Population structure and dynamics of the black-cheeked gnateater (Conopophaga melanops) were studied at Salto Morato Nature Reserve, in Paraná, southern Brazil, from October 2006 to September 2007. Territory size and population density, breeding season (timing and length), reproductive success and annual survival rates were estimated from sightings of 18 marked adult birds and the success of 18 nesting attempts. The black-cheeked gnateater is socially monogamous and territorial, with a breeding-season length of approximately 3 mo beginning in early October. Predation caused most nest failures, nest survival was 0.96 d−1 and apparent annual nesting success was 22%, resulting in annual productivity of 0.36 individuals per adult. Apparent adult annual survival was ~0.44 y−1. Seventy-five per cent of fledglings survived at least 2 mo after fledging. Two methods of estimating population growth rate suggest very different rates: r = −0.04 (~ stable), or λ varies between 0.475–0.616 (declining). Yet, low apparent adult survival suggests that territories are not permanent, perhaps abandoned after nest failure. We find that by estimating population growth, even in short-term studies, testable hypotheses can be generated that will allow better understanding of population dynamics.

The pollination ecology, breeding system and population genetic structure of three climbing Bauhinia species B. championii (4 populations, 23 individuals), B. corymbosa (2 populations, 25 individuals) and B. glauca (8 populations, 76 individuals) were studied in Hong Kong, southern China. We hypothesize that the climbing Bauhinia species will attract targeted pollinators to achieve out-cross success and high levels of self-incompatibility will be expected to maintain diversity, with local population expansion relying on vegetative propagation. All three species have inflorescences consisting of numerous small, pale, fragrant flowers, which show diurnal anthesis. Field observations revealed that all three species are predominantly pollinated by bees (particularly Apis mellifera) and butterflies (Graphium and Papilio species), although B. championii is also pollinated by wasps and flies. Bauhinia corymbosa and B. glauca have sucrose-dominant nectar, whereas B. championii has hexose-dominant nectar. In controlled-pollination experiments fruit and seed set were generally highest following artificial out-crossing. The index of self-incompatibility of B. championii is 1.07, indicating self-compatibility; B. corymbosa and B. glauca were obligately self-incompatible. The population genetic structure and variation of the Bauhinia species was investigated using ISSR markers. Generally the three species have moderate within-population (mean HS = 0.206) and high among-population genetic variation (mean GST = 0.284). No correlation exists between the geographical and genetic distance, possibly due to the small local population size. All three species showed high levels of heterozygosity as expected for predominantly out-crossing long-lived K-selected species.

Forests are being converted to grasslands and croplands across Africa and natural regeneration of forests is typically poor. In Serengeti National Park, Tanzania, the savanna tree species Acacia polyacantha established in riparian grasslands and forest trees subsequently established within these stands. We examined the conditions for establishment of: (1) A. polyacantha and (2) riparian (non-Acacia) forests. Fire was excluded from three grassland areas for 5 y allowing A. polyacantha to establish during 1999 when dry-season rainfall was high. The seedlings of forest tree species did not establish in grasslands, but were found in large A. polyacantha stands (> 0.3 ha) with reduced grass cover (< 10%), higher cover of herbs (> 80%) and thorny shrubs (> 90%). Seeding survival was high in large stands (0.87 y−1), but declined in artificial canopy gaps due to the ingrowth of grasses (0.21 y−1) and subsequent fires (0.07 y−1). Shrub removal also reduced seedling survival (0.46 y−1) due to browsing by antelope. We propose that: (1) A. polyacantha establishes in pulses perhaps as infrequently as twice per century, and (2) riparian forests in Serengeti have established via facilitation under larger stands where shade excludes grass, and therefore fires and thorny shrubs exclude browsers.

Our study presents experimentally based results on how large herbivore species affect savanna vegetation and thus murid rodents in the Hluhluwe-iMfolozi Park in KwaZulu-Natal, South Africa. We permanently excluded groups of large herbivore guilds of various body sizes (ranging from white rhino to hares) from sixteen 40 × 40-m plots of vegetation by using different fence types. We determined grass species composition and vegetation height and collected capture–mark–recapture data on murid rodents. Nutrient concentrations of the dominant grass species and rodent diet compositions were analysed. We found that herbivore species of different body sizes had different effects on murid rodents. The exclusion of medium-sized herbivores, such as warthog, impala and nyala increased the abundance of high-quality grass species, especially Panicum maximum. However, the dominant rodent species Lemniscomys rosalia preferred the most abundant grass species, rather than high-quality grasses. The absence of large bulk feeders, such as zebra, buffalo and white rhino led to an increase in vegetation height. In response, tall vegetation promoted both rodent abundance and species diversity and altered rodent species composition. Ultimately, our results indicate that the greatest effect on murid rodents came from the reduction of vegetation cover by large bulk feeders, which likely increased rodent predation risk.

To understand how fruit tree characteristics and microhabitats shape the assemblage of birds on fig trees and the pattern of fig–bird interactions, we observed and recorded, over 96 d and 816 h, the frugivorous birds visiting 32 individual trees belonging to 14 species of Ficus that were distributed across four different sites. A total of 30 bird species were recorded as eating figs, comprising 66.7% of the total number of frugivorous bird species recorded at the four sites. Small passerine birds such as bulbuls were the dominant frugivores for fig species. The number of bird species visiting different fig trees was significantly influenced by the crop size and canopy volume. Fruit colour and fruit size did not significantly influence the number of bird species, whereas habitats appeared to influence the composition of visiting birds. The fig–frugivorous bird interaction was asymmetrically structured, and the degree of nestedness appeared to be influenced by the forest type and degree of disturbance: the degree of nestedness in non-limestone forest tended to be higher than limestone forest; forest with less disturbance tend to be more nested compared with the open forest with high disturbance.

During a 4-y study of the palm Oenocarpus bataua, 368 reproductive structures on 102 palms were monitored. A reproductive structure required nearly 2 y for successful completion, from bud to ripe fruit. We found correlations with summed rainfall and averaged relative humidity and/or solar radiation for initiation of bud appearance, flowering and fruit maturation over 0–4 mo prior to the events, and another set of correlations over longer periods up to 11–12 mo before. Climatic variables showing short-term correlations (apparently triggering an event) often differed from those showing long-term correlations (which presumably initiated developmental processes culminating in the event itself). A high degree of asynchrony occurred in production of reproductive structures both within and between individual palms even within major reproductive peaks, and there were pronounced differences between individuals in total reproductive effort. Nearly all palms passed 1–3 y with little or no reproduction despite similar environmental conditions between years. We conclude that the supra-annual cycle of this palm is not the result of inadequate environmental cues in some years. There appear to be at least two different types of supra-annual cycles in tropical plants, differing in the relative importance of extrinsic cues vs. intrinsic physiological rhythms and in intrapopulation synchrony.

A sample of 1834 leaves from 83 plants in 26 families was collected in tropical rain forest in Madagascar from three vertical strata: top of emergent trees (up to 37 m), top of trees in upper canopy (about 22 m), and shrubs and saplings at ground level. These leaves were examined for damage by seven different agents: fungi, epiphyllae, mechanical injury, galls, leaf miners, grazing insects and skeletonizing insects. Fungi affected more than 60% of the leaves and grazing insects 45–65%, with other agents each affecting 3–30%; fewer than 4% of the leaves escaped unscathed by any agent. Individual leaves were attacked by up to five agents. There was a sharp decline in proportion of leaves affected by fungi, leaf miners, epiphyllae and mechanical breakage with increasing category of severity. Grazing insects, mechanical injury, and perhaps galls, had greater impact at ground level than in the canopy, with fungi and skeletonizing insects showing the opposite pattern. Leaf miners had lower incidence in the canopy than elsewhere. The observed vertical stratification means that a tree not only needs to balance its defences to meet multiple threats in any stratum, but must adapt to a different suite of challenges during its lifetime. Attack by grazing insects and fungi are major challenges for saplings at ground level, but with increasing height above the ground fungal attack on leaves becomes more prevalent, but attack by grazing insects less so.

We studied the effect of climate on the plant-pollinator communities in the West Indies. We constructed plots of 200 m × 5 m in two distinct habitats on the islands of Dominica, Grenada and Puerto Rico (total of six plots) and recorded visitors to all plant species in flower. In total we recorded 447 interactions among 144 plants and 226 pollinator species. Specifically we describe how rainfall and temperature affect proportional richness and importance of the different pollinator functional groups. We used three measures of pollinator importance: number of interactions, number of plant species visited and betweenness centrality. Overall rainfall explained most of the variation in pollinator richness and relative importance. Bird pollination tended to increase with rainfall, although not significantly, whereas insects were significantly negatively affected by rainfall. However, the response among insect groups was more complex; bees were strongly negatively affected by rainfall, whereas dipterans showed similar trends to birds. Bird, bee and dipteran variation along the climate gradient can be largely explained by their physiological capabilities to respond to rainfall and temperature, but the effect of climate on other insect pollinator groups was more obscure. This study contributes to the understanding of how climate may affect neotropical plant-pollinator communities.

Carbon dioxide emission through soil respiration is an important component of the carbon balance in forest ecosystems. However, little information is available on the rates of soil respiration in mangrove forests. We studied the rate of soil respiration in a secondary mangrove forest in eastern Thailand on an estuary of the Trat River during both the wet and dry seasons. A study site of 40 × 110 m was established and a series of vegetation zones identified: Sonneratia, Avicennia, Rhizophora and Xylocarpus, in order of increasing elevation inland. Soil respiration was measured during low tide, using an infrared gas analyser connected to a respiratory chamber, by excluding the respiration of above-ground roots from the chamber. At least 19 measurements were performed in each zone for each season. The rate of soil respiration significantly increased with increasing soil temperature. The soil temperature which was usually lower than that of sea water showed a trend that decreased with distance from the river in both wet and dry seasons. The relative land elevation causes different periods of inundation among the vegetation zones. The period was longest in the Sonneratia zone located on the river fringe, and became shorter moving inland. Thus, the elevation and relevant period of inundation are considered to be causal factors warming the soil. Consequently, the difference in soil temperature caused significantly different rates of soil respiration among the vegetation zones in the mangrove forest. Overall, the average rate of soil respiration ranged from 0.456 to 0.876 μmol CO2 m−2 s−1, supporting the view that mangrove forests have lower rates of soil respiration than do upland forests.

The objective of this study was to explore the leaf tissue water relations in terminal branches, as well as the relations between xylem structure and function of five sclerophyllous species coexisting on white sands within the Amazon region. In these species, which possess costly leaves and thrive in an extremely nutrient-poor habitat, the preservation of leaf survival would be of comparable importance to the preservation of xylem vessels. Three trees per species were tagged in the field for all measurements. Minimum leaf water potential (Ψ) was −1.53 ± 0.61 and −0.94 ± 0.10 MPa during rainless and rainy days, respectively. The Ψ for turgor loss averaged −1.92 ± 0.05 MPa. Therefore, minimum Ψ was maintained within a safety range above the critical value for turgor loss. Xylem (Kx) and leaf (Kl) specific conductivity averaged 1.4 ± 0.22 and 0.00033 ± 0.000045 kg m−1 s−1 MPa−1, respectively. Water supply was favoured in species with higher vessel density, and all species depended on relatively less abundant larger vessels for water transport. This would be advantageous because leaves were unable to develop very negative water potentials in order to maintain transpiration. High transpiration rates may be restricted to a few hours daily so as to prevent cavitation of widest vessels.

Diversity is positively correlated with water availability at global, continental and regional scales. With the objective of better understanding the mechanisms that drive these relationships, we investigated the degree to which variation in water availability affects the performance (recruitment, growth and survival) of juvenile trees. Precipitation was supplemented throughout two dry seasons in a seasonal moist forest in south-eastern Peru. Supplementing precipitation by 160 mm mo−1, we increased soil moisture by 17%. To generate seedling communities of known species composition, we sowed 3840 seeds of 12 species. We monitored the fates of the 554 seedlings recruited from the sown seeds, as well as 1856 older non-sown seedlings (10 cm ≤ height < 50 cm), and 2353 saplings (> 1 m tall). Watering significantly enhanced young seedling growth and survival, increasing stem density and diversity. Watering diminished the recruitment of species associated with upland forests, but increased the survival of both upland- and lowland-associated species. Though supplemental watering increased the growth of older seedlings, their density and diversity were unaffected. Sapling performance was insensitive to watering. We infer that variation in dry-season water availability may affect seedling community structure by differentially affecting recruitment and increasing overall survival. These results suggest that differential seedling recruitment and survival may contribute to the observed relationships between water availability, habitat associations and patterns of tree species richness.

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.

The Dipterocarpaceae in South-East Asia are known for their strict mast fruiting. During fruiting, pre-dispersal seed predation by insects contributes to mortality of dipterocarp seeds. We documented the community structure of insect seed predators on 11 Shorea species in Peninsular Malaysia. Fruits were sampled sequentially throughout seed development, and 2144 and 1655 individuals of seed predator weevils and moths were collected in two mast-fruiting events. Four weevils: Nanophyes shoreae, nanophyid sp. 1, Alcidodes dipterocarpi and Alcidodes humeralis, and one moth Andrioplecta shoreae were abundant in seeds of the Shorea species. The proportion of N. shoreae to the total predators became larger in the latter fruiting event than the former while that of Alcidodes spp. became smaller. The predator species composition changed during seed development; nanophyid spp. emerged from immature fruits while Alcidodes spp. emerged from mature fruits. Andrioplecta shoreae emerged from both immature and mature fruits. The level of host specificity measured by Kullback–Leibler distance was low for most predator species in both events. Predator species composition of many Shorea was similar to each other due to the dominance of N. shoreae though it might gradually differ with the phylogenetic distance between hosts. In conclusion, predator species composition of Shorea varied during seed development within a host rather than among hosts. Intermittent synchronized fruiting by congeneric Shorea trees would be advantageous to avoid pre-dispersal insect seed predators, and contribute to their reproduction.

Hornbills are important dispersers of a wide range of tree species. Many of these species bear fruits with large, lipid-rich seeds that could attract terrestrial rodents. Rodents have multiple effects on seed fates, many of which remain poorly understood in the Palaeotropics. The role of terrestrial rodents was investigated by tracking seed fate of five hornbill-dispersed tree species in a tropical forest in north-east India. Seeds were marked inside and outside of exclosures below 6–12 parent fruiting trees (undispersed seed rain) and six hornbill nest trees (a post-dispersal site). Rodent visitors and seed removal were monitored using camera traps. Our findings suggest that several rodent species, especially two species of porcupine were major on-site seed predators. Scatter-hoarding was rare (1.4%). Seeds at hornbill nest trees had lower survival compared with parent fruiting trees, indicating that clumped dispersal by hornbills may not necessarily improve seed survival. Seed survival in the presence and absence of rodents varied with tree species. Some species (e.g. Polyalthia simiarum) showed no difference, others (e.g. Dysoxylum binectariferum) experienced up to a 64% decrease in survival in the presence of rodents. The differing magnitude of seed predation by rodents can have significant consequences at the seed establishment stage.

We studied the relationships between soil nutrient availability and microbial biomass and activity of two contrasting soil conditions in a tropical deciduous forest in western Mexico. Hilltops have higher pH, water, dissolved organic C, and ammonium concentrations than hillslopes. Our main hypothesis was that soil microbial biomass, microbial activity and bacterium species richness would be higher in soils with high availability of nutrients. Fifteen soil cores, 0–5 cm depth, were taken in the dry, early rainy and rainy season, from each of the ten replicate plots in hilltop and hillslope positions located on three contiguous small watersheds. We measured moisture, C, N and P availability, potential C mineralization, net nitrification, microbial biomass and culturable heterotrophic and nitrifying bacteria in composite samples from each plot. Microbial biomass, species richness of culturable heterotrophic bacteria and C mineralization were significantly higher on hilltops than on hillslopes. Net nitrification was, in contrast, significantly higher on hillslopes than on hilltops and counts of culturable nitrifying bacteria were also significantly higher in the rainy-season samples. Hilltops and hillslopes had low similarity in composition of culturable heterotrophic bacterial species, particularly during the rainy season. The results suggested that C and N availability and seasonal changes in soil moisture are important controlling factors for some soil culturable-bacterial species, which may affect both C mineralization and nitrification in these tropical deciduous forest soils.

The response of tropical fauna to landscape-level habitat change is poorly understood. Increased conversion of native primary forest to alternative land-uses, including secondary forest and exotic tree plantations, highlights the importance of assessing diversity patterns within these forest types. We sampled 1848 moths from 335 species of Arctiidae, Saturniidae and Sphingidae, over a total of 30 trap-nights. Sampling was conducted during the wet season 2005, using three light-traps at 15 sites within areas of primary forest, secondary forest and Eucalyptus urograndis plantations in northern Brazilian Amazonia. The Jari study region provides one of the best opportunities to investigate the ecological consequences of land-use change, and this study is one of the first to examine patterns of diversity for a neotropical moth assemblage in a human-dominated landscape in lowland Amazonia. We found that the three moth families responded consistently to disturbance in terms of abundance and community structure but variably in terms of species richness, in a manner apparently supporting a life-history hypothesis. Our results suggest that secondary forests and Eucalyptus plantations can support a substantial level of moth diversity but also show that these forest types hold assemblages with significantly distinct community structures and composition from primary forest. In addition, the ability of these converted land-uses to support primary forest species may be enhanced by proximity to surrounding primary forest, an issue which requires consideration when assessing the diversity and composition of mobile taxa in human-dominated landscapes.

Plant responses to herbivory vary depending on herbivory type, yet the comparative effects of defoliation (e.g. by insects) and pruning (e.g. by large mammals) on a single tree species are poorly documented. We investigated this in the Northern Province of South Africa by comparing the regrowth of Colophospermum mopane trees previously defoliated by caterpillars or pruned by elephants, the two main browsers of C. mopane foliage. Shoots were up to 160% and 125% longer after natural (elephant) and simulated pruning and leaves ~25% longer in regrowth after natural pruning (n = 13–15 trees per treatment). Shoot density and chemical defences in leaves (tannin:protein ratio and total polyphenolic concentration) were, however, no different from control trees. Simulated defoliation resulted in statistically insignificant changes to regrowth in terms of leaf and shoot size (both slightly decreased) and shoot density (slightly increased). Natural (caterpillar) defoliation, however, resulted in regrowth with significantly decreased shoot and leaf size (about 50% and 20% of control lengths, respectively), as well as decreased leaf chemical defence. Shoot and leaf length were longer on trees flushing for the first time after pruning and late-season defoliation had a greater negative impact than mid-season defoliation. Despite the differences in regrowth characteristics after pruning and defoliation, mopane plants showed no apparent trade-off in investment between tolerance and resistance after either herbivory type, as neither regrowth nor chemical defence occurred at the expense of the other.

Little is known about how land-use changes affect interspecific interactions such as fruit–frugivore mutualisms. Forest age could affect both fruit sugar concentrations via differences in light availability or disperser abundance, and fruit removal rates via differences in bird and plant community composition. We examined how these two factors are affected by forest age in a Costa Rican rain forest. We compared seven young-secondary forest species, seven old-growth forest species, and Miconia nervosa growing in both forests. We measured sugar concentrations in fruits and manipulated the location of paired fruiting branches, measuring subsequent fruit removal. Sugar concentration means were on average 2.1 percentage points higher in young-secondary forest species than in old-growth forest species, but did not differ among Miconia nervosa fruits from the two forests. Fruit removal rates were higher in young-secondary forest for 86% of young-secondary forest species, 71% of old-growth forest species, and on average for both young-secondary and old-growth forest Miconia nervosa individuals. Higher sugar concentrations in young-secondary forest plants could reflect stronger competition for dispersers, while experimental fruit removal results suggests the opposite patterns of competition; fruits are more likely to be removed by dispersers in young-secondary forest independent of fruit nutrient concentration.

Young snakes are rarely seen in the field and little is known about their habits, mostly because they are too small for radio-telemetry (the primary method for studying snake spatial ecology). However, the offspring of some larger species can be fitted with transmitters and we investigated the spatial ecology and habitat use of ten hatchling water pythons (Liasis fuscus: Pythonidae) in the floodplain of the Adelaide River, tropical Australia. Patterns of habitat use in the late wet season and during the dry season were similar to those of adults tracked in the same vicinity in an earlier study. Soon after release the young snakes moved to the floodplain, avoiding pasture areas. Diurnal refuge sites were typically in the base of grass clumps or below the soil surface, especially in sites with thick vegetation and deep, wide soil cracks. Adult snakes are more sedentary but move longer absolute distances (mean ± SE = 252 ± 50 m wk−1) than hatchlings (66.3 ± 41 m wk−1). However, hatchling snakes moved longer distances relative to body size (84.4 ± 1.1 body lengths wk−1) than did the previously studied adults (66.0 ± 1.1 body lengths wk−1). Mean and minimum body temperatures of the hatchlings were correlated with mean and minimum air temperatures, respectively.

To evaluate N limitation on above-ground net primary production in a tropical lower montane rain forest, an N fertilization experiment was conducted for 2 y. The study site is located at 1200–1300 m asl in the Fortuna forest reserve in western Panama and has a mature, mixed-species stand growing on an Andisol soil. Control and N-fertilized (125 kg urea-N ha−1 y−1) treatments were represented by four replicate plots (each 40 × 40 m, separated by at least 40 m). Stem diameter growth was analysed by diameter at breast height classes and also for the three most abundant species. The three species did not respond to N addition. The response of stem growth and above-ground woody biomass production to N fertilization varied among dbh classes. Stem growth of trees of 10–30 cm dbh increased only in the first year of N addition while trees of 30–50 cm dbh responded in the second year of N addition, which may be due to differences in light conditions between years. Trees >50 cm dbh did not respond during 2 years of N addition. As a result, the overall stem growth and above-ground woody biomass production were not affected by N fertilization. Annual total fine litterfall increased in the first year of N fertilization, while annual leaf litterfall increased in both years of N addition. Above-ground net primary production, of which total fine litterfall constituted 68%, also increased only in the first year of N addition. The magnitude and timing of response of stem diameter growth and litterfall suggest that these aspects of above-ground productivity are not uniformly limited by N availability.