Termites are renowned ecosystem engineers. Their mounds have been described as an important element of savanna vegetation dynamics, but little is known about their large-scale impact on vegetation composition. To investigate the influence of termite-induced heterogeneity in savannas along a climatic gradient in West Africa termite mound vegetation was compared with adjacent savanna vegetation using 256 paired plots (size of the termite mound and a corresponding savanna area) in five protected areas from northern Burkina Faso to northern Benin. On each plot vegetation and soil sampling was performed. Additionally bioclimatic variables from the WORLDCLIM database were used. The vegetation on the mounds and the surrounding savanna differed within all study sites (DCA length of gradient 3.85 SD) and showed complete turnover along the climatic gradient (DCA length of gradient 5.99 SD). Differences between mounds and savanna were significantly related to termite-induced changes in soil parameters, specifically clay enrichment and increased cation concentrations (base saturation). On a local scale, termite-induced differences in soil conditions were found to be the most important factor affecting mound vegetation, while on a regional scale, annual precipitation showed the strongest significant correlations. However, with increasing precipitation, differences between mounds and the surrounding matrix became more pronounced, and the contribution of mounds to local phytodiversity increased. Eleven plant species were identified as characteristic termite mound species. In the more humid parts of the gradient, more characteristic plant species were found that may benefit from favourable soil conditions, good water availability, and a low fire impact in the mound microhabitat.

The relationship between mycorrhizal colonisation and phosphorus acquired by seedlings of the arbuscular mycorrhizal tree Oubanguia alata Bak f. (Scytopetalaceae) and the ectomycorrhizal tree Tetraberlinia moreliana Aubr. (Caesalpiniodeae) was evaluated at low and high inorganic phosphorus availability. AM colonisation was positively correlated with phosphorus uptake by O. alata at low, but not at high phosphorus availability. Seedlings growth was positively related to arbuscular mycorrhizal colonisation at both low and high phosphorus availability, suggesting that growth promotion by arbuscular mycorrhizas is not simply related to an increase of phosphorus uptake. In contrast, phosphorus uptake by T. moreliana was correlated with EM colonisation at both low and high phosphorus availability, but there was no relationship between growth and ectomycorrhizal colonisation. Promotion of phosphorus uptake by arbuscular mycorrhizas and ectomycorrhizas at low phosphorus availability is consistent with the co-occurrence of the two types of mycorrhiza in tropical rain forests where available soil phosphorus is low. However, ectomycorrhizal colonisation may also be of advantage where inputs of phosphorus rich litter raise the phosphorus status of the soil, as seen in the groves of ectomycorrhizal trees in Korup National Park, and may be one of the factors reinforcing local dominance by these trees.

The photosynthetic light response of Amazonian semi-deciduous forest trees of the rain forest–savanna transition near Sinop Mato Grosso, Brazil was measured between July 2000 and September 2003 to test the hypothesis that the photosynthetic capacity of trees acclimated to different growth light environments will decline during the dry season. Maximum photosynthesis (Amax) and stomatal conductance (gmax) were significantly higher during the wet season; however, the physiological response to drought was not a clear function of growth light environment. For some species, such as Psychotria sp. growing in the mid-canopy, internal leaf CO2 concentration (Ci) was >30% lower during the dry season suggesting that declines in Amax were caused in part by stomatal limitations to CO2 diffusion. For other species, such as Brosimum lactescens growing at the top of the canopy, Tovomita schomburgkii growing in the mid-canopy, and Dinizia excelsa growing in the understorey, dry season Ci declined by <20% suggesting that factors independent of CO2 diffusion were more important in limiting Amax. Dry-season declines in gmax appeared to be important for maintaining a more consistent leaf water potential for some species (T. schomburgkii and D. excelsa) but not others (Psychotria sp.). These results indicate that while seasonal drought exerts an important limitation on the physiological capacity of semi-deciduous Amazonian forest trees, the mechanism of this limitation may differ between species.

The influence of gamma- (γ) and beta- (β) diversity on modern pollen rain is assessed using data from three Amazonian forests. Pollen rain of 79 forest locations was collected in modified Oldfield pollen traps between 1991 and 1993. Pollen diversity in the traps was high with > 280 palynomorph types recognized. Gamma diversity was assessed by comparing lowland terra firme forests in Cuyabeno, Ecuador, with two terra firme forests near Manaus, Brazil. The influence of β-diversity on local pollen rain was investigated using samples collected from neighbouring terra firme forests, seasonally flooded forests, and Mauritia-rich forests at Cuyabeno, Ecuador. Multivariate analyses revealed that γ-diversity produces a stronger signal in the pollen rain than β-diversity. However, β-diversity is accurately reflected in the pollen rain when the diversity is an expression of strong environmental gradients.

Seed density and seed bank species composition were determined by germination trials on soils collected during the initial phase of deforestation in a Mexican tropical deciduous forest. The reference forest, pre-burn, 1-d post-burn, and 1-y post-burn soils contained 700, 1000, 70 and 3500 germinating seeds m−2, of 30, 30, 8 and 13 species, respectively. A total of 43 dicotyledonous species were identified. Percentages of herbs, vines, shrubs and small trees/shrubs were similar in reference forest, pre-burn, and 1-d post-burn soils; herbs were the most common growth form. Pasture conversion greatly altered seed bank species composition; 81% of the species that germinated from the seed bank before burning were absent from the seed bank 1 d after the fires. One-year post-burn soil was dominated by monocots; only 3% of the seedlings were herbs; no vines, small trees/shrubs or trees germinated. The reference forest and the pre-burn soils had 18 dicot species in common and the highest similarity index, 0.43; six of the shared species were herbs. One-day and 1-y post-burn soils had the lowest similarity index, 0.05. Burning the slashed forest and conversion to cattle pasture depleted the original seed bank, replacing it by one dominated by pasture grasses.

Malaysia is establishing large-scale plantations for reforestation and the production of wood for pulp and paper as well as for light construction. The main species used currently is the exotic legume Acacia mangium. The above-ground biomass, litter production and litter accumulation in a four-year-old stand in Peninsular Malaysia were studied. The mean diameter at breast height (dbh) was 12 cm. The mean annual increment (MAI) in dbh of individual trees ranged from 0.9 to 5.1 cm while MAI in height of sample trees ranged from 2.9 to 5.5 m. The total above-ground biomass of the stand was 90.4 t ha−1, consisting of 57.6 t stem, 14.1 t branch and 5.4 t leaf. Litter production averaged 10.23 t ha−1 yr−1 with leaf litter making up 87.4% of the total. Leaf litter accumulation amounted to 6.64 t ha−1 and the turnover constant of leaf litter was estimated at 1.35. The high productivity is discussed in relation to the high turnover of foliage and the low turnover of litter.

In tropical rain forest, the interface between leaf surfaces and the atmosphere is a fundamental pathway for nutrient cycling (particulary nitrogen), possibly even more important than the soil–plant interface (Parker 1994, Silver et al. 1996). Most important nutrient exchanges in the phyllosphere–atmosphere interface are mediated by microbial populations. For example, some authors have considered that nitrogen fixation in the phyllosphere is the main mechanism for nitrogen gain in humid tropical ecosystems, because of the substantial nutrient demand resulting from a high plant productivity and the constraint imposed by the generally low nitrogen availability in soil (Ruinen 1974, Salati et al. 1982, Silver et al. 1996).

Bat communities in the understorey of primary lowland dipterocarp forest in peninsular Malaysia and Sabah were sampled with mist nets and harp traps to estimate their trophic structure. Overall, 4 of 26 species (15%) at one site, and 6 of 33 species (18%) at the other site were frugivores, while the remainder were insectivores. In terms of individuals, 7–12% of all captures were frugivores. However, the true proportion of frugivores at both sites was probably closer to 1%, because the sampling procedures were strongly biased towards frugivores. In contrast, previously published studies indicate that frugivores comprise 34–48% of species, and up to 80% of individuals in bat communities in the understorey of Neotropical forest. These results support the hypothesis, developed from studies of bird communities, that the under-storey of Malaysian dipterocarp forest supports relatively few obligate frugivores, at least in non-masting years. However, further data are required on bats in the canopy, and on the foraging ranges of bats to compare the absolute densities of bats in Malaysian and Neotropical forests.

The agouti (Dasyprocta punctata) meticulously defleshes Astrocaryum standleyanum palm seeds before scatter hoarding. On Barro Colorado Island, Panama, we experimentally tested three hypotheses on how this behaviour could reduce seed predation to the mutual benefit of the tree and the rodent. The first and established hypothesis – that defleshing reduces seed predation by bruchid beetles by intercepting larvae – was rejected. Experiments in which manually defleshed seeds or entire fruits were incubated at different times showed that defleshing reduced bruchid infestation before fruit fall but not after fruit fall. The second hypothesis – that defleshing reduces cache pilferage by making seeds less conspicuous – was supported. An experiment in which intact fruits and manually defleshed seeds were placed in mimicked agouti caches and followed showed that seeds with flesh were pilfered at higher rates than defleshed seeds. The third hypothesis – that defleshing reduces post-dispersal infestation of cached seeds – was rejected. An experiment in which intact fruits and manually defleshed seeds were placed in mammal exclosures and later collected to assess infestation showed that burial reduced seed infestation but defleshing did not. Thus, seed defleshing reduced palm seed predation, but in a different way than previously believed. We also found that (1) bruchid beetles can be pre-dispersal rather than post-dispersal seed predators, (2) seed infestation by scolytid beetles may control bruchid larvae, and (3) scolytids rather than bruchids are the main invertebrate seed predators of this palm.

The decomposition of litter of two tree species Graffenrieda emarginata (Melastomataceae), Purdiaea nutans (Cyrillaceae) and the mixture of both was investigated in a tropical montane rain forest in southern Ecuador at two different altitudes (1850 and 2280 m). The two litter types differed strongly in nitrogen concentration, suggesting that G. emarginata (1.21% N) decomposes faster than P. nutans (0.73% N). To study the effect of soil micro-arthropods on the decomposition process, litterbags with mesh-size of 48 μm, excluding soil micro-arthropods, and 1 mm, allowing colonization by soil micro-arthropods, were used. Litter mass loss was measured after 2, 6 and 12 mo exposure in the field; further, microbial biomass and micro-arthropod colonization of the litter were investigated after 2 and 12 mo. Generally, litter decomposed faster at 1850 m than at 2280 m (60% and 76% dry mass remaining after 12 mo, respectively); G. emarginata and mixed litter decomposed faster than P. nutans litter. After 12 mo mixed litter decomposed faster (65% of dry mass remaining) than both individual litter species (70% and 71% of dry mass of G. emarginata and P. nutans litter remaining, respectively) indicating that non-additive effects contributed to litter decomposition. Microbial biomass increased during the experiment and was higher at 1850 m than at 2280 m. The most abundant micro-arthropods in both litter types were oribatid mites followed by Collembola, Gamasina, Uropodina and Prostigmata + Astigmata. Micro-arthropods were generally more abundant at 1850 m suggesting higher biotic activity at lower altitudes. Soil micro-arthropods contributed little to decomposition processes indicating that litter decomposition is mainly due to micro-organisms.

Lizards mainly eat arthropods, fruit, nectar, pollen and animal scats (Pérez-Mellado & Casas 1997, Whitaker 1987), using their sense of smell and good colour vision while foraging (Vinson & Vinson 1969). Although several papers have contributed to the knowledge on the relationship between lizards and floral resources, this topic is often still regarded as anecdotal. However, a few detailed ecological studies on lizard and flower interactions have been conducted, e.g. in New Zealand and the Balearic Isles (Eifler 1995, Sáez & Traveset 1995, Traveset & Sáez 1997,Whitaker 1987). Pollination by lizards was rendered likely by the following findings: first, Mediterranean lacertid lizards and New Zealand geckos have pollen adhering to their belly, throat and labium; second, they may carry pollen for several hours, and thus also transport pollen some distance away from a pollen donor plant. New Zealand geckos carry pollen up to 72 m away from donors. Good experimental evidence of lizard pollination was produced by Pérez-Mellado & Casas (1997). They showed that an umbellifer species produced less viable seeds if Podarcis lilfordi lizards were excluded from flowers.

The land crab, Gecarcinus quadratus (Gecarcinidae), affects plant diversity in a mainland, neotropical rain forest through selective seedling consumption. In Costa Rica's Corcovado National Park, G. quadratus lives in fossorial populations with up to six crabs m−2 in coastal forest extending c. 600 m inland from the Pacific Ocean. A narrow transition zone (c. 30 m) separates the crab zone from the crabless zone that comprises the remainder of the 55 000-ha park. The composition of dicotyledonous plants from the adjacent zones were distinct: crabless zone transects (240 m2) contained 97 species representing 76 genera and 41 families; crab zone transects contained 46 species representing 38 genera and 25 families. Despite the narrow zonal separation, the crabless zone shared only 27.4, 29.9 and 52.8% of its species, genera and families, respectively, with the crab zone; in contrast, crab zone transects shared 56.5, 60.5 and 88% of their species, genera and families with the crabless zone. This abrupt diversity gradient suggests a powerful selection pressure in the crab zone preventing the establishment of certain dicotyledonous species. Two years of experimental crab exclusion suggested that G. quadratus reduces seedling density and diversity. Densities of seedlings (3–25 cm tall) within exclosures increased 144% over baseline values while control densities decreased. In contrast, seedlings at the cotyledon stage and taller (26–50 cm) were unaffected by crab exclusion. Preference tests conducted in the crab zone revealed a five-fold ratio of mortality rates for seedlings transplanted from the crabless zone and crab zone respectively. However, when protected from crabs, transplanted crabless and crab zone seedlings survived similarly well over 6 mo (83 and 70% respectively). Together, data from transects and experiments suggest that G. quadratus influences plant community composition.

The intra-crop variation in the concentrations of major nutrients in the embryo-cum-endosperm (EE) fraction of seeds of 12 tree species of SE Asian lowland rain forest was investigated. Increased seed size was associated with a significant decrease in the EE concentration of N in 10 species, P and K in seven, Mg in six, and Ca in four. In contrast, the EE nutrient content increased with seed size, typically by about 1.6-fold where seed mass was 2-fold greater. In three species the allocation to protective tissues decreased with increased seed size. The results are potentially relevant to competition among young seedlings, optimal foraging by predators, allocation to defence by plants, and understanding the controls on filling of seeds.

Palm seeds of the genus Astrocaryum are known to attract a wide range of seed predators, including insects, rodents and peccaries. We investigated the removal of seeds of Astrocaryum murumuru var. macrocalyx in dense groves and under solitary palms, both within and outside of peccary exclosures. We set out arrays of 40 seeds at each of 40 sites representing four treatments: in the open and in peccary exclosures, in groves and under solitary palms. Seed removal from each site was monitored daily for 55 d. Infra-red-triggered cameras were installed to identify the species that removed seeds. From the known and hypothesized behaviour of vertebrate seed predators under various circumstances, we predicted that (1) overall seed loss should be higher under solitary trees, (2) peccaries should forage preferentially in groves, (3) the variance in the rate of seed removal should be higher in groves, (4) a greater fraction of the seeds removed from solitary palms should be scatterhoarded, and consequently, (5) greater numbers of seedlings should recruit near solitary palms than in groves. The first four of these predictions were confirmed and the last was rejected by the results. Peccaries preferred to forage in groves, and small rodents preferred to forage under solitary palms. Whether in groves or under solitary palms, peccaries preferentially removed seeds from large arrays (21–40 seeds), and mostly ignored small arrays (≤ 20 seeds). Camera trapping demonstrated that the most frequent visitors to seed arrays were Myoprocta pratti and Proechimys spp. There was no significant difference in the numbers of seedlings around trees in groves versus solitary trees.

Frugivorous dacine fruit flies were studied in a lowland tropical rain forest in Papua New Guinea to determine their host specificity, abundance, and the number of species attacking various plant species. Plant species hosted 0–3 fruit fly species at median (1–3 quartile) densities of 1 (0–17) fruit flies per 100 fruits. Fruit flies were mostly specialized to a single plant family (83% species) and within each family to a single genus (88% species), while most of the species (66%) were able to feed on >1 congeneric plant species. Only 30 from the 53 studied plant species were colonized by fruit flies. The plant–fruit fly food web, including these 30 plant species and the total of 29 fruit fly species feeding on them, was divided into 14 compartments, each including 1–8 plant species hosting mutually disjunct assemblages of fruit flies. This structure minimizes indirect interactions among plant species via shared herbivores. The local species pool was estimated at 152±32 (±SE) fruit fly species. Forty per cent of all taxonomically described species known from Papua New Guinea were reared or trapped in our study area. Such a high proportion indicates low beta-diversity of fruit flies. Steiner traps were highly efficient in sampling the lure-responsive fruit fly species as they re-collected 84% of all species trapped in the same area 5 y before. Fruit fly monitoring by these traps is a cheap, simple and efficient method for the study of spatial and temporal changes in rain-forest communities.

Canopy observations of the rain forest tree Parkia velutina (Leguminosae: Mimosoideae) in Amazonian Brazil indicate that it is pollinated by night-flying bees. The small red flowers are organized into spherical heads; they open in the late afternoon and attract Megalopta bees (Halictidae: Augochlorini) which forage for pollen after dark. In contrast to the numerous bat-pollinated species of Parkia, no nectar was detected. Nocturnal melittophily is proposed as a possible intermediate stage in the evolution of chiropterophily from diurnal entomophily in Parkia.

Geographic variation in behaviour of individuals within a species is well known (Foster & Endler 1999), both across ranges (Iriarte et al. 1990) and locally (Hertz & Huey 1981). For predators, variation in prey use within a given site is often seasonal (Brillhart & Kaufman 1995), and related to changes in relative abundance and/or vulnerability of various prey (Kunkel et al. 2004). Behavioural diversity also occurs because prey behaviours vary and predators change foraging tactics, even on a daily basis (Ropert-Coudert et al. 2002).