We studied the interaction between the bromeliad Werauhia gladioliflora and its flower visitors in the Caribbean lowland forest of Costa Rica, in order to quantify the mutual benefits to both partners. Over 6 y, the bromeliads flowered mainly between October and December; with an individual inflorescence flowering for an average of 34 d (n = 233 inflorescences). The bromeliad showed a flexible breeding system with autogamy occurring in addition to cross-pollination. Exclusive pollinators were small nectar-feeding bats (Phyllostomidae: Glossophaginae). The average volume of nectar produced per flower was 1.1 ml (n = 25 flowers). The main visitor was the bat Glossophaga commissarisi, which approached the flowers exclusively using hovering flight. Visitation by bats, measured by infrared light sensors, occurred throughout the night with an activity peak after midnight. Median hovering duration of the bats at the flowers was 320 ms (n = 1246 visits). Hourly mean of hovering duration was negatively correlated with hourly nectar secretion rate. The flower visitation behaviour of a bat over the night seems to be shaped by a combination of intrinsic physiological factors and by nectar availability. Size of both flowers and visitors make Werauhia gladioliflora a very accessible system for quantification of factors affecting evolution of bat–plant interactions.

The single most important food source for Pteropus rufus at Berenty, in south-east Madagascar, is the pollen of Agave sisalana, a commercial species introduced to the area 60 y ago, which was widely available and constantly eaten by the bats during this 28-mo study. The diet of the bats at this site is unique in this respect when compared with P. rufus elsewhere in Madagascar and with other Pteropus species. The dietary breadth of P. rufus at Berenty is narrow, consisting of only 14 plant species, identified through microsopic faecal analysis and direct field observations, and three unidentified ones. The bats also eat locally cultivated and introduced fruits (Mangifera indica, Psidium cf. cattleianum, Sclerocarya caffra, Cordia sinensis and Hylocereus species) and native and endemic forest species (Tamarindus indica, Celtis philippensis, Ficus megapoda, F. grevei, F. pachyclada and Grewia species). The majority of the plant species used by P. rufus for food are located within the gallery forests of the Mandrare valley. No evidence of adjacent endemic spiny forest species was identified in their diet. Thus, conservation of the remaining gallery forest as well as retention of the sisal plantations is important to maintain the food sources of P. rufus at this site.

Evaluation of proximate mechanisms (e.g. dispersal, immigration, competition, facilitation) that determine patterns of assemblage or community structure is an important step in the development of paradigms in ecology. Host–parasite systems are useful for such studies because host-parasite assemblages are easily defined units of study, each host individual harbours a sample from a community or assemblage, and many host species are common, providing replicate samples. I used ectoparasite assemblages from Noctilio leporinus collected from Paraguay to evaluate effects of host sex and body size on ectoparasite abundance and to determine if these assemblages exhibit a nested pattern of species co-occurrence. A total of 533 ectoparasites representing seven species and four families were collected from 28 hosts. Abundances of Paradyschiria fusca and Noctiliostrebla aitkeni responded positively to host body size. Host sex had no affect on ectoparasite abundances. Streblid bat fly assemblages from Noctilio leporinus were strongly and significantly nested. Abundances of all species of streblid were positively correlated with one another with Pearson product moment correlation coefficients between 0.424 and 0.646. Competition does not appear to affect community structure of streblids from Paraguayan Noctilio leporinus. Independent responses of species of streblid to host characteristics appear to mould assemblage structure in this system.

Neotropical species richness is often estimated using accumulation or rarefaction curves and extrapolations based on various methods, but the efficacy of these methods is rarely tested. We used both a time-limited trapping session and previous knowledge of the mammal fauna from a site in French Guiana to validate these different methods. Three currently used extrapolation models were tested on our data. In a 2.5-mo trapping period we caught 75 individuals representing 18 small non-volant mammal species in three different habitats. We found that for comparable trapping efforts, village edges presented a higher abundance and species richness than primary and secondary forests. Species richness extrapolations using current models demonstrated that the exponential dependence model fits the known diversity of the site better, although this model is usually applied to large geographic areas and to relatively poorly documented taxa. Both Clench equation and linear dependence models underestimate small-mammal species richness in our study. We finally emphasize the interest of sampling in such edges surrounded by either primary or secondary forest, to maximize the probability of trapping rare species.

Spatial patterns presented by the opossums Caluromys philander, Philander frenata and Micoureus demerarae were studied, through radio-tracking, in a landscape composed of eight small (1.3–13.3 ha) forest fragments surrounded by a matrix of open vegetation in south-eastern Brazil. Sixteen individuals were fitted with radio-collar transmitters and monitored for 2–8 mo. Fixes were obtained by the ‘homing-in on the animal’ technique. Numbers of locations of each individual varied from 6 to 117. Home ranges sizes ranged from 2.5–7.0 ha for C. philander, 0.6–7.4 ha for P. frenata and 0.8–1.7 ha for M. demerarae. Fragments, both edges and interiors, were used more often than the matrix; they are the primary habitat for these marsupials in the landscape. The matrix was used for foraging by P. frenata and C. philander, and traversed in five movements between fragments by P. frenata. Ability to use fragment edges and the matrix is important in explaining how these marsupials are able to persist in the landscape.

The objective of this study was to investigate the effects of tree cover and season on soil N dynamics and microbial biomass in a semi-arid southern African savanna in Zimbabwe. We used a randomized complete block design with five blocks of 100 × 100 m, demarcated in a 10-ha pocket of Colophospermum mopane-dominated woodland protected from grazing and fire. In each block, we randomly selected three mopane trees with large canopies (8.3 m crown diameter) and another three with small canopies (2.7 m crown diameter). We determined soil organic carbon and nutrient concentrations, litterfall N and C inputs, microbial biomass and N transformations beneath large and small mopane trees as well as in the intercanopy areas. Soil organic carbon, microbial biomass, N, P and K were more than twice those beneath large trees than in the intercanopy areas. Rainy-season net mineral N accumulation rate in the surface soil (0–10 cm) ranged from 3.71 μg g−1 mo−1 in the intercanopy areas to 8.80 μg g−1 mo−1 beneath large trees; correspondingly, net nitrate accumulation rate ranged from 1.33 to 3.60 μg g−1 mo−1. Dry-season net mineral N and net nitrate accumulation rates were similar across sampling sites and did not exceed 2 and 0.4 μg g−1 mo−1, respectively. Litterfall N inputs were positively and significantly correlated with soil N availability, microbial biomass N and N transformations. At all sampling sites, microbial biomass and mineral N pools in the dry season were maximum when soil moisture (∼5%) and N transformations were minimum. In contrast, when soil moisture (9–13%) and N transformations were maximum in the rainy season, microbial biomass and mineral N pools were minimum. It is concluded that the improved soil conditions beneath isolated trees in semi-arid savannas may enhance herbaceous biomass yield especially of canopy shade-tolerant species.

Drip tips are thought to resist the growth of epiphyllous fungi, lichens, bryophytes and algae on leaf surfaces by promoting the drainage of water following rain. This hypothesis was tested by altering the tip of one leaf in each of 50 pairs of opposite leaves on plants of each of two woody species in the understorey of Barro Colorado Island, Panama. After 11 mo in situ, there were no statistical differences between the mean epiphyll cover on leaves with and leaves without drip tips. Epiphyll cover was, however, strongly correlated between the opposite leaves at a node, even though one had a drip tip and the other had the tip removed. This correlation could be due to small-scale heterogeneity of insolation, temperature and humidity in the crowns of plants. A relationship between epiphyll cover and growth of the branch containing the leaves provides qualitative support for this interpretation. It seems clear that drip tips do not have a large, consistent, easily detectable effect on epiphyll cover. However, because of the tiny cost of drip tips, reductions in epiphyll growth that are small and transitory and occur in only a portion of a plant's leaves may provide sufficient advantage to explain the evolution of drip tips. No experiment to date has been capable of detecting such effects.

Gallery and floodplain forests in monsoonal northern Australia are mostly sclerophyllous and dominated by five closely related species of Melaleuca (Myrtaceae) amongst which niche differentiation is unclear. We present a floristic and environmental analysis of ‘the flooded forest’ using data from 340 plots distributed across 450 000 km2 of the Top End of the Northern Territory. Melaleuca argentea was confined to streams and occurred on sandier substrates, whereas M. cajuputi mostly occurred in the near-coastal lowlands on clay soils. The greater basal area of M. cajuputi suggests an association with productive sites. Melaleuca dealbata, M. viridiflora and M. leucadendra occurred on a wide range of soils. More deeply floodprone sites were occupied by M. argentea and M. leucadendra along streams and by M. leucadendra and M. cajuputi on floodplains and in swamps. A general deficiency but occasional abundance of Melaleuca seedlings suggests that regeneration is episodic. Seedlings were more frequent in recently burnt areas and especially where fires had been severe. We propose that Melaleuca forests occur where disturbance by fire and/or floodwater is too great for rain forest to persist, rendering them the wetland analogue to the eucalypts that dominate well-drained portions of the north Australian environment.

Although indigenous farmers and other traditional peoples have disturbed Amazonian forests for centuries, few studies investigate the effects of these disturbances on biodiversity. This short-term study investigates how bird assemblages are affected by agricultural practices adopted by the residents of a national park in the Brazilian Amazon. Twelve sites in secondary forest (four sites in three age categories) and 12 sites in primary forest were selected for bird sampling. Audio-visual censuses of birds were conducted in small plots (1 ha) of young secondary growth (4–5 y), middle-aged (7–15 y), and old (20–35 y) secondary forests. Each site in secondary forest had a corresponding control site in adjacent primary forest. Young secondary growth had fewer species than old secondary and primary forests. Bird species richness was similar in middle-aged, old secondary and primary forests. Bird communities of young secondary habitat were dominated by species normally found in open habitats, such as agricultural fields and igapó flooded forests. The bird species composition of young secondary growth was more similar to that of middle-aged forest, which in turn was more similar to that of old secondary forests. Bird species composition differed between young secondary growth and old secondary forests and primary forests and between middle-aged secondary and primary forests. Nectarivore/insectivores and frugivore/insectivores of monospecific flocks are significantly associated with secondary forests, especially in initial stages of forest regeneration. In contrast, specialized insectivorous birds that join mixed-flocks show a significant association with primary forest.

This study provides the first quantitative description of vertical stratification in calling heights of ensiferan species constituting most of the dry-season nocturnal acoustic community of an evergreen forest in Kudremukh National Park in south-west India. Calling heights of an average of 26 individuals of each of the 20 ensiferan species were measured and subjected to an analysis of variance to test for differences in mean calling height between species and a cluster analysis to check for the presence of discontinuous calling height layers. There were significant differences in mean calling heights between species. Calling heights of different gryllid and tettigoniid species ranged from the ground to the canopy. More gryllid than tettigoniid species occupied the ground and herb layer. Our study revealed vertical stratification of calling heights, with discrete layers corresponding to the canopy, understorey and the ground layer. These clusters emerged from the raw data of calling heights of individuals without a priori distinction of layers. We found no significant correlation between the calling heights of species and call features, including mean dominant frequency of narrow band calls, mean syllable rate and mean duty cycle.

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.

Heterogeneous agroforestry systems play an important role in maintaining animal pollinator diversity (Klein et al. 2003, Perfecto et al. 1996), most likely by extending floral resources in lean periods. An understanding of the mutualistic relationship between flower-visiting insects and crop species in such agroforestry systems (Kearns et al. 1998), particularly on the diversity of pollinator species, their spatio-temporal variations, foraging behaviour (Cunningham 2000, Greenleaf & Kremen 2006, Klein et al. 2003) and their pollination efficiency (Motten et al. 1981), is important as they are some of the crucial biological predictors of pollination success.

Rainfall and soil moisture availability vary greatly both spatially and temporally. They are prime factors influencing species distribution patterns, diversity and habitat associations in a range of biomes, and limit primary productivity in many natural ecosystems, as well as in forestry and agricultural systems (Hawkins et al. 2003, Kozlowski & Pallardy 1997, Lieth 1975). Projections of drying trends, and increased frequency and intensity of drought events with climate and land-use changes (Hulme & Viner 1998, IPCC 2001) have fuelled an increased interest in the role of drought in determining the structure and function of natural and managed forest systems (Allen & Breshears 1998, Miles et al. 2004). Such projections accentuate the need to assess, understand and predict plant reactions to drought, as well as soil moisture variation at different scales.

Leaf-cutting ants (genera Atta and Acromyrmex) have been denoted key species of American rain-forest ecosystems (Fowler et al. 1989) because of their multifarious effects on the vegetation. Being dominant herbivores, cutting up to 13% of the standing leaf crop in a colony's territory per year, they affect directly and significantly individual plants, plant communities and ecosystems (Wirth et al. 2003). The considerable ecological impact of these ants is paralleled by the well-known fact that some species strongly benefit from human-driven habitat alterations and represent prime pests throughout Latin America (Cherrett 1986). Numerous studies have documented populations of leaf-cutting ant to increase with increasing agricultural land use, deforestation and/or disturbance (Fowler et al. 1986, Jaffe & Vilela 1989, Jonkman 1979). Specifically, elevated colony densities have been recorded in (1) transformed vegetation such as pastures (Fowler 1983) and plantations (Jaffe 1986, Oliveira et al. 1998), (2) early successional forests (Vasconcelos & Cherrett 1995), and recently (3) isolated forest remnants (Terborgh et al. 2001).