Interactions among fleshy fruits and frugivore assemblages are presented from a 1-y study in the littoral forest of Sainte Luce, south-eastern Madagascar. This community-level approach allowed us to determine food selection by all consumer species and to evaluate the role different frugivores play in seed dispersal and predation. For this, interactions between 136 consumed fruit species and 13 frugivorous species were studied. Fruit and seed size were the most important physical factors determining food selection of all consumer species. Nutritionally birds favoured and mammals avoided lipid-rich fruits. For Cheirogaleus spp., that go into torpor, there was a trend to select sugar-rich fruit pulp. However, for numerous fruit traits the consumer species had no clear feeding preferences and they seemed to be quite flexible, eating whatever was available. This might be related to unpredictable fruit availability and low fruit productivity in the littoral forest, which may also partially explain the low number of frugivores present. Nevertheless frugivores have different impacts on seed dispersal. Eulemur fulvus collaris is particularly important for the dispersal of large-seeded species, while frugivorous birds and flying foxes ensure plant regeneration between and outside forest fragments. In terms of conservation, heterogeneous seed transport is particularly important for this severely degraded littoral forest.

Occasional strong droughts are an important feature of the climatic environment of tropical rain forest in much of Borneo. This paper compares the response of a lowland dipterocarp forest at Danum, Sabah, in a period of low (LDI) and a period of high (HDI) drought intensity (1986–96, 9.98 y; 1996–99, 2.62 y). Mean annual drought intensity was two-fold higher in the HDI than LDI period (1997 v. 976 mm), and each period had one moderately strong main drought (viz. 1992, 1998). Mortality of ‘all’ trees ≥10 cm gbh (girth at breast height) and stem growth rates of ‘small’ trees 10–<50 cm gbh were measured in sixteen 0.16-ha subplots (half on ridge, half on lower slope sites) within two 4-ha plots. These 10–50-cm trees were composed largely of true understorey species. A new procedure was developed to correct for the effect of differences in length of census interval when comparing tree mortality rates. Mortality rates of small trees declined slightly but not significantly between the LDI and HDI periods (1.53 to 1.48% y−1): mortality of all trees showed a similar pattern. Relative growth rates declined significantly by 23% from LDI to HDI periods (11.1 to 8.6 mm m−1 y−1): for absolute growth rates the decrease was 28% (2.45 to 1.77 mm y−1). Neither mortality nor growth rates were significantly influenced by topography. For small trees, across subplots, absolute growth rate was positively correlated in the LDI period, but negatively correlated in the HDI period, with mortality rate. There was no consistent pattern in the responses among the 19 most abundant species (n≥50 trees) which included a proposed drought-tolerant guild. In terms of tree survival, the forest at Danum was resistant to increasing drought intensity, but showed decreased stem growth attributable to increasing water stress.

A severe outbreak of Lepidoptera followed the 1997–98 El Niño Southern Oscillation event, during which the climate in central Panama was unusually dry. The outbreak involved the larvae of at least 12 species of Lepidoptera and occurred at a seasonally dry, deciduous forest site, where extensive background data were available regarding climate, tree species and non-outbreak herbivory levels. Most Lepidoptera were associated with only one or two larval host plant species belonging to the same family, and the majority were monophagous during this study. During the outbreak, caterpillar densities for the major outbreak species averaged 1.6 larvae per young leaf and 0.18 larvae per leaf for leaves of all ages. For canopy trees and lianas, the mean level of leaf damage was 13.8%, ranging from 1–100%. Seven out of 20 tree species sustained most of the damage, with 21–37% of the leaf area consumed. Relative to non-outbreak years, damage levels increased by more than 250% during the outbreak. Single-species outbreaks were observed in other areas with a similar drought, but wetter forests in central Panama did not experience outbreaks during this period. Historically, fewer outbreaks have been reported from tropical forests than from temperate forests, however, similar El Niño-related outbreaks have occurred recently in several other locations throughout the tropics.

Many studies have shown that plant or bird invasions can be facilitated by native species, but few have demonstrated the possibility of a positive interaction between introduced species. We analysed the relationships between four invasive alien fleshy-fruited plants, Clidemia hirta, Rubus alceifolius, Lantana camara, Schinus terebinthifolius, and an invasive alien bird, the red-whiskered bulbul Pycnonotus jocosus introduced to Reunion Island (Indian Ocean). We compared the distribution of food items in the bulbul diet according to seasons and to abundance classes of this bird. Pycnonotus jocosus is mostly frugivorous and frequently eats the main alien plants (more than 80% frequency of food items). Sites with alien species, such as Clidemia hirta, providing fruits throughout the year supported more birds than sites providing fruits, such as Schinus terebinthifolius, seasonally. The birds facilitated seed germination by removing the pulp of fruit: the final per cent germination (FG) of cleaned seeds was higher than those within the fruit for three of the four plant species and in some cases passage through birds significantly increased FG (Schinus terebinthifolius) or Coefficient of Velocity (CV) (Lantana camara).

The dependent flora was surveyed on 20 trees at a 1.5-ha site in montane rain forest at 2600 m altitude in western Venezuela. Vascular species were recorded over the whole site and totalled 120 epiphytes, 21 climbers, 3 hemiepiphytes, 5 nomadic vines and 6 mistletoes. Non-vascular species were recorded within 95 sample plots and totalled 22 mosses, 66 liverworts and 46 macrolichens. The angiosperm species were restricted in geographical range to the Neotropics; 22.1% were endemic to Venezuela. Pteridophyte and bryophyte species were largely restricted to the Neotropics but few were endemic. Macrolichen species were mostly pantropical or cosmopolitan; only 9.6% were restricted to the Neotropics and none was endemic. Canonical Correspondence Analysis found the environmental variables most closely correlated with variation in community composition to be height above ground and a horizontal gradient reflecting differences in forest structure. The epiphytic vegetation was classified using Two-way Indicator Species Analysis into a Syrrhopodon gaudichaudii–Elaphoglossum hoffmannii group of lower trunks, an Omphalanthus filiformis–Maxillaria miniata group of intermediate levels and an Usnea–Parmotrema group of upper crowns. Diversity increased with height above ground; non-vascular diversity was greatest in upper crowns whereas vascular diversity was greatest at intermediate levels. Similarity levels were low among sample plots of the same community, whereas between-tree and between-stand similarities were relatively high.

This study investigated the vertical stratification of Old World fruit bats (Chiroptera: Pteropodidae) in relation to habitat structure and wing morphology, in a lowland Malaysian rain forest. In total, 352 fruit bats of eight species were captured within the subcanopy of the structurally complex old-growth forest during 72 306 m2 mist net hours of sampling. Fruit bat species that were grouped in relation to capture height were also grouped in relation to wing morphology – with those species predicted to have more manoeuvrable flight (i.e. lower wing-loadings and lower aspect-ratios) captured in increasingly cluttered airspaces. Thus, small differences in wing morphology are likely to be ecologically significant to the vertical stratification of bats. Hence, habitat heterogeneity may be a key factor promoting fruit bat species diversity in old-growth palaeotropical forests.

Allomerus octoarticulatus is a plant-ant that colonizes domatia of the understorey tree Hirtella myrmecophila in the Central Amazon and forages for invertebrates, including leaf herbivores, on the host plant. We conducted manipulative experiments to study the ant's recruitment response to damaged leaves and leaf extracts of the host and to extracts of Protium hebetatum, a non-myrmecophytic sympatric tree species. Artificial damage to leaves of H. myrmecophila caused an increase in the number of recruits to the leaf. Ant response was stronger in young than in mature leaves. Recruitment was restricted to damaged leaves. No increment in recruitment rates was observed in undamaged, adjacent leaves. Different levels of leaf damage did not elicit differences in recruitment rates. Aqueous extract of leaves, placed on undamaged leaves of the host plant, also led to increased recruitment compared with water (control), and more ants were recruited to extracts from young than from mature and old leaves. Extracts of both H. myrmecophila and Protium hebetatum induced recruitment. We discuss the evolutionary importance of plant leaf components for maintenance of the ant-plant mutualism.

The soil seed bank in a 5-y-old Sahelian fallow was studied through seed extraction and compared with germinations recorded either in controlled conditions, ex situ in a glasshouse, or in the field. The influence of phosphorus fertilizer and mulch application during the preceding crop period, and that of seasonal grazing regimes applied the last 2 y of fallowing, were assessed on the composition of the seed stock. Ctenium elegans, Fimbristylis hispidula, Merremia pinnata and Phyllanthus pentandrus accounted together for 75% of extracted seeds, 72% of ex situ, and 62% of in situ seedlings. Mulch treatment was correlated with the first axis of the canonical correspondence analyses performed on the seedling datasets. Mulch and phosphorus fertilizer treatments held similar responses, as they both favoured the seed bank of erect dicotyledons such as P. pentandrus and Cassia mimosoides. On the whole, the effects of grazing remained modest compared with the residual effects of past crop management practices. However, seedling densities increased as a result of dry-season grazing, while the soil seed bank decreased with wet-season grazing. Grazing also reduced the spatial heterogeneity of the seed bank rather than the overall number of species.

The epiphytic habitat is assumed to be nutrient deficient, although this generally held notion is based almost completely on circumstantial evidence (Zotz & Hietz 2001). Most studies on the nutrient relations of vascular epiphytes focus on nitrogen (Bergstrom & Tweedie 1998, Hietz & Wanek 2003, Stewart et al. 1995). Although nitrogen plays a key role in limiting plant growth worldwide, there is an on-going discussion whether nitrogen or rather phosphorus are more limiting in many tropical forests (Grubb 1989, Harrington et al. 2001, Vitousek & Howarth 1991). To identify which nutritional factor is most limiting for plant growth, nutrient ratios have been proposed as a very useful tool (Koerselman & Meuleman 1996). These authors stated that N:P ratios exceeding 16 are indicative of P limitation, while an N:P ratio <14 suggests N limitation. Some reports of such ratios in the epiphyte literature indicate that phosphorus may indeed be limiting for epiphytes in tropical forests. For example, the N:P ratio of two field-grown bromeliads (Tillandsia circinnata and T. usneoides) decreased dramatically from 23.6 and 40.4, respectively, to 3.6 and 3.4, respectively, when fertilized with both N and P in the laboratory (Benzing & Renfrow 1974a). On the other hand, however, the average N:P ratios of mature leaves of 41 epiphyte species compiled from a number of papers did not appear particularly high (12.1±10.5, cf. Zotz & Hietz 2001).

Tropical rain forests are evergreen and experience a climate suitable for plant growth year round (Whitmore 1998). However, most tropical rain-forest trees display periodic shoot growth (Borchert 1991) and show synchronous leaf flushing at the community level (Itioka & Yamauti in press, Medway 1972, Ng 1981). Synchronous leaf flushing may have a great impact on animal population such as herbivores, because young leaves are suitable food resources for many herbivores (Aide 1988, 1992; Coley 1983, Itioka & Yamauti 2004, Lowman 1985).

Variation in the ant species associated with myrmecophytes (plants that provide their associated ants with nesting space, and sometimes with a complete diet) has been noted at both the regional and local levels, with plant distribution generally wider than that of the ants (Fonseca & Ganade 1996). This is the case for Cordia nodosa Lamark (Boraginaceae, subfamily Ehretioideae) whose most frequent associate ant species in Peru are Allomerus demararae (Wheeler) and Azteca spp. (Yu & Pierce 1998), while Azteca sp.1 and Allomerus octoarticulatus are the most frequent in Amazonian Brazil and French Guiana, respectively (Fowler 1993, Solano et al. 2003). Cordia nodosa plants are understorey treelets mostly less than 2 m tall, but taller individuals can be found. Their domatia are swollen, hollow stem nodes that form as the growing shoot tip invaginates through a subapical pore that then closes over when the domatium is mature (Yu 2001). So, plant-ants must reopen the chamber where the pore used to be, thus forming a kind of prostoma.

The Old-World tropics encompass one of the floristically richest zones of the world and some of the hot spots of ant diversity. This results in a large variety of ecological interactions between both groups. One of them is the phenomenon of myrmecochory, seed dispersal by ants, which is also well known from temperate forests (Gorb & Gorb 2003, Ulbrich 1919), and which is most prominent in sclerophyll shrublands of Australia and southern Africa (Andersen 1988). Beattie (1983), who reviewed the distribution of ant-dispersed plants (at least 80 plant families worldwide) proposed that species richness and abundance of myrmecochores and diaspore-dispersing ants increases with decreasing latitude and thus predicted a greater variety of ant-dispersal systems in the tropics. However, up to now, few tropical myrmecochores have been described (Horvitz 1981, Horvitz & Schemske 1986), especially in the palaeotropics (Kaufmann et al. 2001). Here we report myrmecochory in two species of rain-forest herb of the Zingiberaceae, give the first evidence for seed dispersal by ants in this plant family and present a list of seed-dispersing ant species. An important benefit of myrmecochory is the dispersal distance of the ant-transported seeds (Andersen 1988), that has been found to be positively correlated with ant size (Gomez & Espadaler 1998a, Pudlo et al. 1980). In this study, we checked whether this correlation is also true for the conditions of the tropical rain forest, where Globba plants occur.

In forested ecosystems leaf litter is generally the primary pathway through which nutrients are cycled from the canopy to the forest floor (other pathways include throughfall, stemflow and animal faeces; Jordan 1985). Consequently, any disturbance that alters the quantity or quality of litter can have dramatic impacts on nutrient cycling and the availability of essential nutrients to plants (Vitousek 1984). Fragmentation of tropical forests has been demonstrated to cause several changes in both the biotic (Cosson et al. 1999, Laurance et al. 1998, Saunders et al. 1991) and abiotic environments (Camargo & Kapos 1995, Debinski & Holt 2000, Laurance 2002, Laurance et al. 2002) and thus may influence litter accumulation in the remnant patches (Carvalho & Vasconcelos 1999, Didham 1998, Laurance et al. 2002).