Climate change may increase the intensity of hurricanes (Emanuel 1987, 2003), and thus the size of disturbance in tropical forests. As a consequence, disturbance-specialist plants, such as lianas, may increase in abundance there (Phillips & Gentry 1994). Putz (1984) hypothesized that lianas create larger treefall gaps by connecting trees together and pulling down multiple trees during storms. This positive-feedback cycle may increase the prevalence of lianas in disturbed tropical forests (Schnitzer & Bongers 2002, Schnitzer & Carson 2001). Alternatively, Putz (1984) proposed that lianas tie and stabilize canopies together, resulting in less disturbance. Forest age may determine the role of lianas during disturbance because liana abundance and composition vary through secondary succession (De Walt et al. 2000, Schnitzer et al. 2000). To test the two hypotheses of Putz (1984), we evaluated the effect of liana cutting between forests of different successional ages on tree damage by hurricane Wilma.

An important challenge of invasion biology is to understand how interactions between species traits and ecosystem properties enable alien species to become invasive at particular locations. We investigated how gap dynamics in a tropical rain forest on the island of Réunion affected the invasiveness of alien plants. In the 12 000-m2 study area, alien plants occupied 24.9% of the area of gaps, which represented 5.62% of the forest area, but only 0.8% of the understorey area. The most abundant invasive species was Rubus alceifolius, which formed dense, monospecific stands in the largest gaps (> 25 m2). Although plants could persist in the shade, a germination experiment revealed that canopy openings were essential for seedling establishment. A cyclone that struck the study area in 2002 caused a temporary thinning of the canopy, increasing light levels to above the threshold needed for germination of R. alceifolius and also stimulating the growth of established plants. We conclude that the ability of this and other alien species to colonize intact lowland tropical rain forest is strongly influenced by the prevailing gap dynamics. Because gaps are also essential for the regeneration of many native trees in our study area, there is a real danger of the forest being progressively degraded by alien plants. There are no simple solutions to controlling species such as Rubus alceifolius, but efforts should be focused mainly upon the larger gaps where the species are most invasive.

Many ecological relationships that are inherently reciprocal are often studied from one perspective only (Agrawal et al. 2007). One example is the interaction between tropical forests and nearctic-neotropical migratory songbirds (hereafter migrants). Several studies have determined that some migrant populations are limited by conditions at their tropical wintering grounds in Central America, South America and the Caribbean (Marra et al. 1998, Mills 2006); however, the ecological role of migrants in these tropical forests is poorly understood.

Montane tropical and subtropical rain forests are complex ecosystems, characterized by marked rainfall and temperature gradients with altitude, which in turn control the vegetation altitudinal zones (Hueck 1978). Montane forests are often referred to as cloud forests in recognition of the important influence of a dense and frequent cloud cover that conditions forest structure and functioning (Bautista-Cruz & del Castillo 2005, Holder 2004).

Studies of seed dispersal and fruit production often use fruit traps. Different trap designs may give dissimilar estimates; however, prior to this study there has been no tropical forest field comparison of trap designs. Likewise, there are no recommendations about the number of traps required to assess ecological parameters, such as fruit production, mass and number of seeds dispersed, and number of plant species producing fruits. We compared the effectiveness of five trap designs in terms of fruit/seed bouncing out of traps, wind effects, area effects and seed removal by predators. These studies took place in Colombia in two tropical rain forests and in laboratory conditions. We found that 300 traps (0.085 m2 each) were not enough to obtain stable estimates in two out of four parameters (number of species and dispersed seeds). All estimates were highly variable when using fewer than 100 traps. All trap designs evaluated (mesh on PVC frame, hanging mesh, basin and funnel traps) prevent seed removal by predators, in sharp contrast with removal from the ground. Mesh traps were less affected by bouncing effects than plastic traps, and this factor was a large source of bias among estimates from different traps. Since up to 68% of dry mass may bounce out, it is important to consider adequate trap designs and to be careful when comparing studies using different methodologies. Small traps received fewer seeds per area, however area affects were not evident when bouncing effects were controlled for. We recommend the use of mesh traps on PVC frames, although hanging mesh traps are a good option in tropical forests without strong winds.

The yellow-throated marten, Martes flavigula, is the only living species of the genus Martes found in subtropical and tropical forests (Harrison et al. 2004). It is distributed throughout central and southern Asia in a wide variety of habitats. Despite its extensive geographical range, the ecology and behaviour of this species has so far received little attention, aside from a study of habitat use (Grassman et al. 2005). Studies on other martens have shown that fruits are an important food resource (e.g. M. martes, Bermejo & Guitian 2000; M. foina, Pandolfi et al. 1996). Thus, they are considered to be important potential seed dispersers (Corlett 1998, Herrera 1989, Willson 1993), as confirmed by recent studies (M. melampus, Otani 2002; M. americana, Hickey et al. 1999; M. foina and M. martes, Schaumann & Heinken 2002). Although no systematic study of the diet of M. flavigula has been conducted (Harrison et al. 2004), it is known to be omnivorous and to consume fruit (Gao & Wang 1987). To date, however, there has been no comprehensive study of frugivory and seed dispersal by M. flavigula (but see Corlett 1998).

With the spread of angiosperms some lineages of ants, originally ground-dwellers and predators, adapted to arboreal life. Ground-nesting worker ants probably constituted the first case of biotic plant protection through their predatory activity while foraging on plant foliage. Then, ants developed tight evolutionary bonds with plants varying from facultative diffuse relationships to obligatory specific associations, necessary to the survival of both partners. In diffuse relationships plants induce different ant species to patrol their foliage by producing energy-rich food rewards such as extra-floral nectar (EFN) and/or food bodies (FBs) (Dejean et al. 2007, Heil 2008, Heil & McKey 2003). First described by Janzen (1966), myrmecophytes, or plants that provide specialized plant-ants a nesting place in hollow structures called domatia, represent a good example of a strict association as, in return, they are protected from several kinds of enemies, particularly defoliating insects (Heil & McKey 2003, Hölldobler & Wilson 1990).

Bats and birds carry out most of the seed dispersal in the Neotropics (Galindo-Gonzáles et al. 2000), and are crucial for the dynamics and regeneration of tropical forests (Whittaker & Jones 1994). However, only a few details are known about the interactions in particular bat–fruit systems. Most frugivorous bats are highly mobile (Bernard & Fenton 2003), and do not harm seeds (Fleming & Sosa 1994), suggesting that they are legitimate and effective seed dispersers (sensu Fleming & Sosa 1994).

An important deficiency of the tropical forest data set on above-ground net primary productivity (ANPP) is the paucity of studies where requisite components of forest productivity have been measured at the same location. Missing data on above-ground biomass increment (ABI, which refers to the incremental growth of trees) and fine-litter production (leaves, fruit, flowers, small twigs, but excluding coarse woody debris) is particularly problematic as these are the two major components of ANPP. The fragmentary nature of the data is reflected by the fact that only 13 of 39 (33%) plots reviewed by Clark et al. (2001) and 8 of 104 (8%) plots reviewed by Malhi et al. (2004) had data on both major components of productivity. In an attempt to retain the geographic coverage and replication of data in analyses, researchers have proposed ways to infer missing data. Typically ratios or (more recently) fitted relationships between ABI and litter production have been used for this purpose (Bray & Gorham 1964, Clark et al. 2001, Murphy 1975).

Even though the great majority of the biomass and diversity of mammals in tropical forests inhabit the canopy (Eisenberg & Thorington 1973), most knowledge of this group is based on forest-floor samples (Lowman & Moffett 1993). Studies that include trapping efforts in the canopy are becoming increasingly common (Grelle 2003, Lambert et al. 2005, Malcolm 1995, Patton et al. 2000, Vieira & Monteiro-Filho 2003, Voss et al. 2001), but aspects on the ecology of arboreal small mammals still remain poorly understood. Many species of non-flying mammals co-occur in the canopy and, thus, are expected to use niche dimensions differently to permit coexistence (Cameron et al. 1979). Despite the difficulties of access to and in understanding the three-dimensional use of the arboreal strata by the different species (Emmons 1995), some studies have demonstrated that the differential use of the habitat (Cunha & Vieira 2002, Gentile & Fernandez 1999), of food items (Cáceres et al. 2002, Santori et al. 1995) or both (Leite et al. 1996, Mauffrey & Catzeflis 2003), include strategies involved in the division of resources.

Dioecious plant populations have generally been considered to maintain sex ratios of 1:1 (Allen & Antos 1993, Carroll & Mulcahy 1993, Charnov 1982). The sex ratio does, however, change if the plants are growing in a stressful environment, often being male-biased under these conditions (Ortiz et al. 1998, 2002). This pattern has been explained by differences in how the sexes resolve their respective energy requirements (Obeso et al. 1998). Females generally assign more resources to reproduction in comparison to growth and maintenance than do males, and they are smaller and longer-lived (Allen & Antos 1993, Nicotra 1999, Obeso et al. 1998, Willson 1983). Thus their higher reproductive costs take a toll on females, modifying the population sex ratio in favour of males (Allen & Antos 1993, Lovett-Doust & Lovett-Doust 1988). However, in order to determine the reproductive cost it is necessary to consider the compensatory mechanisms (Obeso 2002). These reduce the reproductive cost and include plastic response in terms of plant architecture and plant physiology. For example, nutrient resorption is a process that may help decrease dependence on nutrient intake, thereby constituting an important nutrient economy mechanism that can also reduce the reproductive cost if a significant proportion of the nutrients had been reassigned to reproduction (Killingbeck 1986, Obeso 2002).

Biological N fixation by symbiotic micro-organisms plays a key role in making atmospheric N largely available to other organisms and nodule formation by rhizobia in roots of many legume species represents a very important pathway (Postgate 1998). Estimates of the contribution of symbiotic fixation to total N content in soils range from 44 to 200 Tg y−1 (Bøckman 1997).

Most ecological studies of fungi associated with tropical plants have focused on the rhizosphere or phyllosphere of seedlings, saplings and adult trees (Augspurger 1983, 1984; Bell et al. 2006, Gilbert 2002, Gilbert et al. 2002, Husband et al. 2002, Kiers et al. 2000, Mangan et al. 2004). However, fungi also infect the seeds of tropical trees, reducing seed survival and potentially affecting adult distributions (Gallery et al. 2007a, b). Fungicide experiments have shown that fungal and oomyceteous pathogens are the major cause of seed mortality in the soil for a variety of tropical pioneers (Dalling et al. 1998, Gallery et al. 2007b, Murray & Garcia 2002), which depend on recruitment from seed banks to colonize gaps and other disturbances in mature forest (Alvarez-Buylla & Martinez-Ramos 1990, Dalling et al. 1997, Hall & Swaine 1980). Persistence in the soil prolongs exposure of seeds to infection by soil-borne fungi and is especially problematic for small-seeded species with thin fruit or seed walls (Baskin & Baskin 1998, Blaney & Kotanen 2002, Crist & Friese 1993). At present little is known about the host affinity of fungi associated with seeds of tropical trees, and consequently, whether seed-infecting fungi influence plant species coexistence through differential infection of, or effects on, potential hosts.

The El Niño-Southern Oscillation (ENSO) phenomenon occurs irregularly and supra-annually at intervals of 2–7 y (Hughen et al. 1999, McPhaden et al. 2006), and is the strongest source of supra-annual climate fluctuation (Hughen et al. 1999, Philander 1990). During ENSO, the interior of the South-East Asian tropics, which is characterized by constant high temperature and no distinct dry season, experiences severe drought (Walsh 1996).

A close relationship has been reported between seed size and many different plant traits such as seedling size, relative growth rate, seedling survival, distance of dispersion, colonization and density of seeds in the soil (Coomes & Grubb 2003, Jurado & Westoby 1992, Lahoreau et al. 2006, Saverimuttu & Westoby 1996, Souza & Valio 2001). Although the association of seed size and shade tolerance is unclear (Westoby et al. 1996) some authors have suggested that a larger-seeded species is better able to tolerate low light availability (Foster 1986, Foster & Janson 1985, Leishman & Westoby 1994) by producing a vigorous seedling with a higher ability to withstand predation (Armstrong & Westoby 1993, Foster 1986) and delaying the beginning of carbon fixation so as to increase survival under a canopy and under leaf litter.

Philornis is a neotropical, monophyletic genus of Muscidae (Diptera) (Couri et al. 2007) that includes many bird parasites (Skidmore 1985). The interaction system of Philornis and birds is very peculiar: fly adults are free-living and only larvae interact with birds (Couri 1985, 1999; Dodge 1963). Larval trophic habits are known for 22 of the 49 species (de Carvalho et al. 2005) and are divided into three groups: coprophagous (P. aitkeni and P. rufoscutellaris), free-living haematophagous (P. falsificus) and subcutaneous (18 spp.). Philornis downsi is unusual because the first and the early second instars display a subcutaneous phase, whereas the late second and third phases show a nest-dwelling haematophagous phase (Fessl et al. 2006).