The abundance, richness and species composition of frog, reptile, bird and mammal faunas varied along an extensive gradient from 470 to 1406 mm annual rainfall, and between three contrasting soil types (clay, loam and sand) in northern Australia. Patterns varied between and within vertebrate classes. In general, the most fertile soils in the highest rainfall sites supported the greatest species richness and abundance, but this association with fertility broke down at lower rainfall sites. Frogs were richest and most abundant at high rainfall sites, especially on clay soils, presumably because these had greatest water availability. Clay soils supported few reptile species, but these were often at relatively high abundance. High rainfall sites supported the richest reptile faunas. On sand and loam soils, bird species richness varied little along the rainfall gradient, but richness declined very substantially on clay soils. This was probably largely due to the far more marked vegetation structural change on clay soils than on other substrates. Few mammals were reported, and no clear trends were associated with either rainfall gradient or soil texture. Turnover in species composition along the rainfall gradient was gradual and limited on sand and loam soils, but far more marked on clay soils. There were few cases of replacements of ecologically comparable species along the gradient. These patterns reflect the disparate history, fragmentation and landscape positioning of clay soil environments, relative to the far more homogeneous eucalypt-dominated vegetation on sand and loam soils. Although comparable studies are lacking on other continents, patterns revealed here may be idiosyncratic due to the virtual monopolisation by eucalypts of the environment across the very extensive rainfall gradient.

Fruit biomass and frugivore abundance were quantified over 3 y in a rain forest of the south Western Ghats, India. Fruit biomass was estimated by sampling fruit fall in the primary forest, and frugivore abundance by a 2.5-km transect. A total of 645 kg ha−1 of fruit was produced annually in the forest. Only 49% of this is edible to the frugivores and the remaining 51% is in the form of non-edible husks. Mammalian frugivores outnumbered avian frugivores and the majority of the mammals were seed predators. The total fruit biomass produced at Kakachi is lower than in the lowland forest and mountain forests in the neotropics but higher than in the wet sclerophyll forest of Australia. Lower diversity of trees and edaphic factors at Kakachi could be some of the reasons for these differences. On the other hand, paucity of fleshy fruits, low density of trees producing fleshy fruits and irregular fruiting of these species, account for the low number of obligate avian frugivores at Kakachi.

All dead trees ≥ 20 cm DBH were counted in the first 6 mo of 1994 in 10 ha of wet lowland rain forest, in the Hoja Blanca Hills, western Ecuador. The trees were classified by their mode of death. Thirty-four per cent of the trees were uprooted, 35% had snapped, 15% had died standing and 16% were unclassified. Regression analyses found that slope position and whether an individual was a dicotyledonous tree or a palm (Iriartea deltoidea) to be both strongly related to the mode of death. Slope, altitude and the presence of buttresses also influenced the mode of tree death. Tree diameter, however, was not found to have any effect. Dicotyledonous trees predominantly uprooted and snapped while Iriartea mostly died standing and snapped. Uprooted and snapped trees were significantly spatially clumped while trees which died standing were distributed at random. It was concluded that the predominance of uprooting and snapping in Hoja Blanca mostly resulted from the steep terrain and high precipitation (c. 5000 mm y−1) as well as El Niño Southern Oscillation (ENSO) downpours. The implications of mode of death are discussed. The different modes created different types of gaps and could thereby potentially influence forest regeneration.

The mechanism of general flowering in Dipterocarpaceae in the Malay Peninsula is revealed through field survey and meteorological data analyses. The regions of general flowering coincide with those which experienced a low night-time temperature (LNT) c. 2 mo before flowering. This supports the hypothesis that low air temperature induces the development of floral buds of dipterocarps. LNT was found to be caused by radiative cooling during dry spells in winter when the northern subtropical ridge (STR) occasionally migrates southwards with a dry air mass into the equatorial region. LNT events usually occur in La Niña episodes, not in El Niño episodes as believed previously. This is because the southward migration of the STR is associated with the intensification of local meridional Hadley Circulation in the western Pacific, which is strengthened in a La Niña episode. Results suggest that El Niño-like climate change in increased atmospheric carbon dioxide concentrations may be critical for the tropical rain forest biome in south-east Asia.

The spatial patterns of canopy tree and seedling life stages in the African Tropical Tree Milicia excelsa were examined to test the Janzen–Connell hypothesis (escape hypothesis). The Janzen–Connell hypothesis states that the mortality of seeds and seedlings is highest near the adult tree and declines with distance away from the adult tree of the same species. This hypothesis argues that this effect is partially responsible for maintaining the high tree species diversity of tropical forests. Solar radiation and fruit dispersal were investigated as possible explanations of observed patterns in seedling distribution. Milicia excelsa trees ≥30 cm DBH were found to be randomly dispersed and occurred at a density of ≤1 ha. Milicia excelsa seedlings were located in small clumps between parent trees and up to 150 m from parents at a mean density of 65 seedlings ha−1. Fruits were in abundance (>9000 on the ground) beneath female trees. Light levels at locations of natural seedlings ranged from 2–29% of full irradiance. Planted seedlings did not suffer greater mortality closer to adult conspecifics, and survived at light levels between 2–37% of full irradiance. Phytolyma spp., gall-forming psyllids which cause high mortality in Milicia seedlings in large openings and plantations, were not observed on any natural or planted seedlings, although galls were present in the crowns of dominant trees.

Reproductive phenology of 13 sympatric taxa of Chamaecrista in three sections was surveyed at Serra do Cipó, south-east Brazil. Mean abundance of flowers and fruits per plant and mean number of aborted, predated, and surviving seeds per fruit were estimated. Monthly average number of developed seeds per fruit multiplied by the monthly mean number of fruits per plant gave the monthly average number of seeds produced by a plant of each taxon. Five types of phenological behaviour were differentiated by cluster analyses according to the season during which each species produced most of its mature seeds. This behaviour was related to the taxonomic section to which the taxa belong, to plant architecture, to geographical range, to seed predation and to local climatic seasonality. Herbs were more affected by variation in rainfall than shrubs and trees. Two species did not show any clear seasonal behaviour. Widespread taxa produced most of their mature seeds in the rainy season or immediately after it, and all but one of the narrowly distributed species produced most of their mature seeds in the dry season or in the transition from dry to rainy season. Seed predation is probably not an important selective force affecting reproductive phenology of larger taxa, while the smaller taxa seemed too constrained by abiotic factors for biotic factors to influence their phenology significantly.

Seed dispersal of Guarea glabra and G. kunthiana (Meliaceae) in Monteverde, Costa Rica was studied to determine how seed predation and secondary dispersal affect the distribution of seeds available for recruitment. The arillate seeds are consumed mainly by birds that regurgitate or defecate the seeds intact. After dispersal, 45.6% of G. glabra and 26.6% of G. kunthiana seeds were buried 1–3 cm in the soil, presumably by scatterhoarding rodents such as agoutis (Dasyprocta punctata). G. glabra seeds that were not cached were eaten mostly by beetles, and 33.7% of the seeds remained cached after 12 wk. The cached G. glabra seeds did not germinate, however, perhaps as a result of experimental procedures used to mark the seeds. In greenhouse experiments, G. glabra seeds buried to mimic scatterhoarding had higher germination success than seeds on the soil surface. G. kunthiana seeds not cached were eaten by peccaries (Tayassu tajacu) and other seed predators (60%) or were inviable (10%). Only nine (7.5%) viable G. kunthiana seeds remained in caches after 12 wk. Secondary dispersal resulted in a rearrangement of the seed shadow. G. glabra seeds were moved to sites with less leaf litter and lower vegetation density, while G. kunthiana seeds were moved farther from conspecific trees and closer to fallen logs during secondary dispersal. Considering the high rates of seed predation in the field for both species, the germination advantages for G. glabra in the greenhouse, and the shifts in microhabitat during scatterhoarding, it is likely that secondary dispersal by scatterhoarding rodents is an important stage in Guarea recruitment.

RESUMEN. Dispersión de semillas de Guarea glabra y G. kunthiana (Meliaceae) en Monteverde, Costa Rica fureon examinadas para determinar como la predación de semillas y dispersión secundaria afectan la distribución de semillas disponibles para recrutamiento. Las semillas ariladas son consumidas principalmente por aves que regurgitan o defecan la semilla intacta. Luego de dispersión, 30–45% de las semillas fueron enterradas 1–3 cm en el suelo, posiblemente por roedores que disperan y acumulan como al agouti (Dasyprocta puncaata). Semillas de G. kunthiana que no fueron escondidas fueron comidas por pécaris (Tayassu tajacu) y otros predadores de semillas (60%) o no fueron viables (10%). Solo neuve (7.5%) semillas viables de G. kunthiana permanecieron en los escondites luego de 12 semanas. En contraste, semillas de G. glabra que no fueron escondidas fueron comidas mayormente por escarabajos que por pécaris, y 33.7% de las semillas permanecieron escondidas luego de 12 semanas. Las semillas esconditas de G. glabra enterradas para imitar dispersión y acumulión tuvieron una germinación mayor que semillas en la superficie del suelo. Dispersión secundaria resulto en un rearreglo de la sombra de semillas. Las dos especies experimentaron un leve aumento neto en la distancia promedio de conspecificos en frutos luego de dispersión y acumulación. Semillas de G. kunthiana fueron movidas cerca de troncos caidos durante dispersión secundaria, mientras semillas de G. glabra fueron movidas a lugares con menos lecho de hojas y baja densidad de vegetación. Considerando la alta proporción de predación de semillas en el campo para ambas especies, la ventaja de germinación de G. glabra en el invernáculo, y el cambio en micrambiente durante dispersión y acumulación, es posible que dispersión secundaria por roedores que dispersan y acumulan es importante in etapas de recrutamiento en Guarea.

Leafing, flowering and fruiting of the 24 most representative species of trees and shrubs in Sudanian savannas and fallows near Bondoukuy (Burkina Faso) were studied for 2 y (May 1992 to June 1994). The period of defoliation was generally brief, and leaf flushing, flowering and fruiting occurred mostly in the dry season. The phenological behaviour varied nonetheless across species and individuals. A classification taking into account synchrony/asynchrony and duration in foliation, flowering, fruit ripening and seed dispersal phases allowed comparison of species' phenological plasticity. Species were distributed along a scale of increasing plasticity, from trees to shrubs. Along this scale, species of the Leguminosae appeared to be separated from those of the Combretaceae, the latter being generally considered as characterising fallow farming systems. These results provide new evidence about the effect of phylogenetic constraints on the phenological behaviour of the woody species of the Sudanian savannas.

RÉSUMÉ. La feuillaison, la floraison et la fructification des 24 espèces d'arbres et d'arbustes les plus représentatives des jachères et savanes soudaniennes de la région de Bondoukuy (Burkina Faso), ont été étudiées pendant 2 ans (mai 1992 à juin 1994). La défeuillaison est généralement brève et l'émergence des feuilles, la floraison et la fructification se produisent principalement pendant la saison sèche. Les comportements phénologiques varient cependant entre les individus et entre les espèces. Une classification prenant en compte le degré de synchronisme ainsi que la durée de la feuillaison, de la floraison, de la maturation des fruits et de la dispersion des graines a permis de comparer la plasticité phénologique des espèces. Celles-ci sont distribuées selon un gradient de plasticité croissante des arbres aux arbustes. Sur ce gradient les Légumineuses se dissocient des Combrétacées, espèces qui sont par ailleurs généralement considérées comme caractéristiques des jachères. Ces résultats sont une nouvelle illustration de l'effet des contraintes phylogénétiques sur le comportement phénologique des espèces ligneuses des savanes soudaniennes.

The effects of tropical forest fragmentation on frugivorous and nectarivorous bats were studied on recent islands created by the flooding of a dam in French Guiana. Study sites include forest islands isolated by water, and control plots in nearby continuous forest. Studies began 1y before the onset of forest fragmentation and encompassed the first 3y after flooding. Forest fragmentation greatly modified the diversity and abundance of bats. Changes occurred more rapidly in the smallest fragments than in the largest one, and trends were remarkably similar among all the studied islands. Bat captures in islands were characterised by the scarcity of understorey frugivores. Differences in home range size and foraging strategies may explain why understorey fruit bat species are more sensitive to fragmentation than canopy ones. Changes in the frugivorous bat community may have indirect consequences on both the demographic and the genetic structures of plant populations inside forest fragments.

Although undisturbed tropical evergreen forests are often thought to be fire- resistant ecosystems due to lack of sufficiently dry fuel loads (Bond & van Wilgen 1996, Kauffman et al. 1988, Uhl et al. 1988), this myth is rapidly collapsing with the proliferation of recent forest fires throughout south-east Asia (Kinnard & O'Brien 1998, Leighton & Wirawan 1986), Central America (Anon. 1998a), and northern South America (Anon. 1998b) following unusually severe seasonal droughts.