多层次防护林体系生态服务价值评价方法

利用对和田地区多层次防护林区的调查研究,进行了林区生态服务功能价值的估算。评估结果表明,在和田玉北的多层次防护林体系中,生态服务价值居第一位的是生物多样性保护,总价值为2.12×106元,占总比例的43.09%;位居第二位的是净化大气环境,价值1.08×106元,占总比例的21.95%;调节大气组分价值排在第三位,为19.35%;涵养水源价值占总比例的11.85%,固土保肥价值量最小,仅占3.76%;在不同的治沙工程措施中,与天然稀疏植被封育区、草方格固沙-人工林区和人工林区相比,多种植物配置区土壤肥力较高,单位面积的价值最高,达到了266.67元/hm2。     

我国西部农村发展的内源性跨越新解——基于回乡“创业经济”的另类思维

做大做强农民工回乡"创业经济"是劳务经济发展的本源,它对西部农村社会发展能起到"治本"作用,即有助于西部农村经济、社会、人与自然关系的协调发展,以及西部"人"自身全面发展。调查发现,西部地区农民工返乡创业中面临着缺资金、缺项目、缺环境、缺信息等难题,且在创业实践中还存在倾向"单干"、模仿跟风、依赖思想、规模小、技术化程度不高、资源型创业等特殊性现象需重视。解决这些问题亟需完善相关体制机制,主要是对返乡农民工予以立体式创业培训,加大金融支持,强化政策扶持,加强创业组织建设等。     

Criteria and guidance considerations for sustainable tree stump harvesting in British Columbia

Abstract

Stump extraction for forest health has been carried out operationally in British Columbia (BC) for many years. Emerging bioenergy opportunities plus the anticipated need for more fibre because of reductions in timber supply may increase interest in stump harvesting, but there are numerous environmental, economic and policy barriers that must be overcome first before industrial-scale stump harvesting can be seriously considered in BC. The potential for a future change in practice provides an opportunity to learn from the existing literature and identify knowledge gaps. In this article we review the available literature on stump harvesting from the European Union within the context of BC's forests, economy, biodiversity, environment and policies. We provide recommendations on how the government of BC could move forward if they decide to enable stump harvesting for fibre and bioenergy, including assessment of net economic and carbon benefits and environmental effects, improvements in inventory and the scientific knowledge base needed to support policy and guidance, and investigation of operational enhancements.     

Exploring the silvicultural and economic viability of gap cutting in Mediterranean softwood plantations

Gap cutting consists of the removal of all trees growing on a small surface,varying in size from 200 to 600 m 2.In Italy,gap cutting has been successfully tested for introducing the natural regeneration of native species into softwood plantations,thus accelerating the transition towards climax hardwood stands.Depending on plantation types and conditions,gap cutting should be started at an age between 70 and 80 years and the system should include at least 12 to 15 gaps,in order to produce enough wood to cover costs.Generally,natural regeneration is firmly established within 5-7 years from treatment.Gap cutting also offers superior results to selection thinning,the latter producing about 35% less value and incurring 25% to 30% more costs.As for all regeneration cuts,the success of gap cutting depends on wildlife control in order to prevent extensive damage to the regeneration.     

An Assessment of Forest Policy Changes in Western Washington

Abstract

Changing forest policies in both riparian and upland areas to help protect threatened and endangered species have contributed to the reduction of timber harvests in western Washington. The economic, biodiversity, and environmental impacts of these policy actions have been substantial. Policy simulations across 9.4 million acres of timber-land show that relative to proactive management strategies, current habitat conservation and environmental programs (largely based on a reservation strategy) result in net present value reductions to forestland owners of $9.9 billion. Accompanying these asset value reductions are employment losses (sustained) of 30% and tax receipt losses of 26%. The policy simulations further demonstrate that proactive management will not decrease the long-term percentage of the upland landscape occupied by functionally old forests relative to the reservation strategy. In the riparian area, adoption of a reservation strategy actually decreases (by 29%) the percent of the landscape occupied by functionally old forests relative to a proactive management approach. These results illustrate the importance of proactively managing western Washington forests to provide maximum functionally old forest habitat for endangered upland animals (such as the northern spotted owl and the marbled murrelet) as well as riparian species.     

消费者对转基因食品的消费偏好研究

转基因食品自问世以来在各个国家都饱受争议。消费者对转基因食品的消费偏好是转基因食品推广的基础。在前人的研究基础上,采用实地实验的方法来研究消费者的消费偏好。同时,在实地实验中加入风险偏好的测量实验,研究消费者的风险偏好对转基因食品消费偏好的影响。研究结果表明,消费者对转基因食品的消费偏好有明显的下降,风险偏好程度对转基因食品的消费态度并没有显著的影响。     

农业高校政治经济学课堂翻转实验研究

为了进一步增强高校学生学习政治经济学的主动性、积极性,提升教学效果,翻转课堂教学实验被看作是一种较为新颖的教学模式,也是一种提升教学效果的有益尝试。通过在政治经济学课程教学中进行的课堂翻转实验证明,翻转课堂这种教学模式可以有效提升课程教学效果,对强化本科生综合素质培养、加快高校思想理论教育水平提升具有重要的借鉴作用。     

信息经济学与图书馆学的契合与碰撞

信息经济学与图书馆学的相互契合渗透和影响,促进了图书馆学的发展,扩大了其研究对象,深化了图书馆学的发展,这对于认识图书馆学“名”和“实”的歧见是有启示的。     

Breeding against mycorrhizal symbiosis: Modern cotton (Gossypium hirsutum L.) varieties perform more poorly than older varieties except at very high phosphorus supply levels

Cotton (Gossypium hirsutum L.) is an important fiber cash crop, but its root traits related to phosphorus (P) acquisition, including mycorrhizal root traits, are poorly understood.  Eight cotton varieties bred in northwestern China that were released between 1950 and 2013 were grown in pots with or without one arbuscular mycorrhizal fungal (AMF) species (Funneliformis mosseae) at three P supply levels (0, 50 and 300 mg P as KH₂PO₄ kg^–1).  Eleven root traits were measured and calculated after 7 wk of growth.  The more recent accessions had smaller root diameters, acquired less P and produced less biomass, indicating an (inadvertent) varietal selection for thinner roots that provided less cortical space for AMF, which then increased the need for a high P fertilizer level.  At the two lower P levels, the mycorrhizal plants acquired more P and produced more biomass than non-mycorrhizal plants (3.2 vs. 0.9 mg P per plant; 1.8 vs. 0.9 g biomass per plant at P₀; 14.5 vs. 1.7 mg P per plant; and 4.7 vs. 1.6 g biomass per plant at P₅₀).  At the highest P level, the mycorrhizal plants acquired more P than non-mycorrhizal plants (18.8 vs. 13.4 mg per P plant), but there was no difference in biomass (6.2 vs. 6.3 g per plant).  At the intermediate P level, root diameter was significantly positively correlated with shoot biomass, P concentration and the P content of mycorrhizal plants.  The results of our study support the importance of the outsourcing model of P acquisition in the root economics space framework.  Inadvertent varietal selection in the last decades, resulting in thinner roots and a lower benefit from AMF, has led to a lower productivity of cotton varieties at moderate P supply (i.e., when mycorrhizal, the average biomass of older varieties 5.0 g per plant vs. biomass of newer varieties 4.4 g per plant), indicating the need to rethink cotton breeding efforts in order to achieve high yields without very high P input.  One feasible way to solve the problem of inadvertent varietal selection for cotton is to be aware of the trade-offs between the root do-it-yourself strategy and the outsourcing towards AMF strategy, and to consider both morphological and mycorrhizal root traits when breeding cotton varieties.     

辽宁东部山区生态经济现状及持续发展

通过对辽宁东部山区的自然资源和生态经济发展状况的分析,指出目前东部山区生态经济发展中存在的一些问题及必须走生态经济持续发展之路。同时提出了生态经济持续发展的指导思想和原则,为今后制定东部山区生态经济持续发展提供依据。