bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of thermal ecology on the distribution of three nymphalid butterflies
Authors: Bryant Simon R. , Thomas Chris D. , Bale Jeffrey S.
Published: March 2003

Studies have shown that many adult and immature insects are able to maintain body temperature well above, and often independently of, ambient temperature in the presence of direct solar radiation. They may do so directly by basking, or indirectly via microhabitat choice. The implications for this are often ignored in development models that serve to predict species’ responses to climate change.

To investigate the difference in development times attributable to solar input, field development of Aglais urticae, Inachis io and Polygonia c‐album larvae (Lepidoptera: Nymphalidae) was followed both in a natural open situation and in an artificially shaded environment. Each species completed development more quickly in the open, equivalent to a 20%, 10% and 15% reduction in development time, respectively.

Observed development times in the artificially shaded environment were used to compare the techniques of rate summation and degree‐day modelling. Rate summation models were found to describe development in the shade best for A. urticae and I. io, although a degree‐day model performed best for P. c‐album, possible reasons for which are discussed. The best‐performing models for each species were modified to include larval thermoregulation data, assuming a linear relationship between body and ambient temperatures during the measured sunshine hours each day, and tested against observed development times in the open situation. Times for 50% adult emergence were predicted exactly for A. urticae, and to an accuracy of 1 day for I. io and 5 days for P. c‐album.

The models were tested further using climate data from 128 UK Meteorological Office weather stations across England, Wales and Scotland. Thermoregulation model predictions matched observed UK distribution and voltinism better than predictions made by the standard unmodified models. It was estimated that larval thermoregulation allows A. urticae and I. io populations to persist approximately 200 km further north than would otherwise be possible, and that the extent of bivoltinism may be shifted northwards by around 300 km.

These results have significant implications for predicting the effects of global warming on insects’ geographical ranges, the potential distributions of invasive species, and the phenology and voltinism of introduced biocontrol agents as one component of their likely success.
Birds and wine grapes: foraging activity causes small‐scale damage patterns in single vineyards
Authors: Somers Christopher M. , Morris Ralph D.
Published: March 2003

Crop damage caused by pest bird species is an economic problem in agricultural areas world‐wide. Previous research in North America has focused on estimating regional loss of yield for economic purposes, and largely ignored small‐scale variation in crop damage. If a bird depredation problem is perceived, farmers need to know how to identify areas of their farms that are most susceptible to bird damage so that they may focus their deterrent efforts most efficiently.

 We developed sensitive sampling and analysis techniques to allow the identification of spatial and temporal patterns in bird damage to wine grapes at the level of single vineyards.

 We used visual estimation techniques and novel data collection and management procedures to detect small‐scale spatiotemporal patterns in bird damage to Baco Noir and Vidal (ice‐wine) grape varieties in the St Catharine’s area of Ontario, Canada, during the 1998 and 1999 ripening seasons. We detected three overall trends in study vineyards: (i) bird damage was greatest on the edges of vineyards and decreased with distance towards the centre; (ii) bird damage was vertically stratified in vineyards, with grape clusters near the top of vines sustaining more damage than those close to the ground; and (iii) bird damage increased at specific times during the ripening season.

 An exotic species, the European starling, was responsible for most of the crop damage. Starlings foraged by making short forays into vineyards from perches in adjacent vegetation. This kind of foraging behaviour was reflected in the spatial damage patterns measured in our study plots.

 We suggest that the data presented here are more useful than estimates of total loss of yield to the managers of individual farms, because they identify the areas of vineyards most susceptible to bird damage. Future field experiments should evaluate the utility of focusing deterrent measures only in the most highly susceptible areas of crop fields. More detailed knowledge of where birds concentrate their foraging efforts, when crops become susceptible, and which species are responsible will allow farmers to focus their deterrent efforts most effectively, while attenuating conflict with non‐offending species.
Comparing biological productivity in cropping systems: a competition approach
Authors: Park Sarah E. , Benjamin Laurence R. , Watkinson Andrew R.
Published: March 2003

Intercropping, the practice of growing two or more crops in close association, is attracting increasing interest in developed countries, primarily due to claims that it can provide increased yields in an environmentally sustainable manner.

 The land equivalent ratio (LER) is frequently used to attest the claim that intercropping produces a greater total biological productivity per unit area of land than monocropping. However, similar to other indices, the value of the LER is dependent on the relative densities of the two crops and fails to provide an indication of the optimal crop density combination required to produce maximum biological productivity. We used an alternative methodology to predict the optimum density for planting two crops in a mixed stand.

 Maize and beans were grown both in monoculture and in intercropped stands at a range of densities. Monocrop stands of both maize and bean displayed an asymptotic yield–density relationship. When a second crop was introduced into the stand there was no effect on the yield of maize, but there was a large reduction in the yield of bean.

 The LER did not demonstrate an unequivocal advantage to intercropping. Less than a third of the LER values, over the range of densities considered, were greater than one, although none was significantly different to unity. The highest values were obtained from those plots sown with a high density of maize.

 An alternative method of analysing the biological productivity of an intercrop system is proposed. This approach requires a combination of (i) an additive experimental design, (ii) the use of a regression model to measure the competitive effect of two species, and (iii) the presentation of the net competitive effect on individual and total yields using a response surface. The reciprocal model was used to dissociate and quantify intra‐ and interspecific competition, estimate a competitive equivalence coefficient and predict the individual yields of the full complement of density combinations included in the maize and bean experiment.

 The model explained up to 90% of the variation in the observed yields of maize and bean in an intercrop. An inspection of the response surface for the LER indicated that the minimum density combination required to produce the maximum yield advantage within the density range considered comprised maize being planted at a density of 11 plants m−2 and bean being planted at a density of 39 plants m−2. Although this combination would provide the maximum biological productivity, it is considered unlikely to provide the maximum gross economic margin.

 The above methodology may provide a useful tool for managing competition, either between two or more crops in an intercrop, or within a crop–weed interaction.
Red deer management and vegetation on the Isle of Rum
Authors: Virtanen R. , Edwards G. R. , Crawley M. J.
Published: March 2003

Understanding the effects of red deer Cervus elaphus grazing on a range of plant communities is important for formulating guidelines for the management of forestry plantations, nature reserves and deer hunting enterprises.

The effects of red deer on the species composition of plant communities varying in productivity were examined on the Isle of Rum, Inner Hebrides, north‐west Scotland.

The study compared vegetation inside and outside fences erected to exclude deer for more than 20 years, and between areas of the island where different deer culling policies were instigated in 1991.

The effect of the exclusion of deer was directly proportional to vegetation type. Long‐term deer exclusion (20–40 years) had negligible effects on the species composition of the most unproductive plant communities, but caused a marked decline in the species richness of productive grassland. The decline was due to the loss of prostrate herb species inside exclosures where Festuca rubra had assumed a high dominance.

Changes in the size and sex ratio of the deer populations were not associated with major changes in plant species richness or relative abundance. The most notable change occurred in productive grassland. Here, Festuca rubra had greater cover and several low‐growing herbs such as Polygala serpyllifolia and Thymus polytrichus had lower cover in areas where hind numbers had been reduced than in areas where there was no culling.

High deer densities within an unculled food‐limited population were associated with negligible effects on plants in Molinia caerulea flush and Calluna–Molinia wet heath vegetation.

Tree regeneration inside the exclosures or in areas where deer were culled was minor; only two solitary rowan Sorbus aucuparia saplings were found.

Flowerhead densities of herbaceous plant species and grasses showed trends that could be associated with cattle grazing. It is suggested that this may lead to changed recruitment, although seed sowing experiments are required to test this.

The results suggest that red deer grazing sustains the plant species diversity of productive grasslands, with reduced deer grazing leading to the loss of plant species in these communities. In contrast, the effects of reduced deer densities and altered culling policies on unproductive vegetation types are negligible.
Effects of nutrient addition and acidification on plant species diversity and seed germination in heathland
Authors: Roem W. J. , Klees H. , Berendse F.
Published: March 2003

The atmospheric deposition of sulphur and nitrogen compounds in the Netherlands has been responsible for decreasing plant species diversity in heathland. To unravel the relative importance of nitrogen compounds on soil acidification and eutrophication, and hence on the vegetation, we carried out a factorial addition experiment and a germination experiment in heathland on nutrient‐poor sandy soil.

We changed nutrient availability and acidity independently in eight different treatments that, respectively, added nutrients or carbon in various combinations (N, P, glucose) or added acidifying or neutralizing compounds. One treatment also involved adding Al. Additions occurred five times per year during 5 years, in an area from which sods had been removed before the experiment began. The same design was used for the germination experiment, but the treatments were applied for 2 years.

Our results showed that acidification was the most important factor in reducing species diversity. In addition, the germination of several heathland species was significantly reduced in plots with a pH below 5, and germination was very poor in plots where Al had been added.

The number of plant species declined particularly with increasing Al in the upper soil horizons. We conclude that this relationship is responsible for the influence of acidification on plant species richness in heathland.

The influence of nutrient availability on species composition in heathland was subsidiary to acidity, but nutrient availability influenced species composition in an independent way. The growth of the three dominant species (Molinia caerulea, Calluna vulgaris and Erica tetralix) was limited by different nutrients. Erica tetralix was limited by N, Calluna vulgaris by P and Molinia caerulea by both N and P. We argue that increased N availability will change the relative availability of N and P, which can decrease species diversity.

Together these results show how factorial experiments can elucidate the complex ecological effects arising from sulphur and nitrogen deposition, revealing different mechanisms that change species richness and community composition.
Ascopyrone P, a novel antibacterial derived from fungi
Authors: Thomas L.V. , Yu S. , Ingram R.E. , Refdahl C. , Elsser D. , Delves-Broughton J.
Published: March 2003

Aims: To assess the antimicrobial efficacy of ascopyrone P (APP), a secondary metabolite formed by the fungi Anthracobia melaloma, Plicaria anthracina, Plic. leiocarpa and Peziza petersi belonging to the order Pezizales. Methods and Results:In vitro testing using a well diffusion procedure showed that APP at a high concentration (approximately 5%) inhibited the growth of Gram-positive and Gram-negative bacteria. Using an automated microbiology reader, growth curve analysis showed that 2000–4000 mg l−1 APP caused total or significant bacterial inhibition after incubation for 24 h at 30°C. Against certain yeast strains, 1000– 2000 mg l−1 APP enhanced growth, although at higher concentrations inhibition of some yeasts was observed. Clostridium and fungal strains were not sensitive to 2000 mg l−1 APP. No significant cidal effect was observed after 2 h against Listeria monocytogenes or Escherichia coli. Results were identical whether the APP samples tested had been produced enzymatically or chemically. Conclusions: At a level of 2000 mg l−1, APP demonstrated growth inhibitory activity against a broad range of bacteria, but not yeasts or moulds. Significance and Impact of the Study: A possible application for this novel natural antimicrobial is in food preservation, to control the growth of Gram-negative and Gram-positive bacteria in raw and cooked foods. Effective dosage levels would be 500–4000 mg kg−1, depending on food type. The efficacy, organoleptic and safety aspects of this compound in food still need to be assessed.
Role of peptidase and cyclooxygenase inhibitors in the guinea‐pig bronchial response to the synthetic endothelin ETB agonist IRL 1620 and antagonist BQ‐788
Authors: Lazzeri N. , Nieri P. , Lenzi P. , Ratti C. , Breschi M. C.
Published: March 2003

1ŸIn isolated guinea‐pig bronchial preparations the selective endothelin ETB agonist, IRL 1620 caused a concentration‐dependent contraction. The pD2 value (7.16_±0.09, n_=6) was significantly increased in the presence of peptidase inhibitors (thiorfan 1_μm, captopril 1_μm, bestatin 1_μm) (pD2_=7.75_±0.09, n_=6). Indomethacin (5_μm) did not appear to influence the ETB‐agonist pD2 value (6.92_+0.11, n_=6) but potentiated its maximal response significantly (67.23_±4.81% vs. 53.37_±4.80%).

2ŸThe concentration‐response curve for the contractile response to IRL 1620 (pD2=7.83__0.01, n=16); was reproducible, although not completely, since the second curve to this selective ETB agonist was shifted significantly to the right (pD2_=7.34_±0.09, n_=_16) and a decrease in the maximal response was observed (20.0_±2.0%).

3ŸBQ 788, a selective antagonist for ETB receptors, employed in concentrations ranging from 1.5 to 150_n
m, caused a dose‐dependent shift to the right of the concentration‐response curve to IRL 1620, with a pIC50 value of 8.11_±0.03; this action was not influenced by adding enzyme inhibitors (pIC50_=8.17_±0.29).

4ŸOur data show that IRL 1620 undergoes a hydrolytic metabolism in guinea‐pig bronchial preparations, which could influence the calculation of the pD2. Pretreatment of the tissue with peptidase inhibitors and indomethacin is consequently significant in the evaluation of IRL 1620 activity, while it does not influence the action of the antagonist, BQ 788.
The comparison of vitamin C and vitamin E on the protein oxidation of diabetic rats
Authors: Je H. D. , Shin C. Y. , Park H. S. , Huh I. H. , Sohn U. D.
Published: March 2003

1 We measured the plasma glucose and the glycosylated haemoglobin at the time of sacrifice in streptozotocin‐induced diabetic mellitus (DM) rats.

2 In diabetic rats, plasma glucose and glycosylated haemoglobin was increased as compared with normal rats, and vitamin E inhibited the increase of glycosylated haemoglobin level but vitamin C had no effect.

3 The peroxidized proteins and lipids from the diabetic organs such as liver or kidney were measured to assess the oxidative damage. The 2,4‐dinitrophenyl‐hydrazine (DNPH) incorporation method was used to measure the peroxidized protein. In diabetic rats, DNPH incorporation was increased as compared with normal rats and vitamin E also inhibited the increase of DNPH incorporation but vitamin C had no effect. It suggests that the protein oxidation occurred on the liver in diabetic rats and the oxidative stress is general in the diabetic condition.

4 We measured the systolic arterial pressure and mean arterial pressure in normal rats, nephrectomy (NEPH)‐rats, diabetic rats (DM), and NEPH‐diabetic rats (NEPH‐DM). Blood pressure was significantly increased in DM and NEPH‐DM as compared with normal rats.

5 In conclusion, plasma glucose, glycosylated haemoglobin, and the oxidation of proteins or lipid were increased in diabetic rats. Vitamin E decreased the plasma glucose, glycosylated haemoglobin and the oxidation of proteins and lipid, but vitamin C had no effects.
The extent of extinctions of mammals on islands
Authors: Alcover Josep Antoni , Sans Antònia , Palmer Miquel
Published: March 2003

Many of the world's oceanic and oceanic‐like islands possessed endemic mammal faunas before they were colonized by humans. These faunas, unbalanced and impoverished compared to continental faunas, usually lacked large mammalian carnivores. In virtually all cases, the arrival of humans and their domesticants and commensals on these islands is related to the extirpation of large numbers of endemic insular mammals. These extinction events affected at least 27% of autochthonous mammal species on the world's oceanic and oceanic‐like islands. This percentage rises the 35% when volant mammals are excluded. This reduction in the natural biodiversity brought about the disappearance of several unique biological types that apparently never existed on the continents.
Upper Triassic Pacific vicariance as a test of geological theories
Authors: Shields Oakley
Published: March 2003

Upper Triassic vicariance that spans the Pacific involving terrestrial biotas in south east Asia/south western North America and Queensland/Chile/Argentina is sum‐ marized. These terrestrial and freshwater organisms did not migrate via high‐latitude landbridges or across ocean barriers or Pangaea, are endemic to these vicariant fragments, and are mostly identical species. Rejoining the vicariant fragments is compatible with rapid earth expansion but is incompatible with other geological theories that call upon Panthalassa, Pacifica, displaced terranes and slow earth expansion. Vicariance biogeography yields a rigorous test of these models since its data are derived entirely independently of them. The Upper Triassic time‐frame was selected because it immediately preceded the break‐up of Pangaea.
Evidence for the recent dispersal of Sophora (Leguminosae) around the Southern Oceans: molecular data
Authors: Hurr Kathryn A , Lockhart Peter J , Heenan Peter B , Penny David
Published: March 2003

Aim The aim is to use DNA sequence data to test between vicariance and long range dispersal (by floating seed‐pods) explanations for the origin and range of the Edwardsia species of Sophora (Sophoreae: Papilionoideae: Leguminosae).

Location This group is widely distributed around the South Pacific and into the South Atlantic on both continental fragments and oceanic islands.

Methods DNA sequences from an intergene region (atpB‐rbcL) of the chloroplast were determined for twelve taxa (including outgroups) and used to test these hypotheses. Sophora fossils were used to calibrate the evolutionary tree.

Results The Edwardsia group of Sophora appears monophyletic and is well differentiated from other Sophora. However, the genetic difference between species within the South Pacific and to the South Atlantic is very low.

Main conclusionsThe results eliminate vicariance explanations for this section of Sophora and strongly support an origin from other (non‐Edwardsia) Sophora in the north‐west Pacific. Dispersal appears initially to be to Tuvalu, Lord Howe Island, New Zealand, and subsequently across the South Pacific, probably within the last 2–5 million years. Dispersal of buoyant Sophora seeds to oceanic islands is the most likely explanation of its distributions. Fossil pollen dates in New Zealand are consistent with the conclusion.
Regional tectonics, disturbance, and population size of isolated stands of Nothofagus fusca (Nothofagaceae) in a forest ecotone in south‐western New Zealand
Authors: Haase P.
Published: March 2003

AimNew Zealand's cool temperate forests are usually dominated by one or more of the five native taxa of Nothofagus (Nothofagaceae; southern beech), but in certain regions there are sharp boundaries against podocarp–broadleaved forest where Nothofagus is rare or completely absent, either for historical (Pleistocene Glaciation) or climatic/biological (mild superhumid climate and competition) reasons. The dynamics of a Nothofagus boundary was investigated by monitoring disturbance‐initiated establishment of isolated stands of N. fusca at the extreme limits of its regional distribution.

LocationThe research was carried out in a regional forest ecotone between Nothofagus forest and podocarp–broadleaved forest in the upper Taramakau Valley, South Island, New Zealand. The survey region straddles a major, active fault system and associated tectonic movements and earthquakes with more distant epicentres have contributed to intermittent canopy disturbance of the local forests.

MethodsIsolated stands of Nothofagus fusca beyond the limits of continuous Nothofagus forest were investigated during two field surveys, separated by 7–10 years. Changes in population size, stem diameter of individual trees, stand basal area and mean annual diameter increment were calculated for each of fifty‐four isolated stands. Types of past and recent disturbance and the probable cause of mortality of trees were noted.

ResultsThe total population of fifty‐four sample stands, ranging in size from one to > 400 stems, increased by 37.4%, and compound basal area increased by 4.7% between the two surveys. Mean stem diameter growth of isolated stands was lower than expected by empirical data for N. fusca, suggesting reduced wood increment at the limits of its distribution. Tree mortality was 0.8% per year. Fifty‐one per cent of the dead stems had died as a consequence of various types of natural disturbance, uproots being more common than snaps and crown breakage.

Main conclusionsThe isolated N. fusca stands preferentially occupy sites likely to experience intermittent disturbance, mostly including disturbance of the soil cover, which facilitates their initial establishment and persistence. Because of causal relationships between mass movement on steep slopes and erosion/deposition of talus fans and river terraces, disturbance‐initiated changes in forest composition are observed across a range of different landforms.
Abundance distribution, morphological variation and juvenile condition of robins, Erithacus rubecula (L.), in their Mediterranean range boundary
Authors: Pérez‐Tris Javier , Carbonell Roberto , Tellería José Luis
Published: March 2003

Aim

It has been suggested that populations nearing the border of a species’ range should be maladapted because they occupy progressively less suitable environments. In some instances, however, peripheral populations might acclimate or even be adapted to local conditions. We studied Iberian robins to evaluate whether southern, peripheral populations become more restrictive in selecting their habitats, are locally differentiated or show evidence of maladaptation.

Location

We divided the Iberian Peninsula into three regions (the Eurosiberian and Supra‐Mediterranean regions in northern Iberia, and the Mediterranean Lowlands in southern Iberia), which define a gradient of increasing dryness southwards. In each region, we selected one representative locality, where we captured individuals during three study years.

Methods

We reviewed 72 community studies to test whether Iberian robins occupy fewer forests and decrease in abundance southwards. Because robins are sedentary in the southernmost region, but largely abandon both northern areas in winter, we analysed the variation in migration‐related morphology to test for population differentiation in the range boundary. To examine how populations cope with environmental variation, we studied four indices of juvenile condition (fluctuating asymmetry, fledgling size, ptilochronology and size‐corrected body mass), each related to nutritional conditions in a particular stage of growth, from early development to independence.

Results

Although robins restricted their range southwards, there was no change in local abundance between regions. Southernmost robins, consistent with their sedentary behaviour, had shorter and more rounded wings than northern robins, although the populations did not differ in terms of body size. Fluctuating asymmetry and fledgling size did not evidence a higher developmental stress in peripheral populations, although southernmost robins had a lower juvenile condition during their independence (as shown by ptilochronology and residual body mass).

Main conclusions

The distribution of abundance found in this study supports the idea that Iberian robins could select habitats above a somehow restrictive threshold of quality. In addition, morphological correlates of migratory behaviour provided evidence of population differentiation at the range edge. This introduces the possibility that among‐region variations in juvenile condition actually reflect reproductive benefits for migrants, related to the occupation of seasonally productive habitats, rather than the maladaptation of sedentary, peripheral populations. From this perspective, and in view of the patterns of distribution and morphology that we found, southern Iberian robins might be independent populations locally adapted in the range boundary.
Shiitake mushrooms and molecular clocks: historical biogeography of Lentinula
Authors: Hibbett David S.
Published: March 2003

Aim

Fungi make up a large, ecologically important group of eukaryotes that has been neglected in historical biogeography. In this study, molecular phylogenies and molecular clock dating were used to infer historical biogeography of the shiitake genus, Lentinula Earle, which occurs in both the Old World and New World. The major goals of this study were to determine if the Old World and New World groups are monophyletic, and whether the Old World/New World disjunction is the result of vicariance or long distance dispersal.

Location

Collections studied are from Asia, Australasia, the Gulf Coast region of North America, the Caribbean, Central America, and northern South America.

Methods

Phylogenetic trees were inferred with nuclear large subunit (nuc‐Isu) ribosomal DNA (rDNA) and internal transcribed spacer (ITS) sequences. Molecular clock dating was performed using trees derived from nuc‐Isu rDNA and mitochondrial small‐subunit (mt‐ssu) rDNA sequences. Rate constancy was tested with maximum likelihood, and clocks were calibrated using evidence from fossils or other molecular clock studies, or according to expected ages under different historical biogeographic scenarios.

Results

Analyses of ITS and nuc‐Isu rDNA sequences suggest that there are seven species of Lentinula worldwide, which occur in two main clades, one in the New World the other in the Old World. Rate constancy cannot be rejected in nuc‐Isu rDNA, but can be rejected in mt‐ssu rDNA. Both genes suggest that the Old World/New World disjunction could be due to fragmentation of an ancient Laurasian range. An alternative Gondwanan hypothesis is not supported by the molecular clock age estimates.

Main conclusions

Only one long distance dispersal event must be invoked in Lentinula, that being between Australia and New Zealand. Despite having airborne spores, it appears that long distance dispersal is rare in Lentinula. This may also be true in other fungi, which are therefore excellent candidates for historical biogeographic studies using molecular characters.
Vicariance or dispersal: the use of natural historical data to test competing hypotheses of disjunction on the Tyrrhenian coast
Authors: Estabrook George F.
Published: March 2003

Aim

To illustrate the use of natural historical data to evaluate vicariance and dispersal as hypotheses competing to explain disjunct populations.

Location

Nine disjunct areas on the margin of the Tyrrhenian basin of the Mediterranean Sea.

Methods

First describe how each hypothesized mechanism might explain the observed morphological variation in the model species complex, Genista ephedroides (Fabaceae); then confront the hypotheses with natural historical data including geology, oxygen isotopes, palynology, macro‐, micro‐ and nano‐fossils, and sea level changes, and with the ecological tolerances of the model species complex.

Results

Dispersal seems the more credible explanation.

Main conclusion

Patterns of morphological (or other) variation among related disjunct taxa can fit both vicariance and dispersal hypotheses. However they can possibly be distinguished by considering natural historical data.
Distribution of forest birds in the Andaman islands: importance of key habitats
Authors: Davidar Priya , Yoganand K. , Ganesh T.
Published: March 2003

Aim

The aim of this study was to assess the influence of island area, distance to source pool, latitude, habitat diversity and habitat type on species richness of forest birds in the Andaman islands.

Location

The Andaman islands (India) in the Bay of Bengal.

Methods

The distributions of 47 species of forest birds were surveyed on 45 islands in the Andaman islands across a latitudinal gradient. The size of the island and distance to the nearest large island were assessed on a satellite image of 1 : 250,000 scale. The number and types of habitats and the species richness of birds on each island were recorded during a field survey. The effects of the variables measured on the species richness of forest birds were assessed using regression analyses. The best fit models were selected for interpretation of the results. Separate analyses were conducted with selected islands to eliminate the effects of latitude and to control the effects of area and habitat diversity.

Results

The number of species of forest birds was strongly influenced by island area and habitat diversity. However the key determinant of species richness was habitat type, particularly the presence of wet forests. Wet forests, either semi‐evergreen or evergreen tropical forests are more common towards the southern islands and are usually restricted to larger islands.

Main conclusions

Area, habitat diversity and the presence of wet forests on islands significantly influenced species richness of forest birds. The wet forests maintain the biodiversity of the Andamans and should be regarded as a ‘keystone habitat’. This is probably because wet forests are species rich and also because the Andaman biota has affinities with that of the Malay peninsula where wet forests predominate. Therefore biogeographical history probably plays an important role in influencing biodiversity at a regional scale.
Patterns and processes in a seasonally flooded tropical plain: the Apure Llanos, Venezuela
Authors: Sarmiento Guillermo , Pinillos Marcela
Published: March 2003

Aim

The factors and processes determining the ecology and distribution of ecosystems in the Apure lowlands, Venezuela, are critically discussed.

Location

The Middle Apure region, an alluvial Quaternary plain built by the Arauca and Apure rivers, occupies a subsidence area caused by faulting of the geological basement during the last and most active phases of the Andean uplift.

Methods

To assess the determinants of the hydrological and ecological variability in this region, we used remote imagery and field surveys.

Results

The hydrological and ecological variability responds to a set of interconnected processes of different nature: geological, climatic and paleoclimatic and hydrographic, which together have conditioned the geomorphological history of the regional landscape. This evolution, in turn, has guided the soil forming processes and the functional behaviour of the different types of savanna, forest and wetland ecosystems. The continuously subsiding trend of the Llanos that accompanied the Andean Orogeny, together with the Quaternary climatic oscillations, settled the framework in which successive depositional and erosional events took place. Five Quaternary depositional events, gave rise to the actual landscape pattern. The youngest, Q0a is the actual flood plain, Q0b is the Holocene flood plain, Q1 is from Upper Pleistocene, Q2 from Middle Pleistocene, while Q3 the oldest sedimentary material in this area, is of Lower Pleistocene age. Within each sedimentary unit, we analysed the pattern of land forms, soils and natural ecosystems. The Q0 and Q1 land units show a characteristic unstable drainage system, with frequent changes in the course of rivers and their affluents and diffluents. Soil genesis mainly correlates with the contrasting characteristics of the wet and dry tropical climate, and with the water regime of each land form on each sedimentary unit. So, a sequence from entisols, through inceptisols and alfisols, to ultisols, correlates with the sequence of land units from Q0 to Q3. Different vegetation types predominate on each land form/soil unit. Gallery forest (evergreen and semi‐evergreen) exclusively occurs on Q0a entisols, semi‐deciduous forest characterizes Q0b and Q1 inceptisols, semi‐seasonal savanna is almost entirely restricted to Q0 and Q1 units, hyperseasonal savanna widely dominates on Q2 and Q3 alfisols and ultisols, while seasonal savanna just occurs on the well‐drained Q1 and Q2 alfisols, and on dunes.

Main conclusions

The genesis and dynamics of the various land forms and soils throughout the Quaternary, provide the key to their particular hydrology, and determines the kind of plant formation able to occupy each habitat, thus explaining the complex pattern of quite different ecosystems found in the region.
Increase in the woody component of seasonal savannas under different fire regimes in Calabozo, Venezuela
Authors: Silva Juan F. , Zambrano Alexis , Fariñas Mario R.
Published: March 2003

Aim

We tested the hypothesis that exclusion from fire and cattle is responsible for the increase in tree cover in open savanna vegetation.

Location

Four plots in open savanna vegetation from the Calabozo region in central Venezuela were studied. Plot A was located in a Biological Station (EBL) that was excluded from fire and cattle between 1961 and 1991, with only two burning events in 1964 and 1968. The other plots (B, C, D) were located within 2 km distance from A, in neighbouring farms with soils similar to those in A but under various regimes of land use and fire frequency.

Methods

We measured the cover of isolated trees, small tree groups and groves of each plot in 1960 and 1977 using geographic information system (GIS) and digitalized aerial photographs. Additionally, the plots were located in the field and the open grassland was sampled in 1995 for species composition and density of stems above 20 cm height. Information on land use was obtained surveying people at the farms.

Results

There was an increase in the woody component of all plots during the 17‐year interval (1960–1977). Total woody cover in the four plots as a whole increased from 4.5% to 17.9%. All three components measured, groves, tree groups and isolated trees, increased despite differences in land use and fire frequency between plots. Contrary to our expectations, the field survey performed in 1995 showed that fire‐sensitive species were abundant in the open savanna in plots B, C and D, which were not excluded. Plot B, with the most intense agricultural use showed the highest rate of woody increase, and plot C, under extensive cattle ranching, was second. The results also showed that woody cover increased by aggregation from single trees and small tree groups into groves. As a consequence of these changes, savanna physiognomy changed from open to dense savanna parkland with a woody cover reaching over 25% in one of the four plots.

Conclusions

The results agree with other reported increases in woody cover in savannas under exclusion or with annual fires during the same time period in Africa (Dauget & Menaut, 1992). Our results support evidence from previous studies showing that fire and grazing are only part of a complex system of interacting factors affecting the structure of savanna communities.
Tree seed dispersal among forest fragments: I. Conifer plantations as seed traps
Authors: Hewitt Nina , Kellman Martin
Published: March 2003

Aim

In fragmented landscapes, the survival of plant populations may depend on sufficient rates of migration between fragments with which to counteract local extinctions. Empirical information on the plant migration process is limited because of the difficulties of directly measuring the rare medium to long‐distance dispersal events involved. The potential for hardwood tree species' seedlings growing in conifer plantations to offer `a posteriori' measures of intermediate to long‐distance dispersal events was evaluated.

Location

Fragmented eastern deciduous forest in a rural, agricultural landscape, Southern Ontario.

Methods

To indicate the degree to which plantations `sample' incoming seed, seedling populations were enumerated in plantations and their species composition and abundances compared with those of mature trees, the presumed seed sources, in the surrounding landscape (to 150 m distance). To further quantify the degree to which hardwood seedling populations in plantations represent seed input, seeds of twelve hardwood species were sown in pine plantations and their emergence and early seedling survival monitored for 2 years. A subset of four of these species was planted in hardwood woodlots and their survival compared with survival in plantations to indicate how well seedlings in plantations reflect colonization in deciduous forest fragments.

Results

Hardwood seedling populations in plantations comprised the majority of tree species present in the surrounding landscape. Species' seedling abundances were significantly related to tree abundances around plantations. These findings indicate that most hardwood species can establish in plantations and do so in approximate proportion to the amount of seed supplied. All species produced first year seedlings in plantations, but rates of seedling survival were variable, ranging from under 5 to over 40% per species. Large‐seeded species had significantly greater seedling survival than smaller‐seeded species, suggesting that seed size—survivorship relationships could be used to adjust seedling frequencies to measure seed rain. Mean light levels photosynthetically active radiation (PAR) were significantly higher in plantations than in hardwood woodlots, yet rates of early seedling establishment were comparable between plantations and woodlots for four experimentally sown species.

Main conclusions

Hardwood seedlings in plantations appear to provide reasonable, although conservative, measures of dispersal to forest fragments, albeit with certain qualifications including adjustments for species' establishment abilities.
Biological images of geological history: through a glass darkly or brightly face to face?
Authors: Holloway Jeremy D.
Published: March 2003

Abstract Aim  To explore the implications for historical biogeography of a recent review of island biogeographical theory in three main thematic areas and to suggest ways in which a synthesis between the two approaches might be achieved to the benefit of both.

Location  The Indo‐Australian tropics.

Theme 1  discusses the relationship of species number to area, and how the nestedness of faunas may influence the methodology used for some types of analysis and also the quality of data expected from an archipelago embracing an extreme range of island sizes.

Theme 2  examines the way in which the processes of speciation may lead to development of biogeographical patterns through a complex archipelago, illustrated in particular with reference to Sulawesi where biotic enrichment from different lepidopteran groups follows predictions from island biogeographical theory. This also has implications for patterns of endemism in the archipelago, another constraint on the quality of data available for historical biogeography.

Theme 3  addresses ecological determinism as an influence in development of biogeographical pattern, focusing on the theme of specificity in insect–plant relationships and the potential for parallel development of pattern in an insect group and its particular plant host group. This theme is developed with particular reference to moth and plant groups that may represent Gondwanan elements in the Oriental fauna, with an analysis of Sarcinodes, a geometrid moth genus associated with Proteaceae.

Main conclusions  Prospects are assessed for the synthesis of the two approaches of island biogeography and historical biogeography. Modelling pattern development with the former may complement the methods of analysis of the latter, particularly if some satisfactory method for dating events of pattern development can also be incorporated.
Patients' experiences of chemotherapy: side‐effects associated with 5‐fluorouracil + folinic acid in the treatment of colorectal cancer
Authors: Dikken Clare , Sitzia John
Published: March 2003

• The purpose of this study was to investigate the side‐effects experienced by patients with colorectal cancer receiving 5‐fluorouracil + folinic acid chemotherapy. A primary objective was to provide quantitative data on the incidence and severity of side‐effects at each cycle of chemotherapy treatment.

• Twelve patients with Duke's B or Duke's C adenocarcinoma participated. Data collection was via a self‐report questionnaire listing 61 possible side‐effects. Participants completed a questionnaire following each cycle of chemotherapy.

• The response rate was 100%. Seventy‐eight side‐effects were reported by the sample. Fatigue was the most common side‐effect (incidence = 97%) and achieved the highest C score (59/100). However, patients ranked mouth ulceration as the worst side‐effect overall. Several previously unreported problems were identified, including nose bleeding, change in taste and weight loss.

• Although limited by a small sample size, this study suggests the problems experienced by patients undergoing 5‐fluorouracil chemotherapy are many and diverse. It is concluded that investigation is needed into associations between side‐effects and the role of patient characteristics in the onset of side‐effects.
Will current clinical effectiveness initiatives encourage and facilitate practitioners to use evidence‐based practice for the benefit of their clients?
Authors: Regan Julie‐Anne
Published: March 2003

• 1996 saw the implementation of Clinical Effectiveness Initiatives by the NHS Executive and the Royal College of Nursing to promote the use of evidence‐based care.

• This paper examines whether or not nurses will be encouraged and facilitated by these initiatives to provide evidence‐based care for their clients.

• Both initiatives appear to assume that the use of evidence‐based care leads to improved client care, but several issues are raised which still need to be resolved before this assumption can be made.

• The NHS Executive advocates the use of randomized controlled trials as the method of choice for providing evidence of clinical effectiveness. However, this may not necessarily be the best methodology for some areas of nursing practice.

• The paper concludes that the Royal College of Nursing's Clinical Effectiveness Initiative has great potential to provide the necessary motivation and facilitation, providing other professional issues are resolved.
Exploring mental health nurses' expectations and experiences of working in the community
Authors: Kipping C. J. , Hickey G.
Published: March 2003

• As mental health care is increasingly being provided in community settings, a variety of job opportunities are becoming available to mental health nurses. The extent to which nurses' views and experiences of working in community settings have been explored, however, is limited.

• This paper reports on newly qualified nurses' plans in relation to taking up work in the community and, for those who thought it likely that they would take up such work, their reasons for doing so.

• Reasons for working in the community were diverse, and suggested that a range of satisfactions could be expected. The extent to which such expectations become a reality is considered in the light of findings from interviews with 12 nurses who were working in community settings.

• Satisfactions and difficulties experienced by the 12 nurses are described, and suggestions for tackling some of the difficulties are made.
The prevalence and perception of pain amongst hospital in‐patients
Authors: YATES PATSY , DEWAR ANNE , EDWARDS HELEN , FENTIMAN BELINDA , NAJMAN JAKE , NASH ROBYN , RICHARDSON VAL , FRASER JENNY
Published: March 2003

• The aim of this paper is to describe the prevalence and perceptions of pain and pain management amongst hospital in‐patients.

• A cross‐sectional descriptive survey of 205 patients was conducted.

• Presence and severity of pain was assessed using verbal descriptor and visual analogue scales, and perceptions of pain were assessed using multi‐item scales.

• Although the severity of pain reported was consistent across age groups and clinical areas, women in the study sample were significantly more likely to report high levels of pain than men.

• Differences in how men and women communicate their pain were observed, with women indicating that they were less willing to ask for help with their pain.

• Results suggest that pain continues to be an important problem for a large number of men and women in hospital, and that the experience of pain impacts negatively upon their well‐being.

• Gender differences in the experience of and response to pain remain important considerations for clinical nurses who have major responsibilities for the management of pain in hospitalized patients.
An evaluative study of the basic life support skills of nurses in an independent hospital
Authors: DEVLIN MICHAEL
Published: March 2003

• This paper reports on a research study carried out in an independent hospital in the south east of England.

• The aim of the study was to assess the basic life support skills of nurses in order to compare the results with those reported for nurses in public hospitals.

• The findings show that the basic life support skills of the nurses studied are poor but no worse than those of their public sector colleagues.