The pollination ecology and reproductive phenology of a dioecious palm, Chamaedorea alternans were studied at Los Tuxtlas Biological Station in Veracruz state, Mexico during the 1995-96 flowering season. The sexes flower synchronously from October to January. Field observations investigated reproductive phenology, flower visitors and inflorescence and fruit production. Males produce more flowers and inflorescences than females. Seed-set was 13%, indicating low reproductive efficiency. Individual plants showed a great variation in number of inflorescences produced. Five female and eight male plants (out of 25 and 37 plants, respectively) produced 45% of all inflorescences in the population studied. These five females also produced c. 75% of all fruits. Seed production did not show significant differences between insect-excluded and open-pollinated inflorescences, in experiments to test the efficiency of wind pollination. Flowers of this species are wind-pollinated but a great activity of undetermined species of thrips (Thysanoptera) was observed in male inflorescences.

The aims of this study were to investigate the roosting ecology and social organization of the spotted-winged fruit bat, Balionycteris maculata (Megachiroptera), within an old-growth Malaysian dipterocarp forest, and test the hypothesis that males spend a significantly greater proportion of the night in the immediate vicinity of their day roosts than females. Balionycteris maculata roosted in cavities and formed small harem groups that consisted of one adult male accompanied by up to nine adult females and their dependent young. Both male and female bats foraged locally, within approximately 1 km of their roost sites. However, in contrast to females, which remained away from the roost site throughout the night, both harem and solitary adult males divided their nightly activity between foraging and returning to their roost sites. Individual females were also found roosting sequentially with up to three different males. Hence, these results suggest that B. maculata has a resource-defence polygynous mating system, in which the roost cavity may represent a critical and defendable resource by which males recruit and gain improved reproductive access to females. Roost cavities occupied by B. maculata were found within a number of different forest structures, including ant nests, termite nests and the root masses of epiphytes. The consistent shape and position of the cavities, along with a single observation of cavity enlargement, provide the first evidence of roost-cavity excavation, by a megachiropteran bat, within the nests of social insects. Although the cues by which females select their roost sites are unclear, some aspect of roost cavity size, or condition, may provide a possible means by which females can assess the reproducÍtive fitness of potential mates.

The temporal pattern of reproduction and its consequences for age structure and density were investigated in a population of the gracile mouse opossum Gracilinanus microtarsus in south-eastern Brazil. Individuals of G. microtarsus were monitored through capture–mark–recapture methods from August 2000 to February 2003 in a remnant of cerradão, a forest-like physiognomy of the highly seasonal cerrado biome. The temporal pattern of reproduction of the population studied was highly seasonal with rearing of the offspring occurring in the first half of the warm-wet season, when the abundance of food resources – primarily insects – in the cerrado is high. Shortly after reproduction, the density of adults decreased sharply, possibly because of high post-mating mortality, leading to a gradual replacement of adults by their offspring in the following months and little overlap of generations. Our data suggest that climatic and environmental factors affect the onset of reproduction and interact with endogenous factors that decrease post-mating survival to produce the observed pattern of seasonal variation in age structure and density. It is suggested that the dynamics of populations of G. microtarsus may be driven primarily by food limitation and that long-term studies are needed to understand its feedback structure.

Natural levels and consequences of insect herbivory were studied for a Kandelia candel (Rhizophoraceae) dominated mangal at the Mai Po Marshes, Hong Kong. Grazing insects (mainly lepidopteran larvae) consumed, on average, 10.3% of the leaf area on K. candel, with >90% of the leaves suffering <30% loss. Natural median leaf longevity was significantly different between winter and summer-exposed leaves, being, respectively, 423.2 and 269.6 days. Observations showed that herbivore damage caused a reduction of leaf longevity, as severely damaged leaves were abscissed before intact, older leaves on the same branch. Experimental leaf area removal suggested that leaf life span reduction was significantly influenced by leaf age and degree of damage. However, the reduction was only significant (>40 days) when area loss was >40%. Leaves produced in summer were also more sensitive to damage than those produced in winter. As <5% of the leaves suffered >40% of area removal by insect grazing in nature, insect herbivory is considered an unimportant regulator of leaf litter dynamics for K. candel. At this intensity level, herbivory consumes 2.8–3.5% of the net above-ground primary production of the mangrove. There was also no significant difference in the final number of leaves and twigs produced by the branches with various degrees of leaf area removal. Other observed impacts of insects on the structure and function of the K. candel mangal are discussed.

Amorphophallus johnsonii (N. E. Brown) flowers during April in the main rainy season in Ghana. Anthesis starts at dusk with fluid oozing from the upper spadix accompanied by a strong aminoid odour. Just after dark large numbers of carrion beetles (Phaeochrous amplus) and occasional dung fly species (Hemigymnochaeta unicolor and Paryphodes tigrinus) visit the inflorescences. The beetles become trapped in the lower spathe overnight and remain in the spadix until the following evening. Between 1630 and 1645 h the following day, the anthers produce long threads of sticky pollen. The trapped beetles escape just after dark by crawling up the spadix, past the dehisced anthers and fly away from the spadix tip. Marked beetles were seen to transfer pollen from male phase to female phase inflorescences. Successful fertilisation was only effected if pollen was transferred on the same night from a male inflorescence 30 m or less away. Pollen is psilate and typical of beetle pollinated Araceae. Berries ripen approximately 70 d after fertilization and ripen basisetally in the infructescence.

Differentiation of limiting nutrients within small spatial scales has been observed in coastal mangrove forests, but research on other tropical peatlands suggests it is a more widespread phenomenon. In the Changuinola mire of coastal Panama, oligotrophy was hypothesized to increase along a gradient of peat development (peat doming). Nutrient and carbon concentration of leaf tissue, soil, and soil porewater were characterised over a successive sequence of plant communities along the gradient. Soil phosphorus (P) and nitrogen (N) concentrations decreased from 1200 μg P g−1 and 27 mg N g−1 to 377 μg P g−1 and 22 mg N g−1 within 2.7 km into the mire interior. These changes coincided with an increase in soil and average leaf N:P molar ratios from 52–128 and 24–41, respectively. Soil P was strongly related to leaf P and soil N:P to foliar N:P. There was a wide range in δ15N values for canopy (4.0 to −9.4‰), Campnosperma panamense (4.0 to −7.8‰) and understorey (4.8 to −3.1‰) species. Foliar δ15N values of canopy species were strongly related to soil N:P, soil P and leaf P. The depleted foliar δ15N values appeared to be an effect of both the N atmospheric source and P limitation. Here, P limitation is likely associated with ombrotrophic conditions that developed as hydrologic inputs became dominated by precipitation.

Six Vochysia species occurring in cerrado vegetation or gallery forest in central Brazil were studied for their pollination biology and breeding system. The species showed rather different flowering phenologies, but presented a relatively uniform floral morphology and attracted a mostly similar spectrum of visitors. Principal pollinators were large Anthophoridae bees, but three species were also visited by sphingid moths while hummingbirds were opportunistic visitors to all species. Some observations indicated that the slight differences in flower size or habitat between species may have influenced the relative importance of bees versus hummingbirds or sphingids as effective pollinators. All six species were found to be self-incompatible with self-pollen tube rejection, usually accompanied by callose deposition, occurring in the mid-style.

Field experiments and survival analysis were used to test whether the Janzen-Connell model operated for two common Amazonian tree species in Peru: the midstorey palm, Astrocaryum murumuru, and the canopy-emergent legume, Dipteryx micrantha. Seed and seedling survival patterns of these species partially supported the model, depending on tree species, type of predator, spatial scale and the particular year. At a small scale of a 2.5-ha plot, Astrocaryum seed predation by insects and mammals was density-dependent. At a larger scale of 100 ha, Dipteryx seed survival increased with distance from conspecific adults, but for Astrocaryum seeds there was no distance dependence. At the scale of 200–400 ha Dipteryx seed survival was negatively related to the number of individuals present in groups of conspecific adult trees. In 1992 a higher proportion of Astrocaryum seedlings survived far from, compared with close to, conspecific adult trees, whilst in 1993 more Dipteryx seedlings survived beneath conspecific adult trees than farther away.

Occasional strong droughts are an important feature of the climatic environment of tropical rain forest in much of Borneo. This paper compares the response of a lowland dipterocarp forest at Danum, Sabah, in a period of low (LDI) and a period of high (HDI) drought intensity (1986–96, 9.98 y; 1996–99, 2.62 y). Mean annual drought intensity was two-fold higher in the HDI than LDI period (1997 v. 976 mm), and each period had one moderately strong main drought (viz. 1992, 1998). Mortality of ‘all’ trees ≥10 cm gbh (girth at breast height) and stem growth rates of ‘small’ trees 10–<50 cm gbh were measured in sixteen 0.16-ha subplots (half on ridge, half on lower slope sites) within two 4-ha plots. These 10–50-cm trees were composed largely of true understorey species. A new procedure was developed to correct for the effect of differences in length of census interval when comparing tree mortality rates. Mortality rates of small trees declined slightly but not significantly between the LDI and HDI periods (1.53 to 1.48% y−1): mortality of all trees showed a similar pattern. Relative growth rates declined significantly by 23% from LDI to HDI periods (11.1 to 8.6 mm m−1 y−1): for absolute growth rates the decrease was 28% (2.45 to 1.77 mm y−1). Neither mortality nor growth rates were significantly influenced by topography. For small trees, across subplots, absolute growth rate was positively correlated in the LDI period, but negatively correlated in the HDI period, with mortality rate. There was no consistent pattern in the responses among the 19 most abundant species (n≥50 trees) which included a proposed drought-tolerant guild. In terms of tree survival, the forest at Danum was resistant to increasing drought intensity, but showed decreased stem growth attributable to increasing water stress.

Understanding tropical succession requires insight into propagule availability, which constrains possible woody plant recruitment, yet seed rain composition in multiple post-agricultural sites has seldom been examined. We monitored seed rain for 60 wk in five abandoned pastures in southern Costa Rica, collecting a total of 1 140 688 seeds of 165 morphospecies. Most seeds (80.1%) arrived during the wet season. Species richness was highest in the wet season and greater in forest than in pasture. Seed rain density was greatest at the forest/pasture edge and decreased drastically just a few metres into pastures. In and near the forest, animal-dispersed seeds were more abundant than seeds dispersed by other means, while wind-dispersed taxa increased in relative importance at greater distances from the forest. Total seed input to pastures did not reflect size of adjacent forest fragments, although seed rain density varied more than threefold among sites. Among-site variation in density of regenerating woody seedlings was roughly proportional to among-site variation in seed rain. Morphospecies composition differed significantly among sites. Also, seed rain and woody plant colonists were rather dissimilar in composition, suggesting that while propagule availability is necessary for early woody plant establishment, it is a poor predictor of successional trajectory.

The Asian elephant Elephas maximus is the only living species of the genus Elephas (Elephantidae) that evolved in Africa c. 5–6 million y ago and migrated into Eurasia (Sukumar 2003). The Asian elephant is one of the few remaining extant megafauna (Owen-Smith 1988) and has disappeared from c. 95% of its historical range (Sukumar 2006). Asian elephants eat fruit when it is available, defecating intact seeds, of which some later germinate in the dung (Lekagul & McNeely 1977, Ridley 1930). However, to date there has been no detailed study of frugivory and seed dispersal by Asian elephants (Corlett 1998). The only common feature of the fruit reported to be eaten by Asian elephants is their relatively large size, but there is no evidence that they are exclusive dispersers of any plant species (Corlett 1998), in contrast to the more frugivorous African forest elephants, Loxodonta africana cyclotis (Babweteera et al. 2007, Chapman et al. 1992, Cochrane 2003, Feer 1995).

Severe tropical cyclones are a major cause of episodic mortality for Pacific Island flying foxes (large fruit bats). Many flying foxes starve after forests are stripped of food sources, and hunting by humans may also increase in the post-cyclone period. In December 2001, Cyclone Waka passed directly over the Vava'u Islands in the Kingdom of Tonga, western Polynesia. We visited the islands 6 mo later to survey the flying fox (Pteropus tonganus) population and assess availability of potential food items (fruit and flower) in primary, secondary and plantation forests. Less than 20% of the pre-cyclone bat population (surveyed in 1999–2001) remained 6 mo after the storm. The density of potential food trees in flower or fruit at this time was only 15% of pre-cyclone density, and the main species available were different in the two time periods. The highest density of potential food trees occurred in secondary forest (26 flowering or fruiting trees ha−1) and plantations (23 ha−1); primary forest offered the least food (18 ha−1). Since 65–70% of the land area has been converted to agricultural plantations, this vegetation type had the highest absolute number of food-bearing trees – almost seven times that of primary forest. Flowering coconuts (Cocos nucifera) were the most abundant food source overall and we suggest that this species may be important in sustaining flying foxes following severe storms.

Succession was monitored over ten years in a 10×10m plot in forest with mor humus at 1550 m in the Blue Mountains of Jamaica, following the removal in January 1975 of all aerial plant parts and some of the root material. In April 1977, August–January 1980/1 and August 1984, all woody recruits in the plot were tagged and numbered, identified and measured (height), and mapped on a 1 m grid. The height of coppice was recorded. Ten of the eleven tree species present before felling produced coppice shoots. Two individuals almost attained canopy height by 1984. Twenty tree species and three shrub species were recruited from seed; six of the tree species were normally absent from the forest. Species composition changed very little with time.

The rate of seedling recruitment was greatest immediately after clearing. The overall den-sity of individuals changed little after 1977. Overall mortality of recruits was about 10% per annum. Mortality of the earliest recruits declined with time since establishment. Later recruits and individuals with poor growth had higher mortality than other plants. Mortality was not density-dependent. Growth rates of recruits were relatively slow. Only ten individuals exceeded 4 m by 1984.

Recruitment rates, density, growth and species diversity were greatest in the parts of the plot where the mor humus had been removed or piled up during the initial clearance. Recruit-ment, growth and density were least, and mortality was greatest, at the edge. There was no relationship between any of these parameters and the presence of coppicing stumps.

Tree species showed a clear spectrum from obligate gap-demanders to obligate shade-bearers. The persistence of gap-demanding species in this forest (in which gaps are normally rare) may be due to infrequent hurricanes, and also to a natural ability to produce basal sprouts. The succession conforms to an initial floristic composition model; it is slow, and we suggest that at least 50 years will elapse before the plot begins to resemble the undisturbed forest.

Leaf and grass canopy photosynthetic rates were measured in a West African humid savanna during several stages of the early growing season. The results obtained on the dominant grass species Hyparrhenia diplandra and data published previously show that C4 savanna grasses exhibit a remarkably high leaf photosynthetic capacity despite their low nitrogen content. A variation of leaf photosynthetic capacity in relation to leaf rank on stems is observed which is interpreted by ageing and shading effects within the canopy. Seasonal variations of the canopy CO2 assimilation rate is explained in relation to variations of leaf area index and canopy nitrogen content. Despite low nitrogen content or low leaf area index, maximum canopy net photosynthesis was high (24 μmol CO2 m-3 s-1 for LAI = 1.5). The high photosynthetic nitrogen use efficiency exhibited by leaves of humid savanna grass species is a major attribute explaining high photosynthetic rates of the grass canopy in this environment. This result sustains the emerging opinion that tropical savannas could be highly productive despite the generally low nutrient status they experience.

Lianas are abundant in tropical forests around the world, yet little is known about their ecology. In this study we report the results of a survey of ten common liana species on 27 host tree species in Cooloola National Park, Queensland, Australia. We found significant associations between some liana and tree species. Our results indicate that host tree diameter was important in explaining liana presence or absence. Host tree fruit type was correlated with the presence or absence of different liana types. Tendrillar and root-climbing lianas tended to occur most often on mid-sized, fleshy-fruited trees, and on smaller, non-fleshy-fruited trees. The presence of stem twining lianas tended to decrease with increasing tree diameter for both fleshy- and non-fleshy-fruited trees, although this effect was more pronounced for fleshy-fruited trees. In general, lianas were most prevalent on trees possessing intermediate levels of bark roughness and flakiness. Although we established associative patterns between liana species and these host characteristics, the model suggested that other unidentified variables may also be important in determining presence or absence of liana species.

Effects of litter cover on insect herbivory, leaf-fungal damage, and seedling performance (survival, growth in height and leaf number), were assessed on established Nectandra ambigens seedlings in three sites of a Mexican tropical rain forest. Naturally occurring seedlings were measured for height, leaf number and standing levels of leaf damage by herbivores and pathogens. Thereafter, seedlings were exposed for 1 y to three litter treatments: (1) litter addition, (2) control and (3) continuous litter removal. There was a significant effect of site on the proportion of surviving seedlings and on the relative growth rates in terms of leaf number. Overall, seedlings with higher initial leaf number showed higher survival and produced more leaves after 12 mo than seedlings with lower initial leaf number. Litter addition resulted in seedlings with lower relative growth rates in height and higher levels of damage by herbivores and pathogens. On average, leaf area damaged by pathogens was < 6% and herbivory was < 27%. Seedlings with higher levels of herbivory showed higher levels of pathogen attack. Herbivory and pathogen attack had no effect on seedling performance. This study reveals the importance of litter-cover on the interactions between seedlings, herbivores and pathogens, as well as on the performance of tropical seedlings.

The relationship between sepal and nut size of fruits was studied in fruit of 394 species of Dipterocarpaceae in Malesia and Sri Lanka. The fruits of many dipterocarps have long twisted sepals which have a role as blades for dispersal by gyration. But long sepals decrease resource allocation to other parts, and increase the chance of fruit being trapped in the canopy. The frequency distribution of the ratio of sepal length to nut length was bimodal. The gyrationdispersed group with longer sepals comprised 74% of Dipterocarpaceae studied. The group with short sepal mainly comprised understorey trees, but there were a few emergents. In both groups, sepal areas were expressed as a power function of nut volumes'. Because fruit weight per sepal area increases with fruit size, larger fruits fall more quickly than smaller fruits, and sepals of the former can not serve so effectively as propeller blades. This is consistent with the fact that a few emergent trees with large nuts have short sepals and are not dispersed by gyration. Therefore, the re-evolution of short fruit sepals appears to have been mainly due to two reasons: reduction of tree height and enlargement of nut size.

The epiphytic habitat is assumed to be nutrient deficient, although this generally held notion is based almost completely on circumstantial evidence (Zotz & Hietz 2001). Most studies on the nutrient relations of vascular epiphytes focus on nitrogen (Bergstrom & Tweedie 1998, Hietz & Wanek 2003, Stewart et al. 1995). Although nitrogen plays a key role in limiting plant growth worldwide, there is an on-going discussion whether nitrogen or rather phosphorus are more limiting in many tropical forests (Grubb 1989, Harrington et al. 2001, Vitousek & Howarth 1991). To identify which nutritional factor is most limiting for plant growth, nutrient ratios have been proposed as a very useful tool (Koerselman & Meuleman 1996). These authors stated that N:P ratios exceeding 16 are indicative of P limitation, while an N:P ratio <14 suggests N limitation. Some reports of such ratios in the epiphyte literature indicate that phosphorus may indeed be limiting for epiphytes in tropical forests. For example, the N:P ratio of two field-grown bromeliads (Tillandsia circinnata and T. usneoides) decreased dramatically from 23.6 and 40.4, respectively, to 3.6 and 3.4, respectively, when fertilized with both N and P in the laboratory (Benzing & Renfrow 1974a). On the other hand, however, the average N:P ratios of mature leaves of 41 epiphyte species compiled from a number of papers did not appear particularly high (12.1±10.5, cf. Zotz & Hietz 2001).

Following the 2003 invasion of the armoured scale Aulacaspis yasumatsui to Guam, changes to population traits of the dominant Cycas micronesica were determined. Belt transects with a width of 4 m and an average length of 120 m were established in October 2004 to document plant mortality until January 2011. Stem height, basal diameter and leaf number were also measured for each plant and used to determine density, demography and allometric relationships. Allometric traits and a left-skewed demographic structure of the pre-invasion C. micronesica habitat documented a thriving population with high recruitment potential. Aulacaspis yasumatsui dispersed into the study site 4 mo after the initial census. All seedlings were killed within 9 mo and all juvenile plants were killed within 40 ± 10 mo. Mortality reached 92% by 6 y after chronic scale infestations. Allometry and demography of the 2011 survivors described a collapsing C. micronesica population of stressed and reproductively challenged trees with no recruitment. This classic example of the enemy release hypothesis has resulted in a homogeneous decline in plant density from 2007–2011. The trend predicts extirpation of C. micronesica from west Guam habitats by 2019.

Volcán Barva, Costa Rica, has on its northern slope an unbroken sequence of rain forest on volcanic parent materials from near sea level at La Selva Field Station up to its summit at 2906 m. It provides a good area to study forest changes with altitude and their causes. In the present paper we describe the forests as a background for soil and litterfall studies from 1 ha plots at each of the following altitudes: 100 m, 500 m, 1000 m, 1500 m, 2000 m and 2600 m. The canopy heights (with height of the highest emergent in parentheses) ranged from 35–40 m (45 m) at 100 m to 20–23 m (32 m) at 2600 m; basal area was least (22.7 m2) at 100 m and highest (51.2 m2) at 2600 m; the tree (≥10 cm dbh) density ranged from 391 ha–1at 500 m to 617 ha–1 at 2600 m. Most trees were identified and on samples of them we recorded presence of buttresses, lianes, skiophytic climbers, vascular epiphytes and bryophytes; and drew profile diagrams. In the classification of Whitmore (1984) the two lower plots are evergreen lowland rain forests; the other four are lower montane rain forest. Species richness was highest in the plot at 500 m, with at least 135 species of tree, and least at 2600 m, with at least 35 species. The Volcán Barva forest altitudinal sequence is briefly compared with those elsewhere.