In savanna, termite mounds support more diverse vegetation than off-mound areas, but little is known of the patterns in plant assemblages on mounds. To explain vegetation differentiation between (1) component structures of termite mounds (conical centre vs. pediment), (2) active and inactive mounds (termites present vs. termites absent), and (3) sites on and off mounds (on mounds vs. surrounding savanna), species composition, richness and abundances of woody plants were recorded on 70 mounds and in 13 savanna plots (each 20 × 20 m) in north-eastern Namibia, focusing on soil hardness, mound status (active or not) and mound micro-topography as explanatory factors. Woody plants were absent from 33% of active mounds (54% of active cones) but were absent from only 5% of inactive mounds. Species richness and abundance per mound (mean ± SD) were lower on active mounds with (2.0 ± 1.8 and 4.6 ± 6.6, respectively) and without pediments (0.6 ± 0.6 and 0.9 ± 1.1, respectively) than on inactive mounds (4.4 ± 2.7, 19.4 ± 18.8, respectively). Despite the lower woody plant cover, some characteristic species, such as Salvadora persica, occurred preferentially on active mounds; this species occurred on 42% of active mounds. Mean soil hardness (± SD) was higher on conical parts of active mounds (4300 ± 2620 kPa) than on adjacent pediments (583 ± 328 kPa) and inactive mounds (725 ± 619 kPa). This study suggested that mound status, mound micro-topography, and soil hardness promote variability in the vegetation on mounds.

The variations in macronutrient concentrations of the leaves of Terminalia superba and Pycanthus angolensis were studied and the concentrations of nutrients in leaves before abscission were compared with those after abscission. The amounts of nutrients returned to the forest floor were also computed from litter fall data at the start of maximum annual fall in the Reserve. With the exception of potassium in Pycanthus angolensis, there were significant variations in the nutrient concentrations of the two species with the time of year. With increasing leaf age the concentration of nitrogen, phosphorus, potassium and magnesium declined in Terminalia superba while magnesium concentration decreased in Pycanthus angolensis leaves. Furthermore, calcium showed an increasing concentration in Terminalia superba with increase in leaf age. The concentrations of nitrogen, phosphorus and potassium decreased before leaf fall. Estimated losses in nitrogen phosphorus and potassium before abscission were 44, 53 and 50%, respectively, whereas generally there was an increase (40%) in the concentration of calcium at leaf fall. Magnesium did not follow a definite pattern. The return of calcium through litter fall to the forest floor was the greatest of all the major elements. The distribution and variation of foliar nutrient concentrations in the leaves of Terminalia superba and Pycanthus angolensis and the importance of the amount of litter and the concentration of the various nutrients in the influencing soil fertility are discussed.

Predator–prey dynamics are an important aspect of community ecology, but predation events are often difficult to observe. Among African primates, observations of mammal predation are particularly uncommon and generally restricted to a few ape and cercopithecoid species. I report five observations of mammal predation by golden-bellied mangabeys (Cercocebus chrysogaster) living in rainforest at the LuiKotale study site, Democratic Republic of the Congo. Over 46 all-day follows, mangabeys from one group caught and consumed four duikers (Cephalophinae spp.) and one Alexander’s cusimanse (Crossarchus alexandri). Individuals begged from the feeding individual in three of five observations. I observed one successful attempt at begging, which resulted in an adult female tolerating removal of blue duiker by a juvenile. These are the first detailed observations of mammal predation and food sharing by Cercocebus mangabeys and suggest mammals that feed alongside mangabeys may balance predation risk against social foraging benefits. Food sharing is rarely observed in most cercopithecine monkeys and could provide a useful metric to examine socio-ecological patterns of food acquisition.

Devil's gardens are one of the most remarkable mutualistic associations between ants and plants. Myrmelachista ants eliminate all vegetation from around their host plants, resulting in wide forest clearings which have intrigued scientists from the start. Despite their noticeability, here we report the discovery of devil's gardens in remote highland cloud forests of the Eastern Amazon, more than 2000 km away from their nearest known analogues in Western Amazonia. We describe the ecological characteristics of these gardens and consider what factors could have produced the geographic isolation of Eastern Amazonian devil's gardens. Three hypotheses are investigated: (1) the host plant distribution restricts the distribution of the mutualism, (2) the ecological tolerances of Myrmelachista explain the isolation, and (3) the devil's gardens of the Eastern Amazon constitute relicts from ancient forest refugia. The distribution of the possible associated myrmecophytes and previously described ecological ranges of devil's gardens cannot explain their ecological restriction to cloud forests in Eastern Amazonia, but our discovery is consistent with the biogeographic refuge hypothesis (i.e. highlands along the Amazon Basin constitute refugia for humid forests that spread during the Cenozoic). Our finding opens exciting perspectives for comparative studies of the origin, ecology and evolutionary history of this ant–plant mutualism.

Variations in environmental conditions along gradients play an important role in species distribution through environmental filtering of morphological and physiological traits; however, their effects on bat diversity remain poorly understood. Here, we investigate the effect of the distance to the nearest watercourse, terrain elevation, vegetation clutter, basal area and canopy height on taxonomic, functional and phylogenetic diversity and on the predominance of some functional traits (body mass, wing morphology and trophic level) of bat assemblages (phyllostomid and mormoopid bats) in a terra firme forest, in the northeastern Brazilian Amazon. We captured bats using mist nets in 15 permanent plots over a 25 km2 area of continuous forest. We captured 279 individuals belonging to 28 species with a total of 77.760 m2.h of sampling effort. Our results showed that bat richness increases as a function of distance to the nearest watercourse and that the assemblage also changes, with more diverse taxonomic and functional groups in areas further from the watercourse. Furthermore, elevation positively affects species richness, and the basal area of the forest positively influences the average body mass of bats. Taken together, our results demonstrate that subtle variations in the environmental conditions along a local scale gradient impact on the main dimensions of bat diversity in primary forests.

The phytoplankton periodicity of a tropical upland reservoir in Nigeria (Liberty Dam, Jos Plateau) and a temperate-type lake (L. Naranbagh) from the Kashmir Himalaya were compared. Variations in the phytoplankton communities in the water-bodies were both quantitative and qualitative. Liberty Dam conformed to the oligotrophic-desmid plankton type whilst in L.Naranbagh, phytoplankton resembled the eutrophic chlorococcales-diatom plankton type. Contrary to the general belief of muted (or lack of) seasonal changes in tropical regions, phytoplankton succession in the Jos reservoir was pronounced with dense persistence of some species for relatively short periods. The most striking fluctuations, typical of many temperate waters, were characteristic of L. Naranbagh with a build-up of plankton during summer and autumn. Variability in photosynthetic productivity was related to shifts in the climate-dependent population densities. The seasonal growth of the Jos phytoplankton reflected the alteration from the dry ‘Harmattan’ (December–February) to wetter (May–September) periods. These are analogous to the winter (December–February) and summer (June–August) seasons of the Kashmir Himalayan Valley. Phytoplankton associations and periodicities in each of the two warm-belt lakes were strongly driven by their respective local environments, including especially the marked seasonality of the climatic variables (rain, wind and solar radiation). Detailed comparisons of adequate long-term data from tropical and temperate waters are still required.

Life table studies were conducted on the flowers, pods and seeds of the tree Pithecellobium pallens to assess the extent of damage by the seed predators Stator limbatus and Merobruchus insolitus (Coleoptera: Bruchidae). Brachyacma palpigera (Lepidoptera: Gelechiidae) was also found to feed on the seeds of this tree. Seed predation and herbivore damage destroyed 41% of the seeds. Pods were taken to the laboratory and seed predators within were reared and identified. B. palpigera and M. insolitus were major causes of mortality, whereas damage by S. limbatus was slight. The growth ratio of pods to seeds did not indicate a rapid development of seeds as an evasive strategy against bruchid attack. Experiments showed no successful attack by bruchids on seeds exposed on the ground after dispersal from the tree.

In this study, we investigated whether landscape-scale variation of soil P accounts for 13C and 15N composition of detrital invertebrates in a lowland tropical rain forest in Costa Rica. The top 10-cm soil, leaf-litter samples and plant foliage were collected among 18 plots representing a three-fold soil P gradient during 2007–2009. Body tissue of litter invertebrates (extracted from leaf-litter samples) along with soil, leaf litter and green foliage were analysed for total C, total N, δ13C and δ15N values. Differences in δ13C and δ15N signatures across plots and relative trophic distances of detrital food webs (Δ δ15N), and their variation with soil P gradient were evaluated. We found soil P gradient had a significantly positive correlation with δ15N of Asterogyne martiana foliage, leaf litter, collembolans and oribatid mites. The δ15N of the collembolans and pseudoscorpions positively correlated to leaf-litter δ15N. Δ δ15N between the trophic levels remained consistent across the soil P gradient. Higher δ15N in the collembolans and oribatid mites might be derived from their consumption on 15N-enriched decayed debris or fungal hyphae growing on it. It suggests that fine-scale soil P variation can affect trophic dynamics of detrital arthropods via regulation of microbial community and nutrient dynamics.

Litter standing crop (LSC) is the quantity of plant detritus on the floor in forested environments. Knowledge of LSC is important in understanding many ecological phenomena. These include studies of litterfall, decomposition/litter turnover rates and nutrient cycling (Anderson et al. 1983, Dent et al. 2006), general plant performance (Benítez-Malvido & Kossmann-Ferraz 1999), other ecosystem processes such as the effects of fire (Odiwe & Muoghalu 2003) and fauna (Frith & Frith 1990, Giaretta et al. 1999, Levings & Windsor 1985). The determination of accurate annual average LSC data, may require monitoring over long periods due to seasonality and sometimes sporadic nature of litterfall and decomposition rates (Clark et al. 2001). Furthermore, the effects of topography and water movement create the need for both representative site selection and sufficient spatial coverage.

Non-native species impact tropical ecosystems, but the role of different anthropogenic disturbances on the success of non-natives remains unclear, especially in island tropical forests. We sought to understand the influence of anthropogenic habitat degradation and disturbance on non-native plant species in Madagascar. Specifically, we evaluated how densities of non-native species of woody shrub (Lantana camara), climber (Mucuna pruriens) and tree (Mangifera indica, Albizia lebbeck, Tamarindus indica) varied with forest habitat degradation and by disturbance type. We surveyed 60400 m2, recording 482 instances of disturbance and 903 non-native plants in and around the Ankarana National Park. Non-native plant densities were higher in degraded than primary forest. Within degraded forest, densities of non-native trees increased with disturbance. Tree densities correlated with extent of tree damage only in Tamarindus indica, never correlated with extent of tree removal, and always correlated with proximity to roads and trails. Our results suggest roads and trails have relatively greater importance in facilitating the success of non-native tree species than structural changes to habitat. In contrast, densities of Lantana camara and Tamarindus indica did not correlate with any measured type of disturbance; other unmeasured or historical factors may be more important drivers of these smaller, faster-reproducing species.

Although forest tree pattern-dynamics has long been a focus for ecological theory, many aspects of basic analysis remain problematic. This paper describes, examines and illustrates an ‘extreme-value’ approach to clump detection. Simulations demonstrate that the approach, though simple, is sensitive and well suited to identifying aggregation, even in small data sets. The test is complementary to the χ2 approach and significantly outperforms it when high-density clusters form a relatively small fraction of the total area. This difference holds true as density declines, though the power of both tests decreases and the χ2 test eventually fails. Though powerful, the extreme-value tests are slightly conservative. The approach is adaptable to other null distributions and applications. An illustration uses tree data from a Ugandan forest plot with records from 1939 to 1992. One plausible explanation for observed stem increases in this plot is an unusually high incidence of large tree-fall events. Evidence for this is sought through spatial localization of various stem populations. Chi-square tests detect non-random density patterns in the populations that comprise ‘all stems > 10 cm diameter recorded in the 1992 survey’, and ‘all recruits in 1976’. In the extreme-value test three populations are found to be clumped, these are ‘pioneers > 10 cm diameter recorded in the 1992 survey’, ‘all recruits in 1992’ and again ‘all recruits in 1976’. These patterns, particularly the pioneer trees and stem recruitment, signal a ‘gap-dynamic process’ of tree regeneration. Despite this, the trends observed in the Ugandan plot appear unlikely to be caused by tree-falls alone. Various technical and ecological aspects of the extreme-value approach and tree spatial analyses are discussed.

In temperate trees, the extension growth history of stems and branches is easily inferred from the positions of the rings of over-wintering bud-scale scars, allowing one to assess environmental responses from surveys of saplings (Beaudet & Messier 1998, Canham 1988, King 2001). But tropical trees rarely show such distinct demarcations of growth flushes. Furthermore, the frequency of flushing may vary with tree size and environment, and a number of tropical species, often light demanding, show continuous leaf production and extension growth throughout the year (Coley 1983).

Herbaceous plants are often under-studied in tropical forests, despite their high density and diversity, and little is known about the factors that influence their distribution at microscales. In a 25-ha plot in lowland Amazonian rain forest in Yasuní National Park, Ecuador, we censused six species of Heliconia (Heliconiaceae) in a stratified random manner across three topographic habitat types. We observed distribution patterns consistent with habitat filtering. Overall, more individuals occurred in the valley (N = 979) and slope (N = 847) compared with the ridge (N = 571) habitat. At the species level, Heliconia stricta (N = 1135), H. spathocircinata (N = 309) and H. ortotricha (N = 36) all had higher abundance in the valley and slope than ridge. Further, H. vellerigera (N = 20) was completely absent from the ridge. Conversely, H. velutina (N = 903) was most common in the drier ridge habitat. The two most common species (H. stricta and H. velutina) had a reciprocal or negative co-occurrence pattern and occurred preferentially in valley versus ridge habitats. These results suggest that taxa within this family have different adaptations to the wetter valley versus the drier ridge and that habitat partitioning contributes to coexistence.

The den is a multi-purpose critical space of carnivores and provides a growth conducive refuge which ensures both substances and protection from interspecific predation and harsh climate. Selection of optimal den sites determined by various site-specific factors potentially reduces aversive interspecific interactions and provides cost-effective access to food sources. In this study, we have assessed the factors determining the den site selection by a small population of striped hyaena, Hyaena hyaena in a shared landscape dominated by large carnivores. We assessed den site selection as a function of vegetation patch characteristics, site-specific anthropogenic threats/activities and topographical variables using Bayesian algorithm through field collected binomial data on den use by the species. Our model suggested that hyaenas select rocky refugia surrounded by trees and tall grasses, situated on mountain slopes proximate to a water body. Our study consolidated the importance of undulating terrain in the species ecology and postulated the slope as an ‘energy-expensive’ terrain that refrains frequent movement of other carnivores, in turn providing more affordable denning space for the striped hyaena. This study provides critical information on denning ecology of last remaining major breeding population striped hyaena of southern India.

Seed dispersal is an important ecological process that structures plant communities and influences ecosystem functioning. Loss of animal dispersers therefore poses a serious threat to forest ecosystems, particularly in the tropics where zoochory predominates. A prominent example is the near-total extinction of seed dispersers on the tropical island of Guam following the accidental introduction of the invasive brown tree snake (Boiga irregularis), negatively impacting seedling recruitment and forest regeneration. We investigated frugivory by a remnant population of Såli (Micronesian starling – Aplonis opaca) on Guam and two other island populations (Rota, Saipan) to evaluate their ecological role as a seed disperser in the Mariana archipelago. Using a combination of behavioural observations, nest contents and fecal samples, we documented frugivory of 37 plant species. Native plants comprised the majority (66%) of all species and 90% of all seeds identified in fecal and nest contents. Diet was highly similar across age classes and sampling years. In addition, plant species consumed by Såli comprised 88% of bird-dispersed adult trees and 54% of all adult trees in long-term forest monitoring plots, demonstrating the Såli’s broad diet and potential for restoring native forests. Overall, we provide the most comprehensive assessment to date of frugivory by the Såli and confirm its importance as a seed disperser on Guam and throughout the Marianas.

Leaf litter is an important source of nutrients to tropical forest trees, but its importance for understorey seedling growth is not well understood. Seedlings of Licania platypus (n = 190) and Coussarea curvigemmia (n = 304) were transplanted into deeply shaded forest plots in Panama having received 2 y of litter addition or removal and 7 y of fertilization with nitrogen, phosphorus and potassium combined, and their growth and foliar nutrients measured after 13 and 6 mo respectively. Licania platypus growing in litter addition and removal plots had faster height growth and slower leaf growth respectively than in control plots; C. curvigemmia showed no significant effects apart from lower survival in litter addition plots. These effects may be driven by soil nutrients, as suggested by differences in foliar nitrogen and potassium (but not phosphorus) concentrations, and by a pot experiment in a shadehouse using Ochroma pyramidale seedlings, which showed higher leaf area in soils from litter-addition plots, although seedling dry weight was higher only in fertilized soils. Overall, these results show that for one of two species, understorey seedling growth was increased by 2 y of doubled litterfall, and thus that they were probably nutrient limited even in the relatively fertile soils of this semi-deciduous tropical forest.