Tropical pioneer tree species are considered as a functional group characterized by a suite of ecological characteristics such as high light demand and high photosynthetic capacities. This study compared the photosynthetic characteristics of eight co-existing pioneer tree species in 3–4-y-old and about 6-m-tall secondary forest stands in Sulawesi, Indonesia. Its objectives were (1) to determine the range and interspecific variation in six photosynthetic parameters, and (2) to identify morphological and chemical leaf traits that can predict light-saturated net photosynthetic rates (on a leaf area or leaf mass basis, Amax-area or Amax-mass). Species averages of Amax-area in sun leaves ranged between 14.2 and 20.3 μmol m−2 s−1 (mean 17.5) which is high compared with literature data. Among the co-existing species, average leaf size (56–896 cm2) differed by a factor of 16, specific leaf area (SLA, 10.7–21.4 m2 kg−1) and leaf nitrogen content (19.6–33.9 g kg−1) twofold. At the species level, Amax-area was not correlated with leaf N content but decreased significantly with leaf size. Amax-mass showed a higher interspecific variation than Amax-area, and was positively correlated with SLA and leaf N content (slope: 13.4 nmol CO2 g N−1 s−1). Both, Amax-area and Amax-mass were more closely related to leaf morphological attributes than to leaf N. We conclude that the tropical pioneer tree species studied do not form a homogeneous functional group in terms of photosynthetic performance. Rather, a considerable variation in leaf morphology and nitrogen content exists, which also shows up in a substantial variation in Amax-mass and, to a lesser extent, in Amax-area.

The regeneration processes and the spatial distribution of the shade-intolerant Weinmannia tinctoria seedlings in the south of Réunion were investigated, with a special focus on the role of tree-ferns in seedling establishment. Mature individuals and seedling patches of Weinmannia tinctoria, and also tree-ferns, were mapped on two 1-ha rain-forest plots. Weinmannia tinctoria has hemi-epiphytic behaviour since seedlings were generally located on plant supports (99.6%). Regeneration was better on a support than on the ground, and germination tests showed that seeds were light-stimulated. Tall tree-ferns (Cyathea spp.) were suitable supports. Cyathea glauca and C. excelsa were more suitable supports than C. borbonica. Weinmannia tinctoria establishment complies with the facilitation model of succession and is dependent on tree-ferns.

La régénération et la distribution spatiale des semis de Weinmannia tinctoria, espèce intolérante à l'ombre, ont été étudiées dans le sud de La Réunion. Nous nous sommes intéressés au rôle des fougères arborescentes sur l'émergence de plantules. Les adultes matures et les taches de semis (ensembles de plusieurs plantules) de Weinmannia tinctoria, de même que les fougères arborescentes, ont été cartographiés sur deux parcelles de 1 ha en forêt humide. Weinmannia tinctoria a un comportement hémi-épiphyte car les semis se situaient principalement sur des supports (99,6%). La régénération se révélait meilleure sur les supports qu'au sol, et les tests de germination ont montré que les semences germaient mieux à la lumière. Les grandes fougères arborescentes (Cyathea spp.) constituaient des supports privilégiés. Cyathea glauca et Cyathea excelsa représentaient des supports plus favorables que Cyathea borbonica. W. tinctoria apparaît donc comme une espèce qui s'installe principalement en utilisant le modèle de facilitation et qui dépend de la présence de fougères arborescentes.

Amphibians are known to be sensitive to environmental change but their responses at the level of metacommunities to short-term environmental variability are poorly understood. We used field data from two protected areas, La Pera and Nahá (Chiapas, Mexico) to test for variation in metacommunity properties for two consecutive years (2009 and 2010). Amphibians and accompanying environmental data were recorded to a standardized protocol within each landscape, in four or five transects of 50 × 2-m per patch, for 30 and 31 patches, respectively. We found 23 species in La Pera and 30 in Nahá (21 species shared). Metacommunity structure was analysed using reciprocal averaging (RA) ordination by means of metrics for coherence, turnover and boundary clumping, with Spearman rank correlation used to examine relationships with environmental variables. The metacommunity structure varied differentially among the landscapes between years, being classed as quasi-Gleasonian in La Pera in both years, but Clementsian for Nahá in 2009 and Gleasonian for Nahá in 2010. In further illustration of variation between years, in 2009 the principal community gradient (RA axis 1) for La Pera was significantly positively correlated with altitude (r = 0.36), forest disturbance status (r = 0.78), mean canopy cover (r = 0.79) and mean litter depth (r = 0.67), while in 2010 it was correlated with latitude (r = 0.38), mean grass-layer height (r = 0.38), incidence of rainfall prior to sampling (r = 0.35) and presence of temporary ponds (r = 0.45). Our findings support the notion that amphibians respond to short-term environmental changes by individualistic movement within the landscape as well as via population dynamic responses.

The nurse effect is a positive interaction in which one plant (the nurse) provides conditions that enhance the establishment and growth of another plant species (Callaway 1995). Increased environmental severity appeared to increase the strength of nurse effects (Brooker et al. 2008, Lortie & Callaway 2006). On the one hand, the impact of the nurse effect depends on the magnitude of the environmental changes exerted by the nurse plant. On the other hand, the impact could depend on the number of plant species in the regional pool that respond to such changes. For example, better conditions beneath the crowns of nurse plants might allow the occurrence of species that are sensitive to environmental stress and that occur infrequently in open areas. Thus, if a nurse plant modulates environmental conditions that are critical for the persistence of other plant species, it seems likely that such nurse plants would have greater effects in stressful habitats, where they cause relatively larger environmental mitigation (Badano et al. 2006, Callaway et al. 2002).

Hurricanes are major disturbance events in Neotropical mangrove communities, potentially affecting the reproductive success of mangrove species. This was the first investigation of changes in mangrove pollinator assemblages following hurricanes, and the effect of these changes on the mating system of Laguncularia racemosa. Insect pollinator assemblages were investigated in three Florida mangrove communities in 2001–2003, 2005 and 2009; two hurricanes affected the area in 2004. Visitation rates were estimated from 1445 insects observed during 272 10-min intervals; the number of flowers visited by each insect was also recorded. Pollinator diversity was estimated with the Shannon Index. Following the hurricanes, species richness was reduced by 43–65% and diversity declined by 36–70%. Significant declines in insect visitation to L. racemosa resulted in reduced outcrossing frequencies in 2005. Laguncularia racemosa flowers autogamously self-pollinate without insect visitors, so fruit set still occurred. Visitation rates returned to pre-hurricane levels by 2009, but foraging behaviours differed from pre-hurricane patterns; outcrossing was further favoured by reduced frequencies of long foraging bouts and increased frequencies of short foraging bouts. The mixed mating system of L. racemosa provides reproductive assurance following hurricane disturbances, when pollinator abundance is low.

Many tropical pioneer species depend on the presence of high seed densities in the soil for successful recruitment following canopy disturbance (Cheke et al. 1979, Dalling & Hubbell 2002, Guevara Sada & Gómez Pompa 1972, Whitmore 1983). However determinants of variation in the composition and abundance of soil seed banks remain poorly understood. Seed bank densities can be affected by rates of seed predation and pathogen infection on the surface and in the soil, by intrinsic rates of loss in viability following dispersal, and by variation in the timing and duration of fruit production (Dalling et al. 1997, Garwood 1983, Murray & Garcia 2002). Here we compare seasonal fluctuations in seed bank density in five Panamanian forests varying in elevation and seasonality of precipitation (Table 1). We predict that lowland forests should show stronger intra-annual fluctuation in seed bank densities than montane forests because seed production and loss rates should be higher under conditions of greater resource availability, and where consistent high temperatures support greater abundance or activity of seed predators and pathogens (Brühl et al. 1999). Secondly, among lowland sites, we predict greater fluctuations in seed bank densities at drier, more seasonal sites where seasonally favourable conditions for seedling recruitment may select for interspecific synchrony in fruit production (Daubenmire 1972, Garwood 1983).

Environmental factors influencing grass establishment and performance in tropical savannas are poorly understood, particularly in relation to disturbance. We describe a seed sowing experiment that examined the effects of fire regime, canopy cover and litter cover on the emergence, establishment, height and fecundity (seed production) of the regionally dominant annual grass Sorghum intrans in northern Australia. Establishment was significantly lower under the woody canopy compared with canopy gaps, and where seeds were sown on a layer of litter compared with bare soil. However, variation in fire regime had no significant effect on establishment or seed production. Additionally, a shade-house experiment was conducted to test the effects of litter on seedling emergence of S. intrans and six other grass species representative of the local flora (Pseudopogonatherum contortum, Sorghum plumosum, Chrysopogon latifolius, Eriachne triseta, Heteropogon triticeus and Alloteropsis semialata). All species showed reduced emergence when sown either above or below litter, compared with bare soil. Our results demonstrate the importance of the overstorey as a determinant of S. intrans abundance and savanna grass composition more generally, through its effect on establishment. The aversion of savanna grasses to litter (and S. intrans to canopy shading) supports the notion of savanna species being highly adapted to disturbance.

Many Neotropical felids are threatened with extinction due to direct effects of habitat destruction and/or human persecution. However, indirect and synergistic effects of human-felid conflict remain under-studied and potentially include increased stress and diet shifts that may negatively impact felid health. We hypothesized that faecal glucocorticoid metabolites (FGM) and endoparasite species richness (ESR) would be higher, and diet would shift, for felids outside protected areas where conflict occurs. In north-western Belize, a scat-detector dog located 336 faecal samples, identified to species and individual using DNA analyses. DNA amplification success was substantially higher within protected areas than outside. We detected jaguar, puma, ocelot, jaguarundi and domestic cat. FGMs were higher in puma and jaguarundi than in other felids, while ESR was similar across felids with domestic cats exhibiting the highest number of genera. Diet partitioning occurred among felids, but domestic cats may compete with ocelot and jaguarundi for small prey. Outside of protected areas, large cats shifted their diet to smaller prey and livestock remains were not found. Contrary to our hypotheses, FGM and ESR did not differ inside versus outside protected areas, but sample sizes were low in human-modified areas. We provide a baseline on wild felid adrenal activity, endoparasites and diet and suggest improvements to increase sample sizes outside protected areas. Our research provides a template for expanding non-invasive sampling approaches more widely across the range of Neotropical felids.

Mangroves generally grow in nutrient-poor environments and maintain high levels of productivity through unique adaptations for nutrient conservation (Reef et al. 2010). One such adaptation in mangroves is highly efficient resorption of limiting nutrients from senescing leaves prior to abscission (Feller et al. 2003). Thus processes that lead to loss of foliage prior to senescence and nutrient resorption (e.g. storms and herbivory) can be detrimental to tree growth and productivity (Bryant et al. 1983, May & Killingbeck 1992). Furthermore, decomposition of fallen leaves by soil microbial communities (Alongi 1994, Holguin et al. 2001) and crabs (Nagelkerken et al. 2008) is another important process contributing to the recycling of nutrients that are in short supply. Therefore, processes that lead to a substantial reduction in litterfall can have a strong negative effect on nutrient cycling and forest productivity. Mangroves have long been recognized as an important source of organic carbon (both particulate and dissolved) for the surrounding tropical coastal ecosystems (Bouillon et al. 2008, Kristensen et al. 2008). Thus, processes affecting litterfall in mangroves can affect the surrounding marine food webs.

Studies of recently isolated populations are useful because observed differences can often be attributed to current environmental variation. Two populations of the lizard Anolis lemurinus have been isolated on the islands of Cayo Menor and Cayo Mayor in the Cayos Cochinos Archipelago of Honduras for less than 15 000 y. We measured 12 morphometric and 10 habitat-use variables on 220 lizards across these islands in 2 y, 2008 and 2009. The goals of our study were (1) to explore patterns of sexual dimorphism, and (2) to test the hypothesis that differences in environment among islands may have driven divergence in morphology and habitat use despite genetic homogeneity among populations. Although we found no differences among sexes in habitat use, males had narrower pelvic girdles and longer toe pads on both islands. Between islands, males differed in morphology, but neither males nor females differed in habitat use. Our data suggest that either recent selection has operated differentially on males despite low genetic differentiation, or that they display phenotypic plasticity in response to environmental variation. We suggest that patterns may be driven by variation in intrapopulation density or differences in predator diversity among islands.

Interactions between ants and non-myrmecochorous diaspores occur frequently on the forest floor and the results of these interactions (e.g. diaspore cleaning or removal) will often depend on the morpho-chemical characteristics of the diaspores. We conducted two different experiments with seven plant species in the north-eastern Atlantic forest, Brazil. To evaluate whether ant interactions decrease diaspore persistence time on the forest floor, we established sample stations by placing five diaspores of each species spaced every 10 m along a transect and monitored ant interactions over a 24-h period. We also compared diaspore removal by ants and vertebrates through a paired experiment. We monitored removal of the seven plant species in treatments where ants were excluded and treatments where vertebrates were excluded. We recorded 332 ant–diaspore interactions, most resulting in ants cleaning diaspores in situ. Persistence of diaspores on the forest floor varied greatly among studied species and was less than 50% for three species. Ants also removed more diaspores than did vertebrates. Number of diaspores removed by ants was greater for small diaspores and with high lipid concentration. Ant–diaspore interactions may not always exert a positive influence on plant recruitment for diaspores with poor nutrient concentration. Consequently, ants may play a disproportionately important role as secondary dispersers in tropical forests.

High densities of palms are common in many tropical forests. In some cases, the dominance of palms has been associated with a depauperate understorey and high rates of native seedling mortality. A variety of different potential mechanisms has been suggested to explain the sustained palm dominance in the understorey and canopy of these forests. Working in a Cocos nucifera-dominated wet tropical forest at Palmyra Atoll in the central Pacific, we examine how litterfall from this pantropical, and economically important palm, impacts seedling survival. We compare rates of litterfall, and rates of litterfall-associated damage, between forest stands dominated by C. nucifera (coconut palm) and forest stands with low abundance of C. nucifera. To assess litterfall damage we survey damage to both artificial seedlings (n = 711), outplanted real seedlings of two species (with and without protection via caging; n = 204), and standing rates of litterfall damage. We find that rates of large-litterfall damage were an average of five times higher in sites with high densities of C. nucifera. Associated with these increases we observe that levels of physical damage to artificial model seedlings caused by litterfall over a 4-mo period increased from 4.9% in sites with low abundance of C. nucifera to 16.1% in sites with high abundance of C. nucifera. Extrapolated to annual rates, litterfall damage of this magnitude exceeds the average levels observed in other published studies. Living native seedlings also showed more than 300% higher levels of mortality in forest stands with high densities of C. nucifera, a difference that was greatly reduced when protected by caging from litterfall. In contrast, uncaged C. nucifera seedlings actually had slightly higher survivorship in habitats dominated by conspecifics. We suggest that litterfall damage may be an important mechanism by which this tropical palm reaches and maintains near monodominance in many coastal and insular habitats.

Phytotelmata (plant-held waters) are useful ecological models for studying predator–prey interactions. However, the ability of terrestrial predators to influence organism abundance within phytotelmata remains poorly studied. We investigated the predation of two pitcher-dwelling spiders, the red crab spider Misumenops nepenthicola and the yellow crab spider Thomisus nepenthiphilus (Araneae: Thomisidae) on dipteran larval abundance by manipulating their presence in the pitcher Nepenthes gracilis. Lower abundance in the larvae of the mosquito Tripteriodes spp. and increased spider mass were recorded after M. nepenthicola was introduced into laboratory-maintained pitchers (n = 10); T. nepenthiphilus did not affect larval abundance and a decrease in spider mass was recorded. Further investigations on two other dipteran larval species, the scuttle fly Endonepenthia schuitemakeri and gall midges Lestodiplosis spp., reported reduced numbers with the introduction of M. nepenthicola. We further tested this predation on dipteran larval abundance by its introduction, removal, and re-introduction to pitchers in the field (n = 42) over 1 mo. The spider's absence and presence significantly influenced larval numbers: all four dipteran species reported a significant decrease in numbers after M. nepenthicola was introduced. These results are one of the first to demonstrate the influence of a terrestrial phytotelm forager on the abundance of pitcher organisms via direct predation, reiterating the ecological importance of terrestrial phytotelm predators on phytotelm community structure and dynamics.

Determination of the factors that rule the preference of birds for certain fruits is fundamental to the understanding of the co-evolution of plants and their dispersers (Alves-Costa & Lopes 2001). Plants might compete for dispersers, and the response of dispersers will differ according to the variety of fruits available in nature (Denslow & Moermond 1982, Herrera 1981). Seed dispersal by birds is directly related to certain features of fruit, including colour, size, shape, abundance, nutritional value, habitat and distance between plants that are fruiting (Alves-Costa & Lopes 2001, Galetti et al. 2003, Levey et al. 1994, Murray et al. 1993). To understand how birds integrate these features in terms of fruit choice is a complex and widely misunderstood problem (Levey et al. 1994).

The most diverse known communities of insectivorous bats in the Palaeotropics and Neotropics are similar in alpha diversity (number of species). However, they show distinct differences with respect to wing morphology and the echolocation behaviour of their component species. In the Palaeotropics, most bat families are clearly separated in wing morphospace. The morphological niche of Rhinolophidae is vacant in the Neotropics, but primitive echolocators using sound primarily for scanning the environment rather than for prey capture are much more frequent there than in the Palaeotropics. In our opinion, a large portion of this difference can be traced to the different evolutionary histories of the respective communities. Bat families of different geographical origin are involved and their foraging styles obviously evolved differently in the Old and New World.

The application of stable-hydrogen isotope (δD) measurements to the study of animal movement, resource use and physiology depends on understanding factors driving variation in δD in animal tissues. The source of micro-scale variation in δD is poorly known, yet understanding micro-scale patterns of δD could shed light on important ecological processes and improve our abilities to track animal movements. Using linear and additive models, we explored the influence of micro-scale habitat use, moisture and diet on tissue δD values of Nicaraguan cloud-forest birds. Using mist nets, we captured 211 individuals of 22 resident Neotropical species at 500–1390 m asl and collected feather and claw samples. Based on three years of data from year-round sampling, our results suggest that microhabitat, seasonal shifts in moisture δD, and diet all influence bird tissue δD values. Our model results reveal a previously undescribed microgeographical effect on δD, where foraging level (understorey versus overstorey) and foraging location (forest interior versus adjacent coffee plantation) were significant predictors of δD values in bird claws and feathers. Mean claw and feather δD values among species varied from −83‰ to −19‰. Top models for claws and feathers explained 57% and 52% of variation in δD respectively. Direct comparisons of understorey (mean ± SD of −30‰ ± 15‰) versus overstorey (−50‰ ± 15‰) claw values suggest that δD may be useful in tracking vertical, micro-scale movement. Higher δD values in forest understorey birds reveal a heavy reliance upon recycled, fog moisture. Fragmentation and climate change may result in increasingly desiccated cloud forest that may exert a more negative influence on the food webs of understorey species that seem to be supported by recycled sources of moisture in the dry season.

Lowland forests of western Amazonia contain the most species-rich primate communities in the Neotropics, which begs the question of what mechanisms operate to promote species coexistence. This study examines habitat occupancy and its relationship to phylogeny in a primate community in Amazonian Ecuador. First, as potential factors that shape community structure, we determined whether (1) mean height in the forest canopy differed among species; (2) within each species, habitat occupancy was disproportional to habitat availability; and (3) species diverged in habitat occupancy. We then tested hypotheses regarding ecological distance and its relationship to phylogenetic distance among species pairs within this community. We tested these hypotheses primarily with data derived from 15 censuses of primate species on two 100-ha plots in eastern Ecuador. In these censuses, we observed eight primate species over nearly 200 encounters. We observed larger species at greater heights in the forest canopy than smaller ones. Although they occupied habitat types at frequencies proportionate to their availability in the study area, species diverged in habitat occupancy. Although a clear relationship was not observed between phylogenetic and ecological distances among species pairs, this study suggests that ecological differences among the species in this community facilitate their coexistence.

Disentangling local and historical factors that determine species diversity patterns at multiple spatial scales is fundamental to elucidating processes that govern ecological communities. Here we investigated how environmental correlates may influence diversity at local and regional scales. Primarily utilizing published species lists, amphibian and reptile alpha and beta diversity were assessed at 17 well-surveyed sites distributed among ecoregions throughout Costa Rica. The degree to which regional species diversity patterns were related to environmental variables and geographic distance was determined using Canonical Correspondence Analysis and Mantel tests. Amphibian alpha diversity was highest in lowland Pacific sites (mean = 43.3 species) and lowest at the high elevation site (9 species). Reptile alpha diversity values were high for both lowland Atlantic (mean = 69.5 species) and lowland Pacific (mean = 67 species) sites and lowest for the high elevation site (8 species). We found high species turnover between local sites and ecoregions, demonstrating the importance of beta diversity in the determination of regional diversity. For both amphibians and reptiles, beta diversity was highest between the high-elevation site and all others, and lowest among lowland sites within the same ecoregion. The effect of geographic distance on beta diversity was minor. Ecologically significant climatic variables related to rain, temperature, sunshine and insolation were found to be important determinants of local and regional diversity for both amphibians and reptiles in Costa Rica.

Forest fragmentation results in the creation of edge habitats, which can be responsible for large modifications in community dynamics (Murcia 1995, Saunders et al. 1991). Plant recruitment along edges is favoured for early successional species but is limited for core forest species (Fox et al. 1997, Williams-Linera 1990). Because the former generally produce large quantities of small seeds while the latter produce fewer large seeds (Hammond & Brown 1995), seed resource availability along the edge is biased in favour of smaller seeds. Such seeds are more likely to attract small rodents than large scatterhoarding species (Adler 1998, Forget et al. 1998). Moreover, the density and activity of forest animals in edge habitats can also be altered as a consequence of their specific responses to habitat changes, varying from edge avoidance to edge preference (Bowers & Dooley 1993, Goosem 2000). These changes in seed resource availability and rodent communities can have cascading effects on plant–rodent interactions in edge habitats and post-dispersal seed predation processes (Holl & Lulow 1997).