seeds of its host and other plants and insect parts. Hoffmannia vesciculifera (Rubiaceae) hosts only Solenopsis sp. ants which obtain lipid and possibly other nutrients from vescicular tissues. Judging by their abundance in refuse deposits, fern sporangia appear to be a plentiful and evenly distributed resource exploited by both ant species.

Clusters of four circular forest plots, 0.2 ha in total area, were inventoried for canopy tree (≥30 cm gbh) and terrestrial herb floristic composition at 46 sites in the Central Catchment Nature Reserve, Singapore. The Nature Reserve covers a complex mosaic of lowland tropical forest of different successional stages, with much of the area covered in secondary forest 50–100 years old developed on exhausted agricultural soils. A total of 449 species of tree and 59 species of terrestrial herb were recorded from the clusters. Facultatively-terrestrial epiphytes were excluded from the analysis. Possible reasons for the low herb diversity are discussed. There was a marked similarity between ordinations (detrended correspondence analysis) of the clusters based on tree canopy composition weighted by species relative contribution to cluster total basal area and the herb flora composition, with a highly significant correlation between first axis scores of the two ordinations. Both ordinations showed the three clusters from freshwater swamp forest to be highly distinctive from the rest. The two forest strata exhibited a parallel response to the successional gradient, though the low diversity and patchy distribution of the herb flora blurred the distinction between primary and secondary communities more clearly seen in canopy composition.

The relationship between sepal and nut size of fruits was studied in fruit of 394 species of Dipterocarpaceae in Malesia and Sri Lanka. The fruits of many dipterocarps have long twisted sepals which have a role as blades for dispersal by gyration. But long sepals decrease resource allocation to other parts, and increase the chance of fruit being trapped in the canopy. The frequency distribution of the ratio of sepal length to nut length was bimodal. The gyrationdispersed group with longer sepals comprised 74% of Dipterocarpaceae studied. The group with short sepal mainly comprised understorey trees, but there were a few emergents. In both groups, sepal areas were expressed as a power function of nut volumes'. Because fruit weight per sepal area increases with fruit size, larger fruits fall more quickly than smaller fruits, and sepals of the former can not serve so effectively as propeller blades. This is consistent with the fact that a few emergent trees with large nuts have short sepals and are not dispersed by gyration. Therefore, the re-evolution of short fruit sepals appears to have been mainly due to two reasons: reduction of tree height and enlargement of nut size.

Root biomass, root lengths, and mycorrhizal associations were compared in a series of primary and Acacia-dominated secondary rainforest stands on nutrient-poor, red podzolic soils developed from low grade Palaeozoic metasediments. Five soil cores to 200 mm depth were collected at random locations from each of 20 sites. Ten of these sites were in 20–25 m high closed secondary forest (30–40 y old) dominated by Acacia aulacocarpa and ten sites were located in primary, selectively-logged, rainforest (28–32 m tall). Arbuscular mycorrhizas were the only form of association found in the primary forest sites. Ectomycorrhizas dominated the secondary forest sites although arbuscular mycorrhizas were also present. The primary forest sites had significantly higher root biomass (34.4 ± 17.8 t ha-1) and root length (33,400 ± 3,200 km ha-1) than the secondary forests (11.6 ± 4.6 t ha-1 and 25,200 ± 4,800 km ha-1 respectively), and this was interpreted as a reflection of the greater allocation of biomass to roots necessary to support the greater above ground biomass. The specific root length in the secondary forest (340 ± 119 cm g-1) was twice that of the primary forest (154 ± 65 cm g-1) indicating that the trees in the secondary forests achieved a degree of soil exploration which was comparable to that in the primary forest with less than half the biomass allocation to roots. The dominance of ectomycorrhizas in the secondary forest was associated with the prevalence of Acacia aulacocarpa, and the results cannot be extended to other secondary forests in the region. The implications that the dominant ectomycorrhizal associations have for the patterns of successional development and the patterns of species colonization in these Acaria-dominated secondary forests are discussed.