This paper describes estimates of canopy openness and associated light availability in the understorey of a north-east Australian rain forest before and immediately after a tropical cyclone. On the basis of 20 hemispherical (fisheye) canopy photographs it was shown that direct, diffuse and total site factors increased significantly as a result of the slight-to-moderate canopy disturbance caused by the cyclone. In the understorey, median total site factors ranged from 2.5–3.4% before the cyclone and from 6.0–8.6% after the cyclone, representing a 2- to 3-fold increase in potential light availability. Following the cyclone, mean relative gap frequencies increased substantially at all altitudes but particularly at canopy positions more than 70° above the horizon. Cyclone-induced canopy disturbance not only reduced the complexity of the understorey light regime but may have also increased the seasonal variability of light within the understorey of the forest during the interval of canopy recovery. The implications of these results for the ecophysiology of understorey tree seedlings and saplings at several temporal scales are discussed.

The types and causes of death of canopy and subcanopy trees were characterized for the tropical montane cloud forest of Tamaulipas, Mexico. Field work was carried out at the Biosphere Reserve ‘El Cielo’, located on the eastern slope of the Sierra Madre Oriental. Three study plots, each of 2 ha, were selected within the forest differing in their degree of exposure to wind. Results indicate that the tropical montane cloud forest presents a differential treefall regime derived from the great hurricane activity to which this mountain range is exposed. This effect is illustrated by the great number of fallen logs (545 trees in 6 ha) and the high percentage of uprooted (48.3%) and snapped off (37.6%) trees. Other treefall factors included the rocky and shallow soils and weakness of the dominant trees from insect attack. A differential disturbance level was obtained between zones. The disturbance was higher for the exposed zone, where the crown cover of emergent trees was not closed. Species composition of the dead material was related to the abundance of the overstorey species as standing vegetation. Ten of the 20 recorded species were able to sprout and just 7.5% of the 545 fallen trees were sprouting. Quercus germana, Q. sartorii, Clethra pringlei, Liquidambar styraciflua and Ceris canadensis, accounted for 78.5% of the gap-forming species. The type of treefall differed between species of the same genera: Q. germana was generally found uprooted, while Q. sartorii died standing probably because of previous weakening from dipterous insects.

Termites were surveyed at an altitude of 1000 m in Maliau Basin, Sabah (Borneo), in two primary forest habitats: lower montane forest and stunted facies of upper montane forest. Soil, wood, litter, termite nests, and arboreal microhabitats up to a height of 2 m above ground were sampled using a belt transect protocol. Two transects were run in each forest type. The upper montane forest transects collected 11 and 13 species, compared with 15 and 19 in the lower montane forest transects. With the addition of species records from casual sampling (conducted with roughly equal effort in each forest type), totals of 18 species were found in the upper montane forest, and 34 species in the lower montane forest. Similar species richness and relative abundance of wood-feeding termites were found in both forest types. However, the lower montane forest had greater richness and relative abundance of species that feed on soil and extremely decayed soil-like wood. This difference is attributed mainly to (i) the well developed, organic-rich soils of the lower montane forest being more suitable for soil-dwelling and mound-building termites compared with the upper montane forest which has sandy soils with a thick covering of peat, and (ii) the low-stature and open canopy of the upper montane forest creates microclimatic conditions which are adverse for soil-feeding termites compared with the high, closed canopy in the lower montane forest. As expected, comparisons with similar studies in lowland forests in Southeast Asia confirmed that the upland forests are relatively depauperate.

White-eyed vireos (Vireo griseus) winter in the forests and secondary growth of the Yucatan Peninsula where Bursera simaruba (Burseraceae) is an abundant tree. Twenty-five per cent of all white-eyed vireos observed foraging visited Bursera trees. In addition, presence and abundance of territorial white-eyed vireos in small forest patches were correlated with the size of the Bursera crop. Vireos were the most reliable dispersers of Bursera seeds. These birds visited 32 of 35 trees observed for at least three hours. They accounted for approximately half of all bird visits, and two-thirds of the seeds dispersed. Most of the other species rarely visited (<5% of visits) or failed to remove seeds from the tree.

Peculiarities of phenology and fruit structure may contribute to the tendency of Bursera to be dispersed by relatively few species. The capsules of Bursera fruits do not open when the fruit ripens; birds apparently locate ripe fruit using visual cues, although these are few. In addition, only a small portion of the crop ripens daily over a 7- or 8-month period. The vireo-Bursera simaruba relationship, found regionally on the Yucatan Peninsula, may result from the prolonged fruit ripening period (October-March), the relatively depauperate frugivore community and the relatively high density of small Bursera trees in the hurricane-disturbed dry forests.

Small trees at all times, and all trees from October to February, depend upon territorial vireos for continuous, highly efficient local dispersal of a small number of fruits. In March and April residual fruits ripen rapidly and synchronously, attracting a greater variety of visitors for broad spectrum dispersal during a period of food scarcity. Thus, Bursera has an unusual two-phase phenological pattern, perhaps alternately to take advantage of both specialized and opportunistic dispersers.

Tropical forest vegetation occurs within a narrow corridor along the semi-arid lower floodplain of the Tana River, Kenya. An inventory of the woody flora and ecological study of 12 forest areas in the Tana River National Primate Reserve (TRNPR) describe the composition and structure of this riverine forest ecosystem and identify patterns of regional and local diversity. Only 175 species in 49 families are recorded in the woody flora, but the geographic affinities of 98 species are from four major floristic regions in Africa: Zanzibar-Inhambane (31%), Somalia-Masai (16%), Guinea-Congolian (12%), and Zambezian (1%). Ten species are rare and/or disjunct. Forests have a disturbed physiognomy characterized by a low mean height (14.4 m), high species importance attributable to a few trees, low density (409 ha−1) and coverage (23.1 m2 ha−1) of trees > 10 cm dbh, and an abundance of palms and lianes. Changes along the river in sediment deposition and hydrology explain the high diversity of landforms and corresponding forest types in the TRNPR vicinity, but the absence of trees which are most important near Bura, Acacia elalior, and near Wema, Barringtonia racemosa, suggests that the regional diversity of the ecosystem is inadequately protected. Preservation of key resources, such as the endangered primates, should be coupled with protection of the forest heterogeneity that characterizes this dynamic landscape.

The influence of a rainfall gradient on the distribution and species richness of some groups of wood-inhabiting basidiomycetes was explored in Costa Rican tropical forests. The relationships between these fungi and wood size and decay stage were also studied. Basidiocarps of all poroid and some corticoid fungi were recorded in three plots of 30 logs in each of dry, moist, and wet forests. The logs were surveyed three times during one year, covering all seasons. The species richness gradient was inversely related to the rainfall gradient, with most species in the dry forest (51), least in the wet forest (37), and intermediate in the moist forest (44). A total of 102 species were identified. Only six species occurred at all three sites. Two of the four most common species were new to science. The composition of wood-inhabiting fungal species in the dry forest varied from both the moist and the wet forest, while species composition in the two latter forest types was difficult to distinguish. Both frequent and rare species utilized the different decay stages as expected from availability of substrate. Perennials and rare species tended to occur on large logs in the dry forest, while all species tended to occur on large logs in the moist forest, but not in the wet forest.

Temporal niche partitioning can be a viable mechanism for coexistence, but has received less attention than other niche axes. We characterized and compared patterns of activity, and overlap of temporal activity among the five common rodent species from a tropical semideciduous forest (TSF) and between the two common rodent species from cloud forest (CF) at El Cielo Biosphere Reserve in Mexico. Capture frequencies over 2-h intervals, obtained via live trapping (6850 trap-nights) in chosen months over 3 y formed the empirical basis for analyses. Trap transects were set from 19h00 to 07h00 and checked every 2 h. Analyses of 484 captures evinced two distinct assemblages. The TSF assemblage was diverse and with non-random temporal niche segregation, whereas the CF assemblage was depauperate with its two dominant species evincing the same activity pattern. Predator avoidance between open- and closed-microhabitat species, as well as niche complementarity may explain temporal segregation at TSF. This is the first documentation of assemblage-wide non-random temporal segregation of neotropical rodents. Time of activity may be a largely under-appreciated mechanism in other species-rich tropical rodent assemblages as well as in other species-rich biotas.

Deforestation and forest fragmentation are contributing to declines in crop pollinator populations worldwide. Several studies have examined the impact of forest proximity on plant pollination ecology, but concentrated on single crop species. However, it can be more informative to investigate multiple crop and pollinator species in a community, because different pollinator groups may respond differently to forest distance. We evaluated flower visitor diversity, visitation frequency, and fruit set for three crop species (rambutan, durian and mango) in 10 pairs of mixed fruit orchards. Each pair consisted of one orchard near to (< 1 km) and one orchard far from (> 7 km) the forest edge. Rambutan fruit set was significantly influenced by distance to forest. The main visitors of rambutan flowers were stingless bees. In contrast, the dominant visitors to durian and mango flowers were nectarivorous bats and flies, respectively, and the fruit set of these crops were not significantly influenced by distance to forest. However, durian fruit set was negatively affected by distance to the nearest cave inhabited by nectarivorous bats. This study demonstrates that both caves and forests can be important pollinator sources for agricultural crops, and that the dispersal success of pollinators is related to isolation from source habitats. Maintaining forest patches and limestone karsts may provide stepping stones across fragmented landscapes, and attract greater numbers of pollinators to agricultural areas.

Failure of reproduction is hypothesized as being a main reason for the formation of upper tree lines but there is, as yet, little supportive evidence of such. This study investigates the effects of experimental sowing, canopy cover and litter depth on seedling emergence and survival of Polylepis incana and Polylepis pauta at the upper distribution limit of the species in the Páramo de Papallacta, central Ecuador. We established 18 study plots located in the interior, at the edge and at the exterior of closed forests at the upper tree line and analysed seedling dynamics for 1 y following experimental sowing with four different litter treatments. For both species, seedling numbers were significantly higher in the forest interior than outside, and higher in the treatments with the litter layer removed. In P. pauta, sowing significantly increased seedling number, which was more pronounced within and at the edge of the forest than outside. In contrast, there was no impact of sowing on seedling emergence in P. incana. First-year seedling survival and mean growth rate per month were low in both species. Log-linear models did not reveal significant interactions between survival and canopy cover or litter removal. Our data show that seedling recruitment is limited at the upper tree line – presumably due to extreme climatic conditions – which indicates the importance of constraints in sexual regeneration for tree-line formation in central Ecuador.

The ant species were sampled in one campo (grassy shrubland), one mata (semideciduous rain forest) and 11 rehabilitated bauxite mine plots at Poços de Caldas, in the humid sub-tropical climatic region of Brazil. Rehabilitation was either by planting Australian Eucalyptus spp, the Brazilian Mimosa scabrella tree, or by planting mixed mata trees. Sixty-eight ant species were recorded, of which 26 were exclusively found in the native vegetation and 16 were confined to the rehabilitated plots. Ant species richness built up most rapidly in areas rehabilitated with mixed mata species and least rapidly in areas with Eucalyptus. Younger rehabilitated plots appeared to be developing a campo-type ant community, although evidence indicates that more mata ant species will colonise once tree canopy closure takes place. Rate of ant return in Australia is positively correlated with the quantity and distribution of rainfall – the rates in the current study concur with those from humid sub-tropical climatic zones within Australia, suggesting that similar constraints to the succession may be operating. If found to be the case, this would have practical implications for planning and evaluating the success of rehabilitation.

In mixed tropical landscapes, savanna and rain-forest vegetation often support contrasting biotas, and this is the case for ant communities in tropical Australia. Such a contrast is especially pronounced in monsoonal north-western Australia, where boundaries between rain forest and savanna are often extremely abrupt. However, in the humid tropics of north-eastern Queensland there is often an extended gradient between rain forest and savanna through eucalypt-dominated tall open forest. It is not known if ant community structure varies continuously along this gradient, or, if there is a major disjunction, where it occurs. We address this issue by sampling ants at ten sites distributed along a 6-km environmental gradient from rain forest to savanna, encompassing the crest and slopes of Mt. Lewis in North Queensland. Sampling was conducted using ground and baited arboreal pitfall traps, and yielded a total of 95 ant species. Mean trap species richness was identical in rain forest and rain-forest regrowth, somewhat higher in tall open forest, and twice as high again in savanna woodland. The great majority (78%) of the 58 species from savanna woodland were recorded only in this habitat type. MDS ordination of sites based on ant species composition showed a continuum from rain forest through rain-forest regrowth to tall open forest, and then a discontinuity between these habitat types and savanna woodland. These findings indicate that the contrast between rain forest and savanna ant communities in tropical Australia is an extreme manifestation of a broader forest-savanna disjunction.

The presence and density of two sympatric, large-sized vipers (the Gaboon viper, Bitis gabonica and the nose-horned viper, Bitis nasicornis) were studied along several transects, during both dry and wet seasons, and at different times of day, in southern Nigeria (West Africa). Three habitat types were found along the various transects (mature rain forest (MF), secondary rain forest (SF), swamp forest (SW)). The detection probabilities for these vipers were modelled with a set of competing models, and the various models were ordered by Akaike Information Criterion procedures. Two classes of models were used: the single-season model, and the multi-species model. The best models (single-season model) suggested that: for the Gaboon viper, habitat types SF and SW were particularly important in detecting this species, especially during the rainy season at 08h00–16h00. For nose-horned vipers, the best models had SW and MF as site-covariates. Application of the multi-species model revealed that there were different detection functions if both species are present at a site, with a ‘negative’ interaction of occupancy between the species. Females and males were similarly detectable in a logistic regression model, but feeding status and pregnancy slightly increased detection probability in a logistic regression model. Viper density was modelled by a DISTANCE sampling procedure. The density of one species tended to be inversely correlated to the density of the other, suggesting that (1) the rain-forest environment does not support abundant populations of both vipers when sympatric, and (2) the two Bitis species subtly partition the habitat resources.

In a now classic study, Zinke (1962) showed that a single Pinus contorta tree growing on a sand dune along the coast of California modified the chemistry of the soil underneath its crown. He found distinct patterns of pH, exchangeable cations and nitrogen (N) content moving from the bole outward to the crown drip zone, because the acidic bark and stemflow were concentrated around the bole (Zinke 1962). Subsequent studies in temperate forests have also found tree species to affect soil chemical properties such as pH, organic carbon (C) and rates of N mineralization (Boerner & Koslowsky 1989, Boettcher & Kalisz 1990, Finzi et al. 1998). Presumably, these species-specific effects are caused by inter-specific differences in organic acid exudation, nutrient uptake, litter quality or quantity, decomposition rates or nutrient outputs (Binkley & Giardina 1998, Knops et al. 2002, Rhoades 1997). Regardless of the causes, species-generated soil heterogeneity has implications for stand-level estimates of biogeochemical processes such as soil C storage and N-cycling as well as implications for plant diversity and regeneration (Finzi et al. 1998). Although a number of studies have demonstrated that tree species modify soil environments in temperate forests or monospecific tree plantations in the tropics (Fisher 1995, Rhoades 1997), few studies have investigated these processes in species-rich tropical forests (but see Rhoades et al. 1994).

There is little understanding of how large mammalian herbivores in Asia partition habitat and forage resources, and vary their diet and habitat selection seasonally in order to coexist. We studied an assemblage of four large herbivores, chital (Axis axis), sambar (Cervus unicolor), gaur (Bos gaurus) and Asian elephant (Elephas maximus), in the seasonal tropical forests of Bandipur and Mudumalai, South India, and tested predictions regarding the species’ seasonal diet browse : graze ratios, habitat selection and habitat-niche preference and overlap. Field data collected for the study included the seasonal variation in grass quality, the seasonal variation in δ13C in the species’ faeces and the seasonal variation in the species’ habitat selection and overlap using a grid-based survey. Results of the δ13C analyses showed that the chital was more of a grazer in the wet season (−17.9‰ to −21.6‰), but that it increased the proportion of browse in its diet in the dry season (−25.6‰ to −27.7‰); the gaur was a grazer for most of the year (−15.3‰ to −18.6‰); the sambar preferred to browse throughout the year (−21.1‰ to −30.4‰); and that the elephant was a mixed feeder (−14.2‰ to −21.4‰). Elephant habitat-niche breadth was high (0.53 in wet and 0.54 in dry) and overlapped equally with that of the other species in both seasons (0.39–0.94). The gaur had the most restricted habitat-niche breadth in both seasons (0.25 in wet and 0.28 in dry), and it switched from the moist deciduous habitat in the dry season to the dry deciduous habitat in the wet season. These results offer the first insights into the seasonal variation in browse : graze diet ratios and the habitat-niche overlap amongst the common largest-bodied mammalian herbivore species found in South India.

Using data from forest sites in Sarawak, East Malaysia, a demographic comparison is made of pioneer species in the genus Macaranga with understorey trees of the primary forest in the closely related genus Mallotus. In primary forest, saplings and trees of these genera arc uncommon and have low growth rates. For the six years following disturbance by logging, a Macaranga population was characterized by high rates of diameter growth and recruitment. Eleven years after disturbance, seedling and sapling abundance had declined sharply. In contrast, the Mallotus population was stable in size class distribution and increased slightly in total population size during the 11 years after logging. Growth rates of Mallotus trees increased after logging but were still much less than Macaranga trees.

A morphological comparison shows that most Macaranga species, in contrast with Mallotus species, have large hollow twigs that are occupied by ants and have larger, hairier, thicker, more toothed leaves with longer petioles, axillary inflorescences with more flowers, infructescences with more fruit, fruits that are smaller in size and smaller seeds.

Savannas intermingled with gallery forests are dynamic habitats typical in Africa. This study aims to determine if differences in species traits lead to non-overlapping distribution of gallery-forest and savanna species and abrupt transition between gallery forest and savanna. Tree species densities were measured in 375 plots of 1500 m2 covering a total sample area of 56.25 ha along forty 3-km transects located at right angles to a riverbed with gallery forest into surrounding savanna. Location, vegetation type, soil physical properties, erosion and fire occurrence were recorded as site factors. Data analysis included the quantification of co-occurrence patterns, threshold indicator taxa analysis and fuzzy set ordination. The gallery forest–savanna gradient predicted floristic composition of plots with a correlation of 0.595 but its accuracy was locally modified by the occurrence of fire and the physical properties of soil that covered more than 30% of the range of residuals. The distribution of gallery-forest and savanna tree species did not overlap. Along the gallery forest–savanna gradient, savanna species gradually increased in density while gallery-forest species showed a community threshold at 120 m from the river beyond the width of gallery forest. The forest species driving this trend should play an important role in the dynamics of gallery forest–savanna boundaries.

Competition and predation have often been referred to as key forces regulating community structure. However, in the last decade great attention has been paid to the structuring role of positive interactions between plants, which occur when the presence of one species enhances fitness, survival or growth of another (Bruno et al. 2003, Callaway et al. 2002). Positive and negative interactions are unlikely to occur separately in nature (Brooker & Callaghan 1998, Holmgren et al. 1997), and the overall importance of positive interactions on community structure tends to be higher in resource-poor environments (Callaway et al. 2002). Moreover, this balance can be subjected to spatial and temporal shifts (Callaway 1998, Morris & Wood 1989, Tielbörger & Kadmon 1997) linked with plant ontogenetic development and/or changes on resource availability (see Callaway & Walker 1997).

This paper introduces studies of nutrient cycling in disturbed and undisturbed rain forest plots in the upper catchment of Birthday Creek, near Paluma, North Queensland. The catchment is underlain by granite and has soils of comparatively low fertility. Differences between unlogged plots and plots disturbed 25 years previously by selective logging are still apparent. Disturbed plots have soils with higher bulk densities and pH, lower CEC, kjeldahl nitrogen and available phosphorus concentrations, and changed species composition. The data suggest that recovery from selective logging is dependent on soil fertility and intensity of disturbance.

Microhabitat use by tadpole species was investigated in streams of montane meadows of the Serra do Cipó, south-eastern Brazil. Microhabitats were classified into 24 types based on water depth, current, aquatic vegetation and substrate type, and quantified in 16 streams. A total of 844 tadpoles from 19 species was recorded, as well as microhabitat types used. Tadpoles, from all species pooled, used microhabitat types in the proportions available in the set of sampled streams. Diversity of microhabitats used was considered as a measure of niche breadth for tadpoles, and microhabitat diversity in streams was interpreted as available niche space. For the most part, species used microhabitats in different proportions, and conspecifics differed in microhabitat use among different streams. Neither niche breadths nor niche overlaps of tadpoles could be related to the number of species occupying streams. Thus not all available niche space may be occupied by tadpole species. More generalist species (those with broader niches) did not generally occupy more streams. Behavioural flexibility of tadpoles in microhabitat use may be a response to the unpredictability of the montane-meadow stream habitat. The role of adult anurans in choosing oviposition sites may also influence the distribution of tadpole species among streams.