Despite the important functional role of deep roots in withdrawing water during drought, direct measurements of root distribution are very rare in tropical rain forests. The aim of this study was to investigate the root distribution of Entandrophragma cylindricum, a common tree species in the Central African semi-deciduous rain forest, in Ferralsols and Arenosols. We dug two pits to a depth of 6 m in Ferralsols and two pits to a depth of 3 m in Arenosols, close to E. cylindricum trees. The vertical soil profiles were divided into 10 × 10-cm grid cells and the roots counted were distributed in three diameter classes. We fitted a root distribution model to our dataset. We found that vertical root distribution was shallower in Arenosols than in Ferralsols. Root penetration was not stopped even by a Ferralsol with high gravel content in its subsoil. Overall, our measurements showed that 95% of all roots were distributed to depths of between 258 and 564 cm from the soil surface, which is much deeper than the 95 cm depth previously reported in the literature for tropical rain forests. As sampling depth could explain this discrepancy, we recommend a sampling depth of at least 3–5 m to accurately estimate root distribution. The drier the dry season, the deeper the sampling depth should be. Our results are consistent with global models of root distribution in forest ecosystems, which are driven by climate variables. We thus suggest that deep rooting could be common in rain forests with a marked dry season.

The canopy dynamics and light climates within a 20 by 60 m quadrat were studied in a disturbed moist deciduous forest near Bombay, India. A map was drawn of individual trees within the quadrat, the taxa were identified, and their phenology was followed from November 1984 to July 1985. The quadrat contained 14 species, the most common being Tectona grandis, Terminalia tomentosa, Butea monosperma, Mitragyne parviflora and Albizia procera. Some individuals were in leaf at all times, more so at the moister east end of the quadrat. In November at the end of the rainy season, light measurements documented percentages of total daily photosynthetic photon fluence (PPF) at 10.0% of full sunlight; 44% of this flux was due to sun-flecks whose duration was approximately 17% of the daytime hours. Values for six sites were similar to mid-day measurements along a 40 m transect, and consistent with the 94% canopy cover of the sites, photographed with a fish-eye lens. The March dry season measurements revealed a more intense radiation environment (54% of solar PPF), and 59% of the photosynthetic photon flux density at mid-day along the transect. Canopy openings were increased to a mean of 59.4%. Light in the understorey in November was spectrally altered, with typical R:FR ratios of 0.30, compared to March values identical to those of sunlight, at 1.10.

The effects of heat treatment and fire on seed germination of Acacia sieberiana D.C. and Acacia gerrardii Benth. were studied. Dry heat and fire were studied separately. Seeds treated with dry heat were set to germinate in petri-dishes under laboratory conditions. Other seeds were planted in plots at the Uganda Institute of Ecology, Mweya, which were then burnt, and subsequent seedling emergence was monitored. The effect of heat treatment on seed germination depended on heat intensity and duration of exposure. Higher intensities reduced the germination capacity of Acacia seeds. Short exposure of seeds stimulated germination but prolonged exposure rapidly reduced seed viability. A. sieberiana had a higher heat resistance than A. gerrardii. The survival and germination of seeds after fire increased with depth of burial and A. sieberiana survived better than A. gerrardii. The germinability of seeds of A. gerrardii was not significantly increased by fire.

The reciprocal importance of bromeliads and hummingbirds has been proposed for many years, even suggesting coevolution between these two groups. Nevertheless, data are lacking that allow a better test of the relationships involved. Here we investigate the relationship between bromeliads and hummingbirds in an area of secondary Atlantic rain forest in southern Brazil. The study examined the interactions among 12 species of bromeliad and 10 of hummingbird at Reserva Natural Salto Morato, Paraná state. The number of flowering species of bromeliad and the species richness and abundance of hummingbirds were quantified monthly between November 2004 and October 2005. Focal observations on each bromeliad species were made to determine the hummingbird visitors. Neither species richness nor abundance of hummingbirds were related to bromeliad phenology. Together with the monthly variation in visit frequency by a given pollinator to a given plant, these factors indicate a generalization in the use of bromeliads by hummingbirds and argue against tight coevolution. Ramphodon naevius and Thalurania glaucopis were the main pollinators in the community. Aechmea nudicaulis was the most generalist bromeliad species. The generalist species interacted with other generalists or with asymmetric specialists and there was no specialist–specialist interaction. This produced a strongly organized and nested matrix of interactions. This nestedness is similar to other plant-pollinators networks, supporting the hypothesis that the evolutionary relationship between bromeliads and hummingbirds is no stronger than that of other pollination networks.

We investigated the intraspecific variation in propagule mass within red mangrove (Rhizophora mangle) and its effect on carbon assimilation and seedling growth. Propagule sizes of red mangrove varied considerably at all three study sites along the south-eastern coast of Florida, with propagule fresh mass from 3.9 to 20.7 g for the scrub form and from 5.3 to 35.8 g for the tall form. Highly significant correlations were observed between propagule length and fresh weight at all three study sites and for two growth forms. The scrub form had significantly smaller propagules than the tall form. A greenhouse study showed that CO2 assimilation rates were not correlated with propagule mass, but total leaf area per plant increased significantly with increasing initial propagule mass in all three family lines of both the scrub and tall forms. Consequently, total carbon fixation rate by each seedling increased significantly with increasing propagule fresh weight in all cases, and the biomass increment significantly increased with increasing mass. Relative growth rate, however, was not correlated with propagule mass. The differences in leaf areas and biomass accumulation among seedlings from different sizes of propagules seem to have resulted from the differences in maternal reserve of hypocotyls. The considerable intraspecific variation in propagule size observed for red mangrove may have a significant effect on seedling growth and competitive ability.

We sampled riparian frogs along 18 streams at eight localities in Borneo. At four of these sites we sampled during more than one year. Altogether 49 species were included in our study and total sample size was 13,249. We measured overlap in species occurrences and arrays of abundances within and among localities. Variation over the time span of our study was minor within communities. Overlaps between streams at a locality were generally higher than overlaps of pairs of streams from different localities. Environmental variation, particularly in stream width and gradient, had a clear effect on both intra-and inter-locality overlaps. Although rainfall varied between localities and within localities over time, that variation did not seem to affect overlaps among or within communities. Environmental factors did not account for all differences in overlaps between communities. Instead, regional processes, perhaps the timing of barriers or speciation events, appear to have been responsible for geographic restrictions of several species, leading to variation in overlap values.

This study investigated the effects of light and soil fertility, on arbuscular mycorrhizal fungi (AMF) colonization, and the growth responses (height and dry mass) of Syzygium seedlings. Seedlings of four Syzygium spp. were grown for 2 y in six different light treatments at the research station of the Sinharaja Forest, Sri Lanka. The light treatments exposed seedlings to: (1) 3%; (2) 16%; (3) 50%; (4) 100% of full sun (control); (5) short periods (2 h d−1) of direct sunlight; and (6) long periods (6 h d−1) of direct sunlight. In the 16% of full sun treatment five sets of fertilizer applications supplied: (1) magnesium; (2) potassium; (3) phosphorus; (4) all three nutrients combined; and (5) no fertilizer (control). The Syzygium species had the greatest mycorrhizal colonization in brighter treatments that provided direct light. Comparison across species revealed S. firmum to have moderate mycorrhizal colonization but high total dry mass. Syzygium operculatum had high percentages of mycorrhizal colonization while S. rubicundum had low percentages of mycorrhizal colonization especially in deep shade. Syzygium makul showed moderate levels of mycorrhizal colonization and dry mass, but low height growth. Among fertilizer applications, phosphorus enhanced seedling growth and mycorrhizal colonization for all species. However, species showed decreased growth with high amounts of potassium and combined fertilizer applications. Results suggest that AMF colonization will be highest, and Syzygium spp. growth greatest, beneath canopy openings large enough to receive direct sun in phosphorus-rich soils.

Phyllostomide bats are the most important consumers of Piper fruits in the Neotropics (Heithaus et al. 1975) and, in particular, Carollia perspicillata and Glossophaga soricina are the species which demonstrate distinct preferences for these fruits (Charles-Dominique 1991, Fleming 1981, Fleming et al. 1977, Marinho-Filho 1991, Palmeirim el al. 1989). This is also true of Piper arboreum Aubl. (Piperaceae) in the gallery forests of Central Brazil (Bizerril & Raw 1997).

This study examined patterns in the species richness and abundance of small non-volant mammals along a tropical altitudinal gradient in north-eastern Australia. We investigated whether a mid-altitudinal peak in diversity was apparent, and if it occurred, whether it was determined by particular environmental conditions. We sampled a small-mammal assemblage at 17 sites distributed along an altitude-environmental gradient from savanna (350 m) to rain-forest vegetation (1000 m). Over four separate occasions (5100 trap-nights) we recorded 17 species of mammal with 416 captures. A positive non-linear relationship between altitude and mammal species richness and abundance was observed, peaking at the 800–900 m range. Many species were distributed across a range of altitudes, while others were strongly associated with particular habitat conditions. There was a distinct reduction in abundance and species richness at low altitudes associated with the less complex vegetation, lower productivity and possible anthropogenic effects. Key findings were: that small-mammal richness peaked towards the summit of the gradient and not at one-half the maximum altitude predicted by the mid-domain effect; contrasting conditions and greatest vegetation juxtaposition had the greatest influence on the patterns recorded; and that local idiosyncratic influences such as habitat factors, land management and historical biogeography are significant.

The position of Macrotermes michaelseni mounds were mapped in six areas of 1.5 to 31.0 ha in a range of habitats on the fringes of the Okavango delta. Abundance varied significantly between and within habitats with highest densities in relatively stable floodplain woodland. In all sites apparent overdispersion of active mounds was not statistically significant when edge effects were taken into account. When active and inactive mounds were combined some overdispersion was seen but due to the disturbance regime the probability of all mounds being active simultaneously was small. Intraspecific competition was, therefore, not considered likely. Our results and reanalyses of dispersion patterns in published accounts for Macrotermes species suggest that although mound dispersion can appear to be regular this is probably a result of historical precedence and chance events rather than any current density-dependent process.

Nothofagus species dominate small patches of rainforest on ultramafic soils in New Caledonia, forming an almost monospecific upper canopy on some sites. These stands are commonly bordered by rainforests of greater floristic and structural complexity, also on ultramafic soils. In two lowland stands, the population size structures of Nothofagus aequilateralis stems greater than 50 cm high had an approximately skewed bell-shaped distribution with a modal size class of 15–25 cm stem diameter, and with no evidence of old trees. This indicates that the establishment of Nothofagus has occurred over a limited time span, without sufficient recent regeneration to allow the future replacement of the existing canopy trees. The factors initiating the major period of regeneration are not certain, but large-scale disturbance is implicated and evidence of past wild-fire on both sites is consistent with this hypothesis. It is unlikely that significant regeneration of Nothofagus will occur as the stands mature and canopy gaps are created by the death of old trees, since saplings of other species already occur at high densities in the understorey and will probably pre-empt the resources made available by canopy gaps. Two other study sites were situated above 900 m asl. At Dzumac, in an apparently older stand dominated by N. codonandra, there is some evidence of recent regeneration, predominantly confined to a single large canopy gap. The population size structure of N. baumanniae on the fourth site, on the summit of Mt Mou, shows a closer approximation to a reverse-J curve. Seedlings, however, are relatively uncommon on this site, and the numerous saplings may be suppressed rather than young.

Analyses of topsoil provided no consistent evidence to suggest that mineral content is controlling the distribution of Nothofagus across vegetation boundaries.

The environmental factors promoting the formation of these monodominant canopies are uncertain, but appear to involve large-scale disturbance by windstorm or fire. The population size structures suggest that the canopies of the two lowland stands, at least, are likely to become more species-rich, with a progressive decline in the frequency of Nothofagus. Therefore, these lowland monodominant forests cannot be regarded as equilibrium communities, irrespective of whether more detailed studies reveal environmental differences across the community boundaries. The status of the two high altitude sites is less certain.

Recent advances in tracking technology have revealed significant intratropical movement of Nearctic–Neotropical migratory songbirds during their non-breeding season. We report the movement of 25 veeries (Catharus fuscescens) over multiple seasons (2009–2013) through equatorial rain forests of South America. Veeries initially settled on the Brazilian Shield geological formation but undertook an intratropical migration to a second South American region in January, February or March. Consequently, our study is the first to track individual forest passerines to document an annual migration from the Brazilian Shield to the Guiana Shield and into lowland regions of Amazonia. The movement and settlement patterns showed no spatiotemporal relationships with Nearctic–Neotropical migration, remained in accordance with the flood pulse of the Amazon basin, and were spatially and temporally complex suggesting relatively ancient ancestral origins. The ability to isolate the migration event from Nearctic–Neotropical migration is an important contribution to the ongoing discourse regarding the evolution of trans-hemispheric migration in the genus Catharus.

The reproductive biology of the dioecious understorey palm Chamaedorea radicalis was investigated in order to identify the primary pollen vector and quantify the relationship between female fecundity and local neighbourhood sexual composition. The study was conducted in a montane mesophyll forest within the El Cielo Biosphere Reserve, Tamaulipas, Mexico. The species is considered vulnerable in Mexico and there are concerns about the sustainability of leaf harvest. We determined that wind is the primary pollen vector, based both on floral and pollen morphological characters, and on a pollinator exclosure experiment. Successful wind pollination of this understorey palm was facilitated by the extended flowering period of males, which allows one male to be a source of pollen to receptive females for as long as a month. The number of flowers and fruits borne on a female were dependent on female size, however, no size parameter correlated well with fruit set. Fruit set was also not dependent on local sexual composition, male density or distance to the nearest male, suggesting that in this study area female reproductive success is not limited by the availability of pollen.

Livestock graze Indian forests to varying extents but their impact on wild native ungulates is rarely understood. Negative impacts of sympatric livestock on chital (Axis axis) demography and food availability were assessed and compared in the Gir Forest, India, at different spatio-temporal scales. No difference in average group size (mean ± SE) (7.11 ± 0.8 indiv.) (short-term response), fawn to doe ratio (0.43 ± 0.03) (short- to medium-term response), chital density (44.8 ± 7.1 indiv. km−2) (medium- to long-term response), and rate of population increase (r = 0.07 ± 0.014) (long-term response) was found between areas sympatric and livestock-free at the larger spatial scale of Gir Forest. Instead, chital density was correlated with rainfall (r = 0.92). After controlling for confounding factors of rainfall, vegetation community, terrain and lion density, chital density was 62% higher for livestock-free compared with sympatric areas but other demographic parameters showed no statistical difference. Peak above-ground biomass was greater in livestock-free (3255 ± 209 kg ha−1) compared to sympatric areas (1438 ± 152 kg ha−1), but chital food was more abundant in moderately grazed areas compared to livestock-free areas. Overall, long-term livestock grazing has depressive effects on chital but in the short term habitat productivity and suitability overrides the depressive effects of sympatric livestock.

We studied the avian foraging ecology in a single montane forest of northern Kenya, analysing the pattern of seasonal variation (wet vs. dry period) and its relationship with habitat structure. The foraging behaviour of 28 species was described in terms of four major dimensions (i.e. foraging technique, food substrate, perching site and perching height). Seasonal rainfall produced an increase in vegetation growth in the lower vegetation layers, while fruiting and flowering peaked in the dry season. We did not find much seasonal variation in foraging ecology when we analysed our data at the species or at the community levels. At the guild level, however, we found some seasonal shifts in perching height, food substrate and foraging technique. Some of these shifts seemed to be determined by food availability and distribution, as omnivores increased fruit consumption when this resource was more abundant, and nectarivores tracked the vertical distribution of flowers. The vertical biomass distribution of this avian community seemed to be largely determined by food. However, seasonal variation in the total biomass of some guilds was probably related to factors not considered in this study, such as breeding, or intra-African migratory movements. Altogether, despite marked seasonal variation in vegetation structure and food resources, the bird assemblage showed little change in its feeding ecology and micro-habitat use. Hence, we suggest that changes in habitat structure and resource levels were coped with primarily by adjusting population density and food requirements through seasonal breeding or migration.

Light environment, leaf physiological characteristics, and growth were compared for forest-grown saplings of three species of tropical trees with known life histories. Light environment was assessed both by hemispherical canopy photography and a quantitative visual index of crown illumination. Leaf gas exchange characteristics were measured by infrared gas analysis. The species tested included Lecythis ampla, a species tolerant of understorey conditions, Pithecellobium elegans, a species found in relatively bright sites, and Simarouba amara, a fast-growing, light-demanding species.

Annual height and diameter growth did not significantly differ between the three species, but highest average rates were found for Simarouba. Likewise, saplings of the three species were found in similar low light environments although Simarouba saplings were found in slightly brighter sites and Lecythis saplings were found in the lowest light environments. Despite similar light regimes, the species differed markedly in leaf area and gas exchange. Leaf areas of Lecythis saplings were five and ten-fold greater than Simarouba and Pithecellobium saplings, respectively. Light-saturated leaf photosynthesis and leaf dark respiration rates of Lecythis were about half those of Simarouba; rates of Pithecellobium were intermediate. Lecythis had the highest leaf photosynthesis at understorey diffuse light levels. Measures of annual growth were positively correlated with estimates of both direct and diffuse light with the strongest correlations between sapling performance and diffuse light.

Isotopic composition of leaf carbon (δ13C) and nitrogen (δ15N) is determined by biotic and abiotic factors. In order to determine the influence of leaf habit and site on leaf δ13C and δ15N in the understorey of two Atlantic forests in Brazil that differ in annual precipitation (1200 and 1900 mm), we measured these isotopes in the shaded understorey of 38 tropical tree species (20 in the 1200-mm site and 18 in the 1900-mm site). Mean site values for δ15N were significantly lower at the 1200-mm site (−1.4‰) compared with the 1900-mm site (+3.0‰), and δ13C was significantly greater in the 1200-mm site (−30.4‰) than in the 1900-mm site (−31.6‰). Leaf C concentration was greater and leaf N concentration was lower at 1200-mm than at 1900-mm. Leaf δ15N was negatively correlated with δ13C across the two sites. Leaf δ13C and δ15N of evergreen and deciduous species were not significantly different within a site. No significant phylogenetic signal for any traits among the study species was found. Overall, site differences were the main factor distinguishing traits among species, suggesting strong functional convergence to local climate and soils within each site for individuals in the shaded understorey.

Although herbivory in ground-rooted flora is well documented, current knowledge of the herbivore pressure on vascular epiphytes remains mostly anecdotal. Here, we present the results of a 3-year study on the herbivory in a population of the epiphytic bromeliad Vriesea sanguinolenta. In different years, 26–61% of all epiphytes showed traces of herbivore attack, while up to 4.4% of the entire leaf area of the epiphyte population was consumed annually. The recorded levels of damage to photosynthetic tissue, mostly caused by the larvae of Napaea eucharilla (Riodinidae, Lepidoptera), indicate that vascular epiphytes may be regularly and sometimes even lethally attacked by insect herbivores. The level of damage is comparable to ground-rooted tropical flora, which certainly does not support the prevalent notion of low and negligible levels of herbivory in vascular epiphytes.