bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of controlled sheep grazing on the dynamics of upland Agrostis–Festuca grassland
Authors: Hulme P.D. , Pakeman R.J. , Torvell L. , Fisher J.M. , Gordon I.J.
Published: March 2003

1. Agrostis capillaris–Festuca ovina‐dominated communities are widespread in the uplands of Great Britain. They are agriculturally productive but little is known about how to manage this community for specific goals. Vegetation trajectories were examined in this plant community under different sheep grazing management regimes at two sites in Scotland. One site had a substantial presence of moorland species, the other was characterized by a more productive vegetation. Management consisted of maintaining sward heights of 3, 4·5 or 6 cm during the growing season, or complete exclusion of grazing stock.

2. Changes in species composition were small over the 7 years of the experiment. Few species invaded or were lost during the course of the study. The observed changes were largely as a result of shifts in abundance of the dominant species.

3. Maintenance of sward height at low levels (3 or 4·5 cm) during the growing season resulted in the spread of Nardus stricta where present. Where N. stricta was absent, the sward developed a higher content of mosses, specifically Hypnum jutlandicum and Rhytidiadelphus squarrosus.

4. Removal of grazing resulted in an increase of cover of grazing‐intolerant species, such as Deschampsia flexuosa and Molinia caerulea, and in the cover of dwarf shrub species where present.

5. The two sites differed in the treatment that resulted in the smallest change in species composition. At the more productive site, maintenance of the sward at 4·5 cm resulted in the smallest overall change in species composition. At the less productive site, grazing the sward to 6 cm resulted in the smallest shift in vegetation composition. Grazing at this height appeared to prevent the spread of both M. caerulea and N. stricta.

6. The study demonstrates that sustainable grazing regimes for upland Agrostis–Festuca grasslands need to take into account both the initial composition of the vegetation, specifically the presence of species capable of replacing A. capillaris and F. ovina and of achieving dominance, and the overall productivity of the site.
Changes in the abundance of farmland birds in relation to the timing of agricultural intensification in England and Wales
Authors: Chamberlain D.E. , Fuller R.J. , Bunce R.G.H. , Duckworth J.C. , Shrubb M.
Published: March 2003

1. Over the past three decades changes in agricultural management have resulted in increased crop and grass production. This intensification has been accompanied by population declines among farmland bird species and a decline in farmland biodiversity. We have analysed trends in agricultural management in order to quantify the degree of intensification, and have considered how they match change in the farmland bird community.

2. Changes in agriculture through time (1962–95) were examined quantitatively for 31 variables representing crop areas, livestock numbers, fertilizer application, grass production and pesticide use. The majority were highly intercorrelated because factors facilitating intensification simultaneously affected many management activities.

3. Change in agriculture was measured using detrended correspondence analysis (DCA). The period 1970–88 saw most intensification, characterized by increases in the area of oilseed rape, autumn‐sown cereals, and the use of pesticides and inorganic fertilizers. Spring‐sown cereals, bare fallow and root crops declined.

4. Indices of relative population change between 1962 and 1996 were determined for 29 bird species using data from Common Birds Census (CBC) plots on farmland in England and Wales. Principal components analysis (PCA) described a gradient from species that had declined most to those that had increased.

5. The ordinations of agricultural change and bird population change were broadly matching but with a time lag in the response of birds. The most accurately measured agricultural variables for the period 1974–91 matched the changes in farmland birds more closely.

6. We conclude that large shifts in agricultural management are a plausible explanation for the declines in farmland bird populations. We propose a threshold model relating to critical amounts of high‐quality habitat or food resources that may be relevant in explaining the lag in response of birds, and propose it should be taken into account in predicting the effects of future agri‐environment schemes. Identifying individual factors responsible for bird declines is not possible without detailed experimental work because many components of intensification are interdependent. Birds may be responding to a suite of interacting factors rather individual aspects of farm management. Holistic conservation strategy that encourages general extensification of farming practices will be most likely to benefit farmland bird communities.
Effects of late summer cattle grazing on the diversity of riparian pasture vegetation in an upland conifer forest
Authors: Humphrey J.W. , Patterson G.S.
Published: March 2003

1.  Species‐rich grassland is important for biodiversity in upland forests, particularly within riparian zones. Prior to afforestation, the botanical diversity of these grasslands was maintained by domestic stock grazing, but without active management many will revert to coarse, species‐poor grassland and eventually to scrub. The reintroduction of stock grazing is a potential solution to this problem, but has not been tested in upland forests. Here we present results from 9 years of monitoring the effects of cattle grazing on the diversity and composition of riparian pasture vegetation in an upland conifer forest in northern Scotland.

2.
 There were two treatments, late summer grazing and ungrazed. The average stocking density in the grazed treatment was 2·25–2·5 cows ha−1. The cattle were free to range over the entirety of the 40‐ha experimental site from early August to late September each year.

3.
 Assessments of plant species richness and abundance were made in 1988 (prior to the commencement of grazing), 1991 and 1997, in three of the main riparian vegetation types. These were ‘Flush’ vegetation associated with calcareous springs, acid Agrostis capillaris–Festuca ovina grassland (‘Grass’), and Juncus effusus rush pasture (‘Juncus’). Assessments were also made of grazing impacts, cattle usage and water table depths.

4.  Grazing had a significant effect on plant species richness, which declined in ungrazed plots and remained static in grazed plots over the 1988–97 period. There were no recorded effects of grazing on species abundance, nor on the frequency of rare sedges and herbs of particular conservation importance. Litter cover (dead plant material) was significantly higher in ungrazed plots, which may be a causal factor in declining richness values.

5.
 Cattle utilized Grass and Flush vegetation to a significantly greater degree than Juncus vegetation, and this appeared to be related to forage availability rather than wetness as represented by water table depth.

6.  Cattle grazing is of potential value as a management tool for species‐rich grasslands in upland forests provided that: areas to be grazed are large enough to minimize localized impacts and allow free ranging of the cattle; the economics and practicalities of stock husbandry are considered; the type of grazing management used is linked clearly to management objectives.
Habitat preferences of great bustard Otistarda flocks in the arable steppes of central Spain: are potentially suitable areas unoccupied?
Authors: Lane Simon J. , Alonso Juan C. , Martín Carlos A.
Published: March 2003

Great bustards Otistarda are globally endangered and 50% of the world population now occurs in agro‐steppe habitats in Spain. An understanding of the relationship between land use and the species’ habitat requirements is necessary to predict the consequences of land‐use change on this declining species.

 A 2‐year study of great bustard substrate preferences was conducted in a large region in central Spain where most cereals are still cultivated in a traditional 2‐year rotation.

 Great bustards showed year‐round selection of stubble fields, but avoided ploughed and uncultivated areas. Other substrate types were variously selected, avoided or used in proportion to availability depending on season. Patterns were consistent over 2 years.

 Human artefacts such as roads, tracks and powerlines were avoided.

 Variables correlating with flock locations could not discriminate between occupied and unoccupied but apparently suitable areas of traditionally managed cereal steppe. This suggests that great bustard distribution in central Spain is not limited by inappropriate land use in steppe areas.

 The evidence suggests that great bustards show fidelity to sites regardless of the availability of suitable habitat elsewhere. Settlement patterns are probably determined by the presence of conspecifics rather than habitat cues. This result demonstrates the value of integrating observations of habitat use with knowledge of species’ behaviour in order to understand distribution more fully.

 We propose that conservation efforts should be directed towards securing traditional lek sites and we make three recommendations: first all great bustard lek sites should be identified; secondly, existing European Union legislation should be used to protect these and to ensure that compatible land management practices are applied or maintained; and finally, research programmes should be conducted that aim to enhance the conservation value of stubble fields rather than simply demonstrate their selection.
Ecology and genetics of wild‐living cats in the north‐east of Scotland and the implications for the conservation of the wildcat
Authors: Daniels Mike J. , Beaumont Mark A. , Johnson Paul J. , Balharry David , Macdonald David W. , Barratt Elizabeth
Published: March 2003

The wildcat is considered to be threatened by interbreeding with the domestic cat. As a result of interbreeding the definition of a wildcat in Scotland is contentious. Many authors consider pelage characteristics to be diagnostic, yet few data exist on sympatric cats with different pelages.

A study of 31 wild‐living cats was conducted from 1995 to 1997 in an area associated with wildcats. Seventy‐four per cent of cats caught had striped tabby pelages while 26% had other (non‐tabby) phenotypes.

 On the basis of data from eight nuclear DNA microsatellite loci there was no strong evidence of two groups, and tabby and non‐tabby cats did not depart significantly from Hardy–Weinberg equilibrium.

 There were significant differences in gene frequencies and genotypes between the two pelage types. Non‐tabby cats were also significantly more similar to domestic cats than tabby cats, although still noticeably differentiated from them.

There were potential parent–offspring and sibling–sibling relationships between and within tabby and non‐tabby cats, suggesting recent interbreeding. On average, however, non‐tabby cats were genetically less related to each other than tabby cats.

Radio‐tracking revealed that non‐tabby adult females had significantly larger home ranges than tabby adult females. However, for all other aspects of home range size, social organization, activity patterns and habitat use there were no significant differences between cats of different pelage type.

The implications of these results are that traditional approaches for attempting to distinguish wild animals in the face of interbreeding with their domestic forms are neither accurate nor effective. Instead, conservation should focus on mechanisms for dealing with groups of animals below the species level.

Specifically for the wildcat in Scotland, conservation should focus on protection by area. If domestic cat controls were conducted within specified areas then the potential threat posed by interbreeding would be reduced.
Predicting plant species’ responses to grazing
Authors: Vesk Peter A. , Westoby Mark
Published: March 2003

The aim of this study was to identify whether plant species show consistent responses to livestock grazing. The analyses were based on 35 published studies from Australian rangelands providing 55 species response lists. The primary data set comprised 1554 responses from 829 species.

Eight‐hundred and twenty‐nine species were categorized as increasers, decreasers or neutral under grazing. Of 324 species that occurred in at least two response lists, 133 (41%) responded inconsistently, increasing at least once and decreasing at least once. While 59% of species responded consistently, these results suggest that our ability to predict vegetation change under grazing is limited.

Particular species were not inherently more or less consistent. Rather, as species occurred in more trials, the likelihood of at least one opposite response increased; no species that occurred at least eight times was wholly consistent. A binomial model indicated that the probability of an opposite response, across all species, was 0·275.

Contrary responses within species must result from context rather than from species’ traits. Species were more likely to decrease in response to grazing at lower rainfall than at higher rainfall. Forbs tended to increase under grazing at sites where wet seasons were cooler. Changing the grazing animal was weakly correlated with change in response direction, although not enough for it to be useful for manipulating pasture composition. We found little support for ideas that different responses within species are due to differences in alternative forage available, or due to non‐linearity of response to grazing intensity.

At present it appears we can predict species response direction about three‐quarters of the time, at a continental scale. This represents an upper limit of the reliability of prediction based on species’ traits alone. Presently we do not know what aspects of the context might allow us to predict reliably the remaining one‐quarter of responses.
Transgenic weed beets: possible, probable, avoidable?
Authors: Desplanque Benoît , Hautekèete Nina , Van Dijk Henk
Published: March 2003

Weed beets pose a serious problem for sugar beet Beta vulgaris crops. Traditionally, the only efficient method of weed control has been manual removal, but the introduction of transgenic herbicide‐tolerant sugar beets may provide an alternative solution because non‐tolerant weed beets can be destroyed by herbicide. We evaluated the possibility that new, transgenic, weed beets may arise by gene flow between wild and crop plants.

In a study area in northern France, weed beets were present in variable densities in sugar beet fields of up to 80 weed beet plants m−2. Weed beets arise from a long‐lived seed bank, with seeds germinating from depths of 5 cm or less. In addition, diploid F1 crop–wild hybrids and triploid variety bolters (individuals with a low vernalization requirement) were present in low densities in virtually all sugar beet fields. We found gene flow to be possible between all forms, illustrated by both overlapping flowering periods in the field and successful controlled cross‐pollinations.

The F1 crop–wild hybrids result from pollination in the seed‐production region by wild plants possessing the dominant bolting allele B for flowering without experiencing a period of cold. In the case of a transgene for herbicide tolerance incorporated into male‐sterile seed‐bearer plants, such hybrids will contain both the herbicide‐tolerance and the bolting allele. Contamination of the fields by transgenic weed beets will be the result unless bolters are removed manually. The same will apply in the case of a cytoplasmically inherited transgene.

Incorporation of the transgene into the pollinator plants will prevent the immediate formation of transgenic weed beets. However, in sugar beet fields, variety bolters may successfully cross‐pollinate with weed beets in neighbouring fields. The use of diploid pollinator plants instead of tetraploids will considerably enhance gene flow towards wild beets, and is not, therefore, an attractive option.

In conclusion, the appearance of transgenic weed beets is possible but can best be retarded if the transgene for herbicide tolerance is incorporated into the tetraploid pollinator breeding line.
Tracks and riparian zones facilitate the use of Australian regrowth forest by insectivorous bats
Authors: Law Bradley , Chidel Mark
Published: March 2003

Documentation of habitat use by individual bat species is a key issue when assessing impacts after forests are disturbed, for example by logging.

We used bat detectors to compare bat activity in unlogged forest and regrowth forest 15 years after logging in northern New South Wales, Australia. Sites of contrasting management history were replicated at the scale of small catchments, with detectors positioned on tracks, off tracks and in riparian zones in either unlogged or regrowth forest.

The highest bat activity was recorded on forest tracks, with no significant difference between detectors in regrowth (mean = 183 passes night−1) and unlogged forest (196 passes night−1). Activity in riparian zones was intermediate (regrowth = 55 passes night−1; unlogged = 26 passes night−1), while off‐track sites in forest regrowth had the lowest activity levels (5 passes night−1). Species richness was lowest in the off‐track samples in regrowth and highest in the on‐track samples of regrowth.

An index of clutter for different vegetation layers was recorded at each site. Bat activity decreased significantly with increasing clutter formed by the layer of regrowth eucalypts and/or understorey rain forest. This result strongly suggested that low bat activity off tracks was related to vegetation clutter.

Specific identification of calls revealed that the suite of species associated with tracks included both those predicted by ecomorphology to be clutter‐sensitive (Falsistrellus tasmaniensis, Vespadelus darlingtoni, Vespadelus pumilus and Chalinolobus morio) and clutter‐tolerant (Rhinolophus megaphyllus).

Elevation and temperature were also significant covariates of activity for a number of species.

As part of sustainable management of regrowth forests, we advocate maintaining flyways for bats in the form of tracks and riparian zones, in addition to the widely recognized need for the retention of hollow‐bearing trees as roost sites. Research on the effects of silvicultural thinning, which will reduce clutter with possible benefits to some bat species, should also be a priority in forest characterized by secondary regrowth.
Isolation and characterization of a mutant strain of Streptococcus uberis, which fails to utilize a plasmin derived β-casein peptide for the acquisition of methionine
Authors: Smith A.J. , Kitt A.J. , Ward P.N. , Leigh J.A.
Published: March 2003

Aims: To isolate and characterize a mutant of Streptococcus uberis strain 0140J which fails to utilize a plasmin derived β-casein peptide for the acquisition of methionine. Methods and Results: Random insertional mutagenesis was used to isolate a mutant strain of Strep. uberis 0140J which was unable to utilize methionine from within a casein-derived peptide. The altered gene in the mutant strain showed homology to an oligopeptide permease gene of Streptococcus pyogenes (oppF). The mutant was unable to obtain specific amino acids from defined peptides of various lengths and its growth yield in skimmed milk was between 1 and 10% that of the wild-type strain, but was restored following the inclusion of these amino acids. Conclusions: The oligopeptide permease homologue of Strep. uberis 0140J is necessary for the utilization of amino acids from within specific peptides. Efficient acquisition of essential amino acids by Strep. uberis 0140J is required for the bacterium to achieve an optimum yield in milk. Significance and Impact of the Study:Streptococcus uberis is a major agent of bovine mastitis with a corresponding high economic loss. By targeting metabolic pathways essential to the growth of Strep. uberis it may be possible to prevent the establishment of growth of the bacterium in milk. This study has identified the acquisition of essential amino acids as playing a role in the growth of Strep. uberis in milk.
Protective effects of cold temperature and surface-contact on acid tolerance of Salmonella spp.
Authors: Gawande P.V. , Bhagwat A.A.
Published: March 2003

Aims: To determine the effect of cold-storage temperature and surface contact on the survival of Salmonella spp. during acid challenge. To determine the contribution of sigmatranscrip- tional factor (encoded by rpoS) in surface contact-mediated acid tolerance. Methods and Results:Salmonella serovar Typhimurium cells in exponential and stationary growth phase were subjected to acid challenge in planktonic and surface-associated states. Low temperatures offered protection against acid challenge to cells which were in stationary growth phase (but not to those in exponential growth phase). The cells from stationary, as well as logarithmic growth phase, acquired increased acid tolerance upon surface contact with various surfaces, such as fresh-cut apples, agar and polyethersulphone membranes. The alternative sigma transcription factor was not required to acquire surface contact-mediated acid tolerance. Conclusions:Salmonella spp. take advantage of low temperature and surface association to overcome acid challenge. Some of the acid tolerance mechanisms are independent of the sigma transcription factor regulon. Significance and Impact of the Study: Effective control measures during produce processing must take into account the different susceptibilities of planktonic vs surface-associated food-borne pathogens.
Dynamics of experimental vasogenic brain oedema in the rat: changes induced by adrenergic drugs
Authors: Borges N. , Sarmento A. , Azevedo I.
Published: March 2003

1 The effects of adrenergic drugs on the formation and resolution of cerebral oedema in a rat model of cold‐induced vasogenic brain oedema were studied. Evans blue dye extravasation, water content and ultrastructural alterations (pinocytotic vesicle formation in capillary endothelial cells and apparent water accumulation in the brain parenchyma) were evaluated in parietal cortex.

2 Previous administration of the α‐adrenoceptor antagonist phenoxybenzamine produced a reduction of Evans blue extravasation and water content, diminished vesicle formation and reduced water accumulation. Previous administration of the β2‐adrenoceptor agonist clenbuterol reduced Evans blue extravasation and water content, but did not change vesicle frequency.

3 The effects of clenbuterol on Evans blue passage to the brain were blocked by timolol (β‐adrenoceptor antagonist) but not by metoprolol (selective β1‐adrenoceptor antagonist). When given after the application of cold, clenbuterol was also able to reduce Evans blue and water content in the brain. Isoprenaline (β‐adrenoceptor agonist that does not cross the blood–brain barrier) showed a reduction in Evans blue extravasation only when given intracerebroventricularly. Vinblastine (a drug that prevents vesicle formation) produced a reduction of the amount of pinocytotic vesicles.

4 We conclude that there is an influence of the central adrenergic nervous system on the formation and/or resolution of vasogenic brain oedema and that the alterations on water movement and Evans blue transport mediated by adrenergic drugs seem to be due, at least in part, to alterations of pinocytotic activity in capillary endothelial cells.
Action of tacrine on muscarinic receptors in rat intestinal smooth muscle
Authors: Becerra M. A. , Herrera M. D. , Marhuenda E.
Published: March 2003

1 The reversible cholinesterase inhibitor, tacrine (THA) was examined against the contractions of rat duodenum to acetylcholine and carbachol (cholinesterase resistant).

2 Tacrine (10–6 M) showed a similar behaviour to physostigmine (10–6 M), changing the characters of the concentration–response curve to Ach. The contractual responses were shifted to the left at low concentrations of ACh to reveal a bell‐shaped curve with declaring contradictions at high concentrations of ACh.

3 Antagonism by atropine (10–8 M) was reduced in the presence of tacrine (10.54, dose‐ratio) compared with the shift of the curve in the absence of tacrine (73.9, dose‐ratio). The declining phase of the concentration–response curve to ACh was also antagonized by atropine.

4 Further evidence for muscarininc receptor antagonism by tacrine was a small rightward shift of the concentration‐response curve for carbachol, an agonist immune to cholinesterase.

5 This study has shown that tacrine acts both as a cholinesterase inhibitor and muscarinic antagonist on rat intestinal smooth muscle.
Die postglaziale Besiedlung Mitteleuropas durch Libellen, mit besonderer Berücksichtigung Südwestdeutschlands (Insecta, Odonata). The postglacial colonization of Central Europe by dragonflies, with special reference to southwestern Germany (Insecta, Odonata)
Authors: Sternberg Klaus
Published: March 2003

The migratory routes along which the Central European species of dragonflies probably immigrated from their periglacial refuges into Central Europe are reconstructed. Due to the topographical configuration in Central Europe, the postglacial invasions were confined to only a few routes. Mountain chains and also small river valleys, i.e. the Rhine valley between Lake Constance and Waldshut, acted as barriers; while geotectonic depressions, such as the ‘Geneva Gate’, ‘Burgundian Gate’ and ‘Moravian Gate’, played an important role as ‘gateways’ in overcoming these obstacles, the wide river plains were used as corridors to invade the hinterland. The extent of the immigration into Central Europe by the dragonfly species depended on the one hand on the distances which had to be covered from the refugial areas, but, on the other hand, also on the distinct postglacial climatic periods (Preboreal, Boreal, Atlantic, Subboreal, Subatlantic). Depending on their thermal requirements each species started expanding from their refugial areas at different times. Due to variable postglacial climatic conditions, progressive migratory phases alternated with regressive phases. The very different recent distribution patterns of the Central European dragonflies can only be understood if all the climate history, landscape morphology, the thermal requirements of the species, their origin (refugial areas) and history of colonization are considered. Because many Central European dragonfly localities currently lie at the periphery of the range of many species, these species can only survive in these areas if individual ‘reinforcements’ from their centres of distribution are possible. They still take place mainly along the old routes. Thus, disruption of the migratory routes, especially at the gateways, due to anthropogenic actions may influence the fauna of large Central European regions. Due to many anthropogenic influences, the routes already often seem to be interrupted over long distances and the connections to the centre of distribution already broken. As a result of precise knowledge of the courses of the migratory routes a better prediction is possible as to whether species conservation measures or recolonization projects will be successful.
Modelling faunal responses to climatic gradients with GIS: land snails as a case study
Authors: Kadmon Ronen , Heller Joseph
Published: March 2003

Abstract. This study describes and exemplifies a multivariate approach based on geographical information system (GIS) technology for the analysis of faunal responses to climatic gradients. The approach is particularly suitable for the analysis of museum collections, and it combines the data reduction capabilities of multivariate techniques (ordination and classification) with GIS tools for the manipulation of geographically referenced data. The specific steps of the analysis are (1) construction of a grid covering the study area at an appropriate resolution, (2) overlaying the grid with a data base of spatially referenced species records, (3) determining the number of times each species was recorded in each cell, (4) constructing a matrix of grid cells by species where each entry indicates the number of records of a particular species in a particular cell, (5) removing cells whose total number of records is lower than some threshold (to be determined) from the matrix, (6) analysis of the reduced matrix using ordination and classification techniques, (7) construction of maps representing the results of the multivariate analyses, and (8) analysis of these maps with respect to digital maps of relevant climatological factors. The applicability of this approach was evaluated by analysing the response of the land snail fauna of Israel to regional variation in mean annual rainfall. As was expected, patterns of faunal variation were significantly correlated with underlying variation in rainfall. However, the per‐unit effect of rainfall on the composition of the studied fauna was much greater in dry regions than in more rainy areas. Above 450 mm, no relationships could be detected between the observed patterns of faunal variation and rainfall. These patterns were consistent over a wide range of grid cell sizes (5–20 km), and were robust to outliers. The overall results indicate that the integration of GIS tools with standard multivariate techniques may serve as a valuable methodology for the identification and interpretation of regional patterns of faunal variation.
Global patterns in local number of insect galling species
Authors: Price Peter W. , Fernandes G. Wilson , Lara Angela Christina F. , Brawn Jeffrey , Barrios Hector , Wright Mark G. , Ribeiro Servio P. , Rothcliff Nikita
Published: March 2003

Abstract. We evaluate a three‐part hypothesis explaining why gall‐inducing insect species richness is so high in scleromorphic vegetation: (1) persistence of low nutrient status scleromorphic leaves facilitates the galling habit in warm temperate latitudes; (2) favourable colonization sites for gallers result from reduced hygrothermal stress, high phenolics in the outer cortex of the gall, and reduced carnivore and fungal attack in the gall; and (3) in more mesic sites, mortality is high due to carnivore attack and invasion of galls by fungi. Over 280 samples of local species of galling herbivorous insects from fourteen countries on all continents except Antarctica revealed a strong pattern of highest richness in warm temperate latitudes, or their altitudinal equivalents. The peak of galling species richness on the latitudinal gradient from the equator into the Arctic was between 25 to 38° N or S. Galling species were particularly diverse in sclerophyllous vegetation, which commonly had greater than twelve species per local sample. In mesic, non‐sclerophyllous vegetation types the number of galling species was lower with twelve or fewer species present. Many sites in sclerophyllous vegetation supported between thirteen and forty‐six galling species locally, including campina islands in Amazonia, cerrado savanna in central Brazil, the Sonoran Desert in Arizona and Mexico, shrubland in Israel, fynbos in South Africa and coastal scleromorphic vegetation in Australia. At the same latitude, or its elevational equivalent, galling species richness was significantly higher in relatively xeric sites when compared to riparian or otherwise mesic habitats, even when scleromorphic vegetation dominated the mesic sites. The results were consistent with the hypothesis and extend to a more general level the patterns and predictions on the biogeography of gall‐inducing insects.
Latitudinal patterns of mammalian species richness in the New World: the effects of sampling method and faunal group
Authors: Kaufman Dawn M. , Willig Michael R.
Published: March 2003

Abstract. Although the latitudinal gradient of species richness for mammals in North America is well documented, few investigators have quantified the relationship in South America. We examined the pattern in North and South America, at two spatial scales (2.5° and 5°) for each of two sampling methods (quadrats and latitudinal bands). A scale effect was evident for quadrats but not for bands. Significant linear relationships between species richness and latitude were found for three faunal groups: all mammals, nonvolant species, and bats. Effects of area confound the latitudinal relationship. By statistically removing such effects, we found that the latitudinal gradient is not an artifact of the species‐area relationship, and that the latitudinal gradients for North and South America were statistically indistinguishable. Our data suggest that both faunal subgroups, nonvolant species and bats, contributed substantially to the overall mammalian pattern. Further, multiple regression analyses showed that only latitude is a necessary variable to explain bat richness; for nonvolant species, in addition to latitude, area and longitude may be important.
Global distribution of forest soil dictyostelids
Authors: Swanson Andrew R. , Vadell Eduardo M. , Cavender James C.
Published: March 2003

AimThe goal of this project was to compile, organize, and present the known distributional data on the dictyostelid cellular slime moulds (CSMs) found in forest soils worldwide. The question of what factors influence CSM distribution patterns was also addressed.

LocationCSMs have been recovered from soils of temperate deciduous forest, tropical deciduous and seasonal evergreen rainforest, boreal coniferous forest, and tundra by various investigators around the world.

MethodsWithin each of these four biomes, various locations around the world have been sampled by a number of investigators. The current study attempts to synthesize the known dictyostelid distributional data and present specific patterns of distribution.

ResultsWorldwide, sixty‐five species of CSM were found to occupy various forest soils. These species’ distributions fell into one of four categories: cosmopolitan, disjunct, restricted, and pantropical.

Main conclusionsGlobal CSM distribution patterns are influenced by a variety of factors other than the biota (including but not restricted to climate, latitude, altitude, soil pH, and soil‐forming parent materials). The current study supports the thesis that organic inputs from specific plant associations and animal vectors have an important role as well.
Fossil wood charcoal assemblages from Elands Bay Cave, South Africa: implications for Late Quaternary vegetation and climates in the winter‐rainfall fynbos biome
Authors: Cowling R. M. , Cartwright C. R. , Parkington J. E. , Allsopp J. C.
Published: March 2003

Aim The aim of this paper is to analyse fossil charcoal deposits, largely identified to the species level and spanning a sequence from the late Holocene to < 40,000 BP, in order to reconstruct Late Quaternary vegetation and climatic patterns in the western (winter‐rainfall) fynbos biome of South Africa.

Location The charcoals were excavated from the Elands Bay Cave (32°19S, 18°20E) on the semiarid (200–250 mmyr−1), winter‐rainfall coastline of the western fynbos biome.

Methods Patterns in the charcoal data set over time were sought by manual sorting of the charcoal×sample matrix, as well as by subjecting the data to multivariate analysis. Palaeoclimatic reconstruction was attempted by comparing the climatic controls on contemporary vegetation communities that resembled the fossil assemblages. Charcoal diversity was modelled using sample age and number of charcoal fragments as explanatory variables.

Results The fossil assemblages ranged from xeric communities (similar to those presently occurring at the site) during the Holocene, to more mesic thicket and fynbos vegetation in the terminal Pleistocene, to Afromontane forest and riverine woodland communities after about 18,000 BP. Diversity of the charcoal samples increased monotonically with increasing sample age.

Main conclusions The results suggest that, unlike the eastern fynbos biome, which is under fundamentally different climatic controls, soil moisture conditions in the western part of the biome were higher in the Last Glacial than during the Holocene. This scenario may help to explain the higher regional richness and associated diversification in the western than eastern part of the biome.
Competition, coexistence, and adaptation amongst rodent invaders to Pacific and New Zealand islands
Authors: Yom‐Tov Yoram , Yom‐Tov Shlomith , Moller Henrik
Published: March 2003

Variation in skull size was investigated for three species of rats (kiore –Rattus exulans Peale; ship rat –R. rattus L.; Norway rat –R. norvegicus Berkenhout) which were introduced by humans to various islands in New Zealand and other Pacific islands. Data from seventy‐one islands and 882 specimens are examined for evidence of the effects of latitude, island size and interspecific competition among rats and the house mouse (Mus musculus L.) on skull size, using multiple regressions. For R. exulans, skull size increases with latitude as predicted by Bergmann's rule, but no such effect occurs for the other two rats. There was a positive relationship between island size and the number of species inhabiting it, and some species combinations were more likely to occur than others. For example, R. exulans and R. norvegicus were more likely to occur together, while R. rattus and R. exulans were rarely sympatric. R. exulans and R. rattus skull size was negatively correlated with the number of other rodents on the same island. R. exulans skull size increased on smaller islands in some island groups, perhaps because increased density and consequent increased intraspecific competition on smaller islands favours increased body size. This effect is more pronounced in tropical islands (Solomon islands), than in subtropical ones (Hawaiian islands) and less so in temperate New Zealand. Collectively the data demonstrate that rapid evolution of body size in predictable directions can follow within 150 years of the introduction of species to new receiving communities.
Fleshy‐fruitedness in the New Zealand flora
Authors: Lord Janice
Published: March 2003

AimIt has been claimed that the New Zealand flora has an unusually high frequency of fleshy‐fruitedness. This paper tests whether fleshy‐fruitedness is indeed more common in New Zealand than in other temperate floras, then examines the distribution of fleshy‐fruitedness among taxa and floristic elements to determine whether the flora conforms to predictions for a continental island with a relictual floristic element. Lastly, I test the extent to which fleshy‐fruitedness has influenced colonization success and subsequent speciation within New Zealand.

MethodsInformation on fruit characteristics for all indigenous seed plants was extracted from the Flora of New Zealand series and analysed with χ2 tests.

ResultsContrary to previous claims fleshy‐fruitedness was not unusually common in the New Zealand flora as a whole, when compared with other temperate floras. It is only more common in alpine communities and among trees. I also found no evidence for selective immigration; fleshy‐fruited New Zealand genera were not more likely, than dry‐fruited genera, to also occur in Australia. Furthermore there is no evidence that the New Zealand environment has favoured fleshy‐fruited taxa; there has been no autochthonous evolution of fleshy‐fruitedness in New Zealand, fleshy‐fruitedness has had no significant effect on speciation within New Zealand, and endemic genera are no more likely to be fleshy‐fruited than nonendemic genera. Fleshy‐fruitedness in New Zealand is, however, strongly related to floristic elements of the flora. New Zealand is a continental island and therefore, theoretically, those elements of the flora dating from a time when the landmass was less isolated, should show a more balanced representation of dispersal modes. Contrary to this, fleshy‐fruitedness is more common among species in Gondwanan taxa or in taxa with pollen records dating to before the Miocene.

Main conclusionsFleshy‐fruitedness in New Zealand conforms to neither the expectations for an isolated landmasses, namely a disharmonic range of dispersal modes, nor expectations for a continental island. I suggest that this pattern may be a product of selective survival of highly vagile taxa in the low‐lying archipelago that was New Zealand during the late Cretaceous to mid‐Cenozoic, followed by an invasion by taxa with a broader range of dispersal modes facilitated by the establishment of the circumpolar current.
Characterization of the spatio‐temporal patterns of global fire activity using satellite imagery for the period April 1992 to March 1993
Authors: Dwyer Edward , Pereira José M. C. , Grégoire Jean‐Marie , DaCamara Carlos C.
Published: March 2003

Aim This paper describes the characteristics of the spatio‐temporal distribution of vegetation fires as detected from satellite data for the 12 months April 1992 to March 1993.

Location Fires are detected daily at a spatial resolution of 1 km for all land areas of the globe.

Methods From the fire location information a daily gridded product at 0.5° by 0.5° has been constructed. Two methods of characterizing the spatio‐temporal pattern of vegetation fires are discussed. The first applies empirical orthogonal function analysis to the monthly series of gridded data. The second approach defines and extracts a number of spatial and temporal parameters from the gridded product. The descriptive parameters extracted are used in a cluster analysis in order to group cells with similar characteristics into a small number of classes.

Results Using daily global satellite observations, it is possible to characterize the spatial and temporal variability in fire activity. Most of this variability is within the tropical belt, where the majority of fire activity is concentrated, nonetheless fire was also detected in temperate and boreal regions. The period in which fire occurred varied from region to region. Parameterization provided a very synthetic view of this variability facilitating regional intercomparison. Clustering identifies five classes of fire activity, each of which can be associated with particular climatic conditions, vegetation types and land‐use.

Main conclusions Global monitoring of vegetation fire from satellite is possible. The analysis provides a coherent, consistent and synoptic view of global fire activty with one data set. The type of information extracted can be of use in global atmospheric chemistry modelling and for studying the role of fire in relation to global change issues.
Genetic and morphometric diversity in Wallacea: geographical patterning in the horse shoe bat, Rhinolophus affinis
Authors: Maharadatunkamsi  , Hisheh S. , Kitchener D. J. , Schmitt L. H.
Published: March 2003

Genetic and morphometric variation was examined in eleven island populations of the horse‐shoe bat, Rhinolophus affinis, at the easterly end of this widespread species’ range and encompassing the Australian–Oriental biogeographic interface. Allozyme variation revealed mean heterozygosity levels within islands of 0.047, which is near the mammalian average. However, heterozygosity tended to decline from west to east as populations approached the periphery of the species’ distribution, and was lowest in those islands that were separated by the greatest sea‐crossing from source populations. There is extensive between‐island genetic differentiation (mean FST = 0.40) and relationships between islands are associated with their arrangement in geographical space; genetic distance is correlated with geographical distance and the genetic arrangement of islands is associated with longitude. The arrangement of islands as indicated by variation in body and skull metrics is also associated with their geographical positions, and the metric and genetic measures are themselves associated. While other taxa in the region have shown genetic‐geographical concordances, R. affinis is the only one that displays concordant patterns in metrical features. These patterns in biological diversity are interpreted as arising from the sequential island population structure and clines in key biogeographic gradients.
Geography of Pinus elliottii Engelm. and Pinus palustris Mill. leaf life‐spans in the southeastern U.S.A.
Authors: Holder Curtis D.
Published: March 2003

Aim Past studies have investigated differences in leaf life‐spans between deciduous and evergreen species. Environmental controls such as light, temperature, and nutrient and moisture availability explain differences in leaf life‐spans between species. This study examined intraspecific leaf life‐spans across climate and nutrient gradients within the geographical range of Pinus palustris Engelm (longleaf pine) and Pinus elliottii Mill. (slash pine).

Location Five study areas in the southeastern United States were selected along the north–south geographical range of Pinus elliottii and Pinus palustris.

Methods Leaf life‐span was calculated based on stand inventories and annual litterfall totals for each site, and allometric relationships between d.b.h. and foliar biomass.

Results Leaf life‐span of P. elliottii ranged from 1.28 to 1.95 years between sites. Leaf life‐span of P.palustris varied by nearly a factor of 5 between the study site with the lowest and highest value (0.58–2.49 years).
anova indicated that leaf life‐spans of P. elliottii were not significantly different among sites. In contrast,
anova indicated a significant difference for P. palustris leaf life‐spans among sites (P < 0.05). The Tukey multiple comparisons tests showed that 2 study areas were the only pair of P. palustris sites with a significant difference in leaf life‐spans.

Main conclusions The geographical variation in leaf life‐spans between two species illustrates the different phenotypic responses to environmental controls. The variation in leaf life‐spans by individuals of P. palustris across a geographical range illustrated in this study suggests that P. palustris may exhibit a greater phenotypic plasticity than P. elliottii.
Determinants of the northern and southern range limits of a warbler
Authors: Gross Sean J. , Price Trevor D.
Published: March 2003

Aim

To understand the determinants of range limits by studying the behaviour and ecology of a single species (the Hume’s leaf warbler, Phylloscopus humei) at both its northern and southern range limits.

Locations

North‐west India (Himachal Pradesh) and central India (Maharashtra).

Methods

We worked at seven locations primarily in the winter of 1997–98. Five locations spanned the northern range limit of the species and two were close to the southern range limit. We censused arthropod and bird abundance (including both the Hume’s leaf warbler and other ecologically similar species) at each site. We also studied the foraging behaviour of the common warbler species.

Results

Across the whole range of P. humei the abundance of arthropods is tightly correlated with the abundance of all warbler species. The northern range limit of P. humei coincides with the disappearance of arthropod food from its habitat (tree crowns), which is attributed to leaf loss associated with cold temperatures. Two closely related species, P. proregulus and Seicercus xanthoschistos have a northerly range limit beyond that of P. humei. They occupy the understory, which retains leaves and arthropods further north than do the tree crowns. The southern range limit of P. humei is associated with high food levels in its habitat, but also increasing numbers of a potential competitor, P. trochiloides, which is very similar in habits and also occupies the tree crowns, but is about 40% heavier. We attribute the decline of P. humei in the south to competition from P. trochiloides. Because food levels are high in the south, the mechanism of competition is likely to be interference, rather than exploitative.

Main conclusion

Competition for food is likely involved in setting both the northern and southern range limits, but in very different ways. The results are discussed in the light of current theories for the way range limits are ultimately determined.