Cerberiopsis candelabra Vieill. is a long-lived, monocarpic (= semelparous) and mass-flowering rain-forest tree, endemic to New Caledonia. Population size structures suggest establishment has been episodic, followed by a recruitment gap that might signal population decline. Here, we use age structures based on tree rings to better assess population dynamics and persistence, and investigate influences of tree size, age and growth rate on flowering. Age structures of populations surveyed in 2007–2008 were unimodal, with establishment over c. 15–81 y, followed by a recruitment gap of c. 23–79 y. Seedling mortality was generally high. High densities of flowering trees or large-scale exogenous disturbances may be necessary for in-situ regeneration. There was no evidence of a simple flowering threshold: flowering in 2017 occurred across a wide range of tree size, age and growth rate. Instead, evidence suggested that size and age at flowering may vary among plants depending on their growth trajectory. Environmental triggers of flowering were not identified by dating tree establishment, but the last three mass-flowering events occurred in years of tropical cyclones. Regeneration and persistence might be facilitated if large-scale disturbances trigger flowering, improving reproductive efficiency by synchronising flowering and linking reproduction with environmental conditions that enhance seedling recruitment.

Disturbances and successional dynamics shape the composition of tree communities, but data remain scarce for tropical forests of West Africa. We assessed the imprint of past disturbances on the composition of evergreen forests in an Ivorian National Park. We hypothesized that (i) Pioneer indices (PI) based on the relative proportion of pioneer and non-pioneer trees relate to changing floristic composition due to successional dynamics, (ii) local community richness peaks at an intermediate value of PI under the Intermediate Disturbance Hypothesis (IDH) and (iii) early successional communities have higher beta diversity due to erratic founder effects. We performed a Correspondence Analysis of tree composition of 38 plots and examined how the main components of floristic variation related to environmental factors and PI. In addition, we tested the relationship between PI, local richness and beta diversity. The variation of PI better explained the main components of floristic variation than abiotic environmental variation, supporting a primary role of successional dynamics in shaping tree communities. We found a peak of richness at intermediate values of PI, supporting the IDH, with a mixture and earlier and later-successional species and more even abundances. The communities were very diverse and included many endemics and rare species. The results underline that the composition of early successional forests greatly varies depending on chance colonization events, while more similar old-growth communities are eventually observed after several decades. The findings should guide management practices for forest restoration, and for conservation of endangered species depending on their successional status.

Our study is located in northern Beni and aims to improve knowledge on regional landscape changes from the last 8600 years, based on pollen and charcoal analyses from a lacustrine sediment core from Lake Ginebra. Our results showed that gallery forest and lacustrine sediment were observed from 8645 until 3360 cal yr BP. After a change from a lacustrine to a swamp environment at 1700 cal yr BP, the Cerrados and the Mauritia swamp became installed 1000 years ago on our study site. The environmental changes we observed over the last 8600 years in the Ginebra record reinforce the evidence of a west–east climatic gradient with the persistence of rain forest throughout the Holocene on the western side and the presence of the Cerrados until the late Holocene on the eastern side. Moreover, the persistence of a wet forest in the early to mid-Holocene in southwestern Amazonia highlighted some local responses to the global trend that could be related to the distance from the Andes; while in the late Holocene, both an increase in insolation and strengthening of the South American summer monsoon system enabled the installation of a seasonal flooded savanna in northern Beni and of the rain forest in eastern Beni.

Microscopic charcoal preserved in lake and swamp sediments from 10 sites in Indonesia and Papua New Guinea and from 5 sites in Central and South America have been used to reconstruct long-term fire histories for these two regions. Comparison of these records demonstrates that fire is promoted during periods of rapid climate change and high climate variability, regardless of the presence or absence of humans. Broad synchrony of changes in corrected charcoal values in each region supports an atmospheric transmission of the climate signal via the dominant large-scale atmospheric circulation systems (Walker Circulation) that appears to have persisted since 16,000 cal yr B.P. Altered climate boundary conditions under the influence of changing El Niño-related variability, insolation, sea level, and sea surface temperature all influenced the strength of this connection. Correlation of biomass burning records between the regions tends to increase in the Holocene. The main period of inverse correlation occurs during the Younger Dryas Stade, when extratropical climate most affected the tropics. The strongest correlation between the two regions postdates 5000 cal yr B.P., when El Niño-related variability intensified. Fluctuations in tropical biomass burning are at least partly controlled by orbital forcing (precession), although extratropical climate influences and human activity are also important.

Pollen and charcoal records from two large, shallow lakes reveal that throughout most of the past 50,000 yr Noel Kempff Mercado National Park, in northeastern lowland Bolivia (southwestern Amazon Basin), was predominantly covered by savannas and seasonally dry semideciduous forests. Lowered atmospheric CO2 concentrations, in combination with a longer dry season, caused expansion of dry forests and savannas during the last glacial period, especially at the last glacial maximum. These ecosystems persisted until the mid-Holocene, although they underwent significant species reassortment. Forest communities containing a mixture of evergreen and semideciduous species began to expand between 6000 and 3000 14C yr B.P. Humid evergreen rain forests expanded to cover most of the area within the past 2000 14C yr B.P. coincident with a reduction in fire frequencies. Comparisons between modern pollen spectra and vegetation reveal that the Moraceae-dominated rain forest pollen spectra likely have a regional source area at least 2–3 km beyond the lake shore, whereas the grass- and sedge-dominated savanna pollen spectra likely have a predominantly local source area. The Holocene vegetation changes are consistent with independent paleoprecipitation records from the Bolivian Altiplano and paleovegetation records from other parts of southwestern Amazonia. The progressive expansion in rain forests through the Holocene can be largely attributed to enhanced convective activity over Amazonia, due to greater seasonality of insolation in the Southern Hemisphere tropics driven by the precession cycle according to the Milankovitch Astronomical Theory.

Epiphytes represent keystone resources for many arthropod and vertebrate species, however their ecology remains poorly explored, especially within the palaeotropics. Several recent studies have examined relationships between epiphyte richness and characteristics of local habitats, although these have all focused on neotropical forests. Here, we aim to determine whether predictors of neotropical epiphyte richness are consistent at a palaeotropical site. A total of 44 host trees (dbh range 25–288 cm) were sampled at two study sites on Buton Island, Indonesia. For each tree, epiphyte richness and seven variables relating to characteristics of the host tree and surrounding habitats were recorded: site (a proxy value for disturbance level and water availability), host above-ground biomass (agb), altitude, bark texture, exposure, emergence and crown area. Gaussian GLM analyses indicated that the percentage deviance explained in epiphyte richness per host was greatest for agb (20.9%), crown area (19.6%) and site (15.5%); similar to previous findings from the neotropics. Results therefore suggest that high epiphyte diversity within palaeotropical forests is most likely to be found in large tracts of undisturbed forest, supporting large, broad-crowned trees.

Ant gardens (AGs) are specialized ant-plant associations where arboreal ants build their carton nests in association with epiphytes that use the carton as a substrate. Most of the epiphytes are planted by ants; therefore, seed selection by ants is a key driver of the epiphyte composition of AGs. However, deterministic post-dispersal factors, such as the surrounding environmental conditions and plant succession, may also influence epiphyte composition. Here we ask whether epiphyte composition on a local scale is associated with dispersal constraints, local environmental conditions (light availability, number of branches and nest height) or AG successional stage. We sampled all epiphyte species in 18 AGs formed by Camponotus femoratus and Crematogaster levior in Central Amazon, Brazil. AGs were located within a range of 1 km and at a maximum of 20 m from the edges of a dirt road within a primary forest. Epiphytic composition showed strong spatial structure, decreasing in similarity with increasing distance. Environmental conditions and AG successional stage were not related to AG floristic composition, suggesting a key role of stochastic processes related to seed dispersal. A combination of seed abundance and attractiveness in neighbouring AGs seems to drive the higher similarity in epiphyte composition among closer AGs.

Predation pressure is essential in regulating population dynamics of herbivorous insects. We used artificial caterpillars (25 × 4 mm) made from brown-or green-coloured plasticine to compare predation pressure between countryside and near-natural rain-forest habitat in the Gulfo Dulce region (Costa Rica). Within each habitat, 162 caterpillars were placed randomly on different substrates along a 1200-m transect and at heights between 0.5 and 2.0 m. Artificial caterpillars were inspected at 24-h intervals for 3 consecutive days. Predation pressure was almost twice as high for countryside (mean attack frequency per capita: 1.11 ± 0.08 SE) compared with rain forest (0.66 ± 0.07 SE). In both habitats arthropods emerged as chief predator group, followed by birds. Attacks by non-volant mammals were very rare and restricted to rain-forest sites. In the countryside, bird attacks were more than four times as common as in forest, indicating a change in their relative importance across habitats.

Past studies of large, infrequent wind disturbances have shown that topographical, biological and meteorological factors interact to create complex damage patterns to forest ecosystems. However, the extent to which some of these factors change the forest microclimate along a vertical forest profile is poorly known. In a previous study, we correlated tree damage with a hurricane model that estimated past hurricane impacts within Cusuco National Park, Honduras over a 15-y period. Here we use the model to compare physical tree damage among different species in ten 150 ×150-m plots and to correlate modelled exposure of hurricanes to microclimate measurements along the vertical canopy over a 12-mo period. It was found that past hurricane impacts could still be detected long after the events. Different tree species showed different levels of wind damage. Most branch damage was observed on conifers (Pinus spp.), followed by angiosperm species. Vapour pressure deficit increased with height in the canopy and with increased disturbance level. A linear model explained 83% of the total variance in vapour pressure deficit, with 67% attributed to monthly fluctuation, 15% to altitude, 12% to historical hurricane damage and 6% to height in the canopy.

Land-use change in tropical forests can affect the micro-environment for decomposition under modified canopies. In turn, decomposition may have consequences for soil fertility and ecosystem sustainability. The effects of the conversion from primary forest to pastures on leaf-litter decomposition and its recovery in secondary forests 20 y after pasture abandonment were evaluated using litterbags and a general mixed model approach. Litterbags containing leaf-litter of two contrasting qualities were placed in those three ecosystems and the mass remaining after 90 d was quantified. The mass remaining was 50% lower in high- than in low-quality leaves. The effects of the decomposition environment depended on the substrate quality. Although differences among ecosystems were not significant for low-quality leaves, high-quality leaves decomposed more slowly in pastures than in forests (mean dry mass remaining was 38% in pastures, 14% in secondary and 12% in primary forest). The decomposition of common substrates did not differ among forests. Results show that the conversion of primary forest to pasture may produce conditions for slower decomposition; however, these conditions appear be restored to a great extent in 20-y-old secondary forests.

Plants can develop novel adaptations for nutrient acquisition in nutrient-limited ecosystems. These adaptations include colonization by roots of tree trunks and logs that can act as nutrient reservoirs. Termites may facilitate this root colonization by digging tunnels and accelerating decomposition in logs and tree trunks. We measured the frequency with which above-ground tree root colonization co-occurs with the presence of termites or their tunnels inside living trees above 20 cm dbh (n = 178) and dead tree trunks and logs at least 15 cm in diameter (n = 146) in a Bornean tropical forest. Roots above the soil surface co-occur with termite tunnels 39% more frequently than expected by chance in trunks of living trees and 17% more frequently than expected by chance in logs. By categorizing logs according to hardness through ease of penetration, we found that softer logs at a late stage of decay did not show co-occurrence of termite activity and roots to the same extent as harder logs. This suggests that trees forage where termites have removed physical barriers to colonization. In this fashion, termites may accelerate nutrient cycling in tropical rain forests.

Although predation is generally seen as one of the key factors determining the abundance and composition of insect herbivore communities in tropical rain forests, quantitative estimates of predation pressure in rain-forest habitats remain rare. We compared incidence of attacks of different natural enemies on semi-concealed and exposed caterpillars (Lepidoptera) in lowland and montane tropical rain forests, using plasticine models of caterpillars. We recorded attacks on caterpillars in four habitats: primary forest, secondary forest and forest fragment in lowlands (200 m asl), and montane primary forest (1700 m asl). We used 300 exposed and 300 semi-concealed caterpillars daily, and conducted the experiment for 6 d in every habitat. Daily incidence of attacks was higher on exposed caterpillars (4.95%) than on semi-concealed (leaf-rolling) caterpillars (2.99%). Attack pressure of natural enemies differed also among habitats. In the lowlands, continuous primary and secondary forests had similar daily incidence of attacks (2.39% and 2.36%) which was however lower than that found in a primary forest fragment (4.62%). This difference was caused by higher incidence of attacks by birds, ants and wasps in the forest fragment. The most important predators were birds in montane rain forests (61.9% of identified attacks), but insect predators, mostly ants, in the lowlands (58.3% of identified attacks). These results suggest that rapid decrease in the abundance of ants with altitude may be compensated by increased importance of birds as predators in montane forests. Further, it suggests that small rain-forest fragments may suffer from disproportionately high pressure from natural enemies, with potentially serious consequences for survival of their herbivorous communities.

Neotropical fruit-eating bats play a crucial role in forest regeneration by dispersing seeds of pioneer plants from forests into deforested areas. However, later in succession bats may carry seeds in both directions. We used an isotopic approach to reveal the direction of seed transfer mediated by three co-existing short-tailed fruit bats (Carollia castanea, C. sowelli and C. perspicillata) between a forest and an adjacent mid-successional site (>15 y since deforestation); two habitats where individuals of the genus Piper differed in stable carbon isotope ratios by ~2.5‰. In a feeding experiment, we confirmed that δ13C of seeds is not altered by digestive processes. We then collected seeds defecated by bats of the genus Carollia and found that δ13C of these seeds is higher than those of Piper individuals growing in the forest, irrespective of whether bats were captured in or outside the forest. We conclude that bats of the genus Carollia were more likely to carry seeds from successional areas into the forest than in the opposite direction.

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.

Island biotas often have lower species diversity and less intense competition has been hypothesized as a result. This should result in lower habitat specificity compared with mainland habitats due to larger realized niches. We investigate microhabitat associations of canopy trees with regard to differences in topography on an oceanic island (Viti Levu, Fiji) using twenty 10 × 60-m plots. We find high tree-species diversity (112 species with dbh ≥ 10 cm in a total of 1.08 ha) and high endemism (c. 60%), compared with other islands in Western Polynesia. Our sample plots aggregate into three distinct groups that are mostly defined by micro-topography: (1) ridges and steep slopes (well-drained sites), (2) moderate slopes and ridge flats (moderate drainage), and (3) flats (poor drainage). Associations with microhabitat are found for more than 50% of the 41 most common species but only one species is apparently restricted to a single habitat. These findings are similar to other rain forests and demonstrate considerable niche differentiation among island rain-forest tree species.

To improve our knowledge of the influence of land-use on solute behaviour and export rates in neotropical montane catchments we investigated total organic carbon (TOC), Ca, Mg, Na, K, NO3 and SO4 concentrations during April 2007–May 2008 at different flow conditions and over time in six forested and pasture-dominated headwaters (0.7–76 km2) in Ecuador. NO3 and SO4 concentrations decreased during the study period, with a continual decrease in NO3 and an abrupt decrease in February 2008 for SO4. We attribute this to changing weather regimes connected to a weakening La Niña event. Stream Na concentration decreased in all catchments, and Mg and Ca concentration decreased in all but the forested catchments during storm flow. Under all land-uses TOC increased at high flows. The differences in solute behaviour during storm flow might be attributed to largely shallow subsurface and surface flow paths in pasture streams on the one hand, and a predominant origin of storm flow from the organic layer in the forested streams on the other hand. Nutrient export rates in the forested streams were comparable to the values found in literature for tropical streams. They amounted to 6–8 kg ha−1 y−1 for Ca, 7–8 kg ha−1 y−1 for K, 4–5 kg ha−1 y−1 for Mg, 11–14 kg ha−1 y−1 for Na, 19–22 kg ha−1 y−1 for NO3 (i.e. 4.3–5.0 kg ha−1 y−1 NO3-N) and 17 kg ha−1 y−1 for SO4. Our data contradict the assumption that nutrient export increases with the loss of forest cover. For NO3 we observed a positive correlation of export value and percentage forest cover.

The germinable seed bank of the colonizing weed Eupatorium odoratum was studied at the University of Ghana's Agricultural Research Station, near Kade. Five sites representing different successional stages were selected: a closed-canopy forest; intermittent-canopy forest; secondary forest; agricultural land; and a burnt forest. Twenty-five soil samples (each 500 cm3; 10×10×5 cm) were taken at random in each site, to be used for germination experiments. The secondary forest site had significantly more seeds of Eupatorium odoratum (8428 seeds per m2) than any of the other four sites. In this site Eupatorium odoratum constituted 81% of the total seed bank and had significantly more rapid germination of seeds than any other species. The results indicate that the existence of a soil seed bank may depend on: (1) time allowed for seed accumulation; (2) habitat accessibility to dispersing seeds; (3) the type of disturbance that occurs in an area; (4) dispersal capabilities of colonizing species; and (5) the history of the species′ distribution in the area.

In the absence of growth rings it is difficult to give a precise time scale for processes associated with the re-establishment of tropical rain forest. This paper explores other methods by which a time scale may be constructed. The proportions of primary and secondary species, an index of similarity, biomass measurements, girth dimensions and gap size are all considered from sites in East Kalimantan, Indonesia. Data from primary, secondary and experimentally cleared forest sites are compared to estimate the minimum time required for various phases involved in the re-establishment of tropical rain forest after disturbance. A simple model is proposed to accommodate the data and other estimates in the literature. The model predicts a minimum period for the stablization of secondary species numbers as 60–70 years and the replacement of primary species as 150 years at which point gap formation is initiated. After approximately 220–250 years biomass stabilizes while individual trees exist for over 500 years.