Mass flowering of dipterocarp forests in the aseasonal tropics

At irregular intervals of 2 to 10 years the aseasonal tropical rain forests in west Malesia come into heavy mass flowering, followed by mast fruiting. During a heavy flowering almost half the mature individuals and over 80% of the canopy and emergent tree Species in a forest may flower. This involves over 200 tree species in a forest flowering over a short period of 3–4 months. The pollination needs during a mass flowering appears to be overcome in several ways. A rapid increase in the number of pollinators seems to occur in the forest. This is partly caused by the migration of pollinators from the fringes of the forest to forage on the superabundance of flowers. At the same time, some groups of plants which share common pollinators appear to reduce pollinator competition by flowering in interspecific sequence. Many members of the family Dipterocarpaceae have evolved sequential flowering too. They also share unique pollinators, common flower thrips which appear to build up rapidly in numbers by feeding and breeding on the millions of dipterocarp flower buds which are present several weeks before the flowering. The environmental cue for this irregular, but widespread mass flowering can be traced to a small dip of about 2° C below mean night-time temperature for 4 or 5 nights. The conditions for such temperature drops occur during El Nino events.     

Effects of flooding on a wetland bird community

The Lake Izunuma–Uchinuma was extensively flooded in 1998 and vast areas (approximately 200 ha) of rice fields were submerged for the first time since the land was reclaimed in 1963. When the numbers of birds in 1998 were compared with those in normal years (1995–1997), the numbers of black-crowned night herons (Nycticorax nycticorax L.), cattle egrets (Bubulcus ibis L.) and black kites (Milvus migrans Boddaert) increased during the flooding, and the numbers of ducks, especially dabbling ducks (seven species of 11 Anas spp.) were high even after the flooding, while the numbers of the little grebe Tachybaputus ruficollis Pallas were diminished by the flooding.     

Seasonality of canopy invertebrate communities in eucalypt forests of eastern and western Australia

Abstract Chemical knockdown procedures were used to sample canopy arthropods at 3 month intervals over 1 year at two sites, one in eastern Australia and the other in western Australia. Samples were taken from narrow-leaved ironbark, Eucalyptus crebra, and grey box, Eucalyptus moluccana, in the east and from jarrah, Eucalyptus marginata, and marri, Eucalyptus calophylla, in the west. Arthropods were more abundant on trees in eastern Australia and exhibited different seasonal patterns from those in the west. Members of different functional groups exhibited different seasonal patterns, with some herbivorous groups responding to times of leaf production, decomposers and fungus feeders responding to high moisture availability, and predators/parasites responding to the abundance of food items. Seasonal variability was slightly higher in the west, possibly reflecting the greater seasonal amplitude in rainfall. In the eastern forest, proportionately more taxa peaked in spring or summer and declined to minimum numbers in winter. In the western forest several taxa attained peak numbers in autumn, winter or spring, while others declined to minimum values in winter or summer. The phenological patterns of canopy arthropods appear to be linked to the condition of the host plant and/or to climatic factors. Comparison of the western Australian data to those from a second year of sampling at a time when rainfall was greater and fell later into the season indicated that variability in arthropod numbers between years can be as great as that between seasons. Implications of the variability in seasonal and annual patterns of canopy invertebrate communities are discussed in relation to the need for long-term sampling and in relation to evaluating the impact of disturbance on forest communities.     

Role of magpie in bird community formation in secondary forest

We analyzed a bird community in a secondary forest and the results show that the magpie was one of the key groups in the secondary forest. The key group is identified based on the nests used by other birds at a rate of 25%-40.17%. The size of the community is different and the number of these key groups is not certain.     

The peninsula effect on bird species in native eucalypt forests in a wood production landscape in Australia

The peninsula effect – a decrease in species richness from the base to the tip of a peninsula – has been tested for a diverse range of taxa at continental and regional scales. We investigated the peninsula effect at a local scale by examining bird species occurrence in riparian strips (peninsulas) of native eucalypt forest within a radiata pine plantation in the Tumut region, south-eastern Australia. Peninsulas were elongated but 'blind' extensions of a core area of native eucalypt forest. Birds were surveyed by the area search method, within 1.0-ha quadrats established along peninsulas ( n =14), in October and November 2002. Data were analysed using generalized linear mixed models. A significant decrease in bird species richness from the base towards the tip of the peninsulas was observed. The proportion of large bird species recorded per quadrat showed a significant decrease from the base towards the tip of the peninsulas. This pattern was not observed for small birds. Several species were more abundant at the base of the peninsulas than away from the core area of eucalypt forest. The peninsula effect can occur locally in landscape mosaics. Factors leading to the observed patterns of species occurrence may be distinct from those proposed in investigations of the peninsula effect with a biogeographical (macroscale) context. In our microscale study, foraging incursions of individual birds from the core area of native forest through peninsulas were a major factor giving rise to higher bird species richness in the more basal portions of peninsulas.     

Consequences of forest fragmentation for the dynamics of bird populations: conceptual issues and the evidence

This paper reviews the consequences of forest fragmentation for the dynamics of bird populations. Owing to high mobility and large home ranges, birds usually perceive fragmented forests in a finegrained manner, i.e. embrace several forest fragments in functional home ranges. On a regional scale, however, coarse-grained clusters of fine-grained fragments (hierarchical fragmentation may sub-divide bird populations into isolated demes, which enter a domain of metapopulation dynamics. Distinctions are made between pure distance-area or population-level effects and more indirect community-level effects due to changes in landscape composition. Distance-area effects, such as insularization and decreasing fragment size, directly prevent dispersal and reduce population size. Landscape effects, such as reduced fragment-matrix and interior-edge ratios, increase the pressure from surrounding predators, competitors, parasites and disease. In short, forest fragmentation can be viewed as a two-step process. Initially, fine-grained fragmentation triggers distance-area and landscape effects on a local scale, which in turn, results in a range retraction of a population to non-fragmented or less fragmented parts of a region. At a certain point, non-fragmented areas become so widely spaced out that regional distance-area effects come into operation, giving rise to metapopulation dynamics. Although few bird metapopulations have yet been documented, metapopulation dynamics probably is a common characteristic of bird populations confined to 'hierarchical' fragmented forests.     

Effects of fire season on flowering of forbs and shrubs in longleaf pine forests

Summary Effects of variation in fire season on flowering of forbs and shrubs were studied experimentally in two longleaf pine forest habitats in northern Florida, USA. Large, replicated plots were burned at different times of the year, and flowering on each plot was measured over the twelve months following fire. While fire season had little effect on the number of species flowering during the year following fire, fires during the growing season decreased average flowering duration per species and increased synchronization of peak flowering times within species relative to fires between growing seasons. Fires during the growing season also increased the dominance of fall flowering forbs and delayed peak fall flowering. Differences in flowering resulting from variation in fire season were related to seasonal changes in the morphology of clonal forbs, especially fall-flowering composites. Community level differences in flowering phenologies indicated that timing of fire relative to environmental cues that induced flowering was important in determining flowering synchrony among species within the ground cover of longleaf pine forests. Differences in fire season produced qualitatively similar effects on flowering phenologies in both habitats, indicating plant responses to variation in the timing of fires were not habitat specific.     

长江师范学院校园夏季鸟类群落与多样性分析

2008年3～7月采用样线法对长江师范学院李渡校园鸟类组成和种群数量进行了调查,共记录鸟类6目21科28种,数量1633只,物种多样性指数为3．9204,均匀性指数为1．1765,其中国家“三有”名录鸟类25种,CITES名录鸟类1种。鸟类区系以东洋界成分为主。对不同生境鸟类多样性的分析结果表明：（1）乔灌林鸟类多样性指数和均匀性指数最高,水域鸟类多样性指数最低,建筑区均匀性指数最低;（2）乔灌林与竹林的相似性指数最高,竹林与水域的相似性最低。     

Summer bird population in the central part of the Prilenskoe plateau

Bird censuses were taken by routing in the central part of the Prilenskoe plateau, a region poorly explored by ornithologists. The summer population of birds in different habitats at watersheds, in valleys and along riverbanks has been characterized on the basis of the original data obtained.     

Effects of eucalyptus afforestation on leaf litter dynamics and macroinvertebrate community structure of streams in Central Portugal

To test the hypothesis whether afforestation with Eucalyptus globulus affects litter dynamics in streams and the structure of macroinvertebrate aquatic communities, we compared streams flowing through eucalyptus and deciduous forests, paying attention to: (i) litterfall dynamics, (ii) accumulation of organic matter, (iii) processing rates of two dominant leaf species: eucalyptus and chestnut, and (iv) macroinvertebrate community structure. The amount of allochthonous inputs was similar in both vegetation types, but the seasonality of litter inputs differed between eucalyptus and natural deciduous forests. Eucalyptus forest streams accumulated more organic matter than deciduous forest streams. Decomposition of both eucalyptus and chestnut leaf litter was higher in streams flowing through deciduous forests. The eucalyptus forest soils were highly hydrophobic resulting in strong seasonal fluctuations in discharge. In autumn the communities of benthic macroinvertebrates of the two stream types were significantly different. Deciduous forest streams contained higher numbers of invertebrates and more taxa than eucalyptus forest streams. Mixed forest streams (streams flowing through eucalyptus forests but bordered by deciduous vegetation) were intermediate between the two other vegetation types in all studied characteristics (accumulation of benthic organic matter, density and diversity of aquatic invertebrates). These results suggest that monocultures of eucalyptus affect low order stream communities. However, the impact may be attenuated if riparian corridors of original vegetation are kept in plantation forestry.     

Woodland area,species turnover and the conservation of bird assemblages in lowland England

A study over 4 years into the number of breeding bird species and species turnover (extinctions and colonisations) in relation to area was conducted in 35 woodlands, set in an intensively farmed landscape, in north-east Essex, UK. A total of 46 species was recorded. The number of species breeding increased with woodland area; the slope of the species–area relationship did not differ between years. Habitat diversity was the only other measured variable to influence species richness. Absolute species turnover was independent of woodland area but relative turnover declined with increase in woodland area. The numbers of territories of nine species were determined. For four summer visitors the number of woods occupied increased as the overall populations increased but, for the other species, changes in overall population size led to changes in numbers in occupied woods. Chaffinch Fringilla coelebs and Song Thrush Turdus philomelos were more associated with woodland edges, Nightingale Luscinia megarhynchos, Garden Warbler Sylvia borin, Chiffchaff Phylloscopus collybita and Willow Warbler P. trochilus with interiors. Several species showed an inverse relationship between population density and woodland area. Collections of small woods hold similar species richness to single large woods. While the acquisition of large woods for conservation purposes should be a priority, the extension of smaller woods to a size of about 10 ha would be highly beneficial to both the species richness and population stability of regional woodland bird assemblages.     

The convergent trajectories of bird communities along ecological successions in european forests

Summary There is much more variation in the composition of bird communities in the earlier open and semi-open seral stages of ecological successions in forested landscapes of Europe than later on in preforested and forested climactic stages. The demonstration of this trend is achieved from the study of four habitat gradients, two in the mediterranean region (Provence and Corsica) and two in central Europe (Burgundy, France and Poland). A multivariate analysis has been used to illustrate the dynamics of communities along these succession. Displays of the results in bivariate space as well as an illustration of the distributional profiles of some of the most characteristic species show that: i) there is a discrimination between the two mediterranean gradients and the two medioeuropean ones and ii) each succession starts with a very distinct set of species and then the four gradients regularly converge in the last climactic stage where there is almost no discrimination between communities. These results are discussed in the light of the history of European biotas during the Pleistocene. The reason why there is more variation in species composition in the earlier seral stages than in the later forested stages are discussed according to current theories on the role of habitat selection on speciation processes.     

Impact of T-RFLP data analysis choices on assessments of microbial community structure and dynamics

Background

Terminal restriction fragment length polymorphism (T-RFLP) analysis is a common DNA-fingerprinting technique used for comparisons of complex microbial communities. Although the technique is well established there is no consensus on how to treat T-RFLP data to achieve the highest possible accuracy and reproducibility. This study focused on two critical steps in the T-RFLP data treatment: the alignment of the terminal restriction fragments (T-RFs), which enables comparisons of samples, and the normalization of T-RF profiles, which adjusts for differences in signal strength, total fluorescence, between samples.

Results

Variations in the estimation of T-RF sizes were observed and these variations were found to affect the alignment of the T-RFs. A novel method was developed which improved the alignment by adjusting for systematic shifts in the T-RF size estimations between the T-RF profiles. Differences in total fluorescence were shown to be caused by differences in sample concentration and by the gel loading. Five normalization methods were evaluated and the total fluorescence normalization procedure based on peak height data was found to increase the similarity between replicate profiles the most. A high peak detection threshold, alignment correction, normalization and the use of consensus profiles instead of single profiles increased the similarity of replicate T-RF profiles, i.e. lead to an increased reproducibility. The impact of different treatment methods on the outcome of subsequent analyses of T-RFLP data was evaluated using a dataset from a longitudinal study of the bacterial community in an activated sludge wastewater treatment plant. Whether the alignment was corrected or not and if and how the T-RF profiles were normalized had a substantial impact on ordination analyses, assessments of bacterial dynamics and analyses of correlations with environmental parameters.

Conclusions

A novel method for the evaluation and correction of the alignment of T-RF profiles was shown to reduce the uncertainty and ambiguity in alignments of T-RF profiles. Large differences in the outcome of assessments of bacterial community structure and dynamics were observed between different alignment and normalization methods. The results of this study can therefore be of value when considering what methods to use in the analysis of T-RFLP data.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-014-0360-8) contains supplementary material, which is available to authorized users.     

Flowering phenology of a palm community in a central Amazon forest

The flowering phenology of 27 taxa of palms in a lowland moist forest in the central Amazon was recorded over a 40 month period. Phenological data were transformed into measures, of synchrony, regularity, and duration. Flowering was observed at all times of year and there was no correlation with rainfall either for the current month or for any monthly lag interval. The 27 taxa were divided into three pollination groups—weevil, bee/fly, or beetle—based on their behavior at anthesis. Phenology was significantly correlated with pollination groups. Weevilpollinated palms had higher synchrony and shorter duration of flowering than other groups. Bee/fly-pollinated palms had lower synchrony and longer duration of flowering. The beetle-pollinated palms were intermediate between the two other groups. Seasonal regularity of flowering was similar in all three groups. We suggest that, at least inBactris, taxa exhibit staggered flowering.     

The consistency and stability of abundance-occupancy relationships in large-scale population dynamics

1. Abundance-occupancy relationships comprise some of the most general and well-explored patterns in macro-ecology. The theory governing these relationships predicts that species will exhibit a positive interspecific and intraspecific relationship between regional occupancy and local abundance. Abundance-occupancy relationships have important implications in using distributional surveys, such as atlases, to understand and document large-scale population dynamics and the consequences of environmental change. A basic need for interpreting such data bases is a better understanding of whether changes in regional occupancy reflect changes in local abundance across species of varying life-history characteristics. 2. Our objective was to test the predictions of the abundance-occupancy rule using two independent data sets, the New York State Breeding Bird Atlas and the North American Breeding Bird Survey. The New York State Breeding Bird Atlas consists of 5332 25-km(2) survey blocks and is one of the first atlases in the USA to be completed for two time periods (1980-85 and 2000-05). The North American Breeding Survey is a large-scale annual survey intended to document the relative abundance and population change of songbirds throughout the USA. 3. We found that regional occupancy was positively correlated with relative abundance across 98 (beta = 0.60 +/- 0.11 SE, P < 0.001, R(2) = 0.60) and 85 species (beta = 0.67 +/- 0.06 SE, P < 0.001, R(2) = 0.57) in two separate time periods. This relationship proved stable over time and was notably consistent between breeding habitat groups and migratory guilds. 4. Between 1980 and 2005, changes in regional occupancy were highly correlated with long-term abundance trend estimates for 75 species (beta = 5.73 +/- 0.24 SE, P < 0.001, R(2) = 0.88). Over a 20-year period, woodland and resident birds showed an increase in occupancy while grassland species showed the greatest decline; these patterns were mirrored by changes in local abundance. 5. Although exceptions existed, we found most changes in occupancy parallel changes in local abundance. These findings support the basic predictions of the abundance-occupancy rule and demonstrate its consistency and stability in species and groups of varying life-history characteristics.