Air and soil temperatures were measured during dry season heading fires in three different physiognomic forms of native vegetation common in Central Brazil: cerrado sensu stricto (dense scrub of shrubs and trees), campo cerrado (open scrub), and campo sujo (open grassland with scattered shrubs). The vegetation was protected from fire for 15 y in some areas, had been burned once every two years, and once each year in other areas. The temperatures were measured with type-k thermocouples and recorded at intervals of 22.5 sees. Air temperature measurements were taken at 1, 60 and 160 cm. Maximum air temperatures ranged from 85°C to 840°C, and the duration above 60°C varied from 20 to 270 seconds. In the soil, negligible temperature increases were recorded below 5 cm depth, whereas at 2 cm maximum soil temperatures varied from 29 to 38°C. Possible influences of fuel load and moisture on the recorded data and on the behaviour of fire in the cerrado ecosystems are discussed.

Current research efforts to understand the relative invasibility of different plant communities have mostly ignored tropical forests. Only a few studies have treated invasive species in tropical forests, and recent worldwide analyses have not provided clear predictions concerning the relative invasibility of tropical forests. In this review, the extent to which exotic species have invaded tropical forests is summarized and four leading hypotheses to explain the apparently low frequency of invading plants in tropical forests are evaluated. In general, it is found that invasibility positively correlates with human disturbance, and that undisturbed tropical forests harbour few exotic species. To date, there is no evidence to attribute the low invasibility of undisturbed tropical forests to either their high species diversity or their high diversity of functional types. Instead, the low occurrence of exotic species in most tropical forests is most likely due to the fact that the great majority of exotic species that are transported to tropical countries lack specific life history traits, most importantly shade tolerance, necessary for successful invasion of undisturbed tropical forests. Unfortunately, this situation could change in the future with the expected increase in the plantation forestry of high-grade timber combined with common forestry practices that favour the cultivation of exotic species.

A bibliographical and herbarium investigation on the pollination syndrome of Mexican columnar cacti (tribe Pachycereeae) was conducted. Most Mexican species of columnar cacti show a chiropterophilic-pollination syndrome and they flower synchronously in March to May. The floral biology, reproductive system and visitors (to both fruits and flowers) of Neobuxbaumia tetetzo, the most abundant and dominant columnar cactus of succulent forest in the Tehuacan Valley, were studied. This species reached densities of c. 1200 individuals ha−1. The bats Leptonycteris curasoae and Choeronycteris mexicana were its only pollinators, whilst a more diverse array of visitors disperse seeds. Contrary to findings for multiple pollinators of columnar cacti in extratropical deserts in North America, the relationships between N. tetetzo and nectar-feeding bats was strong and tightly coupled in Mexico.

We evaluated occurrence and abundance of lianas and woody hemiepiphytes on canopy and emergent tree species in primary tropical wet forest at the La Selva Biological Station, Costa Rica. Two pioneers, Cecropia obtusifolia and C. insignis, lacked both lianas and hemiepiphytes. The seven non-pioneer species differed significantly in their loads of lianas and hemiepiphytes. For all non-pioneer species, two measures of liana and hemiepiphyte loads (the percentage of the crown occupied and the combined basal area of descending hemiepiphyte and liana roots and stems) increased significantly with tree diameter. In all non-pioneer species, most trees ∵ 70 cm diameter (50–97%) were colonized. Lianas occupied more trees and had a smaller mean host diameter than did hemiepiphytes; however, basal area of descending roots or stems was equivalent for the two life forms in occupied trees. We used partial correlations controlling for tree diameter to evaluate the relationship between annual tree diameter growth and loads of hemiepiphytes and lianas for six non-pioneer species. Five of the six species showed a significant negative correlation between loads and diameter growth. Existing published data show that the high incidence of lianas and hemiepiphytes at La Selva is paralleled in most other Neotropical wet forests.

Permanent plots totalling 12.4 hectares were established in 1969 in primary tropical wet forest at La Selva Biological Station, Costa Rica; all stems ≥10 cm diameter at breast height were tagged and measured. In 1982, the plots were again censused, and all live trees re-measured. Mortality over 13 years was 23.2%, or 2.03% per year based on a logarithmic mortality model. This suggests a stand half-life of around 34 years. Mortality was independent of size class in trees ≥10 cm diameter. Recruitment was equal to mortality. Tree growth curves and age-size relationships for 44 species were projected from 13-year diameter increments using a growth simulation procedure. Understorey trees grow slowly and consistently, and have short life spans; subcanopy trees also grow slowly, but live longer; shade-tolerant canopy trees show variable and often rapid growth and are long-lived; and shade-intolerant canopy trees grow rapidly, show little variation, and have short life spans. The longest imputed life span in our sample was around 440 years (years from 10 cm diameter to the maximum diameter); the shortest life span was around 50 years.

This study provides an estimate of aboveground live biomass for an intact eastern Amazonian forest. An allometric regression biomass equation was developed to estimate the aboveground biomass of live lianas. This equation, together with a previously published equation for trees, was then used to estimate the contributions of lianas and trees to the total biomass of forest patches in four stature classes: gap (openings in the canopy of at least 25 m2 with the dominant vegetation < 3 m high), low (3–15 m canopy height), medium (15–25 m canopy height), and high (> 25 m canopy height). Total stand-level biomass was estimated as the weighted average of the stature classes. In 130 ha of surveyed forest, forest stature classes were found in the following proportions: gap phase 8%; low stature 31%; medium stature 44%; and high stature 17%. Total aboveground biomass was found to be three times higher in high stature forest than in low. Liana biomass, however, showed the opposite result, being three times higher in low stature forest. Stand-level aboveground live biomass was estimated at 314 t ha−1 of which 43 t ha−1 (14%) was lianas. Liana leaf area index (LAI) ranged from 1.3 m m−2 in high stature forest to 5.3 m m−2 in low stature. Abundant lianas are generally interpreted as a sign of past forest disturbance. As forests throughout the Amazon basin are increasingly disturbed through human activities, it is likely that their biomass will be underestimated if the contribution of lianas is ignored.

Examination of phenological patterns of tropical trees at different temporal and spatial scales can elucidate biotic and abiotic factors that correlate with fruiting, flowering and/or leaf set patterns. In this study, 3793 trees from 104 species in Kibale National Park, Uganda were monitored. The trees were selected from two sites (Kanyawara and Ngogo) separated by 10 km. Trees were monitored monthly to document community-wide and population-level fruiting and flowering patterns for a maximum of 76 mo. Analysis of two sites over a number of years permitted examination of generalities of patterns found on smaller spatial and temporal scales. Spectral analysis indicated that community-level flowering and fruiting at Kanyawara exhibited regular annual peaks, although the flowering peaks were of shorter duration. At Ngogo, community-level flowering also displayed regular annual peaks, but fruiting had an irregular pattern with no distinct peaks. The abundance of fruiting trees at Kanyawara was negatively related to the minimum temperature in the previous season (3–7 mo prior). Since fruiting tended to peak when the first wet season of the year was ending and the dry season was beginning, this suggests that the minimum temperature in the previous dry season is important in determining how many individuals fruit. Flowering at Kanyawara peaked immediately after the maximum annual period of high irradiance. Within-species synchronization was evident in the flowering for all species examined at Ngogo and for 64% of those at Kanyawara. Fruiting was synchronous within species for 64% of the species at both sites. Despite this general community-level synchronization, the months of peak fruiting and flowering for some species varied markedly among years. Furthermore, for a number of species the timing of fruiting or flowering events differed between Kanyawara and Ngogo. For some species, trends that were suggested from one year of data were not supported when additional years were considered. Although these two sites are close together, share many of the same species, and experience similar climatic regimes, many phenological patterns were site-dependent.

The scaling of crown size and trunk diameter with tree height (allometry) was determined for 14 common species of the tropical wet lowland forest at La Selva, Costa Rica. The study showed that allometric differences between species are related to adult size, regeneration niche (gap vs. non-gap) and longevity, as follows: (1) adults of understorey species are larger crowned than similar statured (6–15 m) saplings of canopy trees; (2) species commonly found in gaps as saplings are somewhat larger crowned than shade-tolerant species over the 1–6 m height range; and (3) long-lived canopy species show greater increases in crown breadth with increasing height thandoshort-livedspecies.Trunkallometryisrelated to mechanical requirements for support, including the need to withstand greater wind forces in the upper canopy. The common canopy species, Pentaclethra macroloba, which comprises 40% of the basal area at La Selva, is particularly wide-crowned and thick-trunked at its maximum height. On the other hand, the comparatively narrower crowns and trunks of the other canopy species allow them to reach a given height with less biomass. These differences in allometry may influence tree density and forest structure at La Selva.

We studied the population structure, density and biomass of seven ungulate and two primate species in the tropical forests of Nagarahole, southern India, using line transect sampling and roadside/platform counts, during 1986–87. The estimated ecological densities of large herbivore species in the study area are: 4.2 muntjac km−2, 50.6 chital km−2, 5.5 sambar km−2, 0.8 four-horned antelope km−2, 9.6 gaur km−2, 4.2 wild pig km−2, 3.3 elephant km−2, 23.8 hanuman langur km−2 and 0.6 bonnet macaque km−2. Most ungulates have female-biased adult sex ratios. Among common ungulate species, yearlings and young of the year comprise about a third of the population, suggesting relatively high turn-over rates. Three species (muntjac, sambar and four-horned antelope) are solitary, while others form groups. The study area supports a wild herbivore biomass density of 14,744 kg km−2. Among the three habitat types within the study area, biomass is lower in dry deciduous forests when compared with moist deciduous or teak plantation dominant forests. Using our results, we have examined the factors that may contribute towards maintenance of high ungulate biomass in tropical forests.

The seasonality of both rainfall and solar irradiance might influence the evolution of flowering and fruiting in tropical forests. In seasonally dry forests, to the degree that soil moisture limits plant productivity, community-wide peaks in reproduction are expected during the rainy season, with seedfall and germination timed to allow seedlings to become well established while soil moisture is available. Where soil moisture is never seasonally limiting, seasonal changes in light availability caused by periods of cloudiness or seasonally low zenithal sun angles should favour reproduction during seasons when irradiance levels are high. To evaluate these predictions, we documented the timing of flower and fruit fall for 10 and 15 y at El Verde, Puerto Rico, and Barro Colorado Island (BCI), Panama. At El Verde, rainfall is abundant year-round and solar declination largely determines seasonal variation in irradiance. At BCI, rainfall is abundant throughout the 8-mo wet season while drought develops and average solar irradiance increases by 40–50% over the 4-mo dry season. Seasonal variation in the number of species flowering and fruiting at both sites was generally consistent with the hypothesis that seasonal variation in irradiance limits the evolution of reproductive phenologies. Community-level metrics provided no evidence for a similar role for moisture availability at BCI. Seasonal variation in irradiance also strongly influenced seed development times at both sites. Thus, community-wide phenologies reveal a strong signature of seasonal changes in irradiance, even in those forests that exhibit some degree of seasonality in rainfall.

This study describes the fruiting phenology of woody plants and their dispersal syndromes in caatinga (semi-arid region in the northeast of Brazil). The fruiting phenology of 42 species with different dispersal modes and life-forms was followed over a period of 1 y. Animal dispersal was the most commonly observed dispersal mode (36%), followed by anemochory (33%), ballistic dispersal (19%) and barochory (12%). Overall, a greater number of species fruited during the rainy season. Zoochorous species were the most representative in the rainy season, whereas anemochorous species predominated during the dry season. Five different life-forms were observed, and the occurrence of dispersal modes was discussed for each of them. In the caatinga plant community studied the patterns of life-forms, fruiting phenology and seed dispersal syndromes were similar to other tropical seasonal ecosystems.

Este trabalho teve como objetivo principal descrever como se comportam as espécies de caatinga (região semi-árida do Nordeste brasileiro) com relação ao modo de dispersão durante as estações seca e chuvosa. Foram observados também os modos de dispersão apresentados em cada forma de vida. A fenofase de frutificação foi acompanhada em 10 indivíduos de 42 espécies durante um intervalo de um ano. A zoocoria representou o modo de dispersão mais observado (36%), seguido da anemocoria (33%), balística (19%) e barocoria (12%). Um maior número de espécies frutificou durante a estação de chuvas, sendo a zoocoria mais representativa nesta estação, enquanto que a anemocoria foi mais representativa na época de estiagem. Foram observadas várias formas de vida, discutindo-se o modo de dispersão em cada uma delas. Constatou-se que as espécies de caatinga estudadas encontram-se dentro dos padrões gerais de época de dispersão dos diásporos e representatividade das síndromes de dispersão observados em outros ecossistemas com sazonalidade.

A possible mutualistic dispersal system between a large-seeded tree of French Guiana, Vouacapoua americana (Caesalpiniaceae), and caviomorph rodents, Myoprocta exilis and Dasyprocta leporina, is described. Mast fruiting of Vouacapoua at the beginning of the wet season coincides with scatter-hoarding seed dispersal. During the wet season, almost 100% of marked seeds on three sites were removed: nearly 70% were buried and the rest were eaten by mammals. Unburied seeds were attacked by insects and/or lost their ability to germinate. Rodents preferred ungerminated seeds, and had no interest in germinated seeds. Seeds were buried individually near natural objects such as palms, branches, logs, lianas, roots and trees. After predation by rodents, seedling distribution did not differ from seed distribution. Most seeds were transported less than 5 m from the feeding plots but some were carried as far as 22.4 m. Between 40 and 85% of dispersed seeds were retrieved during the following month by rodents and eaten. The disinterest of caviomorph rodents in germinated seeds, because of rapid exhaustion of endosperm reserves, prevents feeding from hoarded Vouacapoua during the long dry season when resources are scarce. Seedlings emerging from forgotten or abandoned cached seeds appear to increase the recruitment of Vouacapoua americana.

An analysis was conducted of floristic patterns contained in 48 1-ha tree plots distributed at 29 sites in seven neotropical countries, with a primary emphasis on the Amazonian region. Analyses were made with family level data, using detrended correspondence analysis and multidimensional scaling to generate two-dimensional ordinations. Dissimilarity values for all pairs of plots were then used to compare forest composition at both local (flooded vs unflooded forests) and regional scales (e.g., western vs central vs eastern Amazonia). The predominate family of trees in a large majority of Amazonian and Guianan forests (by number of stems) is either Palmae or Leguminosae (sensu latu), followed by Moraceae and Euphorbiaceae. The forests of western Amazonia are particularly rich in palms, Moraceae, and Myristicaceae, whereas those of eastern Amazonia and the Guianas are rich in Lecythidaceae and Chrysobalanaceae. Dissimilarity between sites increases with distance for both flooded and unflooded forests. The tree communities of flooded and unflooded forests within a region tended to resemble one another more closely than forests of either type resembled the homologous forests of the adjoining regions. Within Amazonia the edaphic properties of each region and its geological history are tightly interrelated. It is therefore difficult to distinguish between evolutionary and ecological interpretations of the results.

The general flowering of lowland dipterocarp forests of South-east Asia is a unique phenomenon that occurs intermittently, sometimes many years apart, and may be widespread throughout the region or sporadic. During a general flowering a very large number of tree families, including the well-known Dipterocarpaceae, flower and fruit exceptionally heavily. The huge pulse of flowering is echoed by an apparent explosion in the number of pollinators, and this is further augmented by migration of pollinators from the forest fringes. The huge demand for pollinators seems to be solved among several dipterocarps through utilization of tiny, fast breeding, floral-feeding insects such as thrips and hoppers. Competition for pollinators is further reduced through development of sequential flowering among several groups of trees that share similar pollinators. The resulting massive general fruiting seems to contribute to a heightened level of faunal activity and numbers. This long-intervalled flowering and fruiting phenology which dominates these lowland dipterocarp forests may have partly contributed to the lowered animal biomass frequently alluded to when these forests are compared with neotropical forests.

Meteorological variables, bulk cloud water and precipitation (BCWP), and bulk precipitation (BP) were measured above the canopy, and throughfall (TF; n = 20) was collected beneath an epiphyte-laden canopy of a tropical montane forest (TMF) for 1 y at Monteverde, Costa Rica. Total deposition (cloud + wet + dry) of inorganic ions to the canopy was estimated using a sodium (Na+) mass balance technique. Annual BCWP and BP depths were 2678 mm and 1792 for events where mean windspeeds (u) ≥ 2 m s&supminus1;, and 4077 mm and 3191 mm for all events, respectively. Volume-weighted mean pH and concentrations of nitrate-N (NO3−-N) and ammonium-N (NH4+-N) were 4.88, 0.09 and 0.09 mg l&supminus1; in BCWP, and 5.00, 0.05 and 0.05 mg l&supminus1; in BP, respectively. Cloud water and mist deposition to the canopy was estimated to be 356 mm. Estimated deposition of free acidity (H+), NO3−-N, and NH4+-N to the canopy was 0.49, 3.4 and 3.4 kg ha&supminus1; y&supminus1;, respectively. Mean TF depth was 1054 ± 83 mm (mean ± S.E.) for events where u ≥ 2 m s&supminus1;, and 2068 ± 132 mm for all events. Volume-weighted mean pH and concentrations of NO3−-N and NH4+-N in TF were 5.72, 0.04 mg l&supminus1;, and 0.07 mg l&supminus1;, respectively. Mean fluxes of H+, NO3−-N, and NH4+-N in TF were 0.04 ± 0.01, 0.6 ± 0.2 and 1.3 ± 0.2 kg ha&supminus1; y&supminus1;, and percent net retention of these ions by the canopy was 92 ± 2, 80 ±6, and 61 ± 6%, respectively. Phosphate, potassium, calcium and magnesium were leached from the canopy. Seasonal data suggest that biomass burning increased concentrations of NO3− and NH4+ in cloud water and precipitation at the end of the dry season. Regardless, a large majority of the inorganic N in atmospheric deposition was retained by the canopy at this site.

Soil water potentials were measured weekly by psychrometers at 20 cm depth during the dry season in a tropical moist forest on Barro Colorado Island, Panama. There was a persistent gradient of decreasing soil moisture from gap centre to gap edge to adjacent understorey at both a large and a small gap. On both a north-south and an east-west transect, the soil was drier (water potentials were more negative) on an upland surface than on moderate slopes. This trend was reflected in the predawn, total water potentials of shallow-rooted Psychotria horizontalis and deep-rooted Trichilia tuberculata measured in the understorey during the last two months of the dry season. P. horizontalis from the wettest sites on the transects had higher osmotic potentials at full hydration and at zero turgor, indicating less drought resistance than for conspecifics from the driest sites.

We studied the habitat use, activity patterns and use of mineral licks by five species of Amazonian ungulate using data from four 60-d camera trap surveys at two different sites in the lowland rain forest of Madre de Dios, Peru. Camera traps were set out in two regular grids with 40 and 43 camera stations covering an area of 50 and 65 km2, as well as at five mineral licks. Using occupancy analysis we tested the hypothesis that species are spatially separated. The results showed that the grey brocket deer (Mazama gouazoubira) occurred almost exclusively in terra firme forests, and that the white-lipped peccary (Tayassu pecari) used floodplain forest more frequently during some surveys. All other species showed no habitat preference and we did not find any spatial avoidance of species. The white-lipped peccary, the collared peccary (Pecari tajacu) as well as the grey brocket deer were strictly diurnal while the lowland tapir (Tapirus terrestris) was nocturnal. The red brocket deer (Mazama americana) was active day and night. The tapir was the species with the highest number of visits to mineral licks (average 52.8 visits per 100 d) followed by the white-lipped peccary (average 16.1 visits per 100 d) and the red brocket deer (average 17.1 visits per 100 d). The collared peccary was only recorded on three occasions and the grey brocket deer was never seen at a lick. Our results suggest that resource partitioning takes place mainly at the diet level and less at a spatial level; however, differences in small-scale habitat use are still possible.

This paper presents data from a standardized series of line-transect censuses on the species and subspecies composition, population density, and crude biomass of western Amazonian primate communities occurring at eight flooded (= vázea) and 12 unflooded (= terra firme) forests. These were located primarily along one of the largest white-water tributaries of the Amazon (= Solimōes), the Juruá river. On average, terra firme forests contained twice as many primate species, lower population densities, and less than half of the total community biomass than did adjacent várzea forests. There was a clear habitat-dependent positive association among primate species, particularly within várzea forests, as well as marked shifts in guild structure between forest types. Species turnover between these two forest types involved primarily understorey insectivores (e.g. Saguinus sp.), which do not occur in seasonally inundated forest. These were consistently replaced by squirrel monkeys (Saimiri sp.), which are extremely abundant in annually flooded várzea forests. Similarly, large-bodied folivores such as red howler monkeys (Alouatta seniculus) were uncommon or rare in terra firme forests, but very abundant in várzea forests, even though they are hunted less intensively in the former than in the latter. This can be largely explained by the nutrient-rich alluvial soils of young floodplains, compared to the heavily weathered terra firme soils occurring even within short distances of major white-water rivers. This study clearly shows a reversed diversity/density pattern resulting from the lower species richness, but high overall community biomass of seasonally flooded Amazonian forests, which can now be generalized for a wide range of terrestrial vertebrate taxa, including amphibians, birds, and several other orders of mammals.

Leaf litter invertebrates were sampled at eight sites, approximately 250 m apart in elevation, along an altitudinal transect extending from primary lowland rainforest to cloud forest in western Panama. The study focused on several diverse and numerically important litter invertebrate taxa (e.g., ants, spiders, and beetles) that were effectively sampled using a combination of litter sifting and test tube pitfall traps. The mean altitudinal range of species was around 500 m (standard deviation 370 m) and approximately 50% of the species characteristic of a given elevation dropped out after a 500 m change in elevation in either direction. There was no evidence for distinct altitudinal zonation in leaf litter assemblages. Both species richness and number of individuals of most taxa showed a pronounced decline in the vicinity of the upward transition to cloud forests. The data also suggest a broad mid-elevation peak in sample species richness for the litter invertebrate fauna. The implications of the results for biodiversity conservation are discussed.

The dispersal of seeds by howler monkeys (Alouatta palliata) and the activity of dung beetles in modulating the fate of the dispersed seed were studied at Los Tuxtlas, Mexico. Howlers consumed the fruits of 35 species of plants. The seeds of 28 of these were dispersed by the monkeys. The majority (≥90%) of the seeds dispersed by monkeys were destroyed by rodents. Rapid relocation and burial of dung by dung beetles resulted in accidental relocation and burial of large numbers of seeds shortly after deposition. Faecal clumps (20 mg) remained on the ground for an average of only 2.5 h (range 1–3 h). Ball rolling beetles transported balls up to 5.0 m from the site of deposition (range 1–5 m). Burrowing and ball-rolling dung beetles buried seeds at depths ranging from 2.5 to > 12.0cm. The deeper a seed is buried, the less likely it is to be found and eaten by rodents. Eighty percent of the species used by Alouatta as sources of fruit at Los Tuxtlas benefited by the dispersal and post dispersal service provided by howlers and dung beetles respectively. Seasonality in dung beetles abundance in the forest may influence the number of seeds per species escaping post-dispersal predation during the year. Dung beetles play not only an important ecological role in the recycling of matter and energy in the ecosystem, but also in the process of rain forest regeneration.