Relationships of dead wood patterns with biophysical characteristics and ownership according to scale in Coastal Oregon,USA

Dead wood patterns and dynamics vary with biophysical factors, disturbance history, ownership, and management practices; the relative importance of these factors is poorly understood, especially at landscape to regional scales. This study examined current dead wood amounts in the Coastal Province of Oregon, USA, at multiple spatial scales. Objectives were to: (1) describe current regional amounts of several characteristics of dead wood; (2) compare dead wood amounts across ownerships; (3) determine the relative importance, according to spatial scale, of biophysical and ownership characteristics, to regional dead wood abundance. Dead wood plot data were evaluated with respect to explanatory variables at four spatial scales of resolution: plots, subwatersheds, watersheds and subbasins. The relationships of dead wood characteristics with biophysical attributes and ownership were diverse and scale-specific. Region-wide dead wood abundance and types varied among ownerships, with public lands typically having higher amounts of dead wood and more large dead wood than private lands. Regression analysis of total dead wood volume indicated that ownership was important at the subbasin scale. Growing season moisture stress was important at plot, subwatershed, and watershed scales. Topography was important at the two coarser scales. Multivariate analysis of dead wood gradients showed that ownership was important at all scales, topography at the subbasin scale, historical vegetation at watershed and subbasin scales, and current vegetation at plot and subwatershed scales. Management for dead wood and related biodiversity at watershed to landscape scales should consider the distinct dynamics of snags and logs, the importance of historical effects, and the relevance of ownership patterns.     

Protecting the African elephant: A dynamic bioeconomic model of ivory trade

A dynamic bioeconomic model of ivory trade is used to investigate the efficacy of conservation payments, tourism benefits, quota regimes and a trade ban on the protection of the African elephant (Laxadonta africana). The model consists of four ivory exporting regions and one demand region. Results indicate that a trade ban might not be successful in maintaining elephants, even if it increases the costs of marketing ivory and leads to a stigma effect that reduces demand. Indeed, trade in elephant products may offer some hope for the elephant, but only if there exist effective institutions that translate in situ protection into economic values.     

Isozyme diversity within African Manihot germplasm

Summary Isozyme diversity is described among a collection of 365 Manihot esculenta cultivars plus 109 accessions from wild relatives (M. glaziovii and spontaneous hybrids) from Africa. The study is based on 17 polymorphic loci. A natural hybrid swarm is detected between the two species. Although they were recently introduced, M. esculenta and M. glaziovii show high levels of polymorphism: heterozygosity estimates are 0.225 and 0.252 respectively. For the wild species, diversity is structured at the unilocus level, and the multilocus approach reveals a geographical pattern. The organization of the diversity is not so clear for the cultivated cassava, but a multilocus approach, based on both common and rare alleles, led us to identify different groups of clones with many intermediate genotypes between them. Elements of the secondary diversification process of Manihot in Ivory Coast are discussed.     

非洲的国内象牙市场

针对非洲各国象牙市场管理方面存在的问题,对象牙来源、走私方式及数量进行了论述。认为相关法律制度不健全、执法力度薄弱、缺乏必要的宣传等是造成非洲国家象牙走私猖獗的原因。只有严格遵守CITES的规定,制定全面的国内立法,严厉打击非法象牙贸易,规范国内象牙市场,才能使非洲象种群得到有效保护和合理利用。     

热带滨海型园林景观设计人才培养体系的重构与实践

根据广东海洋大学地处热带、濒临南海的区位特征及海洋学科的办学特色,突出热带滨海型景观设计人才的培养目标。分析了园林专业教学改革基础及建设成效,由此研究了热带滨海型景观设计人才培养体系的重构策略,即优化人才培养方案,推进人才培养模式改革,加强教学师资团队建设,整合课程教学资源,强化并创新实践教学环节,健全严格的教学管理制度等。实践成果表明,广东海洋大学新型园林专业人才培养的特色办学思路成效显著。     

昌黎黄金海岸国家级自然保护区生态旅游开发研究

简析了昌黎黄金海岸国家级自然保护区生态旅游资源的特点、发展现状及存在的问题。提出“区内旅游 ,区外服务”的生态旅游开发模式与措施 ,并强调“区内旅游”应注重保护生态环境 ,科学规划 ,突出区域特色 ,以人为本和丰富文化内涵     

Cost analysis of immunisation against East Coast fever on smallholder dairy farms in Kenya

A spreadsheet model was developed and used to estimate the total cost of immunising cattle against East Coast fever (ECF) based on the infection-and-treatment method. Using data from an immunisation trial carried out on 102 calves and yearlings on 64 farms in the Githunguri division, Kiambu district, Kenya, a reference base scenario of a mean herd of five animals, a 10% rate of reaction to immunisation and a 2-day interval monitoring regimen (a total of 10 farm visits) was simulated. Under these conditions, the mean cost of immunisation per animal was US$16.48 (Ksh 955.78); this was equivalent to US$82.39 (Ksh 4778.90) per five-animal farm. A commonly reported reactor rate of 3% would decrease the cost to US$14.63 (Ksh 848.29) per animal. Reducing the number of farm monitoring visits from 10 to 7 would reduce the total cost by 10%, justified if farmers are trained to undertake some of the monitoring work. The fixed costs were 53% of the total cost of immunisation per farm. The cost of immunisation decreased with increasing number of animals per farm, showing economies of scale.     

滨海开发带土壤重金属分布特征及来源分析

以江苏省大丰市为例,研究了土壤中8种重金属的空间分布特征及其与土地利用的关系,并通过主成分分析方法,对其可能的来源进行了探讨。结果表明:研究区8种土壤重金属Cu、Zn、Pb、Cd、Cr、As、Hg、Ni平均含量分别为17.40、74.38、18.14、0.105、55.58、8.33、0.074、25.73mg/kg,不同采样点之间变异不大。沿垂直海岸线方向,随距海岸线距离增加,Cu、Zn、Pb、Cr、Hg、Ni 6种重金属含量逐渐升高,As含量逐渐降低,Cd含量则先升高、后降低。Cu、Zn、Pb、Cr、Hg、Ni 6种重金属均在水田土壤中含量最高,Cd在旱地土壤中含量最高,As则在滩涂土壤中含量最高。相关分析表明,土壤As含量与其他重金属元素含量的相关性均不显著,土壤Cd含量与Zn、Pb、Hg、Cr含量的相关性显著,与Cu、As、Ni含量的相关性不显著,其他各元素间相关性均达极显著水平。基于主成分分析结果,认为研究区土壤Cu、Zn、Pb、Cr、Hg、Ni 6种重金属元素含量受土壤母质影响较大,Cd含量与农业生产中磷肥施用关系密切,As含量的累积受磷肥施用的影响,但以水稻种植为主的耕作土壤As含量总体上呈下降趋势。本研究可为滨海开发带土地利用规划提供指导。     

沿海林区伐区类型评定及木材生产直接成本研讨

本文针对沿海地区国有林场木材生产特点，运用多因子表格化形式，综合量化评定伐区类型；并分类简化处理，定量测算各伐区木材生产直接成本。