bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regional‐scale spatial patterns of fire in relation to rainfall gradients in sub‐tropical mountains, NW Argentina
Authors: Grau Héctor Ricardo 
Published: March 2003

Abstract

Spatial patterns of burns are described using Landsat TM images from the sub‐tropical mountains of north‐west Argentina, over a span of 6 degrees of latitude, and a precipitation range from 250 to 1300 mm/yr. Burns were discriminated easily from unburnt vegetation, mainly by using infrared spectral bands from images taken at the end of the fire season of 1986.
Nineteen sampling units were defined on the basis of geographical proximity and relatively homogeneous rainfall as inferred from topography, and they were characterized in terms of percentage of burnt area and burn size distribution during one fire season. Regression and Correspondence Analysis were used to assess the relationship between rainfall and spatial descriptors of fire regime.
Burnt size area was log‐normally distributed with most fires in the small‐size classes. Of a total of 643 burns, the five largest (more than 2000 hectares each) represented about 30% of the total burnt area.
Percentage of burnt area, density of burns per unit area, and skewness of the burn‐size frequency distribution showed a unimodal pattern along the rainfall gradient, peaking between 700 and 900 mm/yr. Mean and maximum burn size showed a negative but weak correlation with rainfall. The first axis of a Correspondence Analysis ordination of sampling units, on the basis of different descriptors of spatial patterns of fire, was significantly correlated with the rainfall of the sampling unit.
The results suggest that climate is an important factor controlling fuel conditions and therefore fire regime at the spatial scale of this study, which includes different mountain ranges spanning ≈ 700 km.
Reproductive ecology and pollen representation among neotropical trees
Authors: Bush Mark B. , Rivera Robert 
Published: March 2003

AbstractThree years of pollen trapping data from Barro Colorado Island, Panama, are compared with local vegetation inventories. Two hypotheses relating pollen representation to ‘messy’ pollination and flower form are tested. Dioecious taxa were found to be over‐represented in pollen spectra compared with their occurrence in local forests. Similarly, anemophilous and ‘messy’ pollination types were found to be over‐represented. While anemophilous taxa were the best dispersed pollen types, zoophilous taxa were also well‐represented in dispersal classes of 20–40 m and > 40 m. Thus pollen arriving to lake sediments is most likely to be from anemophilous species or those zoophilous species exhibiting ‘messy’ pollination syndromes. Pollination mechanisms will predictably bias the fossil record against certain flower morphologies. These data are of significance to those using the fossil pollen record to reconstruct the timing and sequence of angiosperm evolution. These data help prioritize plants to be included in modern pollen reference collections and to focus the search for ‘unknown’ types on most‐likely candidate families.
Ecological life zones of Saint Lucia
Authors: Isaac Cornelius , Bourque Charles P.‐A. 
Published: March 2003

AbstractAimThe purpose of this study is to apply geographical information and artificial neural network (ANN) technologies in assessing ecosystem distribution on the island of Saint Lucia, as well as to develop an improved ecological classification using Holdridge’s system of natural life zones.LocationSaint Lucia is a Caribbean island state located at 14°N and 61°W and of a land area of 616 km2.MethodsThe main inputs for classifying life zones were a 25‐m × 25‐m digital elevation model of Saint Lucia (DEM), mean annual temperature and annual total precipitation. The DEM was initially obtained by digitizing contour lines on a topographic map. Elevation–temperature regressions developed for Puerto Rico were used to generate point‐estimates of mean temperature across the island of Saint Lucia. A generalized (trained) ANN was employed to create an annual total rainfall surface for the island. The variables of longitude, latitude and elevation were used to construct the rainfall model. Comparison of predicted and observed total precipitation revealed that the ANN explained over 95% of variability exhibited in the observed data, within a standard error of estimate of 123 mm (~6% of the total precipitation).ResultsThree complete and three transitional life zones were identified as occurring on Saint Lucia. Twelve per cent of the island was classified as tropical premontane moist/wet, 20% as tropical premontane wet, 6% as subtropical dry/moist, 29% as subtropical moist, 26% as subtropical moist/wet and 7% as subtropical wet.ConclusionQuality of life zone delineation depends on an objective application of universally accepted criteria and available terrain analysis technologies.
An introduction to the European Terrestrial Ecosystem Modelling Activity
Authors: Sykes Martin T. , Prentice I. Colin , Smith Benjamin , Cramer Wolfgang , Venevsky Sergey 
Published: March 2003

AbstractThe objective of the European Terrestrial Ecosystem Modelling Activity (ETEMA) was to address some of the major challenges in developing generalized models to examine responses of natural and seminatural ecosystems to environmental change at the regional to European scale. The approach described herein was to break down the totality of ecosystem functioning into its key components, each with its characteristic spatial and temporal scales. A conceptual framework was developed describing the configuration of these components as modules within a generalized simulation model. The framework describes the key inputs, outputs and state variables, their spatial and temporal contexts, and information flows between modules. The ‘backbone’ of the model is a system of nested timing loops corresponding to the disparate time scales at which different ecosystem processes occur. The framework is a theoretical construct into which ecosystem models at levels of complexity ranging from the very general to the highly detailed can be mapped, and thus provides a guide for development of models for novel, particularly regional‐scale, applications. A number of subsystem studies of the major components of ecosystem functioning, i.e. modules of the conceptual framework, are briefly introduced herein. The general aim of the subsystem studies was to identify the key alternative formulations (as opposed to minor variants) and test these against observational data. The various subsystem studies concern planetary boundary layer–ecosystem interactions, ecosystem CO2 and H2O fluxes, vegetation physiology and phenology, biogeography and vegetation dynamics, detritus and SOM dynamics, soil moisture and human and natural disturbances and, as individual papers, they complete this special ETEMA issue.
Geographical distributions of spiny pocket mice in South America: insights from predictive models
Authors: Anderson Robert P. , Gómez‐Laverde Marcela , Peterson A. Townsend 
Published: March 2003

AbstractAim Predictive models of species’ distributions use occurrence records and environmental data to produce a model of the species’ requirements and a map of its potential distribution. To determine regions of suitable environmental conditions and assess biogeographical questions regarding their ranges, we modelled the potential geographical distributions of two spiny pocket mice (Rodentia: Heteromyidae) in north‐western South America.Location North‐western South America.Methods We used the Genetic Algorithm for Rule‐Set Prediction (GARP), environmental data from GIS maps and georeferenced collection localities from a recent systematic review of Heteromys australis and H. anomalus to produce the models.Results GARP models indicate the potential presence of H. australis throughout mesic montane regions of north‐western South America, as well as in some lowland regions of moderately high precipitation. In contrast, H. anomalus is predicted to occur primarily in drier areas of the Caribbean coast and rain‐shadowed valleys of the Andes.Conclusions The models support the disjunct status of the population of H. australis in the Cordillera de Mérida, but predict a continuous distribution between known populations of H. anomalus in the upper Magdalena Valley and the Caribbean coast. Regions of suitable environmental conditions exist disjunct from known distributional areas for both species, suggesting possible historical restrictions to their ranges. This technique holds wide application to other study systems.
Are Alaskan trees found in locally more favourable sites in marginal areas?
Authors: Lennon Jack J. , Kunin William E. , Corne Simon , Carver Steve , Van Hees Willem W. S. 
Published: March 2003

AbstractAim Species generally become rarer and more patchily distributed as the margins of their ranges are approached. We predicted that in such marginal sites, tree species would tend to occur where some key environmental factors are at particularly favourable levels, compensating in part for the low overall suitability of marginal sites.Location The article considers the spatial distributions of trees in Southeast Alaska (the Alaskan ‘panhandle’).Methods We quantified range marginality using spatial distributions of eight tree species across more than one thousand surveyed sites in Southeast Alaska. For each species we derived a site core/margin index using a three‐dimensional trend surface generated from logistic regression on site coordinates. For each species, the relationships between the environmental factors slope, aspect and site marginality were then compared for occupied and unoccupied sets of sites.Results We found that site slope is important for more Alaskan tree species than aspect. Three out of eight had a significant core/margin by occupied/unoccupied interaction, tending to be present in significantly shallower‐sloped (more favourable) sites in the marginal areas than the simple core/margin trend predicted. For site aspect, one species had a significant interaction, selecting potentially more favourable northerly aspects in marginal areas. A finer‐scale analysis based on the same data came to the same overall conclusions.Conclusions There is evidence that several tree species in Alaska tend to occur in especially favourable sites in marginal areas. In these marginal areas, these species amplify habitat preferences shown in core areas.
Interspecific abundance–occupancy relationships of British mammals and birds: is it possible to explain the residual variation?
Authors: Holt Alison R. , Gaston Kevin J. 
Published: March 2003

ABSTRACTAimThe majority of studies concerning positive interspecific abundance–occupancy relationships have used broad‐scale and microcosm data to test the occurrence and correlates of the relationship to determine which of the proposed mechanisms give rise to it. It has been argued recently that studying the residual variation about abundance–occupancy relationships is a more logical analysis and may yield faster progress in identifying the relative roles of the mechanisms. However, to date this approach has been largely unsuccessful. Here we test if fundamental species traits such as the status (native and introduced), habitat and trophic group of mammal and bird species may explain any of the residual variation about their respective abundance–occupancy relationships.LocationThe study used British mammal and bird species.MethodsWe tested if species traits explained any of the variation about abundance–occupancy relationships using linear regression techniques both treating species as independent data points for analysis and controlling for phylogenetic association.ResultsNone of the species traits could explain any residual variation about the positive interspecific abundance–occupancy relationships of British mammals and birds. This applied both when treating species as independent data points and after controlling for phylogenetic association.ConclusionsGiven the lack of explanatory power of the species traits here and in other studies using this approach it seems that the variation about positive interspecific abundance–occupancy relationships is not explicable in a simple fashion. Predicting the likely influence of traits that are independent of phylogeny is also problematic. Therefore, the general utility of this approach and its future role in understanding the mechanisms causing positive interspecific abundance–occupancy relationships is doubtful.
Do placentation issues bias twin studies?
Authors: Phillips David 
Published: March 2003

AbstractBecause monozygous twins are almost genetically identical whereas dizygous twins are genetically no more similar than siblings, greater similarity between members of a monozygotic twin pair than between a dizygotic pair is usually taken as evidence that the condition or trait being studied has a genetic contribution. However, besides greater similarity of genes, monozygous pairs may share more similar environments than do dizygotic pairs. This environmental sharing may occur in fetal life where close placental relationships lead to more similar fetal environments. It may also occur postnatally. If the twins are of the same sex and look alike, the parents may dress, feed and in other ways treat the twins more similarly. Whereas the effects of a more similar postnatal environment have been explored by comparisons of twins raised together or separately, remarkably little is known about the influence of prenatal exposures.
Uses of twins in studying the genetics of complex traits
Authors: Spector Tim D. , MacGregor Alex J. , Snieder Harold 
Published: March 2003

AbstractTwins provide a useful and powerful tool for identifying genes, by acting as ideally matched sib‐pairs, but are also uniquely placed to measure the extent of their action, their expression and the nature of their interaction with the environment. Classical twin studies have provided insight into the relative genetic and environmental contribution to characteristics and diseases in human populations. The search for a more detailed understanding of genetic mechanisms through linkage and association has, however, traditionally been regarded as the province of other family designs. The last few years have seen a resurgence of interest in twin research following an increasing awareness that the study of twins can also provide an important contribution to localizing and understanding the function of specific genes.1 In this brief overview, we focus on these newer developments that are currently being applied in the search to uncover the genetic basis of disease.
Fine‐scale mapping of disease loci
Authors: Whittaker J. C. , Morris A. P. , Balding D. J. 
Published: March 2003

AbstractWe review the issues involved in the fine‐scale mapping of disease loci via allelic association. We argue that it is vital to properly account for uncertainty about the genealogy of the disease locus and founding haplotypes at the surrounding markers: we sketch how this might be done in a Bayesian framework using Markov chain Monte Carlo tecniques, and show that this works well for the much analysed data on the location of the Δ508 mutation for cystic fibrosis.
The use of Mx for association and linkage analysis
Authors: Neale Michael C. 
Published: March 2003

AbstractEvidence for genetic linkage, obtained from a correlation between phenotypic similarity and genetic similarity at a specific chromosomal location typically yields a broad genomic region in which a candidate locus might be found. Evidence for association is usually gathered from case control studies and is subject to false positives from phenomena such as population stratification. Data from relatives may be used to distinguish population stratification from genuine allelic effects in an association context. Of special interest is joint linkage and association which may be used for fine mapping because evidence for linkage will be reduced in the presence of evidence for association. This article describes the implementation of these methods using Mx, in both path diagram and script formats, and discusses a number of possible extensions to the model.
Challenges for genetic analysis in the 21st century: localizing and characterizing genes for common complex diseases and their quantitative risk factors
Authors: Almasy L. , Blangero J. 
Published: March 2003

AbstractThe optimal study design and method of analysis for genetic studies of complex traits have received much attention of late. Most previous works on this topic have assumed that investigators will study a single focal disease trait. In this paper, we approach the question of study design from the perspective of the inherently multivariate study which includes a variety of quantitative risk factors as well as one or more common complex disease traits. We conclude that a sample of randomly ascertained extended pedigrees provides both analytical power and flexibility, permitting profitable investigation of numerous traits using both linkage and linkage‐disequilibrium based methods.
A new approach to prioritizing marine fish and shellfish populations for conservation
Authors: Nielsen Einar Eg , Kenchington Ellen 
Published: March 2003

AbstractThere has been increasing awareness of the vulnerability of marine organisms to population extirpation and species extinction. While very few documented cases of species extinction exist in the marine environment, it is anticipated that managers will face the dilemma of prioritizing populations of marine fish and shellfish for protection in the near future. Current prioritization procedures have been developed from salmonid models with the intent of applying them to all marine organisms, and in some cases to freshwater and terrestrial taxa. In this review we provide evidence for the relevance of such a process for marine species and further suggest five broad categories of marine organisms that have distinctive traits influencing their genetic structure. The current prioritization models have been adapted to account for each of these species groups. Emphasis is placed on ‘Classical Marine Species’ which represent the opposite end of the continuum from the salmon model, displaying high within‐population genetic variance. From this category, three cod (Gadus morhua) stocks were selected to evaluate a revised scheme developed specifically for ‘Classical Marine Species’ that includes performance measures such as (i) reduction in number of spawning populations; (ii) reduction of Ne : Nc (ratio of effective to census population size); (iii) changes in life‐history traits; (iv) critical density for spawning success; and (v) patchy vs. continuous distribution pattern. When the salmonid scheme was applied, the cod examples were allocated low values, indicating that they were not under threat. However, when the revised scheme was applied, all three cod stocks were allocated high values, indicating that the revised scheme was more reflective of the particular life‐history traits of this category of organisms.
Co‐management without involvement: the plight of fishing communities
Authors: Schreiber Dorothee K 
Published: March 2003

AbstractThis paper discusses the role of fishing communities in the stewardship of their adjacent fish resources, and the benefits associated with community participation in co‐management. Contrary to the view of most fisheries management agencies, local communities are able to design institutions that can successfully restore equity and limit access to the fishery. The dismissal of local concerns may be at the root of biological and social crises in fisheries, and the privatization of common fishing rights world‐wide through individual transferable quotas (ITQs) is contributing to these problems. Community involvement that is embedded into a network of management at larger spatial scales would allow fishing communities to regain some control over their livelihoods. Meaningful co‐management arrangements must go beyond consultation by redirecting the flow of social and economic benefits from the fishery back into communities. Unless geographically defined communities are allowed to share power and responsibility with government fisheries managers, both fish stocks and fishing as a way of life are in danger of vanishing.
An introduction to species concepts and speciation of fishes
Authors: Ruffing Renea A , Kocovsky Patrick M , Stauffer Jay R 
Published: March 2003

AbstractMore than 22 different species concepts have been proposed. The concepts in general reflect the philosophical outlook, particular expertise, and the groups on which the authors are working. The full‐length papers in this special issue dedicated to species concepts relative to fishes are based on presentations by the authors at the 2001 annual meeting of the American Society of Ichthyologists and Herpetologists at University Park, Pennsylvania, USA and generated much discussion on the topic of what constitutes a species.
Dementia in people with learning disability: a preliminary study into care staff knowledge and attributions
Authors: Whitehouse Richard , Chamberlain Paul , Tunna Kate 
Published: March 2003

SummaryThe present paper describes the findings of a pilot study funded by the NHS Executive Primary and Community Care Research Initiative Small Projects Scheme that investigated the knowledge and attributions of dementia held by care staff who work with older adults with learning disability. Meetings took place with 21 members of care staff identified as keyworkers to older adults with learning disability living in residential houses provided by Solihull Healthcare NHS Trust, Solihull, UK. The results suggest that staff have knowledge of ageing at a similar level to that of college students. Forgetfulness was the sign that they would most expect to see if they thought someone was suffering from dementia. When a change in behaviour was attributed to dementia, it was most likely to be viewed as ‘stable, uncontrollable’ with staff feeling pessimistic about being able to change the behaviour.
Over the top? Reducing staff training in physical interventions
Authors: Kaye Neil , Allen David 
Published: March 2003

SummaryThe use of emergency physical interventions on an acute admission unit for persons with learning disability and challenging behaviour was monitored over a 9‐month period. Only a minority of the physical interventions that were taught to staff were actually used in practice. Possible reasons for this discrepancy are discussed, and a number of potential sources of bias in estimating the original training requirements for the service identified. Implications for changing the training programme are described.