bluuebunny/crossref_metadata_2025 huggingface dataset:
Large scale variation in abundance of five common species of decapod sampled from seagrass in New South Wales
Authors: WORTHINGTON D. G. , MCNEILL S. E. , FERRELL D. J. , BELL J. D.
Published: July 2006

Abstract
Decapods associated with two species of seagrass (Zostera capricorni and Posidonia australis) were sampled at several sites within estuaries on the New South Wales coast for 3 years. Two species of decapod (Macrobrachium intermedium and Penaeus plebejus) were abundant in Z. capricorni. Four species (M. intermedium, P. plebejus, Chlorotocella leptorhynchus and Nectocarcinus tuberculosus) were abundant in P. australis. Abundance of all these species fluctuated greatly among sites and through time. Some seasonal patterns in abundance were evident, and appeared to be caused by recruitment and subsequent mortality or migration of individuals. Similarly, there were some consistent spatial patterns in abundance of most species. In particular, some sites supported consistently more juveniles during the same period of separate years. Within Jervis Bay, P. australis was also sampled in shallow (1–2m) and deep (7–8 m) water. Three species were abundant (C. leptorhynchus, N. tuberculosus and Processa australiense), but showed no consistent differences between the two depths. Abundances of these species did fluctuate greatly among the sites within Jervis Bay and through time. Such observations of the natural rates of change in abundance of populations are essential in order to be able to detect the effects of human disturbances.
The influence of cactus size and previous infection on bird deposition of mistletoe seeds
Authors: DEL RIO C. MARTINEZ , HOURDEQUIN M. , SILVA A. , MEDEL R.
Published: July 2006

AbstractTristerix aphyllus(Loranthaceae) is a bird‐dispersed mistletoe that infects several cactus species in central and north‐central Chile. At Las Chinchillas National Reserve it parasitizes two species of columnar cacti (Echinopsis chilensisandEulychnia acida) and its seeds are dispersed exclusively by the Chilean mockingbirdMimus thenca. The prevalence ofT. aphylluson cacti depended on host species and size.Echinopsis chilensiswas parasitized at a higher, andE. acidaat a lower, frequency than expected from their relative abundances. In both species, the incidence ofT. aphyllusparasitism increased with cactus height. Birds perched and deposited seeds primarily on parasitized cacti, which resulted in an aggregated distribution of seeds. By preventing bird perching and thus reducing seed deposition, the long spines ofE. chilensisandE. acidamay help protect cacti againstT. aphyllusinfestation. However, the seeds ofT. aphyllusproduced a slow‐growing radicle that reached up to 91 mm long in 43 days. Radicles of this length are unique among mistletoe species and may have evolved to overcome the barrier posed by cactus spines.
Thermal ecology of two sympatric skinks (Mabuya macrorhyncha and Mabuya agilis] in a Brazilian restinga habitat
Authors: ROCHA CARLOS FREDERICO DUARTE , VRCIBRADIC DAVOR
Published: July 2006

Abstract
In a restinga habitat of southeastern Brazil, we studied some aspects of the thermal biology of two sympatric skinks (Mabuya macrorhyncha and Mabuya agilis) with distinct microhabitat preferences. The two species did not differ significantly in their mean body temperature. Sex and body size did not explain body temperature variation within either species. The body temperature of both species is significantly affected by air temperature, but only that of M. agilis is significantly influenced by sand surface temperature, presumably due to its more terrestrial habit compared to M. macrorhyncha. We found no significant seasonal variation in body temperature for either species, although environmental temperatures varied seasonally, indicating that both species may be selecting an optimal range of body temperatures, possibly through behavioural thermoregulation.
Hierarchical partitioning as an interpretative tool in multivariate inference
Authors: NALLY R. MAC
Published: July 2006

Abstract
Much of biogeography, conservation and evolutionary biology, and ecology involves very large spatial and temporal extents. Direct manipulation to test hypotheses is usually almost impossible at appropriate scales so that multivariate modelling and especially regression are used to draw causal inferences about which ‘independent’ variables influence the distribution and abundances of species. Such inferences clearly are crucial for the successful management of biological resources and for conserving threatened species. A succession of regression approaches has arisen, many of which yield inconsistent implications. The main problem has been the quest for one (the ‘best’ or the ‘optimal’) regression model from which the impacts of independent variables are inferred. This note is to draw the attention of ecologists to a relatively recent method, hierarchical partitioning, that does not aim to identify a best regression model as such but rather uses all models in a regression hierarchy to distinguish those variables that have high independent correlations with the dependent variable. Such variables are likely to be most influential in controlling variation in the dependent variable. Hierarchical partitioning is not to be regarded as a substitute for experimental manipulation when that is appropriate, but it is likely to produce better deductions than common regression approaches in the many ecological situations in which manipulation is impossible or of doubtful value.
Subcanopy gaps in temperate and tropical forests
Authors: CONNELL JOSEPH H. , LOWMAN MARGARET D. , NOBLE IAN R.
Published: July 2006

Abstract
We present a model of gaps in the vertical structure of forest vegetation. The traditional model of a forest gap assumes the existence of a ‘hole’ in the uppermost canopy layer, often extending down to near the ground. The present model extends the concept to gaps at any level, including those in lower layers below an intact canopy or subcanopy. It assumes that gaps at any level represent spaces with unused resources, especially favourable for plant growth and survival. Evidence from temperate and tropical forests indicates that gaps in the subcanopy and understorey layers below intact canopies are common, and that plants have higher growth rates in them than in non‐gap sites. We also extend this model to below‐ground gaps in the root zone.
Ecological aspects of soil seed‐banks in relation to bauxite mining. II. Twelve year old rehabilitated mines
Authors: GRANT C. D. , KOCH J. M.
Published: July 2006

Abstract
Germinable seed stores were estimated for 12–13 year old rehabilitation sites in the jarrah forest over two seasons (autumn and spring). Collected soils were subjected to combinations of smoking and heating treatments before the germination procedure was commenced. The mean topsoil seed reserve to a depth of 10 cm was 1938 seeds m−2. Of this total reserve, more than 80% was found in the upper 5 cm of soil. The topsoil seed reserve of these rehabilitation areas was almost seven times that of the adjacent native jarrah forest (292 seeds m−2; Ward et al. 1997). There was a seasonal effect with autumn‐collected soils having significantly more germinable seeds (2723 seeds m−2) than soils collected in spring (1153 seeds m−2). More than half (53%) of the topsoil seed reserve in rehabilitated areas was composed of annual weed species, dominated by Aira caryophyllea, Centaurium erythraea and the native Levenhookia pusilla. Of the total of 70 species identified, 13 species showed significantly higher germination in smoked trays while 11 species exhibited significantly higher germination in heated trays. Species responding to the smoking treatment tended to be annuals while those responding to the heating treatment were typically legume shrub species. Examination of the topsoil seed reserve and the vegetation present in these areas showed that while the species composition was similar between the seed store and the vegetation, there was a large difference in densities, with species occurring at much higher densities in the topsoil than in the vegetation. However, the rankings of species were significantly correlated between the topsoil seed reserve and the vegetation present at the site. The implications of these results to prescribed burning of these rehabilitated areas is discussed.
Mobility and metapopulation structure of Geocrinia alba and Geocrinia vitellina, two endangered frog species from southwestern Australia
Authors: DRISCOLL DON A.
Published: July 2006

Abstract
Dispersal rates can have an important impact on many population processes. Dispersal can lead to population regulation and regional stability in the face of local instability through the formation of a metapopulation. This may be particularly true for frogs because they often have patchy distributions. In this paper I investigate dispersal by male Geocrinia alba and Geocrinia vitellina, using a mark‐recapture study. Pit traps were used to determine whether frogs move out of their breeding habitat. I found that both species were very philopatric. Between the 1993 and 1994 breeding seasons, 76–86% of individuals were displaced less than 10m and 90–97% were displaced less than 20m. Dispersal was even lower within each breeding season, with 92–95% of individuals being displaced less than 5 m. Pit trapping indicated that some individuals of both species move out of the swamps in late autumn and return at the beginning of the breeding season, in late winter and early spring. Therefore, although displacement may be very restricted, the frogs are likely to move greater distances. The extreme breeding‐site philopatry exhibited by G. alba and G. vitellina suggests that movement between disjunct populations is unlikely and that populations in continuous habitat may be relatively isolated from one another by distance alone. This is consistent with previous predictions based on genetic studies, which suggested there was very little migration between populations. These data support the contention that neither species is likely to exist as a metapopulation because recolonization of vacant habitat is improbable.
Patterns of co‐occurrence among arboreal marsupials in the forests of central Victoria, southeastern Australia
Authors: LINDENMAYER D. B. , CUNNINGHAM R. B.
Published: July 2006

Abstract
Patterns of co‐occurrence were examined among the suite of species of arboreal marsupials that inhabit the montane ash forests of the Central Highlands of Victoria, southeastern Australia. The data used in our analyses were counts of different species of arboreal marsupials derived from stagwatching surveys of 152 sites throughout the Central Highlands region. Our work investigated both the number of species that tend to occur together, as well as identity of the taxa in such associations. A total of eight different species of arboreal marsupials were recorded from field surveys of montane ash forests: Leadbeater's Possum (Gymnobelideus leadbeateri), Sugar Glider (Petaurus breviceps), Yellow‐bellied Glider (Petaurus australis), Greater Glider (Petauroides volans), Mountain Brushtail Possum (Trichosurus caninus), Feathertail Glider (Acrobates pygmaeus), Common Ringtail Possum (Pseudocheirusperegrinus), and Eastern Pygmy Possum (Cercartetus nanus). Large assemblages of taxa were rare and no sites supported the full array of species of arboreal marsupials– the maximum number of species recorded on a given 3 ha site was five. The results of our analyses indicated that if any one species of arboreal marsupials was present at a site, then on average 1. 5 other taxa will co‐inhabit that site. The exception was the Common Ringtail Possum. When this species was detected, few other arboreal marsupial taxa tended to be recorded with it. Principal Co‐ordinates Analysis showed that although combinations of animals comprised of either Mountain Brushtail Possum, Leadbeater's Possum, or Greater Glider were often recorded, there were no strong patterns in the identities of co‐occurring taxa. This finding, together with the result that most taxa in these forests typically co‐occurred with one or two other species, indicates that none of the arboreal marsupials inhabiting the montane ash forests of the Central Highlands of Victoria would be a good surrogate for (or ‘indicator’ of), the presence of the suite of other species in the assemblage.
The endangered Tunbridge buttercup (Ranunculus prasinus): Ecology, conservation status and introduction to the Township Lagoon Nature Reserve, Tasmania
Authors: GILFEDDER LOUISE , KIRKPATRICK J. B. , WELLS SUSAN
Published: July 2006

AbstractRanunculus prasinusis a mat‐forming species of the marginal herbfields and tussock grasslands of brackish wetlands. It is only known from four wetlands, all on private land, in the driest part of Tasmania. The species has been successfully introduced from divisions from three of the populations into a secure reserve with similar vegetation to that of the natural populations. This is considered to be desirable and morally sound in that it increases the chances of survival of native biological diversity as a whole. However,ex situmeasures and a gaining of security for natural populations would also be prudent.
The soil seed bank and understorey regeneration in Eucalyptus regnans forest, Victoria
Authors: WANG LIANGMIN
Published: July 2006

Abstract
The soil seed bank and its relation to the extant vegetation in a Eucalyptus regnans F. Muell. forest in the Central Highlands of Victoria were examined. The average seed density was 430 germinable seeds m−2 to a depth of 2 cm. There was a polynomial regression relationship between the density and species richness of seeds in soil and forest age (0. 6–54 years). Species richness was not significantly different among soil depths (0‐2, 2‐5, 5–10 and 10–20 cm) in the forest stand of 54 years old. More seeds germinated from the 5–10 cm depth than from the other depths. Forbs accounted for 73% of the total germinable seeds and there was no germination of E. regnans. The number of species, particularly woody plant species, germinating from the soil seed bank were significantly lower than in the extant vegetation. However, almost all species present in the soil seed bank were present in the vegetation. The soil seed bank provides an important source for the rapid regeneration of understorey vegetation following clear‐cutting and slash‐burning in the E. regnans forest. The rapid understorey establishment may play an important role in protecting soil from erosion, in nutrient conservation, replacement and redistribution. The soil seed bank may also be a necessary source of maintaining genetic diversity in the forest over the long term.
The effects of the herbicide tebuthiuron on seedlings of Mimosa pigra and native floodplain vegetation in northern Australia
Authors: LANE A. M. , WILLIAMS R. J. , MULLER W. J. , LONSDALE W. M.
Published: July 2006

Abstract
We studied the seedbank of floodplain vegetation in three major tropical river systems in northern Australia, which had been variously invaded by the tropical woody weed Mimosa pigra. The sites selected had not previously been treated with tebuthiuron, a herbicide which is widely used in northern Australia to control Mimosa. We collected soil seedbank samples from two floodplain vegetation types (Melaleuca swamp and sedgeland), and, within each type, from areas in which Mimosa was either present or absent. The effects of treatment with tebuthiuron at 15 kg ha−1, twice the usual recommended rate, was subsequently assessed in die laboratory on the soil‐seedbank samples. Ordination of the species composition of seedlings which emerged from the soil seedbank samples showed no effect of (i) the vegetation community from which the samples were collected, (ii) the presence of adult Mimosa, or (iii) treatment with tebuthiuron. The effect of tebuthiuron on the emergence and mortality of seedlings from four functional groups (grasses, sedges, forbs and Mimosa) was also tested on the seed bank samples. Emergence was significantly decreased by tebuthiuron only for forbs from Melaleuca swamps. The mortality of Mimosa was significantly higher than that of the other functional groups, but there was some mortality of forb and grass seedlings. Sedges, however, were unaffected. The impact of tebuthiuron on Mimosa depended on soil clay content—in the soils with lowest clay content, tebuthiuron was the most effective in killing Mimosa seedlings. Mortality in forb and grass seedlings, in contrast, was not affected by soil clay content. Tebuthiuron was therefore selective against Mimosa seedlings. However, even at twice the recommended rate of application for killing adult Mimosa, under ideal conditions for distribution of the herbicide through the soil, 43% of Mimosa seedlings survived. Given the size of the Mimosa seedbank under field conditions (∼10 000 seeds/m2), tebuthiuron can therefore not be considered an effective herbicide against Mimosa seedlings.
Population dynamics of coral‐reef fishes: Controversial concepts and hypotheses
Authors: HIXON MARK A.
Published: July 2006

Abstract Knowledge of processes that drive the local population dynamics of coral‐reef fishes is important for managing reef fisheries, and for using these species as models for understanding the ecology of demersal marine fishes in general. However, the reef‐fish literature is replete with poorly defined concepts and vague hypotheses regarding the issue of population dynamics. Dichotomous arguments, such as whether or not recruitment drives population dynamics, are misdirected because they fail to incorporate several important concepts. First, changes in local population size are driven by four demographic rates (birth, death, immigration and emigration), all of which must be studied to understand population dynamics. Second, all populations that persist do so because at least one of these demographic rates operates in a density‐dependent way that is both sufficiently strong and appropriately time‐lagged. Therefore, identifying the source(s) of direct density dependence is critical for understanding the limits to variation in population size (i.e. population regulation). Third, regulation does not imply a simple point equilibrium in population size; density dependence in populations of reef fishes is bound to lie within a field of stochastic variation, and thus be difficult to detect. Since its formal origin in 1981, the ‘recruitment limitation’ hypothesis for explaining local population dynamics in reef fishes has undergone ambiguous changes in definition that threaten its usefulness. ‘Recruitment, ‘originally defined as the appearance of newly settled fish on a reef, more recently is often measured months after settlement, thus confounding pre‐ and post‐settlement processes. ‘Limitation, ‘ which originally referred to recruitment being so low as to preclude local populations from reaching densities where resources were limiting, is more recently defined as an absence of any form of density dependence after settlement. The most effective means of testing whether post‐settlement mortality is in fact density‐independent is to examine patterns of mortality directly, rather than indirectly by interpreting the shape of the relationship between initial recruit density and subsequent adult density within a cohort (the recruit‐adult function). Understanding the population dynamics of coral‐reef fishes will require a more equitable focus on all four demographic rates, be they density dependent or not, as well as greater attention to identifying sources of density dependence. Such a pluralistic focus necessitates integrated studies of both pre‐ and post‐settlement processes conducted at multiple spatial and temporal scales. For example, recent evidence suggests that density‐dependent pre‐dation on new recruits that have settled among reefs at different densities may prove to be an important source of local population regulation, especially via the aggregative response of transient piscivores.
The significance of variable and density‐independent post‐recruitment mortality in local populations of reef fishes
Authors: LEVIN PHILLIP S.
Published: July 2006

Abstract In this paper I focus on how post‐settlement mortality may modify initial patterns of settlement in reef fish. Infrequent recruitment surveys may underestimate the role of early post‐settlement mortality as most mortality in reef fishes occurs shortly after settlement. Consequently, results from infrequent recruitment surveys shed little light on the mechanisms producing patterns of abundance because these surveys ignore early post‐settlement mortality. Variation in density‐independent mortality may be a common mechanism that can prevent a positive relationship between larval settlement and subsequent population abundance. Although density‐dependent mortality is the most commonly recognized mechanism that can disrupt the correlation between settlement and adult abundance, density‐independent mortality’ can also destroy this correlation if the variance associated with post‐settlement mortality is greater than variance in settlement. This point is illustrated with a simulation model in which I modelled two populations: a piscivorous fish population that was recruitment‐limited with constant mortality, and a prey population that had variable recruitment and mortality that was a function of the size of the predator population. The results of this model indicate that even when mortality of prey is density‐independent, predation can determine prey abundance when variation in piscivore recruitment is high relative to prey recruitment. Thus, initial patterns of prey settlement can be modified by a recruitment‐limited predator population.
Season of burning in the Sydney region: The historical records compared with recent prescribed burning
Authors: McLOUGHLIN LYNETTE C.
Published: July 2006

Abstract Prescribed burning is regularly carried out by land management agencies controlling bushland estate in the Sydney region. Despite the volume of research into the interrelationships between fire and Australian ecosystems, season of burning has received comparatively little attention and is poorly understood. This paper considers three aspects of season of burning in the Sydney region, which is located on the boundary of the spring and spring‐summer fire season zones, identified by Luke and McArthur (1978). First the paper reviews research on the responses of biota to fire season to establish what is known of the ecological importance of fire season. The historical records of fires in the early period of Sydney's settlement (1788–1845) are then used to determine the seasonal pattern of fire in that period, and the extent to which these records reflect Aboriginal practices which contributed to the historic fire regime. Recent prescribed burning is sampled through the practices of two major land management authorities in northern Sydney (New South Wales National Parks and Wildlife Service and Hornsby Shire Council) to compare current practices with the early records and the ecological evidence. The results of the very limited ecological research on season is far from conclusive. Positive and negative effects have been shown for both autumn and spring with autumn‐winter perhaps showing the greater degree of negative impacts, although it is often difficult to separate the effects of season from intensity. The historic records show a pattern of fires, including those lit by Aborigines, largely confined to the fire season of spring‐early summer (August to January). By contrast 60% of prescribed burning in northern Sydney by the New South Wales National Parks and Wildlife Service and Hornsby Council from 1980 to 1995 was conducted in autumn‐winter (April to July). Prescribed burning in summer cannot be considered for practical reasons but timing of prescribed burning at other seasons is also largely dictated by pragmatic factors such as suitable weather and availability of personnel.
Patterns of phytophagous insect herbivory and abundance on juvenile regrowth of Eucalyptus subgenera coexisting in southeastern Tasmania
Authors: WOTHERSPOON K. P.
Published: July 2006

Abstract Eucalypts from the subgenus Monocalyptus tend to be more abundant and dominate species from the subgenus Symphyomyrtus where they occur together in the mixed species stands of southeastern Australia. The differential impacts of herbivory by phytophagous insects has been postulated as a causal mechanism in the creation and maintenance of such stands. This research aimed to quantify phytophagous insect abundance and herbivory in mixed species juvenile regrowth of Eucalyptus globulus, E. viminalis (Symphyomyrtus), E. obliqua and E. pulchella (Monocalyptus} southwest of Hobart, Tasmania. Monocalyptus experienced a higher level of herbivory than Symphyomyrtus. However, mean damage levels were relatively low at less than 11% throughout. Furthermore, due to the positively skewed nature of herbivory data the mean was an inappropriate measure of central tendency; median damage levels ranged from 4.9% to 8.4%. Patterns of herbivory tended to be different for each eucalypt species: E. obliqua was particularly prone to chewing damage, E. pulchella and E. globulus suffered higher levels of distortion while E. viminalis was least affected by insect attack. Even though some trends in insect community structure seemed apparent at the level of eucalypt subgenus, closer examination revealed patterns of abundance were characteristic of each Eucalyptus species. The composition of foliar damage corresponded with the prominence of particular insect groups. Sucking insects tended to dominate the fauna except on E. obliqua where chewing insects in general, and chrysomelids in particular, were most prevalent. Both the distribution and magnitude of herbivory suggested that phytophagous insects had a negligible effect on competition between coexisting juvenile eucalypts and were unlikely to be responsible for the dominance of Monocalyptus or the maintenance of mixed species stands.
Mites in the mist: How unique is a rainforest canopy‐knockdown fauna?
Authors: WALTER DAVID EVANS , SEEMAN OWEN , RODGERS DENIS , KITCHING R. L.
Published: July 2006

Abstract We intensively sampled the parasitiform mite faunas of three subtropical rainforest canopy habitats (leaves, bark, hanging humus) and three forest floor habitats (leaf litter, fungal sporocarps, arthropod associates) in the Green Mountains section of Lamington National Park, Queensland, and compared them to 423 specimens collected from the canopy by pyrethrin knockdown (PKD). In total, 165 species (80% new to science) were identified, including 58 from PKD. Few species occurred in more than one habitat, and complementarity averaged 96 ± 1%. About half of the species from PKD were found in canopy habitats, but less than 10% occurred in forest floor habitats. Thus, the canopy fauna is composed primarily of canopy specialists, not of forest floor mites, and habitat specificity is a major component of acarine diversity. An Incidence‐based Coverage estimator (generated by the EstimateS program) proved useful in predicting asymptotes for collector's curves. Conservative extrapolations from this study suggest that more than 2000 species of mites live in subtropical rainforest in the Green Mountains.
Stand structure of the emergent conifer Araucaria laubenfelsii) in maquis and rainforest, Mont Do, New Caledonia
Authors: RIGG L. S. , ENRIGHT N. J. , JAFFRE T.
Published: July 2006

Abstract Despite its small size, New Caledonia has a flora which includes 43 endemic species of conifer. This study examines the stand structure of the New Caledonian conifer, Araucaria laubenfelsii Corbasson, a species which occurs on ukramafic soils as an emergent tree in rainforest and in an unusual structural association with maquis vegetation. Fire and cyclone blow‐down are the primary disturbances in the maquis, but fire is infrequent in the rainforests which is evident from the low proportion of fire scarred trees. Preliminary results show abundant seedlings and saplings of A. laubenfelsii both in maquis and forest. Size class distributions of individuals suggest that the species is continuously regenerating in the maquis and immature forests. Variability in the stand structure in maquis communities reflects the probable patchy nature of disturbance from small‐scale fires and blow‐down from tropical cyclones. In mature forests, Nothofagus codonandra (Baillon) Steenis is the dominant canopy species and ‘other tree species’ are continuously regenerating, while the size class distributions and basal area of A. laubenfelsii suggest that there is, at present, limited regeneration of this species. Tree ring counts indicate that individuals in forest areas grow at a slower rate than those in maquis, but attain greater age, probably as a result of greater protection from fire.
Dynamics of temperate rainforest from fine resolution pollen analysis, Upper Ringarooma River, northeastern Tasmania
Authors: DODSON J. R. , MITCHELL F. J. G. , BÖGEHOLZ H. , JULIAN N.
Published: July 2006

AbstractThe relationship between sclerophyll forest and temperate rainforest in Tasmania is believed to be driven by climate, soils and fire regime; however, this has been tested infrequently on time frames relevant to the longevity of the major forest trees involved. This study uses sediments in four small hollows from within a rainforest stand in the Upper Ringarooma valley in northeastern Tasmania, Australia, to analyse vegetation dynamics and disturbance over the last 1000 years. Pollen‐vegetation relationships were investigated by comparing pollen rain and current vegetation, and the chronology was established by radiocarbon and lead‐210 dates. The lead‐210 data indicate that the twoSphagnumhumus profiles were not always closed systems for inorganic inwash; however, the pollen and charcoal records are generally consistent indicating that a mixedEucalyptus‐Nothofagusforest shifted to a Kothofagus dominated rainforest as fire became a less prominent component of the environment. About 400 years agoLeptospermum lanigeruminvaded the community as canopy gaps developed, possibly as the olderNothofagus Cunninghamiitrees died. There is no strong evidence of invasion byAtherosperma moschatumas suggested by some models of forest dynamics in these forests in Tasmania. In this stand of forest, fire and erosion following flooding have been the major causes of disturbance.
THE VARIATION OF REGIONAL POPULATION IN JAPAN*
Authors: Suzuki Keisuke
Published: July 2006

CONCLUSION

In this paper, firstly a model of the variation of regional population was constructed, based on the work of Klaassen and the wage and job opportunity theories. Secondly, the reduced form of the model was made and fitted to the data of Japan for 1965 and the time period 1960–1965. The model was successfully fitted to the data.

It was therefore concluded that in Japan, the mechanism of determination of a regional population could be shown by the model proposed in this paper, and the population in a region was determined by the natural increase of population and the economic activity of the region.

Moreover, the fact that the densely populated region in Japan has higher population growth as the region has higher economic activity and higher natural increase ratio of population was found.
A RESIDENTIAL ENERGY MARKET MODEL: AN ECONOMETRIC ANALYSIS*
Authors: Wang Young‐Doo , Tannian Francis X. , Solano Paul L.
Published: July 2006

This paper develops a multisector residential energy policy model. This model hypothesizes that household energy behavior is affected by conditions in the housing, the mortgage finance, and the energy markets. The relationships encompassed by the model are specified with 32 single and simultaneous equations and tested with quarterly data drawn from behavior in Delaware. After the testing and evaluation of the model for its statistical performance, thereafter, three energy policies are simulated a 5 percent residential energy consumption tax, a set of conventional insulation requirements for all new housing, and a passive solar‐installation requirement for all new housing. These policy choices are evaluated in terms of their impact on energy consumption, prices, demand and size of different types of housing permits, and mortgage financing. Finally, the economic and social implications of these policy impacts are discussed.
THE ROLE OF ERROR STRUCTURE IN SIMULATIONS ON REGIONAL INPUT‐OUTPUT ANALYSIS*
Authors: Garhart Robert
Published: July 2006

Previous simulation experiments on regional input‐output analysis have concluded that regional purchase coefficients are more important than technical coefficients in contributing to multiplier accuracy. This paper shows that the multiplicative error structure used in those experiments may have biased the results. A new error structure, combining a multiplicative and an additive component is introduced, and simulations are conducted on randomly generated models. The analysis shows that the results are sensitive to the relative magnitudes of the two error components, as well as to the closure of the model.
SPATIAL PRICE POLICY AND THE DEMAND FOR TRANSPORTATION
Authors: Beckmann Martin J.
Published: July 2006

For a spatial market of given radius transportation cost per unit sold is less under mill pricing than under any uniform pricing. This is true whether profit‐maximizing monopoly prices or welfare‐maximizing prices or any other prices are chosen.
THE NET FISCAL IMPACT OF SELECTED FEDERAL BLOCK GRANT PROGRAMS*
Authors: Strauss Robert P. , Harkins Peter B.
Published: July 2006

This paper examines the net fiscal benefits of various federal grants and taxes paid to finance them. Net, effective tax rates are calculated for all county areas in the U.S. for seven measured grant programs, and the distributions of such tax rates are examined in conjunction with the median family incomes of the county areas. Inferences about the progressivity (or regressivity) of the grant programs are made, as well as inferences about the horizontal equity of the grant programs through the use of a new class of index numbers. It was found that more progressive grant formulas, which provide greater rates of subsidy to areas with lower median family incomes, also tend to be less horizontally equitable.
THE MINIMAX‐MIN LOCATION PROBLEM*
Authors: Drezner Z. , Thisse J.‐F. , Wesolowsky G. O.
Published: July 2006

We consider a new objective function for the placement of a public facility with reference to variations in accessibility : the minimization of the range between the maximal and the minimal distances to users. Some properties of the solution are given; algorithms for the Euclidean and rectilinear distance cases are presented.
AUTOMOBILE USE AND LOCATIONAL INTERDEPENDENCIES
Authors: McConnell Virginia D.
Published: July 2006

ABSTRACT. Congestion and pollution externalities from automobile use are simultaneously included in an urban monocentric model. The externalities enter household utility functions directly, and result in a complex interdependency in household location decisions in the city. Implications of the model are drawn out by a simulation and complete sensitivity analysis. The two unpriced externalities are examined for their impact on urban structure, and contrasted with each other. Also, the effect of changes in speed of travel are examined for the impact on urban structure. Speed affects the level of both external effects, and is affected by location decisions.
LOCATION, THEORY OF PRODUCTION, AND VARIABLE TRANSPORTATION RATES*
Authors: Ziegler Joseph A.
Published: July 2006

ABSTRACT. The question of what conditions insure independence between location and output decisions is investigated within the context of triangle space. Assuming that transportation rates vary with quantity and distance, it is shown that this independence is insured if the production function generates a linear expansion path and the following are all constant: transportation rate elasticities with respect to distance and quantity, and the price elasticity of demand for inputs.
COMPUTATIONAL COMPARISONS OF SPATIAL PRICE EQUILIBRIUM METHODS*
Authors: Nagurney Anna
Published: July 2006

ABSTRACT. In this paper we propose new algorithms for the solution of both general and standard spatial price equilibrium problems, and test their performance with existing algorithms on randomly generated problems. For the standard problem, we propose decomposition schemes based on the concept of “equilibration operator” and compare their performance with the Frank‐Wolfe method. For the general problem, we present alternative variational inequality formulations defined over Cartesian products of sets and then exploit these formulations to construct Gauss‐Seidel‐type serial decomposition methods. We then compare their performance with the projection method. Our computational tests suggest that the new schemes are substantially more efficient than earlier ones.
SENSITIVITY ANALYSIS FOR GENERAL SPATIAL PRICE EQUILIBRIA
Authors: Tobin Roger L.
Published: July 2006

ABSTRACT. General spatial price equilibrium models are formulated as variational inequalities. Sensitivity analysis results recently developed for variational inequalities are reviewed which give conditions for existence and equations for calculating the derivatives of solution variables with respect to perturbation parameters. These results are applied to the variational inequality formulations of general spatial price equilibria, and derivatives of supplies, demands, flows, and prices with respect to perturbations of supply functions, demand functions, and transportation‐cost functions are calculated.
A REGIONAL CONSUMER DEMAND MODEL FOR NEW ZEALAND*
Authors: Giles David E. A. , Hampton Peter
Published: July 2006

ABSTRACT. This paper discusses the formulation and estimation of sets of demand systems for six New Zealand regions. The chosen model is based on the Linear Expenditure System, constrained in various ways to take account of interregional differences in consumer behaviour. Our results suggest that income and price elasticities of demand vary significantly between regions, suggesting that regional employment and output patterns are likely to differ in their responses to changes in aggregate demand.
POISSON GRAVITY MODELS OF SPATIAL FLOWS*
Authors: Smith Tony E.
Published: July 2006

ABSTRACT The purpose of this paper is to bring together a number of results on spatial flow models, and to reformulate them within a unified probability framework based on Poisson frequencies. To do so, a class of discrete stochastic processes, designated as independent flow processes, is developed which not only yields a complete characterization of Poisson flow frequencies, but also allows a wide range of gravity‐type flow models to be formulated within this distributional framework. In particular, a hierarchical classification of 12 model types is developed, and each model type is shown to be characterizable directly in terms of behavioral axioms on independent flow processes.
HOUSEHOLD INCOME AND EXPENDITURE IN EXTENDED INPUT‐OUTPUT MODELS: A COMPARATIVE THEORETICAL AND EMPIRICAL ANALYSIS*
Authors: Batey P. W. J. , Madden M. , Weeks M. J.
Published: July 2006

ABSTRACT At the regional level in‐migrant and indigenous workers are likely to have different income levels and consumption propensities. The effects that these differences have upon a local economy are explored within an extended input‐output modeling framework. Two iterative input‐output models, due to Miernyk et al. and Blackwell, are recast as systems of simultaneous equations and are shown to produce identical results. A detailed analysis is made of model structure and a method is outlined for the decomposition of income multipliers. Empirical versions of the two models, for Boulder and Cork, are reconstructed with data from the original studies and are used to make comparisons of the two local economies.
A DYNAMIC MODEL OF REGIONAL POPULATION GROWTH AND DECLINE*
Authors: Mathur Vijay K. , Stein Sheldon H. , Kumar Rishi
Published: July 2006

ABSTRACT. This paper presents a two‐sector dynamic model of regional population change. The model contains a migration equation, an earnings equation, and an amenity equation for each region. In the context of this model, migration is seen as a disequilibrium process through which the regional populations move towards equilibrium positions. Migration occurs when one region is perceived to be superior to the other on the basis of its earnings and amenity levels. Equilibrium is achieved when population movements between the regions eliminate any differences in their relative attractiveness. A comparative‐static analysis of the model is presented to analyze the effects of policy changes and exogenous shocks on the distribution of population among the regions. We find that positive shocks to regional earnings and to amenity tend to increase the population of a region. However the amenity shocks generate two opposing effects on regional population, with stability of the model requiring that the expansionary effect of the amenity shock outweigh the contractionary effect.
A SPATIAL COMPETITION APPROACH TO CENTRAL PLACE THEORY: SOME BASIC PRINCIPLES*
Authors: Fujita Masahisa , Ogawa Hideaki , Thisse Jacques‐François
Published: July 2006

ABSTRACT. This paper investigates the potential offered by the model of spatial competition for the study of central place theory. We consider n firms selling m substitutable or complementary goods to a continuum of consumers evenly distributed along a linear segment. Consumers have the same income and the same utility function which is quadratic in the goods supplied by the firms and linear in the numeraire. The main results are as follows. (1) In any location equilibrium in which all goods are consumed everywhere, each good supplied by a single firm is sold at the market center. In Christaller's terminology, this means that when the exhaustive principle holds in equilibrium, highest‐order goods are made available at the center. (2) When all goods (excluding the numéraire) are complements to each other and each good is sold by a single firm, there always exists an equilibrium in which all the firms locate coincidentally. (3) If the stores selling a given good are under the control of a single owner then, in any equilibrium for which the exhaustive principle holds, the stores are located in a way such that the total transport cost (borne by consumers) is minimized.
THE EFFECTS OF LOCAL TAXES AND PUBLIC SERVICES ON RESIDENTIAL DEVELOPMENT PATTERNS*
Authors: Turnbull Geoffrey K.
Published: July 2006

ABSTRACT. This paper incorporates an exogenous taxing and service‐providing public sector into a dynamic residential land‐use model in order to examine how local‐government fiscal policies alter the pace and pattern of residential development. The model is used to derive the comparative‐dynamic responses to variations in the income, sales, and property taxes and public‐service time paths. The results show how tax and expenditure effects systematically depend upon the anticipated relative growth rates in rents to alternative uses and vary across locations within a given urban area as well as across urban areas themselves.
AN EMPIRICAL ANALYSIS OF INTERREGIONAL PRICE LINKAGES*
Authors: Mjelde James W. , Paggi Mechel S.
Published: July 2006

ABSTRACT Vector autoregression models are used to analyze the relationships between Texas and Illinois corn prices, and the New Orleans export price. Decomposition of error variances suggests an increasing exogeneity in the recent years between the export market and the two U.S. markets. Impulse response functions indicate that the export price influences both the Illinois and Texas prices.
FIRM ENTRY AND EXIT: CAUSALITY TESTS AND ECONOMIC‐BASE LINKAGES*
Authors: Mayo John W. , Flynn Joseph E.
Published: July 2006

ABSTRACT One of the foundations of applied regional economics down through the years has been economic base theory (EBT). EBT presumes that economic activity within the basic sector unidirectionally causes economic activity in nonbasic sectors. In recent years, however, increasing attention has been given to the possibility that traditionally nonbasic activities (e.g., services) may be quite important in determining a region's total economic activity. In this paper, we examine the nature and direction of causality of economic activity within a regional economy. Using novel data on entry and exit of firms, the empirical analysis provides new insights into the strengths and weaknesses of traditional economic base theory.
A DYNAMIC INTRSECTORAL, MODEL OF REGIONAL ECONOMIC GROWTH*
Authors: Kraybï David S. , Dorfman Jeffrey H.
Published: July 2006

ABSTRACT. The dynamic relationship between sectoral value added and regional economic growth is analyzed using a stochastic intersectoral model estimated by ordinary least squares and linear systems techniques. A state‐space portion of the model identifies the time element of sedoral value added. Dynamic multipliers, tracing the temporal path of regional growth, are calculated for the state of Georgia over the period 1963–1986. This application shows that the impacts of sectoral shocks can follow cyclical as well as monotonic patterns and that the direction and magnitude of the impact may change over time.
GENERAL EQUILIBRIUM OF A REGIONAL ECONOMY WITH A FINANCIAL SECTOR–PART II: A SIMPLE BEHAVIORAL MODEL
Authors: Hughes Merritt
Published: July 2006

ABSTRACT. Simple behavioral assumptions are incorporated into an accounting framework that provides linked budget and balance sheets for sectors of a regional economy. A short‐run Keynesian‐type model is developed where quantities rather than prices adjust, and where regional prices and interest rates are equal to national levels. The analysis highlights the importance of the financial services sector as an active factor in regional growth. Consumer deposit and debt preferences, and limitations imposed on credit extension by the financial services sector can have important effects on the regional economy as evidenced by changes in the export multiplier.
TRANSPORTATION COSTS IN REGIONAI, MODELS OF FOREIGN TRADE: AN APPLICATION TO CANADA‐U.S. TRADE*
Authors: Wide Randall M.
Published: July 2006

ABSTRACT. This paper outlines some arguments about the role of transportation costs in determining the welfare consequences of trade restrictions. The analysis uses a computable general equilibrium (CGE) model and presents the relevant features for trade analysis. The model has two alternative spatial formulations. In the first, all production and trade occur at one point, while in the second the regions are separated by distance. The calculated effects of a unilateral tariff increase are compared using the CGE model with the “point” and “distance” formulation. While the presence of transportation costs is crucial to some sectoral trade and production results, most welfare results are relatively insensitive to the spatial structure of the model.
EQUILATERAL TRIANGLE VS. HEXAGON: A MOST SIMPLE DEMONSTRATION
Authors: Tellier Luc‐Normand
Published: July 2006

ABSTRACT. This note presents a most simple proof of the superiority of hexagons over equilateral triangles of the same size in terms of minimization of the average distance between consumers and facilities. It also stresses that, under the same assumptions, facilities are closer to each other in a triangular grid than in an hexagonal grid and that this fact should not be neglected.
SUPPLY ARMS AND OPTIMAL SPATIAL STRUCTURE*
Authors: Parr John B.
Published: July 2006

ABSTRACT. A multi‐plant producer has sole access to a region, and each of the plants processes a raw material which is drawn from its own exclusive supply area. Under these conditions what spatial structure of production (in terms of plant scale, plant frequency, supply‐area size and supply‐area shape) will enable region‐wide or multi‐plant profit to be maximized? The form of this optimal structure is shown to vary with prevailing level of price, which is exogenously determined.