Viable soil seed banks in disturbed lowland tropical rainforest sites in North Queensland

Four 0.125 m² soil samples, 50 mm deep, from each of eight tropical lowland rainforest sites ranging from primary and secondary forests to degraded Imperata grasslands were exposed to shade-house conditions. Germinations of soil seeds were monitored over 28 weeks in April-October. The viable seed banks in the primary forest (592 m^-2) and the secondary forest sites resulting from one cycle of clearing and abandonment (1300–1400 m^-2) were composed predominantly of secondary species. The viable seed banks were small in Imperata grassland sites that had been burnt regularly (200–400 m^-2) and very large (2000–3000 m^-2) in sites that had not been burnt for five years or more. The seed banks of the burnt and unburnt Imperata grassland sites were composed mostly of agricultural weeds whilst seeds of secondary rainforest trees were rare or absent. Similarities between the species composition of soil seed banks and regrowth vegetation types suggest that soil seed composition is important in determining the initial floristic composition following disturbance and that lack of seed of secondary rainforest trees is one factor which restricts re-growth and secondary succession on degraded Imperata grasslands. Species such as Eucalyptus intermedia R. T. Bak., E. pellita F. Muell. and Imperata cylindrica (L.)Beauv. which can establish and deflect the normal rainforest secondary succession were not present in the soil seed bank, and these species appear to rely on fresh seed inputs, lignotubers or rhizomes to colonize and regenerate after disturbance.     

Foraging ecology of insectivorous birds in a mixed forest of Hong Kong

In a mixed forest in Hong Kong, the foraging ecology of nine species of insectivorous birds was studied. Leaves and branches of diameters smaller than 2 cm were the most frequently searched microhabitats. Gleaning was the most frequently used foraging method. Apart from Blue-winged Minla and Japanese White-eye, no two species used similar proportions of vertical strata and microhabitats at the same time. Bird species using similar proportion of microhabitats were foraging in different proportion of vertical strata. This niche segregation enabled the bird species to coexist in the same habitat. Velvet-fronted Nuthatch differed from other species by its more frequent use of branches of diameters larger than 2 cm and tree trunks. This might be one of the reasons why this exotic species successfully established a breeding population in the study area.     

Cuticular morphology and aspects of the ecology and fossil history of North Queensland rainforest Proteaceae

Cuticles of North Queensland rainforest Proteaceae were examined using light and scanning electron microscopy. The genera of North Queensland rainforest Proteaceae are mostly endemic and composed of one or few species, with greatest diversity in the granitic uplands of the region. Knowledge of cuticular morphology may be an important tool in determining the true affinities of several undescribed taxa in the region and can be used to explore hypotheses relating to the history of the Proteaceae. Some species exhibit purported xeromorphic features of thick cuticles, sunken stomates and dense trichome cover on the abaxial surface. Grevillea , Banksieae and Stenocarpus are believed to have radiated into open, much less mesic environments. In the former two taxa this can be interpreted in terms of xeromorphic features expressed in their cuticular morphologies, whereas in Stenocarpus amphistomaty in species of open habitats suggests an alternative mode of evolution more related to physiological factors. Several Cainozoic proteaceous macrofossils temporally and spatially far removed from North Queensland possess cuticular morphologies very similar or identical to extant rainforest taxa in the region.     

Comparative ecology of a lowland and a subalpine species of Mnium in the northern Rocky Mountains

Factors that set the altitudinal limits of plants have been relatively well explored for many land plant groups, but not for bryophytes. Bryophytes typically represent a significant portion of alpine floras with many species specific to highland systems. Differences between highland and lowland bryophytes have been underinvestigated. In the present study spanning three growing seasons, a subalpine and a lowland moss were both reciprocally planted as apical fragments and transplanted as adults between sites at 1400 m and 2000 m in the Front Ranges of the Rocky Mountains, Alberta. The lowland species, Mnium spinulosum, was less tolerant of conditions at 2000 m than the subalpine species, M. arizonicum, was to conditions at 1400 m. In particular, M. spinulosum had lower establishment from both apical fragments and spores at higher elevation sites. Both species had significantly lower establishment during the abnormally cold growing season of 1999, but fragments of M. arizonicum were better able to adjust their investment in establishment. The effect of a dominant feather moss, Hylocomium splendens, on establishment and transplant health was tested for M. arizonicum. Establishment of M. arizonicum was lower in Hylocomium mats than on bare humus regardless of site elevation suggesting allelopathy; however, stem survival in adult transplants was higher in Hylocomium mats than in Mnium dominated microsites at the higher elevation suggesting facilitation. Competition, rather than a lack of physiological plasticity, probably determines the lower elevation limit of the subalpine moss, while poor establishment ability at low temperatures accounts for the upper elevation limit of the montane moss. This revised version was published online in June 2006 with corrections to the Cover Date.     

The hummingbird community of a lowland Amazonian rainforest

Between October 1987 and September 1989, the British Ornithologists' Union Colombia Expedition recorded 16 species of hummingbird at Matamatá in the Amacayacu National Park, Amazonas, Colombia. Most of these species were resident breeders at the study site although two appeared to be local migrants. Six species of hermit hummingbirds (subfamily Phaethornithinae) occurred at Matamatá; although very similar in general morphology and behaviour, they showed different preferences for habitat, food plants and foraging technique. Hermits were predominant in the forest, but in areas of secondary vegetation and along riverine borders, "typical" hummingbirds (subfamily Trochilinae) were more common. The study site consisted of terra firme and várzea forest and an area of riverine secondary vegetation and contained around 60 species of flowering plants visited by hummingbirds. In contrast with most groups of organisms, hummingbirds and hummingbird-pollinated plants had similar species diversity in primary forest and secondary habitats. The overall abundance of hummingbirds and flowers was significantly higher in areas of riverine secondary growth. The hummingbird community at Matamatá is remarkably species rich when compared with study sites elsewhere in North and South America. However, random null model comparisons among Amazonian hummingbird communities reveal that they share many characteristics in their structure and show a high degree of species overlap.     

The pollination ecology of an assemblage of grassland asclepiads in South Africa

The KwaZulu-Natal region of South Africa hosts a large diversity of asclepiads (Apocynaceae: Asclepiadoideae), many of which are endemic to the area. The asclepiads are of particular interest because of their characteristically highly evolved floral morphology. During 3 months of fieldwork (November 2000 to January 2001) the flower visitors and pollinators to an assemblage of nine asclepiads at an upland grassland site were studied. These observations were augmented by laboratory studies of flower morphology (including scanning electron microscopy) and flower colour (using a spectrometer). Two of the specialized pollination systems that were documented are new to the asclepiads: fruit chafer pollination and pompilid wasp pollination. The latter is almost unique in the angiosperms. Taxa possessing these specific pollination systems cluster together in multidimensional phenotype space, suggesting that there has been convergent evolution in response to similar selection to attract identical pollinators. Pollination niche breadth varied from the very specialized species, with only one pollinator, to the more generalized, with up to ten pollinators. Pollinator sharing by the specialized taxa does not appear to have resulted in niche differentiation in terms of the temporal or spatial dimensions, or with regards to placement of pollinaria. Nestedness analysis of the data set showed that there was predictability and structure to the pattern of plant-pollinator interactions, with generalist insects visiting specialized plants and vice versa. The research has shown that there is still much to be learned about plant-pollinator interactions in areas of high plant diversity such as South Africa.     

High plant diversity of lowland rainforest vestiges in eastern Madagascar

Based on cartography, floristic inventory and vegetation analysis in the north and south of the Eastern Domain of Madagascar we identified three original tropical rainforest types which are among the world's most biodiverse known sites for plants: the littoral forest on sand, the lowland forest on gneiss and the lowland forest on basalt. Floristic and structural comparisons were conducted on 37 plots of 50×10m. Multivariate analysis indicates that floristic composition is correlated with abiotic factors of rainfall, latitude, soil composition, and marine influence; the structure of the undergrowth is generally homogeneous and the canopy is more or less open. Many reserves must be created on gneiss, sand and basalt all along the eastern coast to preserve biodiversity from the deforestation process. On basalt, this is especially urgent because about only 10 000 ha of a very ancient forest that shelters numerous botanical novelties remain today.     

Vertical stratification of the termite assemblage in a neotropical rainforest

The importance of termites as decomposers in tropical forests has long been recognized. Studies on the richness and diversity of termite species and their ecological function have flourished in more recent times, but these have been mostly conducted in a thin stratum within a standing man’s reach. Our aims were to evaluate the specific richness and composition of the termite assemblage in the canopy of a tropical rainforest and to determine its originality with respect to the sympatric ground-level fauna. We conducted systematic searches for canopy termites, together with conventional sampling of the sympatric ground-level fauna, in the San Lorenzo forest, Panama. We hypothesized that (1) the canopy accommodates two categories of wood-feeding termites (long-distance foragers and small-colony “one-piece” species) and possibly soil-feeders in suspended soil-like habitats; (2) due to the abundance of soil-feeders, the overall diversity of the ground fauna is higher than that of the canopy; (3) differences in microclimate and resource accessibility favour vertical stratification among wood-feeders. Sixty-three canopy samples yielded ten species of termites, all wood-feeders. Five of these were not found at ground level, although a total of 243 ground samples were collected, representing 29 species. In addition to long-distance foragers (Microcerotermes and Nasutitermes spp.) and small-colony termites (mostly Kalotermitidae), the canopy fauna included Termes hispaniolae, a wood-feeding Termitidae from an allegedly soil-feeding genus, living in large dead branches. Soil-feeders were absent from the canopy, probably because large epiphytes were scarce. As predicted, the ground fauna was much richer than that of the canopy, but the species richness of both habitats was similar when only wood-feeders were considered. Vertical stratification was strongly marked among wood-feeders, as all common species, apart from the arboreal-nesting Microcerotermes arboreus, could unequivocally be assigned to either a ground or a canopy group. The canopy, therefore, contributes significantly to the total species richness of the termite assemblage, and the diversity, abundance and ecological importance of canopy termites in tropical rainforests may be higher than previously recognized.Electronic Supplementary Material Supplementary material is available to authorized users in the online version of this article at .     

Determinants of mortality across a tropical lowland rainforest community

Tree mortality is an important process determining forest dynamics. However, in species‐rich tropical forests it is largely unknown, how species differ in their response of mortality to resource availability and individual condition. We use a hierarchical Bayesian approach to quantify the impact of light availability, tree size and past growth on mortality of 284 woody species in a 50‐ha long‐term forest census plot in Barro Colorado Island, Panama. Light reaching each individual tree was estimated from yearly vertical censuses of vegetation density. Across the community, 78% of the species showed increasing mortality with increasing light. Considering species individually, just 29 species showed a significant response to light, all with increasing mortality at high light. Past growth had a significant impact on all but three species, with higher growth leading to lower mortality. For the majority of species, mortality decreased sharply with diameter in saplings, then levelled off or increased slightly towards the maximum diameter of the species. Diameter had the biggest impact on mortality, followed by past growth and finally light availability. Our results challenge many previous reports of higher mortality in shade, and we suggest that it is crucial to control for size effects when assessing the impact of environmental conditions on mortality.     

Foraging ecology and audition in echolocating bats

The types of echolocation signal and the auditory capacities of echolocating bats are adapted to specific acoustical constraints of the foraging areas. Bats hunting insects above the canopy use low frequencies for echolocation; this is an adaptation to prey detection over long distances. Bats foraging close to and within foliage avoid masking of insect echoes by specializing on 'fluttering target' detection. 'Gleaning' bats are adapted to the auditory detection of very faint noises generated by ground-dwelling prey, and are capable of analysing fine changes in the echo spectrum, which may indicate a stationary prey changing its posture on a substrate. This review of recent research demonstrates that, in bats, foraging ecology and audition are intricately interrelated and interdependent.     

Arboreal ants as key predators in tropical lowland rainforest trees

Ants numerically dominate the canopy fauna of tropical lowland rain forests. They are considered to be key predators but their effects in this regard have only rarely been studied on non-myrmecophytes. A conspicuously low abundance of less mobile, mainly holometabolous arthropods like Lepidoptera larvae corresponds with ant dominance, while hemimetabolous highly mobile nymphs occur regularly and in large numbers in the trees. This is in contrast to the temperate regions where ants are mostly lacking on trees and holometabolous larvae are frequent. In this study we experimentally measured ant predation in the trees by offering caterpillars as baits. Fifty-four ant species were tested, of which 46 killed caterpillars and carried them away to their nests while only eight species ignored the offered larvae. Insecticidal knockdown fogging of ten trees after finishing the prey experiments showed that on average 85% of ant individuals per tree were predacious. With the analysis of another 69 foggings and meticulous observations in many other trees this suggests that arboreal ants are responsible for the low abundance of less mobile arthropods in tropical lowland rain forest canopies. Ant predation was significantly lower in a disturbed forest indicating that human disturbance induces a change in the functional interactions in these ecosystems.     

Spatial heterogeneity of post-dispersal survivorship of Queensland rainforest seeds

Short-term seed survivorship for several species of the Queensland rainforest was compared in forests and early successional fields, treefall gaps and forest interior, and an array of microhabitats (tree buttresses, logs, forest floor with and without leaf litter cover). Seed survivorship was lower in forest than in field at one site, but equal at another. No differences were found in and out of treefall gaps, in contrast to several other studies. Microsites had little consistent influence on short-term seed survivorship. A survey of the literature showed no consistent habitat or microhabitat patterns in seed survivorship.     

Neighbourhood abundance and small-tree survival in a lowland Bornean rainforest

Conspecific effects of neighbours on small-tree survival may have a role in tree population dynamics and community composition of tropical forests. This notion was tested with data from two 4-ha plots in lowland forest at Danum, Sabah (Borneo), for a 21-year interval (censuses at 1986, 1996, 2001, 2007). Species with ≥45 focal trees 10 to <100 cm stem girth per plot in 1986 were selected. Logistic regressions fitted mean focal tree size and mean inverse-distance-weighted basal area abundance of neighbours (within 20 m), for the periods over which each focus tree was alive. Coefficients of variation of neighbourhood basal area abundance, both spatially and temporally, quantified the changing environment of each focus tree. Fits were critically and individually evaluated, with corrections for spatial autocorrelation. Conspecific effects at Danum was generally very weak or non-existent: species’ mortality rates varied also across plots. The main reasons appear to be that (1) species were not dense enough to interact despite frequent although weak spatial aggregation, and their neighbourhoods were highly differing in species composition; and (2) these neighbourhoods were highly variable temporally, meaning that focus trees experienced stochastically fluctuating neighbourhood environments. Only one species, Dimorphocalyx muricatus, showed strong conspecific effects (varying between plots) which can be explained by its distinct ecology. This understorey species is highly aggregated on ridges and is drought-tolerant. That this functionally and habitat-specialized species, has implied intraspecific density-dependent feedback in its dynamics is a remarkable indication of the overall processes maintaining stability of the Danum forest.     

Effects of an ENSO-related fire on birds of a lowland tropical forest in Sumatra

Comparisons of bird community composition in burned and unburned areas of a lowland tropical rainforest in Sumatra, Indonesia indicated the following during the first 5 years after burning: (1) original burn severity strongly affected bird community composition at both the genus and family levels; (2) bird community composition continued to change progressively away from immediate post-burn composition in medium and severely burned forest as well as adjacent unburned forest; and (3) the degree of impact was both taxon and guild specific, with understory insectivores most detrimentally affected. Although species richness may temporarily increase in burned areas, this study suggests that multiple wildfires will lead to a decline in diversity over a large scale as birds of open fields replace interior forest specialists.     

Modelling habitat preferences of feral pigs for rooting in lowland rainforest

Feral pigs (Sus scrofa) occupy many different habitats worldwide. Their rooting foraging behaviour poses a serious threat to biodiversity as the resulting soil disturbance alters ecosystem structure and function. Understanding what characteristics are important in selecting rooting locations can be used to predict the impact of pigs on ecosystems. We investigated patch selection for rooting by feral pigs at two spatial scales: (1) habitat variables at a site level, and (2) dependency between observations in a spatial context. Seasonal influences on the modelled environmental variables were also examined. We applied a generalised linear modelling approach and model-averaging to explain the relative importance of variables, as measured by the standardised parameter estimates and unconditional variance. Soil texture, rock cover, soil compaction and sand texture were important explanatory variables in the presence of pig rooting. Soil compaction and distance to roads had a negative influence. The highest ranking model included seven explanatory variables with a 41 % chance that this is the Kullback–Leibler best model. Six of the 128 candidate models were in the 95 % confidence set indicating low model uncertainty. Although no differences in pig rootings were detected between seasons, most rooting (65.7 %) occurred during the dry season with soil and sand texture having the strongest effect. This study highlights how pig control programmes can focus limited resources on either the strategic positioning of control devices (e.g., traps and baits) to either reduce the number of pigs or help prioritise habitats of high conservation value for protection (e.g., exclusion fencing).     

Effects of nitrogen and phosphorus fertilization in a lowland evergreen rainforest

A nutrient addition experiment was set up in August 1993 in a species-rich primary lowland dipterocarp forest in Barito Ulu, Central Kalimantan, Indonesia. The following treatments were applied: control, +N, +P and +NP. There were five blocks of four 50 m x 50 m plots with a separate treatment for each plot. Fine litterfall was measured on all the plots from 1 May 1994 for 12 months. Litterfall mass and phosphorus concentrations were significantly higher in all the fertilizer treatments compared with the controls. All trees (> or = 10 cm dbh) were measured in August 1993 and in August 1998, and there was no significant girth increment response to fertilization in dipterocarps or non-dipterocarps. Dipterocarps of the red meranti group showed a doubling of girth increment in the +NP treatment, however, the difference from the control fell short of significance.     

Foraging ecology of the red-crowned parakeet (

The diet of red-crowned parakeets (Cyanoramphus novaezelandiae novaezelandiae) and yellow-crowned parakeets (C. auriceps auriceps) was compared on Little Barrier Island, New Zealand between 1986 and 1987. Significant dietary differences were observed in these sympatric, congeneric species. Yellow-crowned parakeets ate significantly more invertebrates than red-crowned parakeets, which fed on a greater variety of plant foods. Red- crowned parakeets were found in all vegetation types depending on the availability of food and were commonly seen foraging on the ground in open habitats. In contrast, yellow-crowned parakeets were more arboreal and showed distinct preferences for forested habitats. The existence of both parakeet species in sympatry is examined as is the ecological importance of invertebrate food sources. Observed differences in the behaviour and ecology of parakeet species on Little Barrier Island are used to provide insight into the present day distribution and status of parakeets on mainland New Zealand.     

Species richness and spatial variation in fish assemblage structure in two rivers of the Wet Tropics of northern Queensland,Australia

Synopsis Fish assemblages were sampled at 22 sites within the Mulgrave and South Johnstone Rivers of the Wet Tropics World Heritage Area, north Queensland. Flow regimes of these rivers are highly predictable, by Australian standards, due to low annual and seasonal variability. A gradual downstream change in fish assemblage structure, correlated with gradual change in habitat, substrate and type of in-stream cover, was observed in the Mulgrave River but not the South Johnstone. A reduced species richness was observed in the South Johnstone relative to the Mulgrave probably due to the effect of two high gradient sections located in the former river and a more diverse array of habitat types present in the latter. Both rivers contained more species than other tropical Australian rivers of greater size. Possible reasons for this included the constant and predictable flow regime and the greater diversity of habitats found in rivers of the Wet Tropics compared to other tropical Australian rivers.To whom correspondence should be addressed     

Spatial and temporal ecology of an assemblage of viverrids in Natal, South Africa

Aspects of community structure and organization are examined in an assemblage offive species of small carnivores (Family Viverridae). Comparative use of the spatial and temporal niches for each species is studied and used to interpret coexistence. The spatial niche segregates the assemblage into three groups, including a three-species mixed-forest group. This mixed-forest group comprises a single-species diurnal branch and a nocturnal branch. Segregation of the nocturnal branch may only be achieved through trophic differences.