Simulating Spatial and Temporal Context of Forest Management Using Hypothetical Landscapes

/ Spatially explicit models that combine remote sensing with geographic information systems (GIS) offer great promise to land managers because they consider the arrangement of landscape elements in time and space. Their visual and geographic nature facilitate the comparison of alternative landscape designs. Among various activities associated with forest management, none cause greater concern than the impacts of timber harvesting on the composition, structure, and function of landscape ecosystems. A timber harvest allocation model (HARVEST) was used to simulate different intensities of timber harvest on 23,592-ha hypothetical landscapes with varying sizes of timber production areas and different initial stand age distributions. Our objectives were to: (1) determine the relative effects of the size of timber production areas, harvest intensity, method used to extract timber, and past timber harvest activity on the production of forest interior and edge; and (2) evaluate how past management (in the form of different initial stand age distributions) constrains future timber production options. Our simulations indicated that the total area of forest interior and the amount of forest edge were primarily influenced by the intensity of timber harvest and the size of openings created by harvest. The size of the largest block of interior forest was influenced most by the size of timber harvests, but the intensity of harvest was also significant, and the size of nontimber production areas was important when harvests were numerous and widely dispersed within timber management areas, as is often the case in managed forests. Stand age-class distributions produced by past harvest activity limited the amount of timber production primarily when group selection was used, but also limited clear-cutting when recent harvest levels were high.KEY WORDS: Simulation modeling; Timber harvest; Historical context; Spatial context; Landscape pattern; Forest interior; Forest edge     

A training consultancy for an Ethiopian I.D.A. urban programme evaluated

The author contributed to a short ‘in service’ course for staff engaged on a World Bank upgrading project for Ethiopian housing. The project includes both the building of new houses by self‐build co‐operatives on the periphery of Addis Ababa, and the upgrading of a dense inner city area in conditions of acute deprivation. The paper is a highly personal account of the author's impressions of the value of such initiatives.     

Biomass and nutrient removals from commercial thinning and whole-tree clearcutting of central hardwoods

The objective of this research was to evaluate the impacts of increasing product removal on biomass and nutrient content of a central hardwood forest ecosystem. Commercial thinning, currently the most common harvesting practice in southern New England, was compared with whole-tree clearcutting or maximum aboveground utilization. Using a paired-watershed approach, we studied three adjacent, first-order streams in Connecticut. During the winter of 1981–82, one was whole-tree clearcut, one was commercially thinned, and one was designated as the untreated reference. Before treatment, living and dead biomass and soil on the whole-tree clearcut site contained 578 Mg ha^–1 organic matter, 5 Mg ha^–1 nitrogen, 1 Mg ha^–1 phosphorus, 5 Mg ha^–1 potassium, 4 Mg ha^–1 calcium, and 13 Mg ha^–1 magnesium. An estimated 158 Mg ha^–1 (27% of total organic matter) were removed during the whole-tree harvest. Calcium appeared to be the nutrient most susceptible to depletion with 13% of total site Ca removed in whole-tree clearcut products. In contrast, only 4% (16 Mg ha^–1) of the total organic matter and 2% of the total nutrients were removed from the thinned site. Partial cuts appear to be a reliable management option, in general, for minimizing nutrient depletion and maximizing long-term productivity of central hardwood sites. Additional data are needed to evaluate the long-term impacts of more intensive harvests.     

Development control standards and industrial applications

Recent Central Government advice to local authorities on the matter of business and industry applications Has been towards a relaxation of controls and a facilitating of development. Also the general worsening of the economy in the last few years has probably increased the interest with which local councillors regard industrial applications for planning permission. A study of refusal rates for industrial applications for 317 Districts taken from the DOE Development Control Returns and a case study in Coventry District of all industrial applications in 1970 and 1980 suggest that despite these pressures planning authorities are not lowering standards.     

Heavy metal concentration in the moss Pleurozium schreberi in the Niepołomice Forest,Poland: changes during 20 years

The Niepoomice Forest is a large forestcomplex (110 km²) situated in southern Poland 10 to 30 kmto the east of the urban industrial Kraków agglomeration andsteelworks, which was built up on the outskirts of the city in1950. Due to prevailing westerly winds, the forest is affectedby pollutants emitted by both the steelworks and the city. Thelevel of heavy metal contamination in the Niepoomice Forestwas described using a sensitive bioindicator – the moss Pleurozium schreberi. Mean concentrations of metals in mosscollected in the Niepoomice Forest were Cd – 0.71, Cr – 2.4,Cu – 8.6, Fe – 673, Pb – 12.7, and Zn – 61 mg/kg.Concentrations of heavy metals in moss in the NiepoomiceForest decreased in time. As compared with the relatively cleanarea in north-eastern Poland (Puszcza Biaowieska), the concentration of Fe was 2–9 fold and Pb 4–6 fold higher in theNiepoomice Forest in 1975, while in 1998 4 fold and 2 fold,respectively. In both 1975 and 1998 the most polluted by heavymetals was the western part of the Niepoomice Forest (closestto the pollution sources) and the area along the roads insidethe forest complex.     

Prescreening teratogenic potential of chlorinated drinking water disinfection by products by using Hydra regeneration assay

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Theory into Practice: Implementing Ecosystem Management Objectives in the USDA Forest Service

In the United States and around the world, scientists and practitioners have debated the definition and merits of ecosystem management as a new approach to natural resource management. While these debates continue, a growing number of organizations formally have adopted ecosystem management. However, adoption does not necessarily lead to successful implementation, and theories are not always put into practice. In this article, we examine how a leading natural resource agency, the United States Department of Agriculture Forest Service, has translated ecosystem management theory into concrete policy objectives and how successfully these objectives are perceived to be implemented throughout the national forest system. Through document analysis, interviews, and survey responses from 345 Forest Service managers (district rangers, forest supervisors, and regional foresters), we find that the agency has incorporated numerous ecosystem management components into its objectives. Agency managers perceive that the greatest attainment of such objectives is related to collaborative stewardship and integration of scientific information, areas in which the organization has considerable prior experience. The objectives perceived to be least attained are adaptive management and integration of social and economic information, areas requiring substantial new resources and a knowledge base not traditionally emphasized by natural resource managers. Overall, success in implementing ecosystem management objectives is linked to committed forest managers.     

载乙醇活性炭在微波场中的升温行为研究

研究了载乙醇活性在微波场中的升温行为，主要包括水和乙醇在微波场中的升温情况，以及微波功率，活性炭量，氮气线速对活性炭升温行为的影响，结果表明，水与乙醇在微波场中能吸收微波能，从而使其温度升高，微波功率越大，活性炭升值越快，活性炭最高温度也更高，活性炭少于5g时温度上升速率随活性炭量的增加而加快，活性炭量多于5g时则相反，氮气线速增加，活性炭升温速率下降，活性炭最高温度降低。     

Postfire Regeneration in <Emphasis Type="Italic">Pinus pinea</Emphasis> L. and <Emphasis Type="Italic">Pinus pinaster</Emphasis> Aiton in Andalucia (Spain)

The objective of this study was to examine postfire regeneration of tree, shrub, and dwarf shrub species, in relation to levels of damage in four planted pine forests (Pinus pinea, Pinus pinaster) in Andalusia. A prefire vegetation map was used for detailing species composition, vertical structure, and density and another for detailing the extent and intensity of fire damage. Between 3 and 7 years after the fires, an inventory was made of the vegetation in each area, using the step-point method. The information thus obtained was used to determine the amount of cover in the dwarf/shrub and tree layers, the frequency of species in each of the layers, floristic richness, and diversity (Shannon index). The botanical composition of the dwarf and shrub layer was analyzed using TWINSPAN. Variables were poorly correlated with level of fire damage, which suggests that the forests in this study followed the autosuccession model. Because of the artificial origin or seminatural condition, regeneration of the dominant tree species is poor, and it seems unlikely that forests will recover to their prefire state. Therefore action is recommended to restore these ecosystems.     

秦皇岛市海洋生态环境保护与建设探讨

本文通过对秦皇岛市海洋生态环境质量的调查分析,提出了影响生态环境 的主要问题,进而对该海域的生态环境保护与生态建设提出了切实可行的对策。