bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative ecology of Varanus in the Great Victoria Desert
Authors: PIANKA ERIC R.
Published: July 2006

Abstract
The ecologies of seven desert species of monitor lizards (Varanus), which are very variable in size, are described and compared. Data are reported on abundance, anatomy, behaviour, body temperature relationships, daily activity patterns, diet, growth, habitat and microhabitat, prey size, reproduction, seasonal patterns of activity, sexual dimorphisms, and tracks. As many as six of the seven species occur together in sympatry at one study site. New results reported here are merged with extensive data collected over the past quarter of a century to provide a comprehensive and detailed overview of numerous aspects of the natural history and ecology of the seven species in the Great Victoria Desert. One species of pygmy monitor has evolved large clutch size for unknown reasons. A food web for 40 species of desert lizards is presented. Hutchinsonian ratios of head lengths (larger/smaller) are significantly greater in two observed assemblages of sympatric varanids than in a null model consisting of all possible pairs of species of all Australian varanids. Evolution of body size and the two adaptive radiations of Varanus in Australia are discussed.
Phosphorus and nitrogen in wetlands with and without egret colonies
Authors: BAXTER G. S. , FAIRWEATHER P. G.
Published: July 2006

Abstract
Colonially nesting birds have been implicated in the destruction of their nest site vegetation, the most likely mechanism being through an overload or imbalance of soil nutrients. The numbers of egrets in coastal New South Wales colonies have increased rapidly in the second half of this century since cattle egrets (Ardeola ibis) were introduced. This species now nests colonially with three native species: great (Egretta alba), intermediate (Egretta intermedia) and little egrets (Egretta garzetta). Thus there is potential for more rapid degradation of the colony site. We measured the levels of phosphorus in surface sediments, and phosphorus and nitrogen in water at eight colony site wetlands, and compared each to four other wetlands in the same region where there were no egret colonies. We conclude that levels of both nutrients were elevated in colony wetlands. The implications of this result for death of colony site vegetation and the conservation of the three native egret species are briefly discussed.
Anodopetalum biglandulosum: Growth form and abundance in Tasmanian rainforest
Authors: BARKER P. C. J. , BROWN M. J.
Published: July 2006

Abstract
Anodopetalum biglandulosum grows in a variety of habits in Tasmanian rainforest. Forty‐eight stands were classified to produce a typology of growth forms for the species. The species has a fundamentally deterministic growth form and exhibits a variety of responses to canopy disruption. The responses are related to community floristics, forest structure and the disturbance regime. The roles of canopy proliferation and clonal spread were investigated for their ecological significance. In some forests A. biglandulosum may dominate the regrowth after tree‐fall, resulting in a late successional shift in the forest structure.
An assessment of the colonizing ability of Emex australis
Authors: PANETTA F. D. , RANDALL R. P.
Published: July 2006

Abstract
Experimental introductions of the annual Emex australis were made in two consecutive years at each of three sites in southern Western Australia. Introductions differed in relation to the numbers of seeds involved (n = 1, 2,4, 8 or 16) and whether seeds were buried or surface sown. Fates of the introductions were monitored for 30 months. Successful introductions were defined as those where at least one viable seed was produced. Generally, introduction success increased with the number of seeds involved and with seed burial. However, major departures from these trends were observed at one site in the second set of introductions.

Most recruitment and most seed production occurred during the first growing season following introduction. The number of seeds produced over the 30 month period usually increased with increasing size of introduction. The year of introduction was a highly significant determinant of seed production. Since seedling mortality was low throughout this study, processes affecting seed burial and seed mortality are considered to be the major stochastic factors that influence the colonizing success of Emex australis.
Mortality of Eucalyptus marginata (jarrah) seedlings in Mediterranean‐climate forest in response to overstorey, site, seedbed, fertilizer application and grazing
Authors: STONEMAN G. L. , DELL B. , TURNER N. C.
Published: July 2006

Abstract
The effects of overstorey, site, seedbed, seedling density, application of fertilizer and grazing on mortality of Eucalyptus marginata (jarrah) seedlings were studied experimentally in the northern jarrah forest of Western Australia. Rainfall, soil temperature, soil water deficits, leaf water potentials and photosynthetically active radiation (PAR) were monitored. Seedlings on sites with the overstorey removed experienced significantly higher soil temperatures for 9 months of the year (of up to 6°C), smaller soil and leaf water deficits during the dry season (minimum predawn leaf water potentials of ‐0.5 MPa compared to ‐1.6 MPa) and higher intensities of PAR (maximum values of 1900 umol m−2 s1 compared to 900 umol m−2 s−1), compared to seedlings on sites with the overstorey retained. Mortality off. marginata seedlings was greater on sites where the overstorey was retained compared to where the overstorey was removed, on low quality sites than high quality sites, and on undisturbed and lightly disturbed seedbeds compared to heavily disturbed seedbeds. Seedling density, application of fertilizer and grazing by vertebrates did not have a significant effect on percentage mortality. Most of the mortality occurred as water deficits developed in late spring and summer and was attributed to these water deficits. Some mortality that occurred prior to the development of substantial water deficits was probably caused by pathogenic fungi, We conclude that mortality of E. marginata seedlings in the northern jarrah forest of Western Australia can be minimized by reducing the density of the overstorey and by seeding into a seedbed that has had litter and groundcover removed and the soil disturbed.
Measuring the impact of sewage effluent on the macroinvertebrate community of an upland stream: The effect of different levels of taxonomic resolution and quantification
Authors: WRIGHT IAN A. , CHESSMAN BRUCE C. , FAIRWEATHER PETER G. , BENSON LEE J.
Published: July 2006

Abstract
Benthic macroinvertebrates were sampled from four sites on upland streams in the Wentworth Falls area of the Blue Mountains, NSW. One site received effluent from a sewage treatment plant and the others were reference sites. Five replicate collections were taken from each site on four occasions at intervals of 3 months. Macroinvertebrate community data were analysed using univariate (ANOVA) and multivariate (NMDS) techniques and comparisons were made between analyses at different levels of taxonomic aggregation and using different methods of data transformation. Similar patterns were observed at both species and family levels, and even the order level showed a clear community response to effluent input. Binary (presence/ absence) data provided similar results to quantitative data for the species and family levels. However, when binary data were used at the order level, the distinctions between the reference sites became blurred. We discuss the implications of these findings for environmental monitoring.
Detection of mining impacts on aquatic macroinvertebrate communities: Results of a disturbance experiment and the design of a multivariate BACIP monitoring programme at Coronation Hill, Northern Territory
Authors: FAITH D. P. , DOSTINE P. L. , HUMPHREY C. L.
Published: July 2006

Abstract
Multivariate methods for the detection of impacts on communities are: (i) explored in the context of a disturbance experiment at a site of previous uranium mining in Kakadu National Park, Northern Territory; and (ii) applied to the design of a monitoring programme for a proposed mining development at nearby Coronation Hill. The disturbance experiment in Rockhole Mine Creek used a gravity‐fed redirection of polluted water from the mine adit to create a point‐source pollutant. Weekly samples of the macroinvertebrate communities were taken both before and after disturbance at the control and‘impact’ site, as part of a multivariate BACIP (Before‐After‐Control‐Impact‐Pairs) design. The results of the experiment show that the multivariate approach provided high sensitivity in detecting impacts on the community, with little difference in sensitivity between species and family level analyses. A simple procedure for deleting those taxa that show poor discrimination between pristine and presently disturbed areas further increased the sensitivity of the tests. In addition to the BACIP analyses, robust ordination of the community data suggested a time/treatment interaction effect.

Application of the multivariate BACIP approach also was explored using baseline data for benthic communities from the South Alligator River near Coronation Hill. The method provides high statistical power for monitoring; a relatively small change in community dissimilarity would be detectable in a programme with 5 years of observations before and after commencement of mining. A robust ordination of the yearly samples for the control and potential‐impact sites showed that, although samples varied along identifiable gradients over time, the two areas changed in parallel so that the difference between the areas was approximately constant over years. This result demonstrates that the multivariate BACIP approach can provide relative constancy of pre‐impact difference values, a key requirement of BACIP designs that is difficult to satisfy using abundance data for a single species.
Optimal digestive strategies for arboreal herbivorous mammals in contrasting forest types: Why Koalas and Colobines are different
Authors: CORK STEVEN J.
Published: July 2006

Abstract
The eucalypt forests of temperate eastern Australia contrast with many forests in tropical Australia, Asia, Africa and Central America in terms of degrees of sclerophylly, concentrations of nutrients in foliage, types and amounts of chemical challenges posed for herbivores, and the range of alternatives to foliage as food. Comparisons between digestive strategies employed by arboreal herbivorous marsupials and primates inhabiting these forests reveal several trends: (i) foregut‐fermenters occur only in tropical and sub‐tropical forests, whereas caecum and caecum‐colon fermenters occur in both temperate eucalypt and the tropical forests; (ii) the arboreal marsupials and primates (koalas, greater gliders, ringtail possums and sportive lemurs) that are the most folivorous are caecum or caecum‐colon fermenters with colonic specializations for selective retention of small panicles of digesta; (iii) no caecum or caecum‐ colon fermenters lacking colonic separation mechanisms achieve consistently high degrees of folivory; (iv) even the most folivorous foregut‐fermenting arboreal marsupials (tree kangaroos) or primates (colobus monkeys) include a substantial proportion of high‐quality components (fruits or seeds) in their diet. Caecum or caecum‐colon fermentation with colonic separation is postulated to be essential for a high degree of folivory in small mammals because it offsets potential limits on intake of high‐fibre food and minimizes losses of faecal nitrogen that otherwise would be prohibitive. This digestive strategy is common among folivores in eucalypt forests because the low abundance of large seeds and fleshy fruits limits folivory‐frugivory and folivory‐granivory. Foregut fermentation employing a sacciform/ tubiform forestomach (as in tree kangaroos and colobus monkeys) is postulated to be optimal for mixed leaf/fruit and leaf/seed diets that are available in many tropical forests, assuming it allows high‐fibre meals to be retained for microbial fermentation while permitting low‐fibre meals to pass rapidly to the hindstomach for acid/enzymic digestion. However, foregut fermentation appears innappropriate for either primary frugivory or exclusive folivory due to the inefficiency of microbial digestion of simple sugars and constraints on microbial fermentation as a primary energy source for small mammals.
Is resource overlap disadvantageous to three sympatric legumes?
Authors: GROSS C. L.
Published: July 2006

Abstract
The sympatric legumes Dillwynia hispida, Dillwynia uncinata and Pultenaea densifolia overlap in flowering phenology, floral characters and native bee pollinators. Tests for pollen‐limitation were conducted to determine whether or not the overlap in pollinator use was detrimental to individuals of these species. Pollen limitation was only detected in D. hispida. Pollen loads on bees were examined and it was found that pollen loads from Dillwynia and P. densifolia were spatially segregated on the pollinator's body reducing the likelihood of pollen transfer between these species. The pollen of D. hispida and D. uncinata overlapped on the heads of bees suggesting that interspecific pollinations may be responsible for lowered fruit‐set in D. hispida. However, hand pollinations involving heterospecific pollen and controlled floral visits by bees to the two Dillwynia species revealed that heterospecific pollen loads did not significantly depress fruit‐set in either D. hispida or D. uncinata. Pollinator preferences were examined in detail and it was found that D. uncinata flowers received twice as many bees in a day compared with D. hispida and P. densifolia. Competition through pollinator preference is implicated here as a mechanism of competition. Intraspecific competition is also implicated as D. hispida was pollen limited in the absence of D. uncinata and P. densifolia.
Biomass and nutrient distribution in a 15.5 year old forest growing on a rehabilitated bauxite mine
Authors: WARD S. C. , KOCH J. M.
Published: July 2006

Abstract
Above‐ground biomass and its nutrient content were measured in a 15.5 year old rehabilitated bauxite mine in the jarrah forest of southwest Australia. The litterfall and its nutrient content was also measured on the same site, 4–6 years and 8–10 years after rehabilitation. The total mass of the vegetation and litter was 103t ha−1, 25% of that in a nearby jarrah forest. The mass of the trees was 58t ha−1, approximately 22% of that in the jarrah forest. The amount of nitrogen in the soil, in the litter and in the understorey, and in the total system, exceeded that in the nearby jarrah forest. Annual litterfall in the rehabilitated area was comparable to that measured in the jarrah forest and other dry sclerophyll forests. The nitrogen content of the litterfall in the rehabilitated area was around three to four times that in other dry sclerophyll forests.
Laboratory studies of ant predation on parapatric reptile ticks
Authors: DAWES‐GROMADZKI T. Z. , BULL C. M.
Published: July 2006

Abstract
Two reptile tick species, Aponomma hydrosauri and Amblyomma limbatum, have a parapatric distribution in South Australia. Predation may play a role in maintaining the boundary. Laboratory colonies of Rhytidoponera and Iridomyrmex ants were collected from near Mt Mary, South Australia, close to the tick boundary. They were tested as predators of the two tick species. In the experiments, ticks in leaf litter were more protected from predation than those on bare soil. When comparing leaf litter types from the Mt Mary area, mallee litter was more protective than bluebush litter of equivalent depth. Ticks positioned at the base of the litter layer were more protected from predation than those at the litter surface, and Amb. limbatum ticks were more resistant to predation than Ap. hydrosauri ticks. These results contribute to our understanding of the mechanisms maintaining the abrupt parapatric boundary between the two tick species. Predators may contribute to preventing the more susceptible Ap. hydrosauri from spreading further north, where bluebush litter is more common, and so predation risk is higher. Predators probably have less influence in preventing Amb. limbatum from spreading further south.
Poisson vs normal‐errors regression in Mac Nally (1996)
Authors: CANDY S. G.
Published: July 2006

Abstract
Mac Nally (1996), in describing the application of ‘hierarchical partitioning’ in regression modelling of species richness of breeding passerine birds with response variable the species count, rejects the use of Poisson regression in favour of normal‐errors regression on an incorrect basis. Mac Nally uses a function of the residual sum of squares, the root‐mean square prediction error (RMSPE), calculated from predictions from each regression and rejects the Poisson regression because its RMSPE was 20% larger. This note points out that the RMSPE will always be larger for the Poisson regression, given the same link function and linear predictor is used, even if the response is truly Poisson. References to appropriate methods of determining the most suitable response distribution and link function in the context of generalized linear models are given.
Inconsistency in the experimentally derived relationship between epilithon abundance and the micro‐distribution of Agapetus monticolus (Trichoptera)
Authors: GAWNE BENJAMIN
Published: July 2006

Abstract
Studies of the micro‐distribution of herbivorous lotic macroinvertebrates have tended to rely on short‐term experiments. While these experiments have provided information on the factors that determine the distributions of herbivorous invertebrates, they ignore the complexity of the epilithon as a food source, any interaction between physical and biological factors and the possibility that the factors that determine an invertebrate species’ distribution may vary through time. Five colonization experiments were performed in an Australian upland stream to determine the role of epilithon abundance in the distribution of an abundant invertebrate (Agapetus monticolus: Trichoptera). Artificial cobbles with different types and amounts of epilithon were placed in the Taggerty River at two sites and the response of A. monticolus recorded. The experiments revealed that, although A. monticolus expressed a preference for patches of epilithon with abundant periphyton, the response varied among experiments performed at different times and was always secondary to the flow preferences of A. monticolus. Studies that fail to acknowledge the presence of temporal variation in the response of animals to their environment run the risk that they will over‐ or underestimate the importance of particular factors because of the timing of their experiment.
Evaluation of the toxicity of eggs, hatchlings and tadpoles of the introduced toad Bufo marinus (Anura: Bufonidae) to native Australian aquatic predators
Authors: CROSSLAND MICHAEL R. , ALFORD ROSS A.
Published: July 2006

Abstract The early life history stages of anurans in the Family Bufonidae often possess chemicals that are noxious or toxic to predators. Predators with no evolutionary history of exposure to bufomds may be particularly susceptible to these toxins. We conducted a series of laboratory experiments to investigate the toxic effects of eggs, hatchlings and tadpoles of the introduced toad, Bufo marinus (Linnaeus), on native Australian aquatic predators. There was considerable interspecific and intraspecific variation in these effects. Bufo marinus were highly toxic to some predator species, but were readily consumed by other species without apparent ill effect. Interspecific variation in toxic effects was not related to predator feeding mode or the number of B. marinus ingested by predators, and there was no clear pattern of distribution of vulnerability among species within higher taxa. Intraspecific variation in responses to toxins may result from individual variation in the resistance of predators to B. marinus toxins, or from individual variation in toxicity among B. marinus. Some native species adversely affected by B. marinus appeared unable to detect and avoid B. marinus toxins. This may result from a general inability to assess the toxicity of food items or from a lack of evolutionary exposure to B. marinus toxins.
What can population genetics tell us about dispersal and biogeographic history of coral‐reef fishes?
Authors: SHULMAN MYRA J.
Published: July 2006

Abstract Coral‐reef fishes, like many other marine organisms, generally possess a benthic adult stage and pelagic larval stage. What can population genetics studies tell us about the demographic, evolutionary and biogeographic consequences of this life cycle? Ten studies of geographical patterns of intraspecific genetic differentiation in reef fishes have been published. These studies have included 2t > species/species complexes (14 in the family Pomacentridae, the remaining 12 in 9 different families) and have been about equally divided between the tropical Pacific and the tropical western Atlantic. A survey of these studies shows the following: (i) the existence of the pelagic larval stage appears to have led to high levels of gene flow even among populations separated by thousands of kilometres of open ocean; (ii) an apparent pattern of increased gene flow among populations connected by intermediate 'stepping stones’; (iii) very tentative evidence for a relationship between length of pelagic larval life and gene flow; (iv) no clear relationship between egg type (pelagic rs non‐pelagic) and gene flow; and (v) suggestive evidence that damselfishes (family Pomacentridae) may have more restricted dispersal (less gene flow) than other reef fishes. The application of current and future molecular tools has the strong potential to clarify some of these relationships, particularly by using relatively neutral genetic markers. Additionally, discoveries of DNA markers having very high rates of mutation may allow tracking of demographically relevant levels of larval dispersal. Molecular tools are becoming especially valuable in uncovering the biogeographic and phylogenetic history of reef fishes. The one molecular study to date has suggested that at least some speciation events may have occurred during the climate changes and sea‐level regressions associated with Pleistocene glacial episodes. Molecular tools need to be used to further explore the means by which high species diversity can be generated in the face of the apparently high gene flow observed in most coral‐reef fishes.
How might recruitment research on coral‐reef fishes help manage tropical reef fisheries?
Authors: DEMARTINI EDWARD E.
Published: July 2006

Abstract ‘Ecologic’ reef fishes (basic research subjects) and ‘Economic’ reef fishes (exploited by humans) share fundamental early life‐history attributes of small, widely dispersed planktonic eggs, larvae, and (for some species in both groups) pelagic juveniles. These attributes predispose the open populations of species in both groups to limitation resulting from environmentally induced fluctuations in recruitment from planktonic/pelagic to benthic stages. Rates of movement within and among reefs, one of several postrecruitment processes likely to be subject to density‐dependent regulation, may differ between Ecologies (mostly small‐bodied) and Economics (generally larger‐bodied). This is because of differences between species in the two groups in size‐related differences in the home ranges of individuals. Existing data, however, neither support the notion that natural growth and mortality rates basically differ between the adults of Ecological and Economic species, nor that the generally larger home ranges of larger‐bodied adult Economics are more subject to density‐dependent control. Further, the small‐bodied young‐of‐year juveniles of both groups on average probably have similar growth and mortality rates and small individual home ranges that are equivalently affected by density dependence. In conclusion I argue that, because of fundamental similarities in the sizes and durations of planktonic propagules and spawning periodicities, certain Ecologies and Economics may comprise a single recruitment guild. Coefficients of growth and mortality for postsettlement Ecologies also may resemble, and be applied as preliminary proxies for, analogous coefficients for Economic species. The efficacy of management strategies such as harvest refugia may differ for Ecological and Economic species, however, depending on whether the refugia are used to counter growth or recruitment overfishing.
The influence of cattle grazing on tree mortality after drought in savanna woodland in north Queensland
Authors: FENSHAM R. J.
Published: July 2006

Abstract Live and dead trees were measured in macropod‐grazed and cattle‐grazed Eucalyptus woodland in north Queensland following a severe drought between 1992 and 1994. ANCOVA revealed no effect of grazing treatment on the proportion of drought death. Twenty‐seven per cent of all tree species were killed by the drought and the value ranged from about 4% for Corymbia dallachiana (Benth.), K. D. Hlll & L. A. S. Johnson to 29% for the dominant species Eucalyptus xanthoclada Brooker and A.R.Bean, although differences were non‐significant. There was also no significant difference in mortality between poles (< 10 cm d.b.h.) and trees (> 10 cm d.b.h.). The study highlights a natural (as in pre‐European), catastrophic structural collapse of tropical eucalypt woodland. Presumably the dramatic declines in basal area as a result of drought are recovered during successive relatively wet years by thickening events, although clearly this severe drought and its after‐effects warrant further study.
Cavity selection for roosting, and roosting ecology of forest‐dwelling Australian Owlet‐nightjars (Aegotheles cristatus)
Authors: BRIGHAM R. MARK , DEBUS STEPHEN J. S. , GEISER FRITZ
Published: July 2006

Abstract We compared a variety of attributes of tree cavities used for roosting by radio‐tagged Australian Owlet‐nightjars Aegotheles cristatus with randomly chosen prospective cavities to test which features are important for the species. Owlet‐nightjars preferentially roosted in tree cavities closer to the ground, in trees with a significantly greater number of cavities and significantly closer to another tree with a cavity than expected by chance. There was also a significant interaction between cavity height and number of cavities in the tree. Tree size, decay stage and tree species were not statistically important cues used for making site choices. The requirements for Owlet‐nightjars differ from those of most other Australian birds that use tree holes and also from most insectivorous bats. Telemetry data indicate that Owlet‐nightjars move ∼300 m between roost sites every 9 days on average. Individual birds used 2‐6 different cavities during the 1–4‐month period over which they were followed. The reasons for the relatively low levels of site fidelity are unknown.
Modelling the recovery of an annual savanna grass following a fire‐induced crash
Authors: LONSDALE W. M. , BRAITHWAITE R. W. , LANE A. M. , FARMER J.
Published: July 2006

Abstract The native annual Sorghum populations of the Australian wet‐dry tropics are highly resilient to dry season fires. During the early wet season, however, fires that occur after the new grass population has emerged can cause catastrophic population crashes. We examined savanna plots that had been burnt in this way, and compared them with adjacent unburnt plots. We found that Sorghum densities in the burnt plots were lower on average by a factor of 10, but that some fires had reduced the density only to one‐third of the unburnt plots. It is not clear whether these differences relate directly to site or seasonal factors, or to differences in the way the burning was carried out. Other vegetation components responded to the fires differently: forbs (dicotyledonous herbs) increased in cover, while perennial grasses, woody plants, and overall species richness, were not significantly affected. The amount of leaf litter declined. A population model for Sorghum based on the demography of unburnt populations predicted that they should recover from a wet season burn, taking 7–16 years to return to normal densities. However, the actual field populations did not seem to be recovering, suggesting that wet season fires not only lower densities, but may also fundamentally change population processes in these annual grasses.
Comparisons of abundance of coral‐reef fish: Catch and effort surveys vs visual census
Authors: CONNELL SEAN D. , SAMOILYS MELITA A. , LINCOLN SMITH MARCUS P. , LEQATA JOHN
Published: July 2006

Abstract Catch per unit effort (CPUE) in fisheries science and visual counts in marine ecology are widely used to provide estimates of relative abundance. Concurrent use of these techniques therefore offers an opportunity for cross‐validation. This study compares CPUE to underwater visual census (UVC) estimates of relative species abundance in a multispecies fishery: coral‐reef fish in the Solomon Islands. Multivariate analyses showed large differences between CPUE and UVC estimates of abundance. The families Acanthuridae and Scandae tended to be the primary cause of differences between the techniques when the full assemblage offish was analysed. However, the relationship between CPUE and UVC did not improve when these families were excluded from the data set and the analyses repeated on families (Serranidae, Lutjamdae, Lethrinidae) caught by the predominant gear type, handlining. This result highlights the point that the choice and use of particular methods require careful consideration in conjunction with the nature of factors being investigated. Many problems of sampling are specific to particular methods and some investigations may benefit from a more pluralistic approach.
POPULATION'S URBAN ENVIRONMENT EVALUATION MODEL AND ITS APPLICATION*
Authors: Maeda Hiroshi , Murakami Shuta
Published: July 2006

We propose the Population's Urban Environment Evaluation Model that quantitatively presents inhabitants’ evaluations of urban environments. Our target is to establish firmly a method to effectively reflect the inhabitants’ consciousness in a regional planning process. The approach taken follows a group decision‐making theory and a multi‐attribute utility theory: a kind of social welfare function (of additive form) is identified by using questionnaire data. The results of application of our model to Kitakyushu show that it presents several useful insights for regional planning.
ON THE SENSITIVITY OF GRAVITY MODEL FORECASTS*
Authors: Weber James S. , Sen Ashish K.
Published: July 2006

In this paper we present a procedure for estimating small changes in gravity model forecasts in response to small changes in input values (trip end totals and/or parameter values). The procedure can be used to derive covariance matrices from which confidence intervals may be obtained and which may be used for tests of hypotheses. While this type of problem has been addressed by others, our approach is the only one that is conveniently applicable to the doubly constrained model and can accommodate the large numbers of origin and destination zones one typically encounters.
TESTING SIZE‐DENSITY RELATIONSHIPS WITHOUT RATIO‐VARIABLES, MULTICOLLINEARITY, LOGARITHMIC TRANSFORMATIONS, OR REGRESSION ANALYSIS*
Authors: Stephan G. Edward , Dorman Dan
Published: July 2006

Using data describing the historical distribution of county seats in the United States, we (1) replicate the traditional ratio‐variable test of the size‐density law, (2) test a new multivariate, nonratio form of the law, and (3) introduce an alternative method of testing, one which avoids three possible problems in traditional analyses: ratio‐variables, multicollinearity, and logarithmic transformation.
A PROPERTY OF THE RANK‐SIZE DISTRIBUTION AND ITS USE IN AN URBAN HIERARCHY CONTEXT
Authors: Beguin Hubert
Published: July 2006

This paper proves the symmetry of the classical rank‐size distribution with respect to any city according to a criterion of relative population difference. This property is used to characterize the distribution of city sizes around the median center of their hierarchical level by the existence of symmetry, of an upper bound to dispersion, and of a regular spacing. An interpretation is suggested.
INTERDEPENDENT BEHAVIOR WITH RELOCATION COSTS: THE COMPARATIVE STATICS OF SPATIAL HISTORY*
Authors: Clapp John M.
Published: July 2006

Relocation costs are a form of sunk costs because they are relevant to new entrants, not to agents at their existing locations. With sufficiently high relocation costs, initial (historically given) locations and other conditions determine the equilibrium assignment of agents to locations. Comparative static results depend on initial conditions, i.e., history matters and historical persistence can be characterized.

The model suggests empirically‐relevant results which can be tested by collecting data on relocation and transportation costs. For example, appropriate levels of these costs imply that suburbanization always occurs with the entry of new firms. Sequential entry strategies may be adopted by existing firms which earn pure profits. This may be contrasted with traditional NUE models which predict changes in the boundaries of central zones.
REGIONAL GROWTH IN THE SOVIET ECONOMY A MODEL AND ANALYSIS*
Authors: Kushnirsky F. I.
Published: July 2006

A multiregional econometric model of the Soviet economy is presented. It consists of 1,391 equations, with time‐series information for 1965‐1980. In conformity with the number of the country's republics, 15 input‐output tables are incorporated. The discussion includes the methodological framework, the structure and equations, theoretical justification for the interaction between the econometric and input‐output components, data and estimation, and forecasting results.
LOCATIONAL FACTORS IN THE DECLINING INDUSTRIAL COMPETITIVE ADVANTAGE OF THE NEW YORK URBAN REGION*
Authors: Tran Dang T.
Published: July 2006

This paper investigates the locational factors that contributed to the decline of the New York urban region's industries during 1972‐1975. Based on the static concept of a specialization index, a dynamic comparative advantage index is constructed. A model is then formulated to test the hypothesis that regional competitive advantage (vis‐à‐vis the nation) is a function of relative disparities in the change of these locational factors. Regression results show that the region's competitive advantage is influenced positively by the differential rate of change in market size, by the differential profit rate before tax, and negatively by the differential rate of change in unit labor cost and in unit energy cost. The differential tax rate does not seem to affect the region's competitive advantage. Nevertheless, a progressive corporate income tax structure tends to neutralize the beneficial effects of the economies of agglomeration and the urban attraction of the region.
ANALYSIS OF A DYNAMIC RESIDENTIAL LOCATION CHOICE MODEL WITH TRANSACTION COSTS*
Authors: Ben‐Akiva Moshe , de Palma André
Published: July 2006

ABSTRACT. This paper incorporates transaction costs in a residential location choice model. An individual's choice is assumed to be an outcome of a two‐stage process: a decision to change, or to undertake a transaction and, conditional on a change occurring, a choice of a new alternative. The dynamic choice model is aggregated to yield a Markovian model of residential location patterns. It is shown that recent contributions to dynamical urban modeling correspond to special cases of the deterministic version of this model. The Markovian model is used in a theoretical analysis of the influence of transaction costs on the properties of the stationary state. The effects of residential mobility rates and of interdependencies among individuals, caused by supply‐side and density‐related interactions, are also analyzed. It is shown how these dynamical factors modify the stationary state, thereby demonstrating the type of errors which may occur with static models that omit them.
A MANAGERIAL MODEL OF THE EFFECT OF PRODUCT MARKET STRUCTURE ON FIRM LOCATION*
Authors: Allen Ralph C. , Rabianski Joseph S. , Stone Jack H.
Published: July 2006

ABSTRACT. This paper develops a model of firm location choice based on managerial theory of discretionary behavior. Specifically, it is assumed that the management of the firm maximizes a utility function which incorporates profits and location‐specific amenities. As the firm moves from one prospective location to another, it faces a profit‐amenity constraint imposed by market conditions. The optimal location decision is derived by maximizing the utility function subject to this market‐imposed constraint. After examining the properties of the optimal solution, the impact of various changes in product market structure (including changes from a contestible markets perspective) on the location decision is investigated. A major finding is that the impact of a change in market structure depends upon the nature of the structure change and upon the substitution and income effects induced by the structural change.
SPATIAL DISEQUILIBRIUM
Authors: Thore Sten
Published: July 2006

ABSTRACT. The well‐known extremal principle for the solution of spatial equilibrium for a single commodity [Samuelson (1952)] is extended to deal with the case of disequilibrium caused by rigid prices and/or price controls. Both disequilibrium in consumer markets and in factor markets is covered.

The study of disequilibrium is well known in general interdependent economic systems (the so‐called fixed‐price model of interdependent systems). The present work extends this approach to the spatial dimension, and shows how it is possible to represent and solve disequilibrium models by mathematical programming rather than by fixed‐point techniques.
OPTIMUM LOCATION OF PUBLIC FACILITIES UNDER THE INFLUENCE OF THE LAND MARKET*
Authors: Sakashita Noboru
Published: July 2006

ABSTRACT. This paper discusses the problem of the optimal location of public facility(ies) in a long narrow city, especially taking into consideration the externality‐internalizing effect of the land market. It shows a systematic approach to dealing with the land market mechanism in first a one‐facility and then a two‐facility case. The analysis assures the importance of posing the location‐optimizing problem even under the influence of the land market.
ONCE AGAIN: TESTING FOR REGIONAL HOMOGENEITY*
Authors: Schulze Peter M.
Published: July 2006

ABSTRACT. Summarizing the foregoing discussions in this journal on testing for regional homogeneity the present note shows that in the model of Zellner's seemingly unrelated regressions one test statistic may be used not only to test for overall homogeneity but also to examine for individual coefficient homogeneity. This aim is achieved by varying the linear restrictions in the test statistic according to different problems. To illustrate these tests regional consumption functions for the 11 Bundesläder (States) of the Federal Republic of Germany are used.
THE LOCATION THEORY OF THE PLANTATION*
Authors: Jones Donald W. , Krummel John R.
Published: July 2006

ABSTRACT This paper develops a method for studying noninfinitesimal operational units, with the Thünen location and land use model. With constant returns to scale and perfect divisibility of nonland inputs, all operational units would occupy only a point on the landscape. The present model uses increasing returns to scale to generate large operational units, called “plantations” and studies the comparative statics. The setting of the model is an agricultural operation in which some processing of raw crop must be conducted prior to shipment to market. The processing is assumed to have increasing returns to scale.
NONSURVEY INPUT‐OUTPUT ESTIMATION TECHNIQUES: EVIDENCE ON THE STRUCTURE OF ERRORS
Authors: Garhart Robert E. , Giarratani Frank
Published: July 2006

ABSTRACT This paper concerns the nature and extent of error introduced to regional input‐output multipliers by errors associated with the estimation of regional purchase coefficients (rpc's). Using the Washington State input‐output model and computer simulations, estimates of multiplier error are generated for two distinct sources of rpc error. The results indicate that multiplier error from both rpc sources may be significant and support the findings of previous studies which highlight the importance of error introduced to the household purchases column for multiplier accuracy.
MEASURING CONTRIBUTING FACTORS TO INTERREGIONAL AGRICULTURAL LABOR PRODUCTIVITY DIFFERENTIALS: A JOINT PROFIT FORMULATION*
Authors: Chan M. W. Luke , Mountain Dean C.
Published: July 2006

ABSTRACT Using Taylor series approximations of joint profit functions, a methodology is outlined to quantify interregional differentials in the Canadian agriculture sector by region and to quantify the contributing factors to regional labor productivity differences. These contributing factors are output price differentials–both crop and livestock, differentials in “land and buildings” capital deepening, “other” capital deepening, energy prices, other material prices, and efficiency. The joint profit formulation permits the analysis of effects of regional specific output price and output mix differentials.
SUFFICIENT CONDITIONS FOR NEGATIVE EXPONENTIAL DENSITIES A FURTHER ANALYSIS
Authors: Kim Kyung‐Hwan , McDonald John F.
Published: July 2006

ABSTRACT Brueckner correctly pointed out that one of the sufficient conditions for negative exponential densities is a unitary price elasticity of the compensated, not the uncompensated, demand for housing. This note shows that the Brueckner condition implies a zero income elasticity of housing demand when income and price elasticities are constrained to be constants. It also derives the utility function that gives rise to negative exponential densities in this case, given that other standard assumptions are satisfied. In light of empirical evidence, justification for the popular negative exponential functional form seems rather weak.
THE CORE OF A SPATIAL PRICE EQUILIBRIUM GAME*
Authors: Harker Patrick T.
Published: July 2006

ABSTRACT This paper presents a critical appraisal of the use of the core as a solution concept for games involving spatially separated producers. Starting from the classical Samuelson/Takayama‐Judge spatial price equilibrium model, the core of a game between the producers of commodities in this economy is defined, the conditions ensuring the nonemptiness of the core are stated, and the problems surrounding the definition and computation of the characteristic function are addressed. An application to the eastern United States’coal market is then presented in order to illustrate the usefulness of the theoretical and algorithmic results of this paper.
DECENTRALIZED TAX COMPETITION FOR BUSINESS CAPITAL AND NATIONAL ECONOMIC EFFICIENCY*
Authors: Gerber Robert I. , Hewitt Daniel P.
Published: July 2006

ABSTRACT For a nation composed of independent regions, the effects of local tax competition for business investments are examined. It is first shown that atomistic regional authorities tax only local resources to finance the provision of public services to business. Thus, an efficient interregional equilibrium is induced. Various political/institutional constraints are shown to cause misallocation of the capital stock and an inefficient provision of public services. The characterization of the inefficiency is shown to vary widely, depending upon the constraint under consideration.
DISGUISED, URBAN UNEMPLOYMENT AND WELFARE IN A GENERAL EQUILIBRIUM MODEL WITH SEGMENTED LABOR MARKETS*
Authors: Hazari Bharat R. , Sgro Pasquale M.
Published: July 2006

ABSTRACT This paper integrates the theory of segmented labor markets with the Ranis‐Fei model of dualism to analyze two types of unemployment; disguised unemployment in the rural sector and urban unemployment. The major results obtained are (1) sector‐specific accumulation in the urban area may raise unemployment and lower welfare and (2) sector‐specific accumulation in the rural sector always raises welfare but increases disguised unemployment. These results highlight the importance of regional resource allocation and the role of the agricultural sector in reducing urban unemployment.
MONOPSONY AND PLANT LOCATION IN A THÜNEN LAND USE MODEL*
Authors: Jones Donald W.
Published: July 2006

ABSTRACT. Previous work has developed a method for studying noninfinitesimal operational units, called “plantations,” with the Thüen model. In that model, increasing returns to scale generate large operational units, but the potential market power conferred by the scale economies is sidestepped as an issue. The present work introduces finite supply elasticities and examines their locational impacts. The profit‐maximizing monopsonistic plantation is smaller, and the shipment distance for its processed output is shorter, than for a comparable competitive plantation. The present approach does not involve spatial competition strategies.
INTERREGIONAL FEEDBACKS IN INPUT‐OUTPUT MODELS: THE LEAST UPPER BOUND*
Authors: Guccione Antonio , Gillen William J. , Blair Peter D. , Miller Ronald E.
Published: July 2006

ABSTRACT. The least upper bound to the overall percentage error resulting from the omission of interregional feedbacks in input‐output analysis is defined. This limiting value is the most informative of all upper bounds. A procedure for its computation is outlined and a number of experiments, using U.S. data, are discussed.
SPATIAL ECONOMIC INTERDEPENDENCE IN AN URBAN HIERARCHY SYSTEM
Authors: Ahn Jeong Keun , Nourse Hugh O.
Published: July 2006

ABSTRACT. This paper develops a model to examine the economic interaction between central places and their hinterlands. The model allows interindustry linkages and upward trade flows in an urban hierarchy system. Trade balance equilibrium between hierarchical levels is established by direct mutual interlevel trade, rather than by indirect trade via the rural sector. The economic base multipliers generally increase with city size but occasionally they could be smaller than those of lower places. A continuous urban hierarchy is formed due to their relative location within the system, not to unspecified randomness.
PRODUCTION TECHNOLOGY UNCERTAINTY AND THE OPTIMAL LOCATION OF THE FIRM*
Authors: Park Keehwan , Mathur Vijay K.
Published: July 2006

ABSTRACT This paper investigates the implication of production‐technology uncertainty for the exclusion theorem. The paper presents the result that the risk‐averse firm facing production technology uncertainty prefers an intermediate location to avoid risk under certain conditions. The firm chooses an intermediate location (over a corner location) particularly if its degree of risk aversion overwhelms the inherent convexity of profit with respect to location. The latter depends, in turn, on the structure of production technology characterized by the elasticity of substitution and returns to scale parameters.
POPULATION DENSITY FUNCTIONS: A DIFFERENTIAL EQUATION APPROACH*
Authors: Nairn Alasdair G. M. , O'Neill Gerard J.
Published: July 2006

ABSTRACT This paper introduces a new mathematical technique to describe population density functions. Two length scales, which characterize the variation of these density functions within a region, are identified. A differential equation is derived and asymptotic solutions obtained. Two specific techniques, the method of matched asymptotic expansions and the method of multiple scales, are introduced and illustrated by application to population densities at both the metropolitan and regional levels.
NETWORK EQUILIBRIUM MODELS OF URBAN LOCATION AND TRAVEL CHOICES: A RETROSPECTIVE SURVEY*
Authors: Boyce David E. , LeBlanc Larry J. , Chon Kyung S.
Published: July 2006

ABSTRACT The origins and development of the network equilibrium problem are traced and interrelated. Two principal formulations are considered the network equilibrium problem with variable travel demand, and the combined model of trip distribution and traffic assignment. The relation of these models to subsequent developments concerning mode choice, residential location, estimation of origin‐destination tables from link flows and stochastic route choice are then reviewed.