Abstract: We examined how differences in local forest‐management institutions relate to disparate anthropogenic forest disturbance and forest conditions among three neighboring montane forests in Tanzania under centralized, comanaged, or communal management. Institutional differences have been shaped by decentralization reforms. We conducted semistructured interviews with members of forest management committees, local government, and village households and measured anthropogenic disturbance, tree structure, and species composition in forest plots. We assessed differences in governance system components of local institutions, including land tenure, decision‐making autonomy by forest users, and official and de facto processes of rule formation, monitoring, and enforcement among the three management strategies. We also assessed differences in frequencies of prohibited logging and subsistence pole cutting, and measures of forest condition. An adjacent research forest served as an ecological reference for comparison of forest conditions. Governance was similar for comanaged and centralized management, whereas communal managers had greater tenure security and decision‐making autonomy over the use and management of their forest. There was significantly less illegal logging in the communal forest, but subsistence pole cutting was common across all management strategies. The comanaged forest was most disturbed by recent logging and pole cutting, as were peripheral areas of the larger centralized forest. This manifested in more degraded indicators of forest conditions (lower mean tree size, basal area, density of trees ≥ 90 cm dbh, and aboveground biomass and higher overall stem density). Greater tenure security and institutional autonomy of the communal strategy contributed to more effective management, less illegal logging, and maintenance of good forest conditions, but generating livelihood benefits was a challenge for both decentralized strategies. Our results underscore the importance of well‐designed institutional arrangements in forest management and illustrate mechanisms for improved forest governance and conservation in the context of Tanzanian decentralization reforms.相似文献
We are witnessing a growing concern with the global dimension of many environmental issues, reflected in the increase in the number and significance of international environmental organizations. Yet there is no internationally applicable strategy for environmental research which is management oriented. A new type of research policy, which integrates ideas derived from environmental and human ecology, is required in order to deal with cultural and ecological diversity and their interactions as reflected in the ecology of landscapes. The newly defined concept of environmental health is proposed to fill this gap. This concept integrates the latest developments in landscape evolutionary ecology and environmental health, bringing out a conflict between making the environment conducive to human health and increasing the available options for supporting the essential biological and ecological processes of the environment. Lessons derived from the evolution of human environments are used in order to illustrate how health may become un umbrella for developing an environmental research policy, which could also serve as a catalyst for international environmental projects. 相似文献
ABSTRACT: The purpose of this study was to assess short term, macroinvertebrate colonization dynamics and biofilm accumulation in two agricultural streams, one of which had been recently exposed to chronic, intermittent organic effluents from a slaughterhouse. During the winter and summer, macroinvertebrates and biofilm were collected from brick substrates from four or three sites in the streams on a geometric time schedule (1, 2, 4, 8, 16, and 32 days of exposure). Invertebrate total densities stabilized quickly, but the mass of biofilm increased throughout the study periods. Invertebrate community indices (diversity, evenness, dominance, richness) differed between the unaffected, “agricultural reference” sites and the affected sites, below the point source. All sites were dominated by Baetis bicaudatus (mayfly), Hydrobia sp. (gastropod), and Dugesia tigrina (Turbellaria). Response of these taxa differed between seasons and exposure to organic effluents. Stream invertebrate colonization processes showed evidence of the perturbation after the inflow of organic effluents had stopped from the slaughterhouse. Chronic organic enrichment reduced the species richness in the potential pool of colonists. Three months after the organic inputs had stopped, colonization timing and community structure was not yet at levels evident in reference and upstream sites. 相似文献
/ We used linear regression to independently and jointly relate specific conductance and pH measured at New Jersey Pinelands stream sites to the percentage of altered land in a watershed. Percentage altered land included developed and agricultural land uses and represented watershed disturbance for a given site. Median values calculated for a 2-year period (September 1992 through August 1994) characterized pH and specific conductance at the study sites. We found the relationships between the median values for both water-quality measures and percentage altered land for a site to be consistent across subregion and dominant altered-land use. Our results also demonstrated that the water-quality/altered-land relationships developed using median values were similar to relationships developed using data from any single-sample period within the entire study period. Individually, pH and specific conductance explained 48% and 56%, respectively, of the variability in watershed disturbance among study sites. The joint use of pH and specific conductance explained 79% of the watershed disturbance variability among sites. The joint use of these easily obtained water-quality measures can provide a quick assessment of instream water-quality impacts from upstream watershed disturbance at any Pinelands stream site. Additionally, a range in pH and specific conductance, and hence a range in ambient water quality, can be predicted for a given altered-land percentage or a change in existing altered-land conditions. 相似文献
提出运用高压变频技术实现电弧炉除尘风机变频调速的工艺.在70 t ABB电弧炉烟气治理运用中,以温度为调速系统主要控制参数,设计工频和变频两套系统,实现除尘风机的转速按工艺要求调节,其功率因数从0.83提高到0.97,除尘系统节电60%,冶炼工况同时也得到改善.表明该工艺具有广阔的应用前景. 相似文献
Now in Russian Federation and other countries large-scale oil terminals (volume of one tank exceeds 100 000 m3, total volume of tanks exceeds 300 000 m3) are designed and constructed. Therefore fire safety of such objects becomes a very important task, solution of which is hardly possible without detail fire risk assessment. This study is aimed to a solution of this problem. Potential, individual and social risks were calculated. The potential risk was defined as a frequency of occurrence of hazardous factors of fires and explosions in a given point of space (the so-called risk contours). The individual risk was defined as a frequency of injuring a given person by hazardous factors of fires and explosions. Time of presence of this person in hazardous zones (near the hazardous installation) is taken into account during calculations of the individual risk. Social risk was defined as a dependence of frequency of injuring a given number of people by hazardous factors of fires and explosions on this number. In practice the social risk is usually determined on injuring not less than 10 people.
The oil terminal under consideration includes the following main parts: crude oil storage consisting of three tanks of volume 100 000 m3 each, input crude oil pipeline of diameter 0.6 m, crude oil pumps, output crude oil pipeline of diameter 0.8 m, auxiliary buildings and facilities. The following main scenarios of tank fires have been considered: rim seal fire, pool fire on a surface of a floating roof, pool fire on a total cross-section surface of the tank, pool fire in a dyke, explosions in closed or semiclosed volumes. Fires and explosions in other parts of the terminal are also taken into account. Effects of escalation of accidents are considered.
Risk contours have been calculated both for the territory of the terminal and for the neighbouring space. The potential risk for the storage zone is near 10−4–10−5 year−1, and at a distance 500 m from the terminal the potential risk values do not exceed 10−6 year−1. The values of the individual risk for various categories of workers are in the range of 10−5–10−6 year−1. Because of low number of the workers on the terminal and large distances to towns and villages the social risk value is negligible. These risk values are consistent with practice of the best oil companies, and fire hazard level of the terminal can be accepted as tolerable. 相似文献