We studied the removal of seeds of three species of large-seeded tree (Astrocaryum standleyanum, Attalea butyracea and Dipteryx oleifera) from three different heights within six study plots in a lowland forest in central Panama. Fresh fruits with intact seeds fitted with industrial sewing bobbins were placed within semi-permeable exclosures. Removed seeds were tracked to deposition sites, and seed fate was determined. Removals were likely perpetrated by two small rodents, the strictly terrestrial Proechimys semispinosus and the scansorial Sciurus granatensis, because they were the most abundant small rodents in the study site during the study period and were of sufficient size to remove large seeds. Rodent abundance and fruit availability were estimated by conducting censuses. Nine microhabitat variables were measured at each deposition site to determine if these two rodents were preferentially depositing seeds in sites with certain characteristics or were randomly depositing seeds. During the study, rodents handled 98 seeds, 85 of which were not predated upon and could potentially germinate. Removal rates were not influenced by rodent abundance or fruit availability. Seeds were most frequently moved <3 m and deposited with the fruit eaten and the seed intact. However, some seeds did experience relatively long-distance dispersal (>10 m). Rodents preferentially deposited seeds in locations with large logs (>10 cm diameter), dense herbaceous cover, and an intact canopy. The number of large logs was different from random locations. Despite not being able to determine long-term fate (greater than c. 1 y), we show that these small rodents are not primarily seed predators and may in fact be important mutualists by dispersing seeds relatively long distances to favourable germination sites.

Stick insects (Phasmida) are important herbivores in tropical ecosystems, but have been poorly investigated in their natural environment. We studied phasmids and their food plants in a tropical lowland rain forest in Borneo (Danum Valley, Sabah, Malaysia). Thirty species of phasmid were collected from 49 plant species during nocturnal surveys in the forest understorey. In most cases (35 plant species), experiments confirmed that these phasmids fed on those plant species from which they were collected. Partitioning of phasmid species among food plant species was highly significant. Two common species had a largely restricted diet: Asceles margaritatus occurred mainly on Mallotus spp. (Euphorbiaceae) and Dinophasma ruficornis on Leea indica (Leeaceae). Other phasmids fed on a broad spectrum of plant families and can be considered polyphagous (e.g. Haaniella echinata, Lonchodes hosei herberti). Feeding experiments were performed on captive phasmids using leaves from eight plant species. Asceles margaritatus showed a significantly higher consumption rate for Mallotus miquelianus leaves than for other plants, while H. echinata showed the opposite trend and the lowest consumption for M. miquelianus. However, A. margaritatus readily accepted foliage from several plant families, particularly when Mallotus was not offered at the same time. Therefore, studies on host specialisation by herbivores need to include their distribution in the natural vegetation.

Guiera senegalensis tolerates repeated cutting and pruning to which it is increasingly subjected at the onset of each cropping period, and one to three times during the annual cropping period (June–September). It responds by profusely branching at the shrub base. The topographic and geomorphic influences, and the effect of clearing on the relationships between shrub density, mean individual above-ground biomass and leaf water status were analysed for seven fallow sites. They were sampled 75 km east of Niamey in Niger. Surprisingly, shrub density and mean individual above-ground biomass were highest in the sites that had been recently in fallow and intensively cultivated prior to crop abandonment. Stand above-ground biomass was also positively related to mean predawn and daily minimum leaf water potentials. Consequently, in the studied G. senegalensis stands, above-ground biomass appeared to be controlled by water availability – rainfall, runoff, infiltration – rather than by cropping intensity. Anisohydric stomatal regulation, resulting in large safety margins from critical transpiration, was inferred from the diurnal amplitude of leaf water potential during the dry season. The plant physiological resistance to water stress combined with its population adjustment in density and growth contributes to the sustainable dominance of G. senegalensis.

Precipitation and temperature are known to have important effects on forest productivity, but these effects may be strongly mediated through their influence on soil and leaf nutrients. We measured indicators of forest productivity and soil and leaf nutrients across independent gradients of precipitation and elevation/temperature in lower montane Hawaiian forests dominated by a single overstorey species, Acacia koa, situated on 1500–3000-y-old soils that were mixtures of volcanic ash and basalt. Stand basal area was highest at the wettest site, 2000 mm mean annual precipitation (MAP), and leaf N and P were lowest at the driest site, 1000 mm MAP. Soil N availability and leaf N concentration declined across an 850-m elevation gradient, but this was not correlated with stand basal area or soil organic matter content. Across all stands, basal area was negatively correlated with the exchangeable soil P fraction. As well, the soil C:N ratio was negatively correlated with both soil P availability and the size of the primary mineral P fraction. Soil P availability and weathering appear to be important determinants of soil organic matter quantity and quality. Overall, precipitation is the major driving force for forest productivity, but P weathering and availability play important roles in limiting productivity in wetter sites and in controlling soil organic matter dynamics in these N-fixing forests.

The spatial and temporal variation in litter disturbance by a medium-sized bird, the chowchilla (Orthonyx spaldingii Ramsay, Orthonychidae) was documented, and its potential impacts on tree seed germination and early seedling survival in an Australian tropical rain forest experimentally investigated. Chowchilla disturbances occurred on ridges, slopes and drainages in all four seasons surveyed. In some areas litter was completely turned over as frequently as every 5 wk. Tethered seeds exposed to disturbance were moved farther and experienced significantly greater variation in litter cover than those protected from disturbance. When seeds of two canopy trees were placed in litter environments simulating those created by chowchillas, the seeds of one species showed significant effects of litter treatment on germination while those of the other showed no significant effects. Seedling cohorts of four tree species were followed for 6 wk soon after germination and all showed higher survival in vertebrate exclosures. The two most abundant species suffered 68% and 35% mortality in six wks, with the majority of that unambiguously due to chowchillas. It is argued that litter-disturbing birds increase litter heterogeneity and significantly impact early seedling mortality. These effects could be important in maintaining evenness and diversity of the seedling community.

Large areas of the Himalayas have become severely deforested although little has been published about the extent of this problem in the closed Kingdom of Bhutan. A preliminary survey was undertaken during 1983. Without detailed information or accurate maps, LANDSAT 2 imagery was used to prepare a sampling stratification and to plot the distribution of defined vegetation types after sampling and analysis. Eleven forest noda are described in relation to their habitats, and area and timber volume estimates given. Deforestation pressures are discussed.

A community of frugivorous weevils was studied by quantitative rearing of 57 weevil species represented by 10485 individuals from 326 woody plant species in lowland rain forest in Papua New Guinea. Only fruits from 35% of plant species were attacked by weevils. On average, weevils were reared from only 1 in 33 fruits and 1 kg of fruit was attacked by 2.51 individuals. Weevil host specificity was relatively high: 42% of weevil species fed on a single plant genus, 19% on a single plant family and only 16% were reared from more than one family. However, monophagous specialists represented only 23% of all reared individuals. The average 1 kg of fruits was infested by 1.84 individuals of generalist weevils (feeding on allogeneric or allofamilial host species), 0.52 individual of specialists (feeding on a single or several congeneric species), and 0.15 individual of unknown host specificity. Large-seeded fruits with thin mesocarp tended to host specialist species whereas those with thick, fleshy mesocarp were often infested with both specialists and generalists. Weevils tended to avoid small-seeded, fleshy fruits. The low incidence of seed damage (3% of seeds) suggests that weevils are unlikely to play a major role in regulating plant populations via density-dependent mortality processes outlined by the Janzen–Connell hypothesis.

In the tropical forest of Barro Colorado Island, habitat characteristics, diel acidity changes, CO2 uptake and growth were investigated for the epiphytic cactus Epiphyllum phyllanthus (L.) Haw. It occurred most frequently in tree cavities with its roots in canopy soil and was especially abundant on two tree species: Platypodium elegans J. Vogel and Tabebuia guayacan (Seem.) Hemsl. Its maximum net CO2 uptake rates were low under natural conditions (1.4 μmol m−1) but were comparable to those of other CAM and C3 epiphytes under wet conditions in a screenhouse. Under both natural conditions and in the screenhouse, partial shade enhanced growth and CAM activity. When plants grew under a photosynthetic photon flux of c. 4 mol m−2 d−1, their nocturnal acidity increase and total net CO2 uptake were twice as much as for plants growing at lower (an average of 2.4 mol m−2 d−1) and higher (7.7 mol m−2 d−1) photosynthetic photon fluxes. Stem elongation was 27% greater at the intermediate photosynthetic photon flux. Seedlings of E. phyllanthus survived three months of drought and responded rapidly to rewetting, recovering fully within three days. Transpiration rates and nocturnal acidity increases also recovered to the values of well-watered plants a few days after rewetting, indicating that this species can take advantage of episodic rainfall during the dry season.

Bird's nest ferns (Asplenium nidus complex) (Yatabe & Murakami 2003) are common epiphytes of the Old World tropics and house a high abundance of arthropods (Ellwood & Foster 2004). Through interception and retention of leaf litter (Paoletti et al. 1991, Piggott 1996, Richardson 1999), epiphytes interrupt litterfall dynamics (Clark et al. 1998, Nadkarni & Matelson 1991) and delay the return of nutrients to the forest floor (Nadkarni 1984). Precipitation percolating through the canopy as throughfall is enriched as nutrients are leached from plant surfaces (Levia & Frost 2006). Water flowing down the trunk of trees as stemflow is further enriched from prolonged contact and accumulated nutrient deposits on the trunk (Levia & Frost 2003, Liu et al. 2002). Epiphytes can alter stemflow nutrient concentrations by slowing water percolation and by nutrient uptake and release (Awasthi et al. 1995, Strigel et al. 1994).

Trees growing in a seasonally tropical dry forest, with its characteristic 5–7-mo rainless interval, possess a variety of physiological adaptations to drought, the most common being leaf abscission. At the Estacion Biologia de Chamela in western Mexico, we experimentally examined the relationship between one-time experimental irrigation ranging as 0 (control) to 200 mm, and (1) the degree of bud burst (and, for a single species, flowering), and (2) the formation of a false ring. Additionally, we used long-term records at a nearby meteorological station to determine the probability of a rain event exceeding a particular intensity (mm). For our seven species (particularly the two most common species: Cordia alliodora and Piptadenia constricta), we found that the degree of budburst and leaf extension was a function of irrigation intensity. In no case, however, did we find false rings, or indeed any indication of cambial activity initiated by the irrigation event. Further, there was no effect of intensity on subsequent relative growth rate in the following wet season. While sufficient rainfall (200 mm) to cause full leaf deployment is rare, nonetheless we estimate that a canopy tree in the study area would experience an event of this magnitude at least a few times per century. In any case, it will have no effect on the reliability of annual rings in this biome, nor any effect on diameter growth in (at least) the following year.

Spider monkeys (Ateles geoffroyi) detect sucrose at a threshold lower than any primate yet tested and prefer sucrose to glucose or fructose in laboratory tests. This preferential selection of sucrose led to the hypothesis that such acute discrimination is related to a diet of sucrose-rich fruits. Furthermore, it has been suggested that fruit sugars may be related to distinct guilds of vertebrate seed-dispersers. The objectives of this study were: (1) to test if spider monkeys select sucrose-rich fruits both within and among plant species and (2) to test the hypothesis that sugar concentration is related to bird, bat or monkey seed-dispersal syndromes. Data were collected from one troop of spider monkeys in south-western Costa Rica. Interspecific comparison of ingested fruits shows that spider monkeys consumed species with significantly higher concentrations of glucose and fructose than sucrose. Similarly, at the intraspecific level, food-fruits had significantly more fructose and glucose than non-food fruits, but no difference was found for sucrose. The three different sugar types were not correlated with the importance of the species in the diet based on the amount of time they spent consuming each species. Although sucrose concentrations were significantly higher in primate-dispersed species compared with those dispersed by other vertebrates, soluble carbohydrates in primate-dispersed fruits were principally composed of glucose and fructose. Neither fructose nor glucose concentrations showed significant differences across the three categories of seed dispersal.

Floral trait correlations were compared between the two flower morphs of a distylous Ophiorrhiza napoensis population in a subtropical evergreen forest at the Defu Natural Animal Preserve, Guangxi, China. Common principal component analyses indicated that overall patterns in correlations among floral traits were morph specific in the study population. Strong positive correlations (r > 0.9) between anther height and corolla-tube length were found in both morphs. Stigma height correlated positively with corolla-tube length in the long-styled morph (r = 0.843), but not in the short-styled morph (r = −0.018). Flower-morph-specific correlation suggests that natural selection by pollinators has moulded trait covariance among floral traits. Because morph-specific correlations are expressed as the patterns of within-morph variation among multiple traits, putative genes responsible for the stigma-corolla tube correlation should not link to the supergene for sex-organ reciprocity between the morphs, but their expression is limited in the long-styled morph.

In Hawaii, where there are no native reptiles or amphibians, 27 species of reptiles and amphibians have established (Kraus 2003); however, few have been studied to determine their ecological impacts. For example, little is known about the impacts of the Puerto Rican frog, Eleutherodactylus coqui Thomas, that recently invaded (late 1980s) (Kraus et al. 1999), and has established on all four main Hawaiian Islands (Kraus & Campbell 2002). However, there are likely to be consequences because E. coqui can attain high densities (20 570 frogs ha−1 on average in Puerto Rico) and consume large quantities of invertebrates (114 000 prey items ha−1 per night on average in Puerto Rico) (Stewart & Woolbright 1996).

In abandoned pastures where the seed bank of forest species has been depleted and a seedling bank does not exist, dispersal events are the only source of forest seeds for natural regeneration (Gómez-Pompa & Vázquez-Yanes 1981). Lack of dispersal has been reported as an important limitation for rain-forest regeneration in pastures (Hardwick et al. 1997 in Thailand; Holl 1999 in Costa Rica; Nepstad et al. 1990 in Brazil) or colonization of fallow land (Kollmann 1995). A high percentage of tropical plant species have fleshy fruits that are dispersed by birds and flying and terrestrial mammals (Howe & Smallwood 1982, Snow 1981). In this study we report the spatial distribution of fleshy-fruited species dispersed to tropical pastures at different distances from the vegetation border in 12 tropical pastures as a measure of the instant regenerative potential of these sites.

Increased shoot growth has recurrently been recorded following real or simulated shoot browsing, although responses may vary between different woody species. We investigated morphological responses to simulated dry-season browsing on Colophospermum mopane, Acacia tortilis, Grewia flava, Peltophorum africanum and Ziziphus mucronata, which differ in growth rate, occurrence of spines and use by mammalian herbivores. Treatment groups included a control, four clipping intensities and cutting at ground level. Responses were monitored during the following growth season on three annual shoots, located in the bottom, middle and top height interval, on each sapling. All five species showed compensatory growth responses, although no obvious relation was found between the strength of responses and growth rate or natural browsing pressure. The general pattern was an increased shoot length, shoot diameter, number of lateral shoots and shoot biomass with increased clipping intensity. These responses are probably an effect of the reduction of competing growing points and disrupted apical dominance. Growth responses were stronger in shoots with higher location on the sapling, which may reflect the pressure on saplings to attain a certain height to avoid browsing, reproduce and increase resistance to fire. We found no evidence of the number of spines being an induced defence in either of the two spinescent species studied.

Whereas broad-scale Amazonian forest types have been shown to influence the structure of the communities of medium- to large-bodied vertebrates, their natural heterogeneity at smaller scale or within the terra firme forests remains poorly described and understood. Diversity indices of such communities and the relative abundance of the 21 most commonly observed species were compared from standardized line-transect data across 25 study sites distributed in undisturbed forests in French Guiana. We first assessed the relevance of a forest typology based on geomorphological landscapes to explain the observed heterogeneity. As previously found for tree beta-diversity patterns, this new typology proved to be a non-negligible factor underlying the beta diversity of the communities of medium- to large bodied vertebrates in French Guianan terra firme forests. Although the species studied are almost ubiquitous across the region, they exhibited habitat preferences through significant variation in abundance and in their association index with the different landscape types. As terra firme forests represent more than 90% of the Amazon basin, characterizing their heterogeneity – including faunal communities – is a major challenge in neotropical forest ecology.

Trapping was conducted in primary and secondary forests to investigate the effects of past logging on small mammal communities. Thirteen I-ha sites were snap-trapped for three consecutive days in tropical monsoon rainforest in Xishuangbanna Nature Reserve, southern China. A total of 3900 trap-days yielded 198 captures, of which 118 were in the primary forest and 80 in the secondary forest. A total of 12 ground-dwelling species (eight Rodentia, Muridae; three Insectivora, Soricidae; one Insectivora, Erinaceidae) were caught, five (all Rodentia, Muridae) occurred in the primary forest and 11 in the secondary forest. The most abundant species was Niviventer confucianus, accounting for 62% and 39% of the total captures in the primary and the secondary forests, respectively. In the secondary forest the mean abundances of the two dominant species, N. confucianus and Maxomys surifer, were reduced, and a non-commensal form of Rattus rattus disappeared, but N. fulvescens showed no change while Mus pahari increased. The seven species which occurred only in secondary forest had very low abundance. Overall, the multivariate Mantel test showed the two communities to be significantly different. After logging, species diversity increased, and the two dominant species had increased body mass and their mean abundance decreased.

Eight species of Myzolecanium Beccari (Hemiptera: Homoptera: Coccoidea: Coccidae) are reported from ant nests in stem cavities of living lowland rain forest trees in Papua New Guinea. The coccids are confined to this microhabitat but are associated with a taxonomically broad range of ants and host trees. Attendant ants belonged to six species in three genera and two subfamilies: Anonychomyrma Donisthorpe (Dolichoderinae), Crematogaster Lund (Myrmicinae) and Podomyrma F. Smith (Myrmicinae). Host plants belonged to at least five families and included both apparently specialized (with domatia) and unspecialized species. Saplings containing the nests of Anonychomyrma scrutator (F. Smith), Anonychomyrma sp. 1 and Podomyrma laevifrons F. Smith were dissected and the structure of nest chambers and their contents recorded. Only some chambers had entrance holes, but many were interconnected by transverse passages. The coccids were in low numbers and fairly evenly distributed between ant-occupied chambers. The characteristics of the Myzolecanium-ant association, the role of the coccids as trophobionts, and the nature of the plant associations are discussed. Taxonomically, new combinations are proposed by P. J. Gullan for three species previously placed in Cryptostigma Ferris: Myzolecanium endoeucalyptus (Qin & Gullan), M. magnetinsulae (Qin & Gullan), and M. robertsi (Williams & Watson).

1211 trees of 3 ft (0.91 m) girth or more were enumerated in 288 1-ch2 (about 400 m2) quadrats forming a 11.7 ha plot on the mainly Segamat soil series, Jengka Forest Reserve, Peninsular Malaysia, in 1964. Of the 261 taxa, 84% were identified to species. Five per cent of the area was of the permanently wetter Akob soil series. The plot was topographically flat and lay about 3 km west of the plot on the Batu Anam soil series, described in an earlier paper. Data on the chemical composition of the three soils are summarized here from a survey in 1967.

The vegetation on the Segamat series is of the Shorea-Dipterocarpus type of lowland dipterocarp forest. It has an unusually high abundance of the Euphorbiaceae (25% of trees) and a clear dominant species, Elateriospermum tapos. E. tapos, which regenerates profusely in the shade, grows up in small gaps and is strongly clumped, and appears well suited to the very friable, relatively nutrient-rich soil of the Segamat series, with lower soil-water holding capacity especially in dry periods.

Forest on the Segamat series is floristically very different from that on the Batu Anam series. This is most likely due to large differences in soil properties, the latter being of lower clay content, less nutrient-rich and, having a greater soil-water holding capacity at least in dry periods. It was dominated by Dipterocarpaceae.

Classification of quadrats on the Segamat series highlighted four classes; vegetation of the main E. tapos-dominated type on relatively dry soil (54% of plot area), vegetation on the wet Akob soil (21%), an association of shade-tolerant, mainly understorey trees beneath non-E. tapos-associated emergents (11%), and an association of long-lived, light-demanding pioneer trees of late-successional stages (11%); 3% of plot had no enumerated trees. Ordination showed that the plot was largely homogeneous with respect to edaphic factors but clearly displayed stages in forest succession.

The possible dynamics of the Segamat forest are inferred in terms of species autecology. Two hypotheses are advanced to explain the composition of the Segamat forest: (a) a dynamic equilibirum, (b) a non-equilibrium recovery from a recent catastrophe. The latter was thought more likely. Compared with the more benign Batu Anam environment, where co-dominants might be ‘ecologically equivalent’, the more selective soil conditions on the Segamat leads to reduced equivalence, with accidents of regeneration playing a smaller role in the local distribution of the most abundant species.

In the Sahel during recent decades, anthropogenic disturbance and periods of drought have caused changes in woody species frequency. The internal water status of six coexisting species was analysed to estimate the importance of water constraints in this process. Predawn and midday xylem pressure potential and stomatal conductance were monitored monthly for two years. The relations between xylem pressure potential and transpiration made it possible to determine the hydraulic conductivity of the soil—plant system. Two types of results were obtained. First, there was considerable diversity in water status of the different species. Minimum predawn xylem pressure potentials (dry season) ranged from – 1.5 MPa to – 5 MPa depending on species, with interseasonal variation from 0.08 MPa to 2 MPa. Response to rainfall was very rapid (a few days) or very slow (several months). The three functioning types defined using these results were compared with the phytogeographical status of the species. Second, more specific phenomena were observed, (a) Some species (Balanites aegyptiaca and Boscia senegalensis) showed an imbalance between the predawn xylem pressure potential and the soil water status during the rainy season; (b) a sharp increase in xylem pressure potential was observed in deciduous species in the middle of the dry season; probably related to bud break; and (c) the water status was always favourable for Combrelum glutinosum. The few remaining individuals seem to benefit from very favourable subsoil water supply conditions.