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PubMed2005

Effects of kaolin-based particle film on spruce budworm (Choristoneura fumiferana (Lepidoptera: Tortricidae)) oviposition in the laboratory.

A laboratory study conducted in 2003 determined the influence of a kaolin-based particle film (Surround WP Crop Protectant) on spruce budworm (Choristoneura fumiferana (Clem)) oviposition. Three concentrations (15, 30 and 60 g litre(-1) spray carrier) were applied to white spruce (Picea glauca (Moench) Voss). When presented with different paired choices of oviposition surfaces, spruce budworms laid very few egg masses overall and showed no significant (P < 0.05) preference between kaolin-coated and untreated foliage. During no-choice tests, spruce budworms were significantly (P < 0.05) less inclined to oviposit on the 60 g kaolin litre(-1) treated foliage than on the controls, but no kaolin treatment completely inhibited spruce budworm oviposition. Egg mass size and percentage hatch were unaffected by the kaolin treatments, and overall the percentage of egg masses laid on foliage was inversely proportional to treatment concentration. It is unlikely that kaolin-based particle film would be practical for wide use in natural forests without significant adaptations to current pesticide application equipment and methods. However, the technique might be feasible in selected urban settings.

Animals↗
PubMed2006

Fumigant distribution in forest nursery soils under water seal and plastic film after application of dazomet, metam-sodium and chloropicrin.

Adequate concentration, exposure time and distribution uniformity of activated fumigant gases are prerequisites for successful soil fumigation. Field experiments were conducted to evaluate gas phase distributions of methyl isothiocyanate (MITC) and chloropicrin (CP) in two forest-tree nurseries. Concentrations of MITC and CP in soil air were measured from replicated microplots that received dazomet, metam-sodium and CP. Half of the plots were covered with high-density polyethylene tarp immediately after fumigation; the other half were not covered but received daily sprinkler irrigation for 1 week to create and maintain a water seal. The magnitude of MITC concentrations was similar between nurseries for metam-sodium in both tarp and water seal treatments and for dazomet in the tarp treatment. Consistently greater MITC and CP concentrations were found in the upper 30 cm of soil in the tarped plots compared with the water-sealed plots. Despite potential environmental and economic benefits with the water seal method, tarp covers were more reliable for achieving and maintaining higher MITC and CP concentrations and less prone to variations due to irrigation/rain, soil bulk density and other environmental conditions.

Forestry↗
PubMed2001

Windbreaks as a pesticide drift mitigation strategy: a review.

The use of natural and artificial barriers to mitigate pesticide drift from agricultural and forest applications is discussed. This technique has been considered as an alternative to current methods at a time when environmental concerns are under great public scrutiny. There has been a variety of research experiments on this subject from New Zealand to The Netherlands which have documented reductions in spray drift of up to 80-90%. However, there are still enormous data gaps to utilize this method accurately. The aerodynamic factors of wind barriers and shelter effects on crop growth and yield have been well investigated. In contrast, some of the important aspects of drift mitigation, e.g. porosity and turbulence, have been difficult to obtain and no standard methodologies are currently available to evaluate and classify windbreaks and shelterbelts or to determine their efficiency in reducing drift. Thus there is a significant opportunity to incorporate windbreaks into the tool set of drift mitigation tactics. Government policies, initiatives, legislation, etc, which currently address water quality, BMP, stewardship, buffers, etc, are issues which so far have not included windbreaks as a valuable drift mitigation strategy.

Agriculture↗
PubMed2002

Fate of spinosad in litter and soils of a white spruce plantation in central Ontario.

Spinosad is a natural insecticide with potential as a novel biorational control agent for spruce budworm (Choristoneura fumiferana [Clem]), the most destructive insect defoliator of spruce and balsam fir in Canada. Concurrent terrestrial fate experiments were conducted under full coniferous canopy and in a natural opening of a mature white spruce (Piecea glauca [Moench]) plantation of central Ontario to examine the fate and persistence of spinosad in the forest floor and underlying soils. Mean initial residues of spinosyn A and D were approximately 0.2 and 0.02 microgram g-1, respectively, in thatch and exposed soils, but were substantially higher, 2.72 and 0.36 micrograms g-1, in litter under coniferous canopy. Results demonstrated that spinosad residues in spruce litter, graminaceous thatch and exposed sandy loam soils dissipated rapidly, following hyperbolic or exponential decline models. Dissipation time (DT50) values ranged from 2.0 to 7.8 days, depending on matrix and experimental conditions. Transient increases in demethylated metabolite residues confirmed that the parent product was degraded in situ. No evidence of vertical mobility of any of the analytes was observed.

Anti-Bacterial Agents↗
PubMed2002

Comparative toxicity of chlorothalonil and chlorpyrifos: Ceriodaphnia dubia and Pimephales promelas.

This study was done to characterize responses of Ceriodaphnia dubia Richard and Pimephales promelas Rafinesque exposed to aqueous solutions of chlorothalonil (tetrachloroisophthalonitrile) and chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate). Chlorothalonil (a fungicide) and chlorpyrifos (an insecticide) are intensely used in agricultural, silvicultural, and urban settings. These pesticides may enter aquatic systems through several pathways including rainfall runoff. C. dubia and P. promelas have been used to monitor surface waters and discern the effects of pesticides that contaminate those waters. Modified static renewal exposures (7 or 10 days) with individual solutions of chlorothalonil and chlorpyrifos were used to obtain mortality data for C. dubia and P. promelas, from which potency curves were derived, as well as sublethal effects data (reproduction or growth). In these experiments P. promelas was more sensitive to chlorothalonil, and C. dubia was more sensitive to chlorpyrifos. Lower and upper thresholds (i.e., LC(0) and LC(100)) for 7-day P. promelas exposures to chlorothalonil were 14.4 and 30.8 microg/L, respectively, in contrast to the lower and upper threshold values, 103 and 210 microg/L, respectively, for C. dubia. Ten-day exposures of C. dubia to chlorpyrifos resulted in lower and upper threshold values of 0.05 and 0.09 microg/L, whereas 10-day exposures of P. promelas to chlorpyrifos yielded threshold values of 26 and 274 microg/L. The results of this study illustrated differences in species' sensitivities to chlorothalonil and chlorpyrifos as well as differences in the duration of the exposure necessary to illustrate effects that might be elicited from pesticide exposures.

Agriculture↗
PubMed2001

Prediction of the impact of logging activities on forest cover: a case-study in the east province of Cameroon.

The objective of this study was to test the value of the concept of the net commercial value of standing timber in predicting the impact of logging activities on forest-cover modifications. A study area was selected in the East province of Cameroon which contains major primary forests and which contributes strongly to national timber production. A Geographic Information System containing ecological and economic variables was used in combination with remote sensing data to define the net commercial value of standing timber in the East province. Taking account of the potential commercial value of standing timber improves our understanding of the spatial determinants of logging activities and of the resulting forest-cover modifications. The occurrence of logging-induced forest-cover modifications increases with the value of forest rent. In one of the study sites, half of the very high rent areas have already been logged. In that site, therefore, it is mostly the low rent or marginal forest areas that remain unlogged. This was not the case, however, throughout the study area as shown by the observations at another site.

Cameroon↗
PubMed2001

Economic valuation of urban forest benefits in Finland.

Urban development projects may cause loss of amenity values of green areas, which should be taken into consideration in planning. Therefore, quantitative information on residents' valuation concerning urban forests is needed for assessing urban land use. The purpose of this investigation was to study the valuation of urban forests in two different urban environments Joensuu and Salo, Finland. The aims were to study the attitudes towards and benefits related to the use of urban forests and, in particular, to measure the valuations in monetary terms using contingent valuation, i.e. measure the residents' willingness-to-pay for larger wooded recreation areas and for small forested parks. Urban forests were seen in both towns as clearly producing positive benefits rather than causing negative effects. The negative features of forests were related to the management of the areas rather than their existence. The main values were related to nature and social functions of forests. In contrast, timber production achieved a distinctively low priority in both study towns. The results stress the importance of defining urban forest policies for municipalities in Finland. More than two-thirds of the respondents were willing to pay for the use of recreation areas. Good location and active management raised the average WTP. Moreover, approximately half of the respondents were willing to pay for preventing construction in urban forests. The results also show that the monetary value of amenity benefits in recreation areas is much higher than the present maintenance costs. The examples concerning the advantageousness of construction on green areas suggest that a limit could be found where the infill of housing areas is not worthwhile from the point of view of society, if the losses of green space benefits are taken into account.

Adolescent↗
PubMed2001

Environmentally sensitive plot-scale timber harvesting: impacts on suspended sediment, bedload and bank erosion dynamics.

The impact on sediment pollution of environmentally sensitive harvesting of a 15 ha plot (20% of the catchment area) of mature coniferous plantation forest in the 0.89 km2 Afon Tanllwyth catchment, Plynlimon, was investigated for 12 months before harvesting began and a further 18 months after. The results revealed: (a) a steepening of the suspended sediment concentration vs. discharge rating curve resulting in a 39% increase in suspended sediment yield (as compared to the adjacent forested Hafren catchment) during the year in which the harvesting operations took place; (b) a statistically significant increase in main channel bank erosion rates, as compared with the nearby Afon Cyff; main channel banks are estimated to have contributed around 80% of the total catchment suspended sediment yield during the two year period (1995-1996), and (c) no significant change in bedload yields over the duration of the study, though a longer post-harvesting time series of bedload data will be required to properly assess the impact of the harvesting operation upon bedload yields. Forest management implications of these findings are discussed in detail with respect to the existing Forest and Water guidelines.

Conservation of Natural Resources↗
PubMed2001

Country 'choices' or deforestation paths: a method for global change analysis of human-forest interactions.

Data used in quantitative studies of global tropical deforestation are typically of poor quality. These studies use either cross-sectional or panel data to measure the contribution of social and land use factors to forest decline world wide. However, there are pitfalls in the use of either type of data. Panel data studies treat each year's observation as a distinct, reliable, data point, when a careful examination of the data reveals this assumption to be implausible. In contrast, cross-sectional studies discard most of the time series information in the data, calculating a single average deforestation rate for each country. In this paper, we argue for a middle road between these two approaches: one that does not treat the time series information as completely reliable but does not disregard it altogether. Using a well-known global forest data set (FAO's Production Series Yearbooks), we argue that the most the data can reliably tell us is whether a country's deforestation rate falls into one of four categories or country 'path choices'. We then use the data categorised in this way in a small empirical investigation of the socio-economic causes of deforestation. This multinomial logit framework allows for the determination of the influence of independent variables on the probability that a country will follow one deforestation path vs. another. Results from the logit analysis of key social and land use indicators chosen for their importance in the literature in driving deforestation suggest that the effect of these variables will differ for countries depending on the particular set of deforestation trajectories in question.

Conservation of Natural Resources↗
PubMed2001

Environmental management in resource-rich Alberta, Canada: first world jurisdiction, Third World analogue?

Economic growth is frequently touted as a cure for environmental ills, particularly for those in Third World countries. Here we examine that paradigm in a case study of Alberta, Canada, a wealthy, resource-rich province within a wealthy nation. Through provincial-scale datasets, we examine the increasing pressures of the forest, petroleum, and agricultural industries upon the ecosystems of Alberta within management, economic, and political contexts. We advance the thesis that economic activity leads to environmental degradation unless ecosystem-based management is integrated into economic decision making. Agricultural lands cover 31.7%, and forest management areas leased to industry cover 33.4% of Alberta; both continue to increase in extent. The rate of logging (focused on old-growth by government policy) continues a decades-long exponential rise. Current Alberta annual petroleum production is 52.5 million m3 crude oil and 117 billion m3 of gas. As of early 1999, there were approximately 199,025 oil and gas wells and a conservative total of approximately 1.5-1.8 million km of seismic lines in Alberta. Fire occurrence data indicate no downward trends in annual area burned by wildfire, which may be characterized as driven by climate and inherently variable. When logging and wildfire are combined, the annual allowable cut in Alberta is unsustainable, even when only timber supply is considered and the effects of expanding agriculture and oil and gas activities are ignored. Ecosystem degradation in Alberta is pervasive and contrasts prominently with a high standard of living. A wealth of ecological data exists that indicates current resource-based economic activities are non-sustainable and destructive of ecosystem health yet these data are not considered within the economic decision making process. Given the complex, compounded, and increasing ecosystem perturbations, a future of unpleasant ecological surprises is likely. We conclude with tentative predictions as to where current trends in Alberta may lead if decisions biased against ecosystems continue.

Agriculture↗
PubMed2002

Urbanization's impact on timber harvesting in the south central United States.

The impact of urbanization on timber harvesting in the south central United States was investigated. Geo-referenced Census and Forest Inventory Analysis (FIA) data were combined using a geographic information system (GIS) in order to examine the effects of various demographic and biophysical forest inventory characteristics on timber harvesting. These effects were estimated for intermediate and final harvests using a multinomial logit model. The probability for both types of harvests decreased with increasing population density, decreasing forest size, and decreasing distance to urban areas; however, the reduction in intermediate harvests was greater for each variable. Harvesting rates decreased by as much as 19% as population densities increased or distance to urban areas decreased. The results indicated that active forest management is curtailed far beyond the urban boundary. In order to model the impact of urbanization adequately, timber supply projections must also account for its impact on harvesting frequencies in surrounding areas.

Cities↗
PubMed2002

Management of old landfills by utilizing forest and energy industry waste flows.

The lack of landfill capacity, forthcoming EU waste disposal and landfill management legislation and the use of non-renewable and energy intensive natural resources for the end-treatment of old landfills increase pressures to develop new landfill management methods. This paper considers a method for the end-management of old landfills in Finland, which is based on the utilization of forest and paper industry waste flows, wastes from paper recycling (de-inking) and wastes from forest industry energy production. Fibre clay wastes from paper mills, de-inking sludges from de-inking of recovered waste paper and incineration ash from forest industry power plants serve to substitute the use of natural clay for the building of landfill structures for closed landfills. Arguably, this method is preferable to existing practices of natural clay use for landfill building, because it (1) substitutes non-renewable natural clay, (2) consumes less energy and generates less CO2 emissions than the use of natural clay, and (3) eliminates considerable amounts of wastes from paper production, paper consumption and from forest industry energy production. Some difficulties in the application of the method are considered and the waste flow utilization is incorporated into a local forest industry recycling network.

Aluminum Silicates↗
PubMed2002

Restoring grassland savannas from degraded pinyon-juniper woodlands: effects of mechanical overstory reduction and slash treatment alternatives.

Although the distribution and structure of pinyon-juiper woodlands in the southwestern United States are thought to be the result of historic fluctuations in regional climatic conditions, more recent increases in the areal extent, tree density, soil erosion rates and loss of understory plant diversity are attributed to heavy grazing by domestic livestock and interruption of the natural fire regime. Prior to 1850, many areas currently occupied by high-density pinyon-juniper woodlands, with their degraded soils and depauperate understories, were very likely savannas dominated by native grasses and forbs and containing sparse tree cover scattered across the landscape. The purpose of this study was to evaluate the effectiveness of mechanical overstory reduction and three slash treatment alternatives (removal, clustering and scattering) followed by prescribed fire as techniques for restoring grassland savannas from degraded woodlands. Plant cover, diversity, biomass and nutrient status, litter cover and soil chemistry and erosion rates were measured prior to and for two years following experimental treatment in a degraded pinyon-juniper woodland in central New Mexico. Treatment resulted in a significant increase in the cover of native grasses and, to a lesser degree, forbs and shrubs. Plant species richness and diversity increased most on sites where slash was either completely removed or scattered to serve as a mulch. Although no changes in soil chemistry or plant nutrient status were observed, understory biomass increased over 200% for all harvest treatments and was significantly greater than controls. While treatment increased litter cover and decreased soil exposure, this improvement did not significantly affect soil loss rates. Even though all slash treatment alternatives increased the cover and biomass of native grasses, scattering slash across the site to serve as a mulch appears most beneficial to improving plant species diversity and conserving site resources.

Biomass↗
PubMed2002

A dynamic model for intertemporal allocation of old-growth forests in the Pacific Northwest.

Across the globe, continued policy debates regarding the management of old-growth forests center around the difficult task of balancing economic and ecological considerations. Though the forests of the Pacific Northwest United States are among the most studied old-growth ecosystems, ecological and economic analyses have yielded public land management directives that remain controversial. Specifically, the recently adopted Northwest Forest Plan lacks explicit goals for maintaining intergenerational equity for the use of forest resources and the diversity of old-growth ecosystems. Unlike previous studies which rely on monetary quantification of costs and benefits, this study develops and applies a conceptual framework for evaluating socially optimal Pacific Northwest old-growth forest utilization strategies. Conditions for the optimal management of old-growth forests are derived using dynamic programming. The objective function synthesizes relevant biological and economic attributes of the old-growth allocation problem. Results in the form of extraction paths are compared given social pressure for consumptive and non-consumptive benefits, as well as different planning horizons, rates of social time preference, and environmental variance. Lengthening the planning horizon results in a vast divergence of optimal policies in the absence of discounting. Extraction rates appear to approach zero as the planning horizon approaches infinity. While higher rates of social time preference increase the rate of extraction, forest stocks remaining at the terminal time period equal levels remaining with a lower discount rate. Increasing environmental variance results in a higher level of stock remaining at the terminal time period. This analysis, while specific to the old-growth controversy of the Pacific Northwest, does provide general guidelines for addressing similar problems of multiple uses of natural areas, particularly where such uses are mutually incompatible, or where one use may be irreversibly destructive to another.

Animals↗
PubMed2000

Population persistence time under intermittent control in stochastic environments.

If there exists a critical population size above which environmental degradation becomes serious, the population should be suppressed or reduced upon reaching that level. Since population size control is accompanied by costs, a reduction in control frequency may be preferable from an economic viewpoint. Although this can be realized by decreasing the population size drastically in each control, such management may result in increased population extinction probability according to environmental stochasticity. The effects of population management on both mean population persistence time and management cost were analyzed theoretically using a diffusion process. The model showed the functional forms of both mean persistence time and control frequency explicitly; these decreased with an increasing number of individuals removed from the population in each control operation. Based on the analysis, indices representing management costs are proposed. Mean persistence time is generally an increasing function of the cost indices. Nevertheless, if the cost of each control increases with the number of individuals removed, even the most conservative management practice (continuous control) may not be overly expensive.

Agriculture↗
PubMed2001

Bimodality for plant sizes and spatial pattern in cohorts: the role of competition and site conditions.

The well-known size bimodality in cohorts of plants is revisited with methods emphasizing generic modeling. A link between bimodality and interface growth in nonequilibrium statistical physics is emphasized: the development of bimodality is understood as a phase transition like interface roughening. A specific model is proposed, inspired by gap models. It is used to illustrate generic results, to understand the end point of mean field approximation and aggregation of variables, and to discuss the role of site and competition for the development of a social hierarchy within a forest stand, in a wider ecological context.

Cohort Studies↗
PubMed1995

Lumbosacral fracture dislocation in a lumberjack.

"Lumberjack fractures" normally occur in the thoracic and upper lumbar spine as a result of hyperextension and shear. This case, however, involves a lumberjack who suffered a lumbosacral fracture dislocation without neurological deficits, which occurred as the result of shear and hyperflexion. Due to the high degree of instability of this lesion, the treatment consisted of dorsoventral fusion with instrumentation.

Adult↗
PubMed1992

Vibration syndrome among Finnish forest workers between 1972 and 1990.

A longitudinal study on vibration syndrome among professional forest workers was carried out in Finland from 1972 to 1990. In the course of the follow-up the weighted vibration acceleration of chain saws decreased from about 14 to 2 m/s2. The prevalence of vibration-induced white finger (VWF) decreased gradually from 40% to 5%. Numbness occurred mainly at night, and its prevalence decreased from 78% to 28%. During part of the follow-up period (1975-1990) the complaints of hand muscle weakness decreased from 19% to 9%. Disorders of the musculoskeletal system were considered to cause more disability than VWF. The decreased vibration acceleration and the lighter weight of chain saws were considered the main reasons for the decrease in the prevalence of vibration-induced symptoms.

Adult↗