The boom in mineral markets: How long might it last?

The commodity price boom that emerged in 2004 has proved far more persevering than its predecessors of 1950 and 1973. Some analysts have suggested that it may represent the start of a “supercycle” caused by the voracious raw materials demand from China and other emerging economies, with prices remaining high for 20-30 years. We offer an alternative explanation. For a variety of reasons, the establishment of new capacity in minerals and energy to match the accelerated demand trends is more time consuming than commonly assumed, and may take a decade or longer. As soon as the new capacity is in place, however, the boom will be punctuated. Prices may collapse much earlier in the event of a severe recession that cuts the growth in commodity demand.     

Optimal fishery policy with artificial enhancement through stocking: California's white sturgeon as an example

Although optimal fishery policy has been derived from different kinds of economic and biological models, the interaction of fishing policy with artificial stocking policy has not been explicitly considered. We here determine optimal size limits, fishing effort, and stocking rate for three cases of interest: (1) recruitment-limited population, pre-recruitment stocking; (2) adult biomass-limited population, post-recruitment stocking; and (3) adult biomass-limited and recruitment-limited population, post-recruitment stocking. Results show that lower size limits should be set at the size at which the current market value exceeds the total future value of an individual, both to the fishery and to reproduction. Imposition of upper size limits is rarely optimal. Stocking is advisable when the hatchery cost times the relative contribution of stocking to recruitment is less than the contribution to the value of the catch. Optimal policy ranges from infinite effort at a specific size limit with maximum stocking when the cost of stocking is zero, to lower values of size limit and effort as stocking costs increase, the amount of stocking decreases, and more natural reproduction is optimal. Thus, as hatchery costs decline (or value of captured fish increases), optimal stocking/fishery policy varies from an unstocked fishery to a “put and take” fishery. The results are applied to the sturgeon fishery in the San Francisco Bay Estuary as an example. They imply that a reduced lower size limit and greater fishing mortality together with stocking would be optimal, but that current levels are conservative. The stocking decision depends critically on the values of parameters that are currently poorly known, such as: hatchery costs, survival to the fishery and the mechanisms controlling the sturgeon population.     

Mineral exploration in the USSR and the USA

This article compares non-fuel mineral exploration in the USSR and the USA. It examines the organization of exploration; recent trends in the level and distribution of expenditures; exploration productivity; and planning and decision making. It shows that although the sequence of exploration stages and activities is very similar in both countries, substantial differences overshadow these similarities, largely because of different economic and political systems and mineral endowments. However, the article concludes that we still have much to learn before making a full comparison of Soviet and US exploration.     

Application of a Wind Model for the El Paso-Juarez Airshed

ABSTRACT

A time-dependent, 3-dimensional mesoscale model, version 5 (MM5), developed by the Penn State University and the National Center for Atmospheric Research, was applied to study the meteorology over complex terrain of the El Paso-Juarez area. MM5 meteorological output data were compared against experimental data from the Texas Natural Resource Conservation Commission on days of reported high ozone concentrations. Model runs were conducted for a 36-, 12-, 4-km grid arrangement. Results indicate that the dispersion of pollutants by wind plays a significant role on days of low peak ozone concentration.     

Evaluation of aerial photography for predicting trends in structural attributes of Australian woodland including comparison with ground-based monitoring data

The accurate assessment of trends in the woody structure of savannas has important implications for greenhouse accounting and land-use industries such as pastoralism. Two recent assessments of live woody biomass change from north-east Australian eucalypt woodland between the 1980s and 1990s present divergent results. The first estimate is derived from a network of permanent monitoring plots and the second from woody cover assessments from aerial photography. The differences between the studies are reviewed and include sample density, spatial scale and design. Further analyses targeting potential biases in the indirect aerial photography technique are conducted including a comparison of basal area estimates derived from 28 permanent monitoring sites with basal area estimates derived by the aerial photography technique. It is concluded that the effect of photo-scale; or the failure to include appropriate back-transformation of biomass estimates in the aerial photography study are not likely to have contributed significantly to the discrepancy. However, temporal changes in the structure of woodlands, for example, woodlands maturing from many smaller trees to fewer larger trees or seasonal changes, which affect the relationship between cover and basal area could impact on the detection of trends using the aerial photography technique. It is also possible that issues concerning photo-quality may bias assessments through time, and that the limited sample of the permanent monitoring network may inadequately represent change at regional scales.     

A land management history for central Queensland,Australia as determined from land-holder questionnaire and aerial photography

Features of the land management history over a 125,755 km(2) area of central Queensland, Australia were determined from a variety of sources. A random sample of 205 site locations provided the basis for determining trends in land use. Trends in vegetation clearing were determined using sequential aerial photography for the sample sites, revealing a steady rate averaging nearly 1% of the region per annum over 41 years. This measure of sustained clearing over a large region is higher than recently published clearing rates from South America. Land types have been selectively cleared with over 90% of the Acacia on clay land type having been cleared. A land-holder questionnaire pertaining to the random sites yielded a response rate of 71% and provided information on vegetation clearing, ploughing, tree killing (ring-barking or tree poisoning), and fire frequency, season and intensity. The land-holder responses were compared with independent data sources where possible and revealed no mis-information. However, land-holders may have been marginally less likely to respond if the sample area had been cleared, although this effect was not statistically significant. Ploughing and tree killing are variable depending on land type, but the former has affected about 40% of the Acacia on clay land type, effectively eliminating options for natural regrowth. The proportion of decade-site combinations that were reported as having no fires increased from 22% in the 1950s to an average of 42% for subsequent decades, although the reporting of more than one fire per decade has been relatively constant through the study period. The reporting of at least one fire per decade varies from 46% for the Acacia on sand land type to 77% for the Eucalypt on sand land type for decade-site combinations. Fires are more intense when associated with clearing than in uncleared vegetation, but the proportion of cool and hot fires is relatively constant between land types in uncleared vegetation. Nearly all fires reported were either in spring or summer and this seasonally restricted regime is probably at variance with Aboriginal fire regimes. This study describes the rapid transformation of central Queensland. This has yielded substantially increased agricultural production but may also result in a range of negative impacts and these are discussed.     

Modelling trends in woody vegetation structure in semi-arid Australia as determined from aerial photography

Accounting of carbon stocks in woody vegetation for greenhouse purposes requires definition of medium term trends with accurate error assessment. Tree and shrub cover was sampled through time at randomly located sites over a large area of central Queensland, Australia using aerial photography from 1945 to 1999. Calibration models developed from field data for the same land types as those represented within the study area allowed for the extrapolation of overstorey and understorey cover, basal area and biomass values and these were modelled as trends over the latter half of the 20th century. These structural attributes have declined over the region because of land clearing with values for biomass changing from a mean of 58.0(+/-1.2)t/ha in 1953 to 41.1(+/-1.0)t/ha in 1991. The biomass of Acacia on clay and Eucalypt on texture contrast soils land types has declined most dramatically. Within uncleared vegetation there was an overall trend of increase from 56.1(+/-1.2)t/ha in 1951 to 67.6(+/-1.3)t/ha in 1995. The increase in structural attributes within uncleared vegetation was most pronounced for the Eucalypt on texture contrast soils and Eucalypt on clay land types. It was demonstrated that the sites sampled were representative of their land types and that spatial bias of the photography, undetected tree-killing, sampling error, inherent variability of structural attributes and measurement error should not have impacted greatly on bias or precision of trend estimates for well-sampled land types. Certainly the errors are not likely to be substantial for trends averaged over all land types and they provide an accurate assessment of the magnitude and direction of change. The technique presented here would appear to be a robust means of accounting for the above-ground woody component of woodlands and open forests and will also contribute to a broader understanding of savanna dynamics.     

Antecedents of union loyalty: The influence of individual dispositions and organizational context

Previous research has consistently found relationships between union loyalty and the antecedent variables of demographics, job related variables, and union related variables. However, little or no research has investigated the relationship between union loyalty and individual dispositions and organizational context. The purpose of this study was to test a causal model which evaluated the influence of individual dispositions and organizational context in predicting union loyalty controlling for the effects of demographics, job related, and union related variables. Contextual data were collected from 405 schools and matched with union loyalty and other attitudinal data from 838 public school teachers in a large U.S. Midwestern city. The LISREL results indicate that the individual dispositions of positive and negative affectivity and the contextual variables of attendance rate, school type, race homogeneity and socio-economic status had significant total causal effects on union loyalty. Implications of these findings are discussed.