Evaluating Domestic Sheep Survival with Different Breeds of Livestock Guardian Dogs

Livestock guard dogs (LGDs; Canis familiaris) have been widely adopted by domestic sheep (Ovis aries) producers because they reduce predation by wild carnivores. LGDs were originally used in the United States to reduce coyote (Canis latrans) depredations, but their efficacy against a suite of large carnivores, including wolves (Canis lupus), brown bears (Ursus arctos), black bears (Ursus americanus), and cougars (Puma concolor), and whether specific breeds perform better than others remains unclear. To assess breed-specific effectiveness at reducing depredations from a suite of livestock predators, we compared survival rates of sheep protected by different breeds of LGDs, including three breeds from Europe (Turkish kangal, Bulgarian karakachan, and Portuguese cão de gado transmontano) and mixed-breed LGDs, “whitedog,” common in the United States. With the help of participating sheep producers, we collected cause-specific mortality data from domestic sheep in Idaho, Montana, Oregon, and Wyoming between 2013 and 2016. All three of the novel breeds of LGD tested were associated with overall reductions in sheep depredation relative to whitedogs, ranging from 61% to 95% (P < 0.05). In terms of predator-specific effectiveness, the Turkish kangal was associated with decreases in depredation from cougars (e^β = 0.31, 95% CI = 0.10–0.94, P = 0.04), black bears (e^β = 0.33, 95% CI = 0.28–0.37, P < 0.01), and coyotes (e^β = 0.56, 95% CI = 0.35–0.90, P = 0.02). The Bulgarian karakachan was associated with a decrease in coyote depredations (e^β = 0.07, 95% CI = 0.01–0.49, P < 0.01). The Portuguese transmontano was not associated with significant reductions in depredation hazard for any specific predator. Although variations in breed-specific effectiveness were subtle and nuanced, these findings will help livestock producers and wildlife managers make tailored decisions about how best to incorporate different breeds of LGD into sheep grazing regimes.     

Sediment remediation: U.S. focus on capping and monitored natural recovery

The Battelle Conferences series represent the state-of-the-art of emerging technologies, science and management issues for contaminated sediment remediation. In the 2007 Conference held in Savannah, GA, two in situ technologies for cleanup sites were at the centre of interest: Sediment capping, a form of in situ containment, which involves the placement of a subaqueous covering of clean sediment and/or other materials to isolate contaminated sediments, and monitored natural recovery (MNR), where natural processes are used to mitigate the transfer of particle-bound contaminants into the water phase and/or biota. A third priority technology in the Superfund program, recommended by the U.S. Environmental Protection Agency (EPA), is environmental dredging, i.e., removing the sediments from the aquatic environment. About 30 platform or poster presentations dealt with in situ capping as a technology, reflecting the rapid developments in this field, both in assessments and enhancements of ‘classic’ passive caps and the development and demonstration of active capping technologies. Issues relevant to monitored natural recovery were spread throughout many sessions; e.g., contaminant source identification, control, remediation strategies; innovative characterization and assessment, chemical/toxicological/biological measurements and characterization, bioavailability of contaminants, contaminant fate and transport and remediation effectiveness: defining, monitoring, and demonstrating success. Presentations addressing the role of science and stakeholder input were complemented by discussions on the importance of data quality considerations, uncertainty analysis, and careful selection of reference sites highlighted the complex nature of these multidisciplinary assessments. Case studies, in which site-specific information was linked to regional management objectives, various approaches to watershed-scale assessment and management, and the role of ecosystem considerations, were all discussed in these sessions, as well as in a complementary panel discussion. One compelling feature of the Savannah Conference 2007 (relative to the first couple of meetings) is that there were a much larger number of presentations that provided the tools, models, case studies, etc to fill in the lines of evidence that allow a fair comparison between removal and in situ management when appropriate, and evidence of a growing acceptance that the residuals and impacts of removal approaches can at times offset perceived benefits, so that in situ management can be considered if exposure risk can be properly assessed.     

ENSO classification indices and summer crop yields in the Southeastern USA

This research uses a quantitative methodology for directly comparing the responses of observed crop yields in the SE USA to ENSO phenomena classified using dissimilar ENSO indices. ENSO condition has been related to agricultural yields in many parts of the world. It has been generally recognized that the strongest effects on spring and summer crops occur during the boreal winter, and therefore most directly affect spring-summer field crops in the southern hemisphere. However, some ENSO effects on northern hemisphere spring and summer crops have been found, particularly when researchers have used sub-annual indicators of ENSO conditions that, unlike annual ENSO indices, distinguish between continuity and change prior to or during the crop season. To evaluate the utility of such sub-annual ENSO indicators for agriculture in the SE USA, a tercile-based scoring system was devised to compare four distinct ENSO indices: three monthly ENSO indices and the JMA annual ENSO index. Each index was scored in its ability to predict crop yields differing from the historically normal tercile for corn (Zea mays L.), cotton (Gossypiumhirsutum L.), and peanut (Arachis hypogaea L.). Annual crop yield data were used from selected counties in five Southeastern USA states. No geographic differentiation among the data was included in the analysis. This aggregation of county data increased the sample size for each crop, to address the limitation of a short time-series (47 years) distributed among up to 9 ENSO categories. Statistical significance was compared using contingency tables and the Fisher exact test. Peanut and corn yield response matched best to the Multivariate ENSO Index (MEI) and cotton, to the Oceanic Niño Index (ONI). The MEI and ONI are quantitative indices, while the lower-scoring JMA and Modified-JMA indices are categorical. Therefore, future efforts may reduce the focus on categorical (Niño, Niña, Neutral) classification, and explore the response of crop yields to quantitative ENSO data.     

美国森林资源调查方法的变化对我们的启示

简要回顾了中美两国的国家级森林资源清查发展的历史,对抽样设计、样地设置与统计方法和机构人员情况进行了较详细的讨论,重点介绍了美国正在建立的森林清查综合监测系统的抽样框架和布局;并对中美两国在立法、人员、经费和监测内容等方面进行了比较;结合其他国家森林清查情况,在抽样体系、样地设计等方面提出了改进我国森林资源监测体系的建议.     

美国金门公园漫游

金门公园位于美国西部加利福尼亚州三藩市的西部太平洋海岸,属地中海型温暖气候。曾于1894年举办世界博览会,现今已成为三藩市一块可供玩乐、休闲、陶冶身心和市民求知识的好地方。主要活动景点有:植物园,日本庭园,温室花园;加州科学院内的天文馆、水族馆、热带雨林馆和自然历史博物馆;世博会遗迹迪杨艺术纪念博物馆及一些具有历史意义的建筑物;还有众多提供娱乐、体育活动场所。     

美国国有林经营及对中国的启示

在介绍美国国有林经营政策的基础上, 针对中国国有林经营现状, 提出应借鉴的经验:减轻税费负担, 加强营造林基础; 提高林业科技水平, 发展高效林业; 构建国有林资源法制化管理体系; 重视跨部门跨学科的交流和合作; 采用生态系统管理方法, 开发和保护并重。     

中美林业发展与林业高等教育联动关系比较与启示

世界各国林业发展与林业高等教育各具特色,两者互为联动。文中在分析中美两国相关林业数据和报告的基础上,比较了两国在不同发展阶段林业行业发展与林业高等教育的相互关系,以及两国林业高等教育尤其是林科专业本科阶段的发展状况;分析其规模变化的影响因素。分析认为,中美两国林业发展都经历了从产业型到公益型的发展阶段,而同期的林业高等教育发展阶段也呈现出相适应的变化,林业高等教育发展与同期的林业发展呈现出正相关关系。文中最后提出要以生态文明建设为导向,注重林业和林业高等教育的联动关系,使其相互促进和共同发展,为我国林业发展提供可靠保障。     

周氏啮小蜂防治桑园内美国白蛾技术研究

释放周氏啮小蜂对桑园内美国白蛾进行防治试验。一是放蜂数量与防治效果对比试验,结果表明,每667m2地投放3万头小蜂,美国白蛾的寄生率最优达到68%。二是周氏啮小蜂扩散距离所需时间,在越冬代美国白蛾老熟幼虫期和化蛹初期释放周氏啮小蜂,周氏啮小蜂扩散到50m、100m、150m、200m所需的时间分别为20天、25天、30天、35天。在第一代美国白蛾老熟幼虫期和化蛹初期释放周氏啮小蜂,花角蚜小蜂扩散到100m只需要20天,三是是周氏啮小蜂扩散距离与寄生率的关系,结果表明,离放蜂点越近处,周氏啮小蜂的寄生率越高,反之则越低。