bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental impact studies on marine communities: Pragmatical considerations
Authors: WARWICK R. M. 
Published: July 2006

Abstract
The measurement of changes in the structure of natural marine communities is widely used for the detection and monitoring of man's impact on the sea. Such studies are almost always a compromise between the scientific ideal and political, financial and logistical constraints. This paper considers a number of these constraints, suggests some possible solutions, and discusses the consequences (in terms of loss of information) of adopting strategies which might be considered suboptimal.Identification of all organisms in a community to species level is a major time and cost constraint. Many recent studies have shown that very little information is lost by working at a taxonomic level higher than species (e.g. family or even phylum). This implies a functional coherence of species within each higher taxon. Indeed, there are theoretical reasons, and some empirical evidence, for supposing that community responses to human perturbations may be more easily detected above the noise of natural variability by working at high taxonomic levels.Many environmental impacts, for example oil spillages from tankers, are accidental and it is unusual to have the luxury of a time‐series of data from the site prior to the incident. Good spatial control samples may also be difficult to obtain in a heterogeneous environment. Absolute rather than comparative measures of community degradation are valuable in this context. Methods which fall into this category include comparisons of community structure with some theoretical expectation or with empirical‘training’ data, comparing attributes of community structure that respond differently to perturbation, or identifying highly conservative properties of unperturbed communities that are modified in a predictable way by perturbation.All studies are selective with regard to which components and attributes of the biota should be investigated. The choice frequently depends on local expertise and research interests, rather than on an objective decision about what biological data are most appropriate for the problem in hand. The paper concludes by a discussion of the relative merits of the various alternatives.
Population‐biomass dynamics and the absence of ‐ 3/2 self‐thinning in the clonal weed Salvinia molesta
Authors: ROOM P. M. , JULIEN M. H. 
Published: July 2006

Abstract
In the field, the population density (n) of crowded, living ramets of Salvinia molesta ranged from 2500 m −2 in nutrient‐poor water to more than 30 000 m−2 in nutrient‐rich water. Biomass of living shoots (B) in some localities exceeded 600 gm−2 dry weight (150 tonnes ha−1 fresh weight) and shoots plus roots of living and floating dead material exceeded 1600 gm−2 dry weight (400 tonnes ha−1 fresh weight). The ultimate limit B= 105n0.5 suggested by previous authors was not exceeded. The highest n and smallest ramets occurred in nutrient‐rich water and B was a linear function of n. Field experiments confirmed no effect of n, but a strong effect of nutrient availability, on ramet weight.In a glasshouse experiment, ramet populations did not ‘self‐thin’ along the log log B‐n trajectory of slope ‐0.5, which has been suggested for aclonal plants, but followed trajectories having slopes closer to +1.0 before halting at the ambient B‐n limit. Nutrient concentrations in the plants increased during the experiment, causing ramet size to decrease and slopes of log log B‐n trajectories to depart from +1.0 by amounts which reflected the degree to which nutrient concentration had changed. Under constant conditions, mean ramet size is expected to remain constant and log log B‐n trajectories to travel in a straight line of slope +1.0 to the ambient B‐n limit. This behaviour of salvinia, whose ramets consist of a single structural module, is contrasted with that expected of clonal plants whose ramets are made up of multiple structural modules.A logistic model explained the increases in n and biomass of living and dead ramets when ramets were assumed to have constant longevity, constant time to decay, and when both the B‐n limit and size of ramets were dependent on nitrogen content of the plant. There was no indication that physiological integration within phenets halted production of new ramets when carrying capacity was reached and new ramets continued to be produced on top of older ramets. Rates of ramet mortality were equal to, and dependent on, rates of ramet natality.
Biological guidelines for freshwater sediment based on BEnthic Assessment of SedimenT (the BEAST) using a multivariate approach for predicting biological state
Authors: REYNOLDSON TREFOR B. , BAILEY R. C. , DAY K. E. , NORRIS R. H. 
Published: July 2006

Abstract
This paper describes the first results for an alternative approach to the development of sediment quality criteria in the nearshore areas of the Laurentian Great Lakes. The approach is derived from methods developed in the United Kingdom for establishing predictive relationships between macroinvertebrate fauna and the physico‐chemistry of riverine environments. The technique involves a multivariate statistical approach using (i) data on the structure of benthic invertebrate communities, (ii) functional responses (survival, growth and reproduction) in four sediment toxicity tests (bioassays) with benthic invertebrates; and (iii) selected environmental variables at 96 reference (‘clean’) sites in the nearshore areas of all five Great Lakes (Lakes Superior, Huron, Erie, Ontario and Michigan). Two pattern recognition techniques (using the computer software package PATN) are employed in the analysis: cluster analysis and ordination. The ordination vector scores from the original axes of the pattern analysis are correlated (using CORR in SAS) with environmental variables which are anticipated to be least affected by anthropogenic activities (e. g. alkalinity, depth, silt, sodium etc.). Multiple discriminant analysis (MDA) is used to relate the site groupings from the pattern analysis to the environmental variables and to generate a model that can be used to predict community assemblages and functional responses at new sites with unknown but potential contamination. The predicted community assemblages and functional responses are then compared with the actual benthic communities and responses at a site, and the need for remedial action is determined.The predictive capability of the discriminant model was confirmed by performing several validation runs on subsets of the data. An example of the use of the model for sediment in Collingwood Bay (an area of concern designated by the IJC in Georgian Bay, Lake Huron) is presented and the technique is shown to be more precise in determining the need for remediation than the currently used provincial sediment quality criteria based on Screening Level Concentration (SLC) and laboratory toxicity tests. The ultimate goal of the study is the development of a method to determine the need for, and the success of, remedial action and to predict what benthic communities should look like at a site if it were clean and what responses of organisms in sediment toxicity tests constitute an acceptable end‐point.
Plant coexistence in coastal heaths: Floristic patterns and species attributes
Authors: MYERSCOUGH P. J. , CLARKE P. J. , SKELTON N. J. 
Published: July 2006

Abstract
An investigation was made of plant coexistence in coastal heaths. A 4 km stretch of Pleistocene beach sand was selected, and patterns of variation in heath vegetation on ridges and slopes in the beach system were studied. The sampling design covered variation with geographic distance among transects, plots within transects and quadrats within plots which were orthogonal to the alignment of ridges and slopes. Cover of vascular plant species was scored within each quadrat and both multivariate and univariate analyses tested the hypothesis that variation in the data was associated with environmental difference and geographic distance. There was a strong flohstic variation between the ridge and slope habitats. However, within these habitats there was no significant variation with distance at scales of kilometres, nor at hundreds of metres within transects nor at tens of metres within plots in floristic composition, in numbers of species, and in cover. Though differing floristically, the vegetation of the slopes and ridges had similar curves of importance values and fairly similar spectra of life forms and forms of post‐fire regeneration in their constituent species, although the ridges had slightly more obligate‐seeding species and fewer species of sedges and herbs than the slopes. The two habitats shared several genera, however, within such genera, species with similar attributes mostly occurred in different habitats.Hypotheses were suggested to explain segregation of species between the two habitats and the coexistence of species within habitats. Since patterns of variation among habitats were consistent over both smaller and larger scales of distance examined, experiments to test hypotheses may be designed so that their findings might be applied generally to the whole system studied.
The distribution and abundance of barnacles in a mangrove forest
Authors: ROSS P. M. , UNDERWOOD A. J. 
Published: July 2006

Abstract
The grey mangrove tree, Avicennia marina, forms a hard substratum in an area otherwise dominated by soft‐sediment. Various intertidal organisms attach to and move about on the trees. The abundant barnacles Elminius covenus, Hexaminius popeiana and Hexaminius foliorum live on a variety of substrata in mangrove forests. Their patterns of distribution and abundance were recorded and models proposed to explain these patterns. Densities of barnacles on bark, leaves and twigs of A. marina were estimated in a locality near Sydney. Elminius covenus were more abundant on bark than on leaves or twigs of A. marina. Hexaminius popeiana, although less abundant on bark than E. covenus, were not found on twigs or leaves. In contrast, H. foliorum were more abundant on twigs than leaves and were not found on the bark of A. marina. Densities of barnacles were greater in the seaward than in landward parts of the forest. Elminius covenus were the most abundant barnacles, H. foliorum were less abundant and H. popeiana were virtually absent in the landward zone. Barnacles in the seaward zone were most abundant at mid‐tidal levels, less at high and low tidal levels of trunks and more abundant on lower than upper surfaces of trunks and leaves. The densities of barnacles differed according to the orientation of the bark or leaf.Models are proposed to explain the patterns of distribution and abundance of these barnacles. Each involves larval supply, settlement and post‐settlement mortality. It is concluded that similar processes determining patterns of distribution and abundance for sessile organisms living on rock platforms may be applicable to sessile organisms living in the very different habitats of mangrove forests.
Resilience of an Australian savanna grassland to selective and non‐selective perturbations
Authors: WALKER B. H. , LANGRIDGE J. L. , McFARLANE F. 
Published: July 2006

Abstract
Using a randomized experimental design, plots of a savanna grassland were subjected to two levels of grass tuft removal (50% and 90%) in two ways; non‐selective (all species removed in proportion to abundance) and selective (tufts of the most palatable species removed first, then the next most palatable, etc.). The plots were maintained in their cleared states for three years, then monitored for the next five. In general, the sward was resilient to the disturbance except for the 90% selectively cleared treatment, in which a dominant, palatable species (Themeda triandra) failed to recover (though die most palatable species, Sorghum plumosum, did recover). The recovery patterns were dependent on post‐disturbance conditions, and markedly influenced by a particular rainy season and a fire during one of the dry seasons. In addition to species effects, the treatments induced changes in spatial patterning and associated micro‐scale hydrology. These effects persisted in the 90% removal treatment. In this regard the results are scale‐dependent, and the same percentage removals at different scales (e. g. 5 × 5 m patches rather than tuft × tuft scale) would lead to differences in ability to recover. In terms of value to livestock the selective 90% removal treatment was in a poor state at the end of die experiment.In all treatments die trajectory of species changes was back towards the controls, but the selective 90% plots were fully re‐vegetated before this could be achieved. In these plots, the final steps to complete recovery will occur only after death of established new tufts.
A LONG RUN ECONOMIC EFFECT ANALYSIS OF ALTERNATIVE TRANSPORTATION FACILITY PLANS—REGIONAL AND NATIONAL
Authors: Amano Kozo , Fujita Masahisa 
Published: July 2006

CONCLUSIONInitially we explained the main part of our model which enabled us to estimate and compare the long run and global economic effects of alternative transportation facility plans.Usually the short run effects of this kind of regional economic impact have been analyzed by input‐output models, and the long run effects by econometric models. However, in this model, the input‐output model and the econometric model were combined so as to enable us to analyze the global and long run economic effects. The interregional trade pattern coefficients and input coefficients change endogenously in each year in this model. It has previously been assumed that the fixedness of interregional trade pattern coefficients and input coefficients are the weakest points in applying the interregional input‐output model for long run studies. In our model, on the contrary, variation of these coefficients has central importance.We then showed the results which were obtained from applying this model to a comparison of the long run economic effects of alternative bridge construction plans over the Japan Inland Sea. The results obtained from this demonstrative calculation are reasonable. Thus, we think, this model has sufficient applicability to the comparison of economic effects of alternative plans for nationwide transportation facility improvement. However, the variations of production cost differentials between regions are given exogenously in this model. To make them endogenous, agglomeration economies should be considered more precisely. In that case, the applicability and the precision of this model could be improved.
A BENEFIT‐COST ANALYSIS OF A REGIONAL DEVELOPMENT INCENTIVE: STATE LOANS*
Authors: Sazama Gerald W. 
Published: July 2006

The luster of economic growth, the existence of depressed regions, and the fear of competition from giveaway programs in other states have all resulted in state governments adopting a rash of programs designed to encourage a strong manufacturing base for their economy.Many economists feel uneasy about the rapid spread of such industrial incentive programs as tax breaks, government loans, and industrial revenue bonds.1 The literature of public finance, development, and regional economics contains many interesting studies examining the wisdom of these undertakings. This paper hopes to contribute by developing a method of benefit‐cost analysis for appraisal of industrial incentive programs. Even though the model is constructed for and applied to the analysis of state government industrial development loans, the principles formulated should be easily adaptable to the assessment of other types of regional development programs.A secondary objective of the paper is to discuss the first empirical application of a model which accounts for possible differences between the social opportunity cost of foregone investment and that of foregone consumption.2
THE OPTIMAL CONVERGENCE OF REGIONAL INCOMES*
Authors: Persky Joseph J. , Tam Mo‐Yin S. 
Published: July 2006

ABSTRACTFor many policy considerations it is assumed that the convergence of regional mean income will improve national equity by reducing overall inequality. The literature on decomposability of social welfare functions implies that this assumption is unwarranted. This paper develops a notion of optimal regional convergence. In general, the point of optimal convergence depends on the shapes of the regional income distributions, the inequality index used, and the rule for distributing interregional transfers. These concepts are illustrated with data on the regional income distributions of the Southern and Northern United States.
A NEOCLASSICAL MODEL OF REGIONAL GROWTH IN INDONESIA
Authors: Giarratani Frank , Soeroso  
Published: July 2006

ABSTRACTIn this paper a neoclassical model of regional growth is specified, estimated, and applied to the provinces of Indonesia. While parametric estimates indicate that factors of production respond as expected to neoclassical incentives, the attractiveness of growing regions for capital and labor inputs leads to instability and divergence among regions when the model is solved dynamically. A simulation of government intervention via a policy of encouraging capital growth in lagging regions demonstrates the potential of reversing such effects and encouraging regional convergence.
THE CHANGING STRUCTURE OF A CITY TEMPORAL CHANGES IN CUBIC SPLINE URBAN DENSITY PATTERNS*
Authors: Anderson John E. 
Published: July 2006

ABSTRACTUsing the basic summary of urban structure given by the population density function, this paper estimates changes which have occurred in the structure of the Detroit metropolitan area during the past two decades. Both overall density changes and direction‐specific changes are estimated using census data and the method of cubic spline regression. The results give more revealing insight into the structural changes which have occurred in the city than has been possible with traditional models of urban population density.
A NOTE ON NEIGHBORHOOD SIZE AND THE MEASUREMENT OF SEGREGATION INDICES*
Authors: Goodman Allen C. 
Published: July 2006

ABSTRACTThis note examines neighborhood segregation measures with respect to size and validity. Conventional measures, while related to within‐neighborhood homogeneity, are not necessarily related to neighborhood size. An empirical test examines racial segregation for Baltimore in 1970 and 1980 using both census tract and specially formulated neighborhood aggregates. For both years, and for all measures of segregation, the values and trends are essentially unchanged by the level of aggregation.
CASINO GAMBLING AS A “GROWTH POLE” STRATEGY AND ITS EFFECT ON CRIME*
Authors: Friedman Joseph , Hakim Simon , Weinblatt J. 
Published: July 2006

ABSTRACTCasinos are often considered as a “growth pole” strategy to revitalize dilapidated regions. However, voters often reject casinos due to their perceived adverse impact on crime.Using a quasi‐experimental design we analyze the impact of the casinos on crime spillover from Atlantic City to other localities in the region. We found that the level of crime in localities adjacent to Atlantic City and along the major nontoll routes to Philadelphia and New York City up to approximately 30 miles from Atlantic City rose significantly following the introduction of casinos. Crime levels are higher than they would have been in the absence of casinos.
NETWORK LOADING VERSUS EQUILIBRIUM ESTIMATION OF THE STOCHASTIC ROUTE CHOICE MODEL MAXIMUM LIKELIHOOD AND LEAST SQUARES REVISITED*
Authors: Anas Alex , Kim Ikki 
Published: July 2006

ABSTRACTDaganzo (1977, 1979), Daganzo and Sheffi (1977), Sheffi (1985), and Sheffi and Daganzo (1980) have used one assumption about traveler behavior in developing estimation techniques for the stochastic route‐choice problem and another assumption in predicting flows on networks by using the same model. In estimation, they calculate the congested travel costs of the network links from observed flows on the network, and the network is loaded based on these costs. In prediction, they follow their stochastic user‐equilibrium assumption by which travelers evaluate costs using the mean of the observed flows (or equilibrium flows). The travel‐cost coefficient obtained from the loading method systematically overestimates the true travel‐cost coefficient from which the observed flow data (which must be used in loading) is generated. The estimates of the same coefficient, obtained in this paper, by constraining the estimation results to conform to the equilibrium conditions are unbiased, and only marginally less efficient (have larger standard deviations). The average percentage error and inefficiency of the link flow predictions based on the loading method increases as the level of congestion on the network rises. In contrast, the average percentage error of link flow predictions based on the equilibrium estimation method declines and their efficiency remains very high as the level of congestion on the network rises.
SPATIAL DEPENDENCE AND SPATIAL STRUCTURAL INSTABILITY IN APPLIED REGRESSION ANALYSIS*
Authors: Anselin Luc 
Published: July 2006

ABSTRACTThe stability of regression coefficients over the observation set (“regional homogeneity”) is typically assessed by means of a Chow test or within a seemingly unrelated regression (SUR) framework. When spatial error autocorrelation is present in cross‐sectional equations the traditional tests are no longer applicable. I evaluate this both in formal terms as well as empirically. I introduce a taxonomy of spatial effects in models for structural instability, and discuss its implication for testing. I compare the performance of traditional tests, robust approaches, maximum‐likelihood procedures and pretest techniques by means of a series of simple Monte Carlo experiments.
THE SENSITIVITY OF INPUT‐OUTPUT MULTIPLIERS*
Authors: Dietzenbacher Erik 
Published: July 2006

ABSTRACTThe present paper derives analytical expressions for the sensitivity of input‐output multipliers to errors in the data. The effects on the simple output multipliers are investigated for additive errors, multiplicative errors in the columns, multiplicative errors in the rows, error rectangles, the error couple and the single error, and price changes. In contrast to earlier investigations, the results are not obtained from the Leontief inverse. The present approach focusses on the effects of errors on the eigenvector corresponding to the dominant eigenvalue. It is indicated how similar expressions may be derived for several other multipliers.
DERIVATIVES OF FLOWS IN A DOUBLY CONSTRAINED GRAVITY MODEL
Authors: Bröcker Johannes 
Published: July 2006

ABSTRACTFor many practical applications it is important to know how the flows in a doubly constrained gravity model react to slight variations in the predetermined marginal totals. The first‐order approximation of these variations is a linear function on the set of feasible variations of marginal totals, i.e., the set of variations not violating the consistency constraint of the model. Several methods to find a matrix describing this linear function are developed and compared with former contributions to this issue. Finally, applicability of the methods to sensitivity and error propagation analysis is demonstrated.
THE IMPACT OF UNEMPLOYMENT INSURANCE BENEFITS ON THE PROBABILITY OF MIGRATION OF THE UNEMPLOYED*
Authors: Goss Ernie , Paul Chris 
Published: July 2006

ABSTRACTBy ignoring individual unemployment compensation benefits and conditions of job termination, past migration research has concluded that personal unemployment doubles the likelihood of interstate labor‐force migration. Findings from the present study indicate that aggregating the unemployed, without adjusting for these two factors, overstates the probability of migration for the involuntarily unemployed benefit recipient and understates the likelihood of migration for the voluntarily unemployed benefit recipient. The results suggest that federal discretionary unemployment‐compensation programs, which are implemented during recessionary periods, likely serve to retard out‐migration of those who are involuntarily unemployed.