Do tourists disperse weed seed? A global review of unintentional human-mediated terrestrial seed dispersal on clothing,vehicles and horses

Human-mediated seed dispersal is recognised as an important, but under-researched, issue. To assess the potential for tourists to act as unintentional seed dispersal agents, we reviewed published and unpublished data on seed dispersal via clothing, vehicles (cars) and in/on horses and donkeys, all of which can be used by tourists. Seeds from 754 species of terrestrial plants have been collected from these vectors, 15% of which are internationally recognised environmental weeds. Seeds were collected from personal clothing and equipment (228 species), the fur of donkeys and horses (42 species), horse dung (216 species) and vehicles (505 species). Most were herbs (429 species) or graminoids (237 species) and native to Europe. Annual Poa, White Clover, Kentucky Bluegrass and Yorkshire Fog were the most frequent species. There have been eight studies specifically on tourists, which identified 12 species on clothing, 26 on vehicles and 133 from horse dung. Methods that minimise the risk of tourists as human-mediated dispersal agents may therefore be appropriate for some tourism activities/destinations: suggestions are made. Further sampling using standardised experimental techniques is required to assess the relative risk associated with specific tourist activities and locations and determine which, and how much, seed is transported.     

Is the rhino worth saving? A sustainable tourism perspective

Southern African countries are increasingly dependent on natural beauty and wildlife for tourism. Conservation is essential for sustainable tourism, and is expensive, especially for threatened and endangered species. The current price of a species only takes into account its current usefulness, often leading to an underestimation of the value of wildlife. This paper contributes to debates on the value of endangered species by estimating current use and non-use values for the rhino, a species under extreme threat. Internationally, literature that values scarce and endangered species uses willingness-to-pay (WTP) to derive a value of the species. This paper uses WTP to determine the non-consumptive use value of the rhino based on three surveys, n = 1291, conducted in South Africa's Kruger National Park (KNP) and compare it to consumptive use values. Non-use and inter-temporal values are also estimated to provide a comprehensive valuation of the rhino. Non-consumptive use values per rhino in KNP are shown to exceed consumptive use values by a minimum of 50%. The threat of extinction is shown to be linked to institutional, market and policy failures. Policy implications include raising poaching fines, raising wildlife value awareness and incentivising the community benefits of wildlife conservation.     

Wildlife viewing: The impact of money-back guarantees

Wildlife sightings are not always guaranteed. To address this risk, tour operators often offer a money-back guarantee as a refund mechanism. However, studies have overlooked the influences of such refund mechanisms on tourists' tour participation decisions and tourism revenue. We conducted choice experiments to examine the impact of such mechanisms using a case of Amami rabbit tourism in Japan. We found that the guarantee significantly influences the tourists’ decision-making and tour revenue. In particular, we found that the expected tourist participation rate and tour guide revenue vary drastically depending on the probability of the rabbit encounter. The maximum expected revenue from the tour with a 90% chance was about 20 times larger than that with a 10% chance. This indicates that conserving wildlife to maintain the sighting probability raises tour benefits, creating a win-win situation by balancing conservation and tourism development.     

我国物种保护拯救与自然保护区建设回顾与展望

总结了我国林业物种保护拯救与自然保护区建设成就。全国野生动植物保护及自然保护区建设工程实施8年来,初步形成了国家、省、市三位一体的野生动植物保护体系,有效保护着我国90%的陆地生态系统类型、85%的野生动物种群和65%的高等植物群。提出今后工程建设的重点是认真编制好规划,积极研究保护立法,完善保护区布局,加强珍稀濒危野生动植物拯救力度,扩大拯救范围,强化野生动植物繁育利用的市场监管和执法监督。     

空分装置运行常见故障与排除

本文介绍了空分装置运行过程中易出现的故障,分析故障产生的原因,并对故障提出了相应的解决方法和措施,对装置的日常运行提出针对性的建议,从而延长装置的运行周期,减少装置检修次数,为企业带来显著的效益。     

水电站厂房渗水原因分析及处理

文章介绍了纪村水电站厂房地面陆续出现向外渗水现象的具体情况,分析了造成这一现象的原因,提出了解决方法及防范措施。希望对水电站厂房的安全、稳定运行起到一定的借鉴作用。     

浅谈现场总线技术在火电厂的应用

近年来,现场总线技术在火电厂中得到了越来越广泛的应用,同时也在业内引起了更广泛的重视。文章对现场总线的结构特点和优势进行了分析,阐述了现场总线技术在智能化现场设备中的应用及智能化设备状态的检修管理等,并对现场总线技术在国内火电厂的应用情况进行了简单的介绍。     

浅谈植物病虫害的防治要点

本文就植物病虫害防治要点进行初步探讨。     

我国火力发电厂环境成本控制研究

在"厂网分开、竞价上网"的竞争环境下,各火力发电厂加强环境成本控制,完善环境成本管理已经成为提高企业竞争力的必然选择.这里首先介绍了我国火力发电厂的环境污染和成本开支现状,重点分析了燃煤火力发电企业的各环境成本项目,得出了环境成本公式,并依据公式确立了环境成本控制的三个核心目标,提出了环境成本控制的方法与绩效考核办法,最后指出加强环境成本控制意义重大,是各火力发电厂可持续发展的必由之路.     

On the duality principle in option pricing: semimartingale setting

The purpose of this paper is to describe the appropriate mathematical framework for the study of the duality principle in option pricing. We consider models where prices evolve as general exponential semimartingales and provide a complete characterization of the dual process under the dual measure. Particular cases of these models are the ones driven by Brownian motions and by Lévy processes, which have been considered in several papers. Generally speaking, the duality principle states that the calculation of the price of a call option for a model with price process S=e ^H (with respect to the measure P) is equivalent to the calculation of the price of a put option for a suitable dual model S′=e ^H′ (with respect to the dual measure P′). More sophisticated duality results are derived for a broad spectrum of exotic options. The second named author acknowledges the financial support from the Deutsche Forschungsgemeinschaft (DFG, Eb 66/9-2). This research was carried out while the third named author was supported by the Alexander von Humboldt foundation.