首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7篇
  免费   0篇
安全科学   1篇
环保管理   4篇
基础理论   2篇
  2020年   1篇
  2009年   1篇
  2006年   1篇
  2005年   1篇
  2003年   1篇
  2002年   1篇
  2000年   1篇
排序方式: 共有7条查询结果,搜索用时 265 毫秒
1
1.
We examined the changes in forest status and people's livelihoods through building future scenarios for Chilimo Forest in Central Ethiopia where participatory forest management (PFM) is being implemented. Participatory methods were employed to collect data, and a dynamic modeling technique was applied to explore trends over time. By integrating the more quantitative model outputs with qualitative insights, information on forests and livelihoods was summarized and returned to users, both to inform them and get feedback. A scenario of open access without PFM provides higher income benefits in the short term but not over the longer term, as compared to a scenario with PFM. Follow up meetings were organized with national decision makers to explore the possibility of new provisions in the national forest proclamation related to joint community-state ownership of forests. Project implementers must constantly work towards improving short term incentives from PFM, as these may be insufficient to garner support for PFM. Other necessary elements for PFM to succeed include: ensuring active participation of the communities in the process; and, clarifying and harmonizing the rules and regulations at different levels.  相似文献   
2.
When cooperation is based on shared genetic interests, as in most social insect colonies, mechanisms which increase the genetic similarity of group members may help to maintain sociality. Such mechanisms can be especially important in colonies with many queens because within-colony relatedness drops quickly as queen number increases. Using microsatellite markers, we examined the Old World, multiple-queen, swarm-founding wasp Polybioides tabidus which belongs to the ropalidiine tribe, and found that relatedness among the workers was four times higher than what would be expected based on queen number alone. Relatedness was elevated by a pattern of queen production known as cyclical oligogyny, under which, queen number varies, and daughter queens are produced only after the number of old queens has reduced to one or a very few. As a result, the queens are highly related, often as full sisters, elevating relatedness among their progeny, the workers. This pattern of queen production is driven by collective worker control of the sex ratios. Workers are three times more highly related to females than to males in colonies with a single queen while they are more equally related to males and females in colonies with more queens. As a result of this difference, workers will prefer to produce new queens in colonies with a single queen and males in colonies with many queens. Cyclical oligogyny has also evolved independently in another group of swarm-founding wasps, the Neotropical epiponine wasps, suggesting that collective worker control of sex ratios is widespread in polistine wasps. Received: 22 May 2000 / Revised: 24 August 2000 / Accepted: 4 September 2000  相似文献   
3.
Introduction: Left-turning vehicles pose considerable safety risks to pedestrians at intersections. Left-turn traffic-calming treatments are designed to slow left-turn traffic. This study examined the effects of one type of left-turn calming, the hardened-centerline treatment, on the numbers of conflicts between left-turning vehicles and pedestrians and left-turn speeds in Washington, DC. Method: Numbers of conflicts between left-turning vehicles and pedestrians, as well as left-turn speeds, were collected at selected intersections in Washington, DC, where the hardened centerline was installed, as well as at control intersections in the city where no treatment was installed, before and after installation. Poisson regression evaluated the change in numbers of conflicts associated with the hardened-centerline treatment. The effect of the treatment on left-turn speeds was estimated by a log-linear regression model, and the effect on the odds of left-turning vehicles exceeding 15 mph was estimated by a logistic regression model. Results: The treatment was associated with a 70.5% reduction in conflicts between left-turning vehicles and pedestrians, a 9.8% reduction in mean left-turn speeds, and a 67.1% reduction in the odds of left-turning vehicles exceeding 15 mph. All the reductions were statistically significant. Conclusions: The study demonstrates that the hardened-centerline treatment can reduce conflicts between left-turning vehicles and pedestrians, and slow down left-turn traffic at intersections. Practical applications: The treatment should be added to the toolbox for communities looking to improve pedestrian safety at intersections.  相似文献   
4.
A new approach was needed to preserve the biodiversity of the Djoudj Park within a context marked by many constraints: drought, regulation of its hydrologic system, and anthropogenic pressure. The local management plan developed in this paper aims at the responsible management and fair distribution of the available water resources in the Djoudj Park to provide a balanced response to conservation issues and the growing needs of the local communities. The opposition between an administration determined to exercise its power and the confidence of local people weary of being stripped of their rights and cultural assets required the setting up of a consensual management plan. This plan would provide a means to determine the timing and the number of sluice gates to operate, based on an efficient command of the needs for water for each activity in the park and its surroundings. This tool will allow the park authority to take full cognizance of the needs and opinions of all interest groups but also their limits while keeping the essential functions of this wetland. It is also suggested that institutional and administrative reform be carried out to associate local populations in the definition and implementation of criteria for an integrated management of the Djoudj resources.  相似文献   
5.
We examined whether value differences between various recreation interest/activity groups are created and sustained by the textual information presented to their readers in magazines. Using a two-stage qualitative approach, our research sought to explore the exact nature of the dialogue in the magazines. We sought detailed, intimate information on a selected number of magazines to assess how the popular press socially constructs knowledge about recreation groups, and we sought to better understand how various recreation group members assign meaning to their activities and interpret the interests of other groups. Findings revealed limited negativity of activity users towards one another; most of the conflict found in the text of the articles in recreational magazines was characterized as macrodispositional. Accordingly, in the articles most of the antipathy was directed towards government because of stricter regulation of activity or towards commercial consumers whose exploitation of resources is perceived to threaten groups' activities. Moreover, such conflict crosscuts various groups whose issues and concerns are often similar. Since environmental battles are no longer any one group's issue, many have coalesced and engaged in conflict with lawmakers and commercial consumers. It is clear that the recreational magazines do play a role in shaping readers' attitudes.  相似文献   
6.
Social Hymenoptera are general models for the study of parent-offspring conflict over sex ratio, because queens and workers frequently have different reproductive optima. The ant Pheidole pallidula shows a split distribution of sex ratios with most of the colonies producing reproductives of a single sex. Sex ratio specialization is tightly associated with the breeding system, with single-queen (monogynous) colonies producing male-biased brood and multiple-queen (polygynous) colonies female-biased brood. Here, we show that this sex specialization is primarily determined by the queens influence over colony sex ratio. Queens from monogynous colonies produce a significantly more male-biased primary sex ratio than queens from polygynous colonies. Moreover, queens from monogynous colonies produce a significantly lower proportion of diploid eggs that develop into queens and this is associated with lower rate of juvenile hormone (JH) production compared to queens from polygynous colonies. These results indicate that queens regulate colony sex ratio in two complementary ways: by determining the proportion of female eggs laid and by hormonally biasing the development of female eggs into either a worker or reproductive form. This is the first time that such a dual system of queen influence over colony sex ratio is identified in an ant.  相似文献   
7.
An emerging conflict with Trans-Himalayan pastoral communities in Ladakh’s Changthang Plateau threatens the conservation prospects of the kiang (Equus kiang) in India. It is locally believed that Changthang’s rangelands are overstocked with kiang, resulting in forage competition with livestock. Here, we provide a review and preliminary data on the causes of this conflict. Erosion of people’s tolerance of the kiang can be attributed to factors such as the loss of traditional pastures during an Indo-Chinese war fought in 1962, immigration of refugees from Tibet, doubling of the livestock population in about 20 years, and increasing commercialization of cashmere (pashmina) production. The perception of kiang overstocking appears misplaced, because our range-wide density estimate of 0.24 kiang km−2 (± 0.44, 95% CL) is comparable to kiang densities reported from Tibet. A catastrophic decline during the war and subsequent recovery of the kiang population apparently led to the overstocking perception in Ladakh. In the Hanle Valley, an important area for the kiang, its density was higher (0.56 km−2) although even here, we estimated the total forage consumed by kiang to be only 3–4% compared to 96–97% consumed by the large livestock population (78 km−2). Our analysis nevertheless suggests that at a localized scale, some herders do face serious forage competition from kiang in key areas such as moist sedge meadows, and thus management strategies also need to be devised at this scale. In-depth socioeconomic surveys are needed to understand the full extent of the conflicts, and herder-centered participatory resolution needs to be facilitated to ensure that a sustainable solution for livelihoods and kiang conservation is achieved.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号