Vertical stratification of vascular epiphytes is frequently attributed to niche partitioning along microclimatic gradients but experimental confirmations of this notion are rare. This study investigates the role of the regeneration phase for the stratification of five bromeliad (Catopsis sessiliflora, Guzmania subcorymbosa, Tillandsia anceps, T. bulbosa and Werauhia gladioliflora) and seven aroid species (Anthurium acutangulum, A. brownii, A. clavigerum, A. durandii, A. friedrichsthalii, A. hacumense and A. scandens) in a Panamanian rain forest. We documented gradients of temperature, vapour pressure deficit and light (n = 10 d) as well as species height distributions (n = 11–120). Microclimatic gradients were substantial (maximal T and RH differences between strata: 5 °C and 18%, respectively) and mean attachment heights of the study species (range = 4–21 m) differed significantly. We tested sensitivity to recurrent drought (four treatments) during germination (all species, cumulative germination of 20 seeds, n = 3) and seedling growth (four aroid species, n = 25). Seedling survival of six aroid species transplanted to three heights (n = 27) was monitored in situ. Some species did not germinate under severe recurrent drought while others germinated at the same rate in all treatments. Seedlings of the most exposed species grew fastest under intermediate recurrent drought while those of the other three species grew fastest when kept constantly wet. Survival of transplanted seedlings did not depend on species attachment height, but this may be attributable to insufficient statistical power. Taken together, the results suggest that the stratification can be explained to a large degree by differential sensitivity to the vertical moisture gradient during the regeneration phase.

Structure and demographics in many tropical forests is changing, but the causes of these changes remain unclear. We studied 5 y (2005–2010) of species turnover, recruitment, mortality and population change data from a 20-ha subtropical forest plot in Dinghushan, China, to identify trends in forest change, and to test whether tree mortality is associated with intraspecific or interspecific competition. We found the Dinghushan forest to be more dynamic than one temperate and two tropical forests in a comparison of large, long-term forest dynamics plots. Within Dinghushan, size-class distributions were bell-shaped only for the three most dominant species and reverse J-shaped for other species. Bell-shaped population distributions can indicate a population in decline, but our data suggest that these large and long-lived species are not in decline because the pattern is driven by increasing probabilities of transition to larger size class with increasing size and fast growth in saplings. Spatially aggregated tree species distributions were common for surviving and dead individuals. Competitive associations were more frequently intraspecific than interspecific. The competition that induced tree mortality was more associated with intraspecific than interspecific interactions. Intraspecific competitive exclusion and density-dependence appear to play important roles in tree mortality in this subtropical forest.

Our study examines the effect of seasonal rains on soil organic C dynamics in a tropical deciduous forest ecosystem in Western Mexico. At the end of the wet season, an accumulation of labile nutrient forms developed and was maintained during the dry season. This accumulation enhances microbial activity in the first rains of the wet season. For example, the litter samples of the dry season had a higher C and N mineralization than those of the wet season. Similarly, the January soil samples had higher C mineralization than October soil samples (55 and 34 μg C g-1 d-1, respectively). These results suggest that the quality of C is strongly affected by the seasonality of rains, which in turn influences microbial activity. This seasonality also influences nutrient redistribution between soil aggregate fractions. Chemical changes across seasons suggest that soil organic matter associated with macro-aggregates represents the main source of energy for microbial activity at the beginning of the wet season, while micro-aggregates protect the labile nutrient forms during the growing season.

Although plant species that attract multiple species of pollinators predominate in tropical plant communities, pollination specialists appear to be at a greater advantage in tropical ecosystems in which pollinators are numerous and many plants flower synchronously. The present study determined the breeding system and legitimate pollinators of Oroxylum indicum Vent. in Songkhla and Patthalung Provinces, Thailand. Oroxylum indicum exhibits steady-state flowering, with one or two flowers per inflorescence opening each night. Flowers open in the evening and drop off shortly after midnight, while its bilabiate stigma is highly sensitive, and quickly close upon being touched. Oroxylum indicum is self-incompatible. Hand-cross pollination and open pollination yielded the highest pollination success (47.7% and 31.2% respectively, n = 7 trees). About 900 pollen grains are needed for initiating fruit set. It is confirmed that a fruit bat, Eonycteris spelaea, is the legitimate pollinator. Bats are responsible for all pollen load and the pollen load from only one visit is generally sufficient to initiate fruit set. Although Eonycteris spelaea is effective, it is an inefficient pollinator. Compared with plant species pollinated by multiple animal species, the likelihood of pollination failure resulting from the decline in populations of Eonycteris spelaea will be much more intense in Oroxylum indicum.

Neotropical bats occupy a large variety of trophic niches, and represent locally abundant, species-rich communities. As such, they are highly suited as a model group for the study of temporal and spatial dynamics of animal communities. However, despite this important research potential, data on the dynamics and turnover rates of Neotropical bat communities are lacking. We here study both aspects for bats inhabiting two natural forests surrounded by savanna in Bolivia. Over a period of 8 y, both bat communities showed high rates of species turnover. As predicted, species relying on fluctuating food resources were more likely to be absent in particular years, whereas species relying on more predictable food supplies were present in all years.

A 272-ha grove of dominant Microberlinia bisulcata (Caesalpinioideae) adult trees ≥50 cm stem diameter was mapped in its entirety in the southern part of Korup National Park, Cameroon. The approach used an earlier-established 82.5-ha permanent plot with a new surrounding 50-m grid of transect lines. Tree diameters were available from the plot but trees on the grid were recorded as being ≥50 cm. The grove consisted of 1028 trees in 2000. Other species occurred within the grove, including the associated subdominants Tetraberlinia bifoliolata and T. korupensis. Microberlinia bisulcata becomes adult at a stem diameter of c. 50 cm and at an estimated age of 50 y. Three oval-shaped subgroves with dimensions c. 850 m×1350 m (90 ha) were defined. For two of them (within the plot) tree diameters were available. Subgroves differed in their scales and intensities of spatial tree patterns, and in their size frequency distributions, these suggesting differing past dynamics. The modal scale of clumping was 40–50 m. Seed dispersal by pod ejection (to c. 50 m) was evident from the semi-circles of trees at the grove's edge and from the many internal circles (100–200 m diameter). The grove has the capacity, therefore, to increase at c. 100 m per century. To form its present extent and structure, it is inferred that it expanded and infilled from a possibly smaller area of lower adult-tree density. This possibly happened in three waves of recruitment, each one determined by a period of several intense disturbances. Climate records for Africa show that 1740–50 and 1820–30 were periods of drought, and that 1870–1895 was also regionally very dry. Canopy openings allow the light-demanding and fast-growing ectomycorrhizal M. bisulcata to establish, but successive releases are thought to be required to achieve effective recruitment. Nevertheless, in the last 50 y there were no major events and recruitment in the grove was very poor. This present study leads to a new hypothesis of the role of periods of multiple extreme events being the driving factor for the population dynamics of many large African tree species such as M. bisulcata.

Perceptual range is used as a measure of the ability of animals to perceive the landscape, and can be used to infer functional connectivity between habitat patches such as forest remnants. A relationship of perceptual range with body mass was proposed by Mech and Zollner, but effects of life-history traits and environmental conditions were also acknowledged. We evaluated perceptual ranges and the influence of body mass, wind speed and direction, and grass height in four marsupial species of the Atlantic Forest of south-eastern Brazil. Release experiments were conducted and orientation towards the forest was determined using the spool-and-line technique. In 111 animals released, Didelphis aurita had the highest perceptual range (200 m), followed by Philander frenatus and Micoureus paraguayanus (100 m), and by Marmosops incanus (< 100 m). None of the species presented homing behaviour, and there was no difference in orientation abilities between sexes. Perceptual range was overestimated based on the equations of Mech and Zollner, but species were ordered in perceptual range according to their body size. Distance to the forest was a common determinant of the orientation in P. frenatus and M. paraguayanus, but grass height and wind direction were also important. Orientation of Didelphis aurita was determined by wind direction, showing anemotactic behaviour. Body mass is likely to affect perceptual ranges in didelphid marsupials, but only in interspecific comparisons. Within a species perception depends on the environmental context. Variables other than distance must be considered to estimate functional connectivity of the landscape based on perceptual range.

Bukit Belalong, Brunei, is a small mountain (913 m) of uniform shale lithology with continuous primary rain forest from its base to its summit. Three 0.25 ha plots were established at each of three altitudes (200, 500 and 850 m) to investigate the altitudinal zonation of the soils and the vegetation. One soil profile from each altitude is described and chemical analyses of the soils indicate that they are similar at all altitudes. In each plot all trees ≥10 cm dbh were measured and identified as far as possible. Maximum tree height was greatest at 200 m (60 m) and least at 850 m (33 m). Tree density (number of individuals ha−1) increased with altitude. The forest at 850 m was the most species- and family-rich, but since the ratio of species to individuals did not vary significantly among altitudes, the higher species richness is attributed partly to the larger number of trees sampled. The Dipterocarpaceae was the most important family in terms of basal area at all altitudes, but its proportion of basal area was much smaller at 850 m than at the other altitudes. The Dipterocarpaceae was the most diverse family at 200 m and 500 m, but at 850 m its diversity was exceeded by the Lauraceae, Myrtaceae and Euphorbiaceae and equalled by the Clusiaceae. The forests at 200 m and 500 m are classified as lowland rain forest and that at 850 m is classified as a lower montane forest.

The abundance of epiphytes has been assumed to be important in explaining the high diversity of tropical canopy arthropods. In this study we assessed the possible role that the presence of epiphytes may have on the diversity and abundance of canopy insects in an experimental study conducted in a coffee plantation in Coatepec, Veracruz, Mexico. Epiphytes were removed from trees in one of two plots in two sites of the coffee plantation. In each plot we collected insects from three Inga jinicuil trees by knockdown insecticide fogging. Insects were sorted to morphospecies, counted and measured. Trees with epiphytes had significantly higher numbers of species and individuals and insects larger than 5 mm were also more species-rich and abundant in trees with epiphytes. The magnitude of the enhancement was surprisingly large with the epiphyte plot samples having on average 90% more individuals and 22% more species than plots without epiphytes. These differences were even greater for large (>5 mm) insects (184% and 113% respectively). Our results support the tenet that epiphytes provide valuable resources to arthropods, which we have illustrated for canopy insects in shade trees of coffee plantations.

Tree species are potential hosts for epiphytes; however in some forests epiphytes have a biased distribution among hosts. In a tropical dry forest of Mexico, previous research showed that there are trees with few epiphytes. It is possible that the bark of these hosts contain allelochemicals that influence epiphyte seed germination. The aims of this study were (1) to determine whether hosts with low epiphyte abundance (Ipomoea murucoides, I. pauciflora and Lysiloma acapulcense) would inhibit seed germination of Tillandsia recurvata through aqueous and organic bark extracts, (2) to determine whether germination of T. recurvata would differ among the hosts with low epiphyte abundance and a host with high epiphyte abundance (Bursera copallifera) and (3) to relate the chemical composition of organic bark extracts with inhibition of T. recurvata seed germination. Hexanic and dichloromethanic extracts were partially chemically characterized. Total phenolics and flavonoids concentrations of methanolic extracts were analysed. Aqueous and organic bark extracts from hosts with few epiphytes inhibited T. recurvata seed germination. Aqueous and dichloromethanic extracts of B. copallifera inhibited slightly the germination of T. recurvata. There was a positive correlation between concentration of flavonoids and inhibition of seed germination. Results suggest that a combination of compounds may be responsible for affecting the germination of T. recurvata. This study demonstrates the chemical effect of aqueous and organic bark extracts from hosts on germination of an epiphytic bromeliad.

The habit, shade-tolerance and dispersal agent of 19 bromeliad species were studied in a rainforest community in order to relate specific traits to the spatial occurrence of the species. Highest density was found in riparian forest (RF), followed by restinga scrub (RE), rocky shore (RS) and dense canopy forest (DF). Terrestrial bromeliads occurred in open sites (RE and RS), epiphytes were absent in RS and facultative species occupied all four habitats. Bird-dispersed bromeliads occurred in the upper canopy, whereas those dispersed by mammals were low in the forest profile. Bromeliads which are dispersed by similar fauna fruit sequentially through the year. Differences in traits may allow the sharing of habitats and strata among species.

To assess the influence of microhabitat and season on predator growth and survival and prey community structure, first instars of native Toxorhynchites haemorrhoidalis, a predatory mosquito, were released into Heliconia bracts, bamboo internodes, and the axils of two species of Aechmea bromeliads during wet and dry seasons in a lowland rain forest in eastern Venezuela. Experimental and control microhabitats were compared by complete censusing of macroscopic invertebrates 10 and 20 days after releases.

Survival of T. haemorrhoidalis differed significantly among habitats and was reduced by desiccation in dry-season bamboos and in Aechmea nudicaulis and by the presence of a predatory damselfly (Odonata: Zygoptera) in bromeliads. Developmental rate differed among habitats in the wet but not in the dry season; rapid wet-season maturation was associated with increased prey abundance in Heliconia.

Larvae of T. haemorrhoidalis consumed particular taxa and size categories of dipterous prey. Predation significantly reduced the abundance and skewed size-class distributions of Culicidae, Ceratopogonidae, Psychodidae, and pooled samples of Thaumaleidae plus Chironomidae. In bamboos, instar distributions of other mosquitoes were skewed in the presence of T. haemorrhoidalis even though a significant reduction in mosquito abundance was not detected. A decrease in species richness of aquatic Diptera was associated with intense predation by Toxorhynchites in Heliconia and A. nudicaulis.

Toxorhynchites theobaldi was recognized as the naturally occurring predator in local bamboos, and released larvae caused significant reductions in abundance or size-class frequency shifts among three families of Diptera. Niche segregation between these sympatric Toxorhynchites is maintained by oviposition preferences: the larger species, T. theobaldi, oviposits in bamboos and the smaller T. haemorrhoidalis occurs in plant bracts and axils.

We investigated the seed dispersal of Aglaia spectabilis, a large-seeded tree species in a moist evergreen forest of Khao Yai National Park in Thailand. Although one-to-one relationships between frugivores and plants are very unlikely, large-seeded plants having to rely on few large frugivores and therefore on limited disperser assemblages, might be vulnerable to extinction. We assessed both the frugivore assemblages foraging on arillate seeds of Aglaia spectabilis and dispersing them and the seed predator assemblages, thereby covering dispersal as well as the post-dispersal aspects such as seed predation. Our results showed that frugivores dispersing seeds were a rather limited set of four hornbill and one pigeon species, whereas two squirrel species were not dispersers, but dropped the seeds on the ground. Three mammal species were identified as seed predators on the forest floor. Heavy seed predation by mammals together with high seed removal rates, short visiting times and regurgitation of intact seeds by mainly hornbills lead us to the conclusion that hornbills show high effectiveness in dispersal of this tree species.

Despite the progress made in understanding the ecophysiology of tropical plants during the past two decades (Lüttge 1997, Mulkey et al. 1996), questions regarding relationships between the environment and physiological diversity remain. It is now recognized that tropical climate can be quite variable (see Coen 1983) which could lead to significant functional diversity (increased variation in life history traits) among species due to the tight association between gas exchange physiology and the environment (see Enquist & Leffler 2001, Guehl et al. 1998, Huc et al. 1994, Martinelli et al. 1998, Sobrado 1993). It remains unclear, however, how the subtleties of variation in tropical climate and tree life history traits are related to the functional diversity of tropical communities (Borchert 1994, 1998).

Myrmecophytic species of the Paleotropical plant genus Macaranga (Euphorbiaceae) have hollow stems that are almost always occupied by ants of the genus Crematogaster and scale insects of the family Coccidae (Hemiptera: Coccoidea). The coccids have a cryptic endophytic lifestyle and are confined to this microhabitat. They are much more diverse than previously recognised. First data are presented on the diversity, prevalence, specificity and distribution of the coccids associated with myrmecophytic Macaranga species. Twenty-two species of Coccidae in total, including 15 previously unknown from Macaranga, were discovered from 19 species of Macaranga in Peninsular Malaysia and Borneo. The original describers tentatively assigned the known coccid species to Coccus (Coccinae) but the Macaranga coccids still require taxonomic research to establish their correct placing. The coccids varied in their host-plant specificity from species that occurred in most of the sampled Macaranga to one species that was found almost exclusively only on a single host species. In addition to their occurrence on Macaranga, only three species, C. macarangae and C. secretus and morphospecies C. 214 were found on rare occasions in the stem interior of a few other myrmecophytes and in a non-myrmecophytic liana, but did not regularly colonise these plants. Most of the coccids can be regarded as highly specific at the plant genus level.

Spatial patterns presented by the opossums Caluromys philander, Philander frenata and Micoureus demerarae were studied, through radio-tracking, in a landscape composed of eight small (1.3–13.3 ha) forest fragments surrounded by a matrix of open vegetation in south-eastern Brazil. Sixteen individuals were fitted with radio-collar transmitters and monitored for 2–8 mo. Fixes were obtained by the ‘homing-in on the animal’ technique. Numbers of locations of each individual varied from 6 to 117. Home ranges sizes ranged from 2.5–7.0 ha for C. philander, 0.6–7.4 ha for P. frenata and 0.8–1.7 ha for M. demerarae. Fragments, both edges and interiors, were used more often than the matrix; they are the primary habitat for these marsupials in the landscape. The matrix was used for foraging by P. frenata and C. philander, and traversed in five movements between fragments by P. frenata. Ability to use fragment edges and the matrix is important in explaining how these marsupials are able to persist in the landscape.

The dependence of tree seedling survival and growth on light availability was evaluated over 15 mo in three second-growth, wet forest stands (15–18 y old) in north-eastern Costa Rica. Seedlings of four canopy tree species (Dipteryx panamensis, Hyeronima alchorneoides, Virola koschnyi and Vochysia guatemalensis) were planted into four canopy treatments in three replicated stands and in a pasture site, spanning a nearly complete gradient of light availability. Survival and growth of all species increased in response to increasing light availability, but species differed in survival in shaded microsites (6–20% light transmittance) and in growth increments per light increase. Hyeronima showed the highest mortality at low light levels and the highest relative height growth increase per light increase. In contrast, Virola showed high survival at low and moderate light, but showed the lowest leaf area and above-ground biomass per light increase among all species. Dipteryx and Vochysia maintained relatively high rates of survival and growth across the entire light gradient. Hyeronima and Virola showed trade-offs between growth and survival responses to light, unlike Dipteryx and Vochysia. Differences among species in seedling survival at low light may be determined by a variety of physiological and morphological traits that may or may not be mechanistically linked to growth responses.

Seed removal was evaluated at the macro- and micro-habitat level in areas differing in successional stage in the Bolivian Amazon. The successional stages consisted of secondary forests of 2, 10 and 20 years old and primary forest. Seeds of nine tree species were artificially dispersed and the number of seeds removed was evaluated over 7 weeks. Several stand characteristics were measured at the sites where seeds were dispersed. Seed removal at the end of the experiment varied from 50 to 100% depending on the species, and from 74 to 90% depending on successional stage. In general, the removal rate decreased with an increase in age of successional stage. The seed removal rate was related to liana density and not to litter thickness. Different microhabitat characteristics explained the seed removal rate of four species but microhabitat characteristics did not explain the decrease in seed removal rate with an increase in forest age. The results support the idea that post-dispersal seed removal reduces the number of seeds available for germination, consequently playing an important role in the regeneration of abandoned agricultural areas.

The relationships between body size and host specificity were studied in leaf-chewing and sap-sucking insect communities, including 792 species, feeding locally on 15 species of Ficus in a lowland rain forest in Papua New Guinea. A negative correlation between body size and host specificity, i.e., the tendency for large species to feed on numerous Ficus hosts and those smaller to have a more restricted host range, was found within both the sap-sucking and the leaf-chewing community. A more detailed analysis, which divided herbivorous species into three sap-sucking and four leaf-chewing guilds, revealed that the correlation between body size and host specificity was caused by differences in these traits between the guilds, while no such correlation was detected within any of the guilds. As the changes in feeding mode, defining various guilds, were unique evolutionary events, it is uncertain whether there is a functional relationship between feeding mode, body size and host specificity, or whether their correlation is only coincidental. It is suggested that, in the sap-sucking community at least, the positive body size versus host specificity correlation is a coincidental by-product of the causal relationship between the feeding mode and both the body size and host specificity. The causes of analogous patterns in a leaf-chewing community require further investigation. Methodological problems in the analysis of tropical insect communities, dominated by rare species, are discussed.