Campos de murundus (earthmound fields) are common throughout the cerrado (savanna) in Brazil. They have a clearly defined distribution particularly where they are associated with ground water. There is a distinctive woody vegetation on the discrete mounds contrasting with surrounding grass-covered depressions.

After a reconnaissance ground and air-photograph survey of the nature and distribution of mounds within the Federal District, four one-hectare plots were chosen for detailed study within the ecological reserve of the University of Brasília. Measurements were made of the size, shape and frequency of mounds. Numbers varied from 26 to 61 ha-1 with a uniform distribution occupying 10–50% of the plots. Heights ranged from 0.05 to over 2 m. The generally semi-elliptical shape in ground plan had an average size of 7 by 5.5 m with no evidence of preferred orientation although water scouring from runoff partly influences the morphology. Volumes varied from 0.01 m3 to 141.5 m3. The soils of the murundus differed from those of surrounding depressions by being better drained, with bright colours and strong cohesive structures; they were more argillic with lower base saturation and pH values. Such sites favour colonization both by cerrado plants and by termites. A classification of the murundus is postulated. Although this paper does not consider the origins of murundus, they appear to relate more closely to drainage and differential erosion than to termite activity.

Tropical Cyclone ‘Rona’ crossed the coast of the Daintree lowlands of northeastern Australia in 1999. This study reports on its impact on forest canopy openness at six lowland rain forest sites with contrasting management histories (old-growth, selectively logged and regrowth). Percentage canopy openness was calculated from individual hemispherical photographs taken from marked points below the forest canopy at nine plots per site 3–4 mo before the cyclone, and at the same points a month afterwards. Before the cyclone, when nine sites were visited, canopy openness in old-growth and logged sites was similar, but significantly higher in regrowth forest. After the cyclone, all six revisited sites showed an increase in canopy openness, but the increase was very patchy amongst plots and sites and varied from insignificant to severe. The most severely impacted site was an old-growth one, the least impacted a logged one. Although proneness to impact was apparently related to forest management history (old-growth being the most impacted), underlying local topography may have had an equally strong influence in this case. It was concluded that the likelihood of severe impact may be determined at the landscape-scale by the interaction of anthropogenic with meteorological, physiographic and biotic factors. In the long term, such interactions may caution against pursuing forest management in cyclone-prone areas.

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.

Miombo woodland in Zambia is divided into wetter and drier types by the 1100 mm mean rainfall isohyet. In the present study two wetter (Northern, Northwestern) and three drier (Central, Eastern, Western) miombo subtypes were recognized.

A survey of the woody flora of 94 old-growth and 58 coppice stands in the five miombo subtypes revealed some significant differences in species diversity among them. The floristic differentiantion of miombo subtypes was best achieved by the use of the Shannon species diversity index (H′) and species density (number of species 0.1 ha−1 or 0.4 ha−1). H′ in miombo decreased from 2.247 in Northwestern to 2.136 in Northern, 2.052 in Eastern, 1.918 in Central and 1.824 in Western subtypes. Although species density was not significantly different between wetter miombo subtypes, this decreased in a similar fashion from 18.78 0.1 ha−1 in Northwestern to 18.30 in Northern, 16.65 in Eastern, 14.79 in Central and 12.29 in Western subtypes. The low species diversity in Western drier miombo was attributed to the combined effects of low soil fertility and rainfall.

Although the mean number of species per 0.1 ha plot was higher in coppice samples, species richness (d) and index of diversity (H′) were lower than in old-growth samples. These results indicate lower species diversity in regenerating miombo. The dynamic aspects of species structure should therefore be considered in the future conservation of biological diversity in miombo woodland.

We evaluated the relative importance of annual rainfall, temperature and their seasonality to tree species distribution in Ghana. We used species presence/absence data from 2505 1-ha plots systematically distributed over Ghana's forests. Logistic regression was used to determine species responses to four climatic variables generated from the Worldclim database. The distribution of 95% of 20 species was significantly associated with annual rainfall, 60% with rainfall seasonality, 45% with isothermality and 40% with temperature seasonality. Annual rainfall explained on average most of the variation (17%, range = 0.5–52%) in species distribution, followed by rainfall seasonality 5% (range = 0.5–27%), isothermality 4% (range = 0.8–24%) and temperature seasonality 1% (range = 0.4–4.5%). Our results suggest that, out of the climatic variables investigated, rainfall is the main factor determining tree species distribution in Ghana; temperature also influences the distribution of a number of species, although it explains much less of the variation. The reduction in annual rainfall that prevailing climate-change scenarios predict for the region will result in a shift in the distribution of most species, whereas the predicted increase in temperature variation is likely to have little effect.

Nests of a fungus-growing termite Macrotermes jeanneli discharge all their metabolic gases through a single outlet to the atmosphere. This made it possible to measure the production of metabolic gases, and the rates of water loss, for intact nests in the field. Rates of production of carbon dioxide and methane from isolated nest components (different termite castes and intact fungus combs) were measured. Using previously published nest population data and fungus comb weights in relation to nest size, the expected gas production rates for intact nests were calculated. These estimates were compared with direct observations of the gaseous outflow from intact nests. The rates were in reasonable agreement, but some nests emitted excess carbon dioxide, probably produced by respiration of tree roots and non-termite soil organisms. Large nests may have a total gas outflow of 100,000 to 400,000 1 d–1 including 800 to 1500 1 d–1 of CO2 and 0.5 to 1.3 1 d–1 of CH4. Nests lose water at the rate of up, to 13 1 d–1 gross, but allowing for ambient humidity the net water loss was up to about 5 1 d–1. Some of this is metabolic water, but the larger proportion comes from the soil. Area-based estimates of gas production were made for this and two other species of Macrotermes, but they are not accurate because the field distribution and mound density are not adequately known.

Investigations of bats in naturally fragmented ecosystems may help refine assumptions about bat responses to fragmentation of their habitats by human activity. Bat species assemblages were studied for a 3.5-y period in a naturally fragmented landscape in the north-west Yucatan Peninsula, Mexico. Bats were systematically sampled using mist nets in a total of 16 forest islands of four categories (four sites each): large (>20 ha), small (<5 ha), far and near (sites located >10 km or <1 km away from the nearest forest island, respectively). We captured a total of 1134 bats representing 17 species. Bat diversity and species richness were similar among categories of forest island. Fruit-eating bats (78–93% of captures) were significantly more abundant in large and in small than in forest islands in the far or near categories. Differences in density of Manilkara zapota trees in the forest islands might underlie the observed variations in the abundance of frugivorous bats. Distances traversed by bats (0.65–38 km) between forest islands (typically 100–300 m away), facilitates the mobility of bats across the landscape. However, the moderately rich bat species assemblage detected, suggests that other species may not be able to persist in such naturally fragmented ecosystems.

A plot of 1200 m2 was selected to represent the average epiphyte abundance of a moist subtropical broadleaved forest at Fushan in north-eastern Taiwan. In this plot, all epiphytes of 18 sample trees with dbh > 5 cm were removed and weighed to estimate their biomass and nutrient content. We found that the biomass of epiphytes and their associated detrital matter in this plot was 3360 kg ha-1. The nutrient capital of the epiphytes (kg ha-1) was: N = 42.4, P = 1.9, Mg = 5.5, Na = 1.3, Ca = 14.5 and K = 28.9. Although the epiphytic biomass constituted less than 2% of the total above-ground biomass of the forest, the epiphytes comprised about 21-43% of the total foliage nutrient capital of the ecosystem. Because nutrients contained in epiphytes and tree foliage are more readily available to other organisms than those in woody components, epiphytes may play a greater role in ecosystem nutrient cycling than their relatively small biomass would suggest.

On clearing fields, Ntumu farmers in southern Cameroon leave some large trees. The seed rain beneath 30 such remnant trees (12 species) was compared with that 10 m away from the edges of their crowns. Of a total of 39 765 seeds recorded in 90 seed traps over 2 y, 73.6% were of species different from the tree associated with each set of traps (‘foreign seed rain’). Seed rain included 100 morphospecies, two-thirds of which possessed endozoochorous seeds. Seeds of the pioneer tree Musanga cecropioides accounted for 71.4% of total foreign seed rain; seeds of this and other animal-dispersed species accounted for 94.5% of the total. Seed rain was 25 times higher beneath remnant trees than 10 m away. Mean species richness of monthly seed rain was three times higher beneath remnant trees than 10 m away. Both fleshy-fruited and wind-dispersed species of remnant trees attracted seed-dispersing animals which greatly enhanced the seed rain; attraction thus did not depend solely on presence of fleshy fruits. Seed rain was lower when human activity in fields was intense and increased during the period of growth of the last crops, which were not usually weeded. Heavy seed rain just before fallow may contribute significantly to regeneration, as does the presence of remnant trees.

We investigated the daily activity patterns of four species of small mammals in an area of cerrado habitat in central Brazil. We checked live traps at 3-hour intervals during the night. Bolomys lasiurus and Calomjis tenet (Rodentia, Muridae), two potential competitors, differed significantly in their daily activity patterns. Bolomys lasiurus had peaks during the twilight, whereas C. tener had a more constant activity through the night, with a peak between 2200 and 0100 h. Thalpomys cerradensis (Rodentia, Muridae) was more active immediately after sunset and in the last three hours before sunrise. Thylamys velutinus (Marsupialia, Marmosidae) was strictly nocturnal with greater activity early in the night. Other factors, such as predation pressure or diet, may be important in determining the activity patterns observed in this study.

All dead trees ≥ 20 cm DBH were counted in the first 6 mo of 1994 in 10 ha of wet lowland rain forest, in the Hoja Blanca Hills, western Ecuador. The trees were classified by their mode of death. Thirty-four per cent of the trees were uprooted, 35% had snapped, 15% had died standing and 16% were unclassified. Regression analyses found that slope position and whether an individual was a dicotyledonous tree or a palm (Iriartea deltoidea) to be both strongly related to the mode of death. Slope, altitude and the presence of buttresses also influenced the mode of tree death. Tree diameter, however, was not found to have any effect. Dicotyledonous trees predominantly uprooted and snapped while Iriartea mostly died standing and snapped. Uprooted and snapped trees were significantly spatially clumped while trees which died standing were distributed at random. It was concluded that the predominance of uprooting and snapping in Hoja Blanca mostly resulted from the steep terrain and high precipitation (c. 5000 mm y−1) as well as El Niño Southern Oscillation (ENSO) downpours. The implications of mode of death are discussed. The different modes created different types of gaps and could thereby potentially influence forest regeneration.

Although the potential contribution to tropical tree species coexistence of niche differentiation along light gradients has received much attention, the degree to which species perform differentially along soil resource gradients remains unclear. To examine differential growth response to soil resources, we grew seedlings of nine tropical tree species at 6.0% of full sun for 12 mo in a factorial design of two soil types (clay and white sand), two phosphate fertilization treatments (control and addition of 100 mg P kg−1) and two watering treatments (field capacity and water limitation to one-third field capacity). Species differed markedly in biomass growth rate, but this hierarchy was almost completely conserved across all eight treatments. All species grew more slowly in sand than clay soils, and no species grew faster with phosphate additions. Only Eperua grandiflora and E. falcata showed significant growth increases in the absence of water limitation. Faster-growing species were characterized by high specific leaf area, high leaf allocation and high net assimilation rate but not lower root allocation. Slower-growing species exhibited greater plasticity in net assimilation rate, suggesting that tolerance of edaphic stress in these species is related more to stomatal control than to whole-plant carbon allocation. Although relative growth rate for biomass was correlated with both its physiological and morphological components, interspecific differences were best explained by differences in net assimilation rate across six of the eight treatments. A suite of traits including high assimilation and high specific leaf area maintains rapid growth rate of faster-growing species across a wide gradient of soil resources, but the lack of plasticity they exhibit may compromise their survival in the poorest soil environments.

We irrigated and fertilized (with nutrients) seedlings of Doliocarpus olivaceus (Dilleniaceae, a shade-tolerant liana), Faramea occidentalis (Rubiaceae, a shade-tolerant understorey tree) and Tetragastris panamensis (Burseraceae, a shade-tolerant canopy tree) growing in the understorey of an old-growth tropical moist forest in Panama to assess the impact of seasonal water availability and nutrient-poor soils on seedling growth rates. In control plots, height growth rates were greater in the dry season than in the wet season for Doliocarpus (21%) and for Faramea (89%), whereas Tetragastris had similar seasonal rates. For numbers of leaves, Faramea had 3.5-fold greater relative growth rates in the dry season than in the wet season, while Doliocarpus and Tetragastris lost leaves (semi-deciduous) during the same period. Irrigation and nutrient augmentation increased height growth rates for all three species (45% to 272%). For Doliocarpus, irrigation and nutrient augmentation prevented leaf fall during the dry season. For Faramea in the dry season, irrigation and nutrient augmentation when applied independently reduced the growth of new leaves by 65% to 87%, but relative growth rates for number of leaves were the same as the control rates in the combined irrigation and nutrient augmentation treatment. The growth of new leaves for Tetragastris responded to dry-season irrigation but not nutrient augmentation. Although all measurements occurred beneath the forest canopy, during the dry season, Tetragastris had a negative relationship between canopy openness and relative growth rate for number of leaves, whereas the other two species had a positive relationship. Our results show that soil resources influence growth rates even in the deep shade of the forest understorey, and demonstrate different responses to soil resources among species that might contribute to niche differentiation and species coexistence.

Two dung beetle assemblages from rainforest and open forest in the wet tropics of north-eastern Australia are described. The fauna was sampled using flight intercept traps, baited pitfall traps and light traps, with flight intercept traps being the most effective sampling technique. Dung beetle species were found to be highly habitat specific with a switch from rainforest to open forest assemblages occurring over tens of metres. The majority of the fauna was active at night. The most abundant species were attracted to a variety of food types but several species appeared to specialize on either dung or mushrooms.

The allometry of crown shape and trunk diameter with tree height were analysed for four tree species in a tropical lowland rain forest, southeast Brazil. The dimensional relationships of a subcanopy species (Garcinia gardneriana) were contrasted with those of two canopy (Chrysophyllum flexuosum and Swartzia simplex) and one emergent species (Sloanea guianensis). For all trees ≥ 1 cm dbh, we recorded dbh, total height, branching height, crown area, crown width and crown length. Observed allometric relationships indicated interspecific variation in trunk diameter and crown shape with height. All species conformed to the elastic similarity model, except the emergent one that showed thicker trunks and a scaling exponent conforming to the constant stress model. The general allometric function used to describe the overall relationship (all sizes combined) did not specify exceptional variation in crown shape between species of contrasting adult stature (emergent vs. subcanopy species). However, when allometric relationships through ontogeny were considered, different strategies of growth, maintenance and expansion of crown became evident. Crown shapes were much more variable in canopy and emergent species than in the subcanopy one, suggesting that larger-statured species might be more flexible in the relative allocation of energy to height, diameter, and crown growth than smaller-statured ones. Notwithstanding, it is suggested that it is not possible adequately to predict allometric relationships only by adult stature/canopy position. Allometric variation may be also related to size-dependent changes in demographic traits and/or different responses to light availability among tree species.

The reproductive process of two species of Kielmeyera, K. coriacea and K. speciosa, sympatric in savanna areas in central Brazil, has been studied. The trees have similar pollination systems and dispersal mechanisms but distinct phenological behaviours. Fast germination after the beginning of the wet season, early root swelling forming a xylopodium which enables survival during the dry season, and recurrent sprouting from the swollen root system during the first years of development were features of an establishment syndrome common to both species. The seedling survival after establishment was high; after five years 64% of the seedling cohort of K. coriacea was still alive. These seedlings, in natural conditions, remain poorly developed and resprout recurrently from the soil during some years. The recruitment of adult plants seems to occur from this ‘seedling bank’. The reproductive process was higher in K. coriacea during most stages of the reproductive process which may explain the smaller population size and distribution range of K. speciosa. For both species, the reproductive process as a whole was mainly affected by biotic factors in the wet season and not by seasonal drought or periodic fire.

Spatial and seasonal variation in soil respiration rates were investigated in a tropical dry forest in Thailand. The spatial variation was examined at 50 points within a 2-ha plot in the forest floor during the dry and wet seasons. The seasonal and diurnal variations in soil respiration were measured at 16 and 5 points, respectively. The mean soil respiration rate during the wet season was 1041 ± 542 mg CO2 m−2 h−1 (mean ± SD), which is about twice that during the dry season. Soil respiration rate was negatively correlated with soil water content during the wet season. A polynomial equation using seasonal data describes soil respiration and water content: soil respiration rate increased with soil water content, but started to drop when soil water content exceeded 21%. The diurnal variation in soil respiration rate during the wet season was positively correlated with soil temperature, whereas during the wet season it was not correlated with soil temperature. The diurnal variation in soil respiration rate during the dry season showed a midday depression. The estimation of soil carbon flux with polynomial equations should incorporate different functions for the wet and dry seasons in tropical dry forests.

Tropical rain forests harbour the most diverse plant and animal assemblages known to science, but our understanding of assemblage structure and species interactions is limited. Bats, as the only flying mammals, have the potential to exploit resources from all strata in forest communities. Thus, fruit-eating phyllostomid bats often have been categorized into canopy-, subcanopy- and understorey-foraging species, based largely upon the height at which they were most frequently captured. Here we challenge this classification and use stable carbon isotopes to assess foraging height of bat species at an Amazonian rain-forest site in Ecuador and at a Caribbean lowland rain-forest site in Costa Rica for comparison with data from mist-net captures. The proportion of the heavy stable carbon isotope 13C in relation to the lighter 12C isotope increases in plants from ground level to the canopy (0.12‰ m−1–0.18‰ m−1), and these differences in stable carbon isotope signatures are reflected in the body tissue of phytophagous bats. We used the stable carbon isotope ratio (δ13C) of wing tissue to estimate the foraging heights of 54 phyllostomid species in two Neotropical bat assemblages. Based on stable isotope data, phyllostomid species exploit food resources at all vertical strata of the forest. Capture height was not a reliable predictor of foraging height and suggests that bats most likely use lower strata to commute between foraging sites to avoid predators. Vertical stratification is likely to be a key factor promoting niche partitioning, thus promoting high local species richness in many tropical animal assemblages.

We examined effects of experimental manipulations of vegetation cover on recruitment, mortality and density of seedlings (20–100 cm tall) and saplings (≥100 cm tall) of woody growth forms over a 2.5-y period. We created four treatments in each of three 15–20-y-old tropical forest stands in Costa Rica: a large canopy gap (270–350 m2), a small canopy gap (50–100 m2), understorey vegetation removal, and an unmanipulated control treatment. Creation of canopy gaps, especially large ones, increased first-year recruitment and density, as well as overall mortality of seedlings. Saplings experienced lower mortality and more prolonged gap-enhanced recruitment and density than seedlings. Removal of understorey vegetation had little or no effect on tree seedling and sapling dynamics. Recruitment and density of lianas responded only to large gaps, whereas understorey species responded to both gap treatments and to spatial heterogeneity within gaps. Tree species exhibited diverse regeneration requirements, whereas liana and understorey species were more specialized to the high and low ends of the light availability gradient, respectively. Canopy gaps provide a critical mechanism for regeneration of lianas, and canopy tree species that dominate during the early stages of secondary forest succession. The choice of management system for these secondary forests can determine the direction and rate of succession.