Sixty bird species ate the figs of 29 Ficus taxa at a lowland forest site in Peninsular Malaysia. Although most bird-eaten figs were brightly coloured, four Ficus species produced dull-coloured ripe fruits. Whilst there was tremendous overlap in the sizes of figs eaten by different bird species, data presented show that the fig resource was partitioned by birds. Large birds were commoner visitors to large-fruited Ficus, but small birds tended to eat small figs. Within two avian genera, the Treron pigeons and Megalaima barbets, there was distinct partitioning of figs consumed according to fig size.

Soil-vegetation relationships were examined in a tabonuco forest community in eastern Puerto Rico using canonical correspondence analysis. Ca and pH were strongly correlated with the first ordination axis (r = 0.84 and 0.76, respectively), while Mg and Na were correlated with the second axis (r = 0.65 and 0.64, respectively); other soil variables were not significantly related to the first two axes. Four previously identified soil series corresponded well with the ordination, and statistically significant differences in soil variables were found among the soil series. Dominant canopy tree species Dacryodes excelsa and Manilkara bidentata were negatively associated with the first ordination axis and positively associated with dry soils having low concentrations of Ca and Mg and low pH. The palm Presloea montana was positively associated with the first axis and with wet soils having high concentrations of Ca and Mg and higher pH values. Another canopy species Sloanea bertenana was associated with the second ordination axis and with lower slope positions having higher concentrations of Mg.

Our common view on water uptake by terrestrial plants is that it occurs via absorption by roots from the soil substrate. However, it has long been known that plants exhibit alternative water-absorption strategies, particularly in drought-prone environments. Examples include many tropical epiphytic orchids which use a specialized structure called velamen radicum around their aerial roots for moisture absorption directly from the air (Capesius & Barthlott 1975), specialized trichomes in bromeliads (Andrade 2003, Benzing 1990), uptake by hydathodes into leaves of species inhabiting dry desert ecosystems of Namibia (Martin & von Willert 2000) and foliar absorption by coastal California redwoods during the summer fog season (Burgess & Dawson 2004). One of the most intriguing and yet, least-studied examples of adaptations to severe water limitation is found with desiccation-tolerant plants (also called resurrection plants). During drought periods, the water content of these plants can equilibrate with the low relative humidity of the air to the point that the plants appear dead. However, when water is supplied, these plants fully rehydrate (Alpert 2000, Bewley & Krochko 1982) and become physiologically active. Desiccation-tolerant vascular plants are rare in most ecosystems but diverse in tropical inselbergs (granitic outcrops; Porembski & Barthlott 2000). Relatively little is known about inselberg species particularly from an ecophysiological perspective (see Lüttge 1997 and Klüge & Brulfert 2000 for reviews).

Tropical montane cloud forests (TMCF) are characterized by short trees, often twisted with multiple stems, with many stems per ground area, a large stem diameter to height ratio, and small, often thick leaves. These forests exhibit high root to shoot ratio, with a moderate leaf area index, low above-ground production, low leaf nutrient concentrations and often with luxuriant epiphytic growth. These traits of TMCF are caused by climatic conditions not geological substrate, and are particularly associated with frequent or persistent fog and low cloud. There are several reasons why fog might result in these features. Firstly, the fog and clouds reduce the amount of light received per unit area of ground and as closed-canopy forests absorb most of the light that reaches them the reduction in the total amount of light reduces growth. Secondly, the rate of photosynthesis per leaf area declines in comparison with that in the lowlands, which leads to less carbon fixation. Nitrogen supply limits growth in several of the few TMCFs where it has been investigated experimentally. High root : shoot biomass and production ratios are common in TMCF, and soils are often wet which may contribute to N limitation. Further study is needed to clarify the causes of several key features of TMCF ecosystems including high tree diameter : height ratio.

Data on densities, biomass and ecological factors governing the distribution of various wild ungulate species in the difFerent management units of Gir forest from 1987 to 1989 were collected. Density of ungulates ranged from 50.8 km−2 to 0.42 km−2, the highest for chital (Axis axis), followed by chinkara (Gazella gazella), sambar (Cervus unicolor), nilgai (Boselaphus tragocamelus) and chowsingha (Tetracerus quadricornis). The density of chital did not vary significantly between different censuses and management units. The wild ungulate biomass ranged from 3290 kg km−2 in the National Park to 1900 kg km−2 in the Sanctuary East. Following the partial removal of people and livestock in the mid-1970s, there was an increase in the population of all wild ungulates except nilgai and wild pig (Sus scrofa). Concurrently, there was an increase in the proportion of wild ungulate prey in the lion's diet. Chital density has shown a 1320% increase. An increase in suitable habitats and a decrease in direct competition with livestock are the most likely factors to have triggered the eruption in chital population. These density estimates are discussed in relation to the prevailing ecological conditions in different management units of Gir.

Although it is well known that riparian zones can contribute strongly to between-habitat beta diversity, for most taxa it is not clear how far this ‘zone’ extends, and whether it corresponds to easily recognizable topographic features. Forty 200-m2 plots were installed in a terra firme tropical forest to detect compositional variation in terrestrial herbs from the margins of small streams to the uplands. Plots were ordinated by their dissimilarity in species composition with non-metric multidimensional scaling. The riparian zone around streams was distinct in understorey herb composition from upland areas for about 100 m from the streams, or about 70 m asl in elevation, the exact distance depending on the size of the stream valley. However, the only assemblage that was almost completely distinct occurred as a narrow band a few metres wide along the streams. The rest of the riparian zone appears to represent an ecotone with continuous change, most of which occurs out to a distance of about half the width of the riparian zone as we defined it. Although riparian zones are legally protected in Brazil, they are frequently degraded. The complex factors leading to zonation around streams need to be understood to effectively manage these areas.

A fire-mediated recruitment bottleneck provides a possible explanation for the coexistence of trees and grasses in mesic savannas. The key element of this hypothesis is that saplings are particularly vulnerable to fire because they are small enough to be top-killed by grass fires, but unlike juveniles, they take several years to recover their original size. This limits the number of recruits into the adult size classes. Thus savanna vegetation may be maintained by a feedback whereby fire restricts the density of adult trees and allows a grass layer to develop, which provides fuel for subsequent fires. Here, we use results from a landscape-scale fire experiment in tropical Australia, to explore the possible existence of a recruitment bottleneck. This experiment compared tree recruitment and survival over 4 y under regimes of no fire, annual early and annual late dry-season fire. Stem mortality decreased with increasing stem height in the fire treatments but not in the unburnt treatment. Tree recruitment was 76–84% lower in the fire treatments than the unburnt treatment. Such fire-induced stem loss of saplings and reduced recruitment to the canopy layer in this eucalypt savanna are consistent with the predictions of the fire-mediated recruitment bottleneck hypothesis.

The food habits of four hypogeous Macrotermitinae species were studied using stable carbon isotope analysis in several biotopes of a humid savanna of West Africa (Lamto, Côte d'Ivoire). The proportion of woody and herbaceous material in the diet of the different species was determined by measuring the 13C natural abundance in the fungus comb. The diet varied with season and biotope, especially tree density. The results confirm the flexibility of the food habits of the fungus-growing termites as a consequence of their exosymbiosis with the fungus Termitomyces sp.

Leaf water and osmotic potentials and gas exchange were monitored during a prolonged El Niño drought in 1998 for saplings of seven species in a Bornean heath forest and compared with measurements taken during a subsequent wet period. The four dipterocarp species maintained reasonably good water status throughout the drought, especially Dipterocarpus borneensis which had thick and deep tap roots. In contrast, two of three non-dipterocarp species, Cleistanthus baramicus and Tristaniopsis obovata displayed predawn leaf water potentials approaching their turgor-loss points. During the drought, all species except D. borneensis displayed strongly reduced stomatal conductance after a brief exposure to sun, and all displayed lower maximum rates of stomatal conductance and net photosynthesis than during the wet period. Only Cotylelobium burckii displayed significant osmotic acclimation to the drought. T. obovata possessing a superficial root system suffered a high mortality due to the drought, but recovered faster after the first rains than the other species all of which had tap roots. Deep roots and strong stomatal control favour trees in tropical heath forests where water deficits probably occur regularly.

Although undisturbed tropical evergreen forests are often thought to be fire- resistant ecosystems due to lack of sufficiently dry fuel loads (Bond & van Wilgen 1996, Kauffman et al. 1988, Uhl et al. 1988), this myth is rapidly collapsing with the proliferation of recent forest fires throughout south-east Asia (Kinnard & O'Brien 1998, Leighton & Wirawan 1986), Central America (Anon. 1998a), and northern South America (Anon. 1998b) following unusually severe seasonal droughts.

Many studies have shown that plant or bird invasions can be facilitated by native species, but few have demonstrated the possibility of a positive interaction between introduced species. We analysed the relationships between four invasive alien fleshy-fruited plants, Clidemia hirta, Rubus alceifolius, Lantana camara, Schinus terebinthifolius, and an invasive alien bird, the red-whiskered bulbul Pycnonotus jocosus introduced to Reunion Island (Indian Ocean). We compared the distribution of food items in the bulbul diet according to seasons and to abundance classes of this bird. Pycnonotus jocosus is mostly frugivorous and frequently eats the main alien plants (more than 80% frequency of food items). Sites with alien species, such as Clidemia hirta, providing fruits throughout the year supported more birds than sites providing fruits, such as Schinus terebinthifolius, seasonally. The birds facilitated seed germination by removing the pulp of fruit: the final per cent germination (FG) of cleaned seeds was higher than those within the fruit for three of the four plant species and in some cases passage through birds significantly increased FG (Schinus terebinthifolius) or Coefficient of Velocity (CV) (Lantana camara).

The distribution and formation of foraging trails have largely been neglected as factors explaining harvesting patterns of leaf-cutting ants. We applied fractal analysis, circular, and conventional statistics to published and newly recorded trail maps of seven Atta colonies focusing on three aspects: permanence, spatio-temporal plasticity and colony life stage. In the long term, trail patterns of young and mature Atta colonies revealed that foraging activities were focused on distinct, static sectors that made up only parts of their potentially available foraging range. Within these foraging sectors, trails were typically ephemeral and highly variable in space and time. These ephemeral trails were concentrated around permanent trunk trails in mature and around nest entrances in young colonies. Besides these similarities, the comparison of trail systems between the two life stages indicated that young colonies exploited fewer leaf sources, used smaller and less-complex systems of foraging trails, preferred different life forms as host plants, and switched hosts more often compared with mature colonies. Based on these analyses, we propose a general hypothesis which describes the foraging pattern in Atta as a result of initial foraging experiences, spatio-temporal distribution of suitable host plants, energetic constraints, and other factors such as seasonality and interspecific predation.

Ants frequently interact with non-myrmecochorous diaspores on the ground in neotropical savannas. Our objective was to quantify the removal rate of these diaspores by ants and vertebrates in order to test the predator avoidance hypothesis, and to test how diaspore traits influence removal by ants and dispersal distance. We also investigated whether seed cleaning (removal of fruit matter simulating ant activity) can influence seed germination. We performed removal experiments with nine diaspore species in a reserve of cerrado savanna in south-east Brazil. Considerable differences in removal rates were found among the nine species. We found a positive linear relationship between lipid content and removal rates for five diaspore species. Vertebrate predation pressure was low for most species, limiting the benefits that ants can provide to plants to escape predators. Ants displace diaspores up to 25 m, which may increase the chance of a seed hitting a safe site. Smaller diaspores attain longer distances of dispersal than large ones. Seed cleaning increased the germination rate for five out of six species tested in greenhouse experiments. Ant activity can have relevant and possibly lasting effects on seed fate of plants adapted for vertebrate dispersal in the cerrado savanna.

Trapping and netting of small mammals on a land-bridge island (Leyte) and on an oceanic island (Negros) revealed similar patterns of elevational change in abundance and species richness. Fruit bats (Pteropodidae) reached their greatest local densities in agricultural areas, and were least abundant in montane mossy forest. The fruit bats found to be common in agri-cultural areas are widespread in Southeast Asia: in contrast, species that were most common in forested areas are Philippine endemics. Fruit bat abundance was greater on the oceanic island than on the land-bridge island. Trappable small mammals (families Soricidae and Muridae) showed no change in species richness with increasing elevation, but did show a gradual increase in overall abundance. Even though the oceanic island was depauperate of non-volant mammal species, it had the higher abundance of non-volant mammal individuals; however, this may have been due primarily to differences associated with the elevation of sampling sites. Murid rodents at the higher elevations on Leyte tend to be those that are members of the old endemic group of Philippine murids, and those at lower elevations tend to be members of more recently arrived groups. Most non-volant small mammals at all elevations on the oceanic Negros, and in agri-cultural areas on Leyte, are non-native species.

Geometroid moth abundance, species richness, weather and plant phenology were monitored monthly for 3 y in the lowland dipterocarp forest at Pasoh Forest Reserve, Negeri Sembilan in Malaysia. The intensity of tree flowering in the previous month (with mass events triggered in response to El Niño Southern Oscillations) was an important environmental factor positively correlated with the numbers of species and individuals of geometroid moths that emerge in any month. Abundance for geometroid moths was greater in months with high flowering and flushing in the previous month but low flowering in the month before that. Important weather parameters that influenced moth abundance were monthly rainfall, relative humidity and minimum temperature in previous months. High rainfall 3 mo previously led to an increase in moth abundance (perhaps by stimulating an increase in fresh plant material), whereas high rainfall and relative humidity thereafter served to decrease abundance, possibly by encouraging the spread and activity of pathogens: all these factors impacted on early life-stage survivorship. Similar trends were observed for individual geometroid families and subfamilies. The diversity measurement for the geometroid moths, α from the log-series, was correlated more with weather parameters than with tree phenology.

Epiphytes are one of the most ubiquitous elements of tropical forest canopies, including seasonally dry tropical forests. Given the temporal variation in weather conditions in the latter, epiphyte populations may be subject to wide temporal variation in seedling recruitment, reproductive success, vegetative propagation and mortality rate. In this study, we use a 3-y demographic data set for Tillandsia brachycaulos to project its long-term population dynamics through the use of average and periodic matrices, as well as stochastic simulations. The results show that demographic behaviour varied over the 3 years of study, apparently in relation to rainfall. The first 2 years yielded a low λ value (0.79 and 0.80 – although only the former was significantly lower than unity), while the third year resulted in a λ = 1.08 (not significantly different from 1.0). When incorporating this demographic variation in an average matrix, a periodic matrix and stochastic simulations, the resulting overall λ was below unity in all three cases. The projections of the stochastic simulations suggest that the population would be able to persist in the long run only if the frequency of “good” years (defined here as those with an August rainfall above 200 mm) was above 0.6, which appears unlikely given that global warming might result in a lower frequency of rainy years in tropical dry forests.

We know surprisingly little about the fate of seeds of the Brazil nut tree (Bertholletia excelsa) under natural conditions. Here we investigate seed removal, predation and caching of Brazil nuts by scatter-hoarding rodents in the wet and dry seasons, based on an experimental approach using 900 thread-marked seeds. We tracked the fate of seeds handled by these animals to examine how seasonal food availability may influence caching rates, dispersal distances and cache longevity. Most seeds exposed to dispersal trials were removed by scatter-hoarders during the first week in both seasons and seeds were generally buried intact in single-seeded caches within 10 m of seed stations. Seeds were removed significantly faster and buried at greater distances during the dry season. The proportion of seeds buried intact was considerably higher in the wet season (74.4%) than in the dry season (38.2%). Most (99.4%) of the 881 primary caches monitored were recovered, but these had a significantly shorter lifetime in the dry season. Our results show that rodents are highly skilled at retrieving buried Brazil nuts and that caching behaviour appears to be affected by seasonal resource abundance. Reduced seed availability due to intensive harvest could potentially create a dry-season scenario where most seeds succumb to pre-dispersal predation, thereby adversely affecting the natural regeneration of Brazil nut trees.

The effects of herbivory by the leaf-cutting ant Atta laevigata Fr. Smith on the re-establishment of forest trees in an abandoned farm near Manaus, central Amazonia, were investigated. Experimental seedling transplants and observations on seedlings which emerged naturally in the study area showed that damage by leaf-cutting ants negatively affected tree seedling survival and growth. However, excluding leaf-cutting ants from experimental plots for 20 mo did not significantly increase tree seedling densities. The number of seedlings emerging varied considerably between plots and this obscured any effect the ants may have had on seedling survivorship. Taller seedlings, and seedlings attacked only once, suffered less mortality than smaller seedlings and seedlings attacked twice or more. In general, mortality was greater for those species preferred by the ants, indicating that selective herbivory by leaf-cutting ants affects tree species composition. The number of seedlings attacked by A. laevigata remained approximately constant throughout the period of this study in spite of the fact that the number available for attack increased. Thus, the chance of any individual seedling being attacked declined with time, suggesting that the effect of Atta herbivory on tree establishment is stronger during the first few years of forest regeneration.

Although tropical forest birds are known to prey upon small lizards and frogs, no study has documented the attributes of vertebrate-eating birds or whether birds prey opportunistically on the different elements of the herpetofauna within tropical communities. This study is based on a 14-mo investigation on avian diet, supplemented with a 3-y census of frogs and a 1-y census of lizards in a humid forest of central Panama. From 91 bird species, 1086 regurgitates were collected, in which were found 75 lizards and 53 frogs. Over 50% of the common, primarily insectivorous bird species preyed upon lizards or frogs, with a mean frequency of 0.26 prey/sample. These birds (22 species, nine families) foraged on various substrates from different strata of the forest, fed on invertebrates averaging from 3.3 to 17.2 mm in length, weighed from 11 to 195 g, and had bill lengths that varied from 12.2 to 49.8 mm. Based on a logistic regression analysis, intensity of foraging at army-ant swarms was the variable that best explained the likelihood that a bird species preyed upon lizards, leading to a classification that was 91% correct. In contrast, bill length and body length classified correctly 88% of the frog-eating birds, which showed a fairly constant 1:7 bill length/body length ratio (as opposed to a mean but highly variable 1:10 ratio in other species). A multiple regression analysis showed that seasonal variation in intensity of lizard predation was positively related to arthropod abundance except during the breeding season when lizard intake decreased, presumably because nesting birds did not follow ant swarms. Intensity of frog predation correlated with frog abundance over time, the latter being inversely related to arthropod availability. Ninety-seven per cent of all lizards and frogs identified in the diet samples (n = 105) were from two genera, Anolis and Eleutherodactylus, respectively. Prey size distribution in the regurgitates suggested an optimal prey size of 33.5 mm snout-vent length (SVL) for lizards and 14.5 mm SVL for frogs. Birds preyed opportunistically on the different Anolis species, but almost exclusively upon juvenile individuals. Abundances of the different Eleutherodactylus species correlated with their predation rates, but these frogs represented only 10% of all the frogs observed during the censuses. The two most common local anurans, Colostethus flotator and Bufo typhonius, were not taken by any bird species.

Subsamples of termite mound soil used by chimpanzees for geophagy, and topsoil never ingested by them, from the forest floor in the Mahale Mountains National Park, Tanzania, were analysed to determine the possible stimulus or stimuli for geophagy. The ingested samples have a dominant clay texture equivalent to a claystone, whereas the control samples are predominantly sandy clay loam or sandy loam, which indicates that particle size plays a significant role in soil selection for this behaviour. One potential function of the clays is to bind and adsorb toxins. Although both termite mound and control samples have similar alkaloid-binding capacities, they are in every case very high, with the majority of the samples being above 80%. The clay size material (<2 μm) contains metahalloysite and halloysite, the latter a hydrated aluminosilicate (Al2Si2O4·nH2O), present in the majority of both the termite mound soil and control soil samples.Metahalloysite, one of the principal ingredients found in the pharmaceutical Kaopectate™, is used to treat minor gastric ailments in humans. The soils commonly ingested could also function as antacids, as over half had pH values between 7.2 and 8.6. The mean concentrations of the majority of elements measured were greater in the termite mound soils than in the control soils. The termite mound soils had more filamentous bacteria, whereas the control soils contained greater numbers of unicellular bacteria and fungi.