Using Scalar Models for Precautionary Assessments of Threatened Species

Abstract:  Scalar population models, commonly referred to as count-based models, are based on time-series data of population sizes and may be useful for screening-level ecological risk assessments when data for more complex models are not available. Appropriate use of such models for management purposes, however, requires understanding inherent biases that may exist in these models. Through a series of simulations, which compared predictions of risk of decline of scalar and matrix-based models, we examined whether discrepancies may arise from different dynamics displayed due to age structure and generation time. We also examined scalar and matrix-based population models of 18 real populations for potential patterns of bias in population viability estimates. In the simulation study, precautionary bias (i.e., overestimating risks of decline) of scalar models increased as a function of generation time. Models of real populations showed poor fit between scalar and matrix-based models, with scalar models predicting significantly higher risks of decline on average. The strength of this bias was not correlated with generation time, suggesting that additional sources of bias may be masking this relationship. Scalar models can be useful for screening-level assessments, which should in general be precautionary, but the potential shortfalls of these models should be considered before using them as a basis for management decisions.     

长江经济带区域空间结构演化研究

在构建城市影响力指数测度指标体系基础上,运用熵值法计算得出1988、2001及2012年长江经济带内110个地级市以上城市影响力指数;在ArcGis软件平台下,利用空间分析方法,依据改进场模型、扩散模型,综合测度了长江经济带内地级市以上城市的可达性、空间场能及扩散效应,并对其进行深入分析。结果表明:城市间影响力指数差异较大但整体呈缩小趋势,城市可达性水平基本呈现出"东部> 中部> 西部"的格局;区域内存在一条主轴、三大核心圈、多条辅轴的区域空间结构,构成区域"1+3+X"发展格局;长江经济带经过城市孕育、极核发展、点轴扩散、网络化、局域一体化发展5个阶段,基本形成串珠式核心-边缘结构,区域内出现同一时期多个阶段并存的现象。为加快长江经济带空间结构的优化重组,依据"以点布轴,以轴拓面"空间思想,进行结构要素优化,主要有:合理构建城市等级体系,培养地方增长极;科学规划交通网络,优化空间扩散轴线;合理优化区域分工与合作,构建多层级城市群。     

环境优化对经济发展的作用分析

依据辽宁省环保厅近年来审批的建设项目,分析环保审批如何在优化经济发展中起到的重要作用。分析表明:严格环境准入,提高环境门槛、引导产业优化,实现循环经济和可持续发展并通过禁止、限制、鼓励、引导等方式,优化经济发展,带动经济发展模式的转变,实现资源节约型社会和环境友好型社会发展的重大战略目标。     

成渝经济区陆地植被碳储量动态及碳汇战略研究

利用卫星遥感数据,对2000年-2007年间成渝经济区耕地、森林和草地等陆地植被的碳储量进行了估算.结果表明:(1)7年间耕地和草地分别减少了2 388.89 km2和1 231.05 km2,林地增加了2 908.70 km2,其中耕地主要转出为林地和建设用地,草地转出主要为林地和耕地;(2)7年间成渝经济区碳储量呈逐渐增加的趋势,共增加了625.16万tC/a,年增长率为0.21%.其中耕地、草地碳储量分别减少了165.79万tC/a和933.87万tC/a,林地碳储量增加了1 724.81万tC/a.(3)结合碳储量变化的趋势,提出了以打造低碳城市为目标的成渝经济区碳汇战略.     

基于夜间灯光的城市居民直接碳排放及影响因素——以中原经济区为例

城市居民直接能源消耗及其碳排放对区域碳减排政策的制定具有重要影响。受统计数据缺乏与研究方法的限制,当前的研究不仅较少探讨精细空间尺度上的城市居民直接碳排放,同时也缺乏在县级尺度上对人均居民直接碳排放的影响因素进行深入分析。鉴于此,论文以中原经济区为例,通过引入夜间灯光数据,利用增强型饱和校正模型估算了网格尺度上的城市居民碳排放,并采用地理加权回归模型对其影响因素进行了分析。主要研究发现：中原经济区的碳排放总体空间特征是西北高、东南低。郑州市市辖区的城市居民直接碳排放总量位于首位,而邢台县、辉县市和襄垣县的人均碳排放较高。此外,就其影响因素来看,人均GDP、碳排放强度、第二产业比重和HDD（Heating Degree Days,热度日）均表现为正效应,城镇化率为负效应,而CDD（Cooling Degree Days,冷度日）的系数有正有负。城市居民直接碳排放的影响因素分析为中原经济区制定切实可行的区域碳排放政策提供了重要的基础理论依据。     

Assessing the impact of driverless haul trucks in Australian surface mining

Australia has been a leading mining nation and its mines continue to attract substantial investment due to its strong mineral endowment, mining tradition and high skills base. In recent years Australian mining companies have been facing higher labour costs, which need to be offset by other savings. Automating mine-site machinery offers one potential source of such savings.Underground mines pioneered automated technology largely for safety and mine accessibility reasons and to reduce operating costs. Yet these operations now represent a much smaller portion of the total ore tonnes mined due to the changing mining techniques meaning larger lower grade deposits are becoming economic. It appears the future of mine automation will be directed by surface mining as this maturing technology finds further applications above ground and in the next decade large scale open pit automation trials gain more momentum.This paper assesses the implications of introducing driverless haul trucks in a typical large remote Australian open-pit mine. Such automation will save employee and associated costs, increase operational productive hours and ultimately will reduce mine site workforce numbers. While there will be fewer jobs per mine, with reduced costs and higher productivity some previously uneconomic mines may again be profitable.The social implications of greater mine site automation are the reduction in population of remote mining towns and a decrease in the lower skilled labour requirements for the mining sector. There will be an increase in fly-in fly-out mining operations and companies will establish remote control centres for automated mines in larger cities. This may decrease overall labour requirements and so reduce employment in the sector; therefore, the government should be mindful of implementing policies that ensure a fair return on the economic rent of mineral leases.     

Irrigation pricing policies and its impact on agricultural inputs demand in Tunisia: a DEA-based methodology

This paper estimates farmers' individual irrigation water demand functions employing the information hidden in individual farmers' technical efficiency. This information is extracted through the development of a new deductive methodology based on inverse Data Envelopment Analysis (DEA) models. The empirical results for Tunisia show that farmers who are more technically efficient have less elastic irrigation water demand functions; these farmers would adjust demand only to a limited extent and they can afford the water price. In contrast, water pricing significantly affects those that are less efficient. These farmers shift towards a different cropping pattern using significantly less water and more land when the price of water increases. Thus, higher water prices would threaten this category's livelihood if their efficiency is not improved. However, if the technical efficiency of these farmers were to improve, then it would be more difficult to reach water saving objectives since their demand will also become highly inelastic. The findings have important implications in view of the objectives of Tunisia water policy which include:full cost recovery, continuity of the irrigation activity, and water saving at the national level.     

区域旅游发展动力机制模式研究——以安徽省会经济圈为例

旅游发展动力机制研究一直是旅游学研究的热点,特别是关于区域旅游发展动力机制模式的研究更是旅游界以及各级政府、旅游规划部门等研究和关注的重点.通过对国内外旅游发展动力机制研究的综述以及旅游发展动力机制模式的评析总结的基础上提出了资源驱动型、经济驱动型、项目带动型、市场推动型、政策主动型、区域联动型等六类区域旅游发展动力机制模式,并以安徽省会经济圈为例进行了案例研究,提出了发展建议和对策.     

Cost-benefit analysis of water-reuse projects for environmental purposes: a case study for Spanish wastewater treatment plants

Water reuse is an emerging and promising non-conventional water resource. Feasibility studies are essential tools in the decision making process for the implementation of water-reuse projects. However, the methods used to assess economic feasibility tend to focus on internal costs, while external impacts are relegated to unsubstantiated statements about the advantages of water reuse. Using the concept of shadow prices for undesirable outputs of water reclamation, the current study developed a theoretical methodology to assess internal and external economic impacts. The proposed methodological approach is applied to 13 wastewater treatment plants in the Valencia region of Spain that reuse effluent for environmental purposes. Internal benefit analyses indicated that only a proportion of projects were economically viable, while when external benefits are incorporated all projects were economically viable. In conclusion, the economic feasibility assessments of water-reuse projects should quantitatively evaluate economic, environmental and resource availability.     

Technology development and cost analysis of multiple pollutant abatement for ultra-low emission coal-fired power plants in China

The implementation of ultra-low emission (ULE) limits (SO₂: 35 mg/m³, NOx: 50 mg/m³, PM: 10 mg/m³) promoted the development of flue gas treatment technologies in China. Pollutant control technology development for Chinese coal-fired power plants was summarized and an analysis of the applicability and cost of pollutant control technologies was conducted. Detailed data were collected from 30 ultra-low emission coal-fired units across China. Based on a cost analysis model, the average unit power generation incremental costs were 0.0144 and 0.0095 CNY/(kW·hr) for SO₂ and NOx control technologies, respectively. The unit power generation incremental cost of twin spray tower technology was 7.2% higher than that of dual-loop spray tower technology. The effect of key parameters on operating cost was analyzed. The unit power generation incremental cost increased because of increments in the electricity price for SO₂ control technology and the price of the reductant in NOx control technology. With high sulfur content or NOx concentration, the unit power generation incremental cost caused by pollutant control increased, whereas the unit pollutant abatement cost decreased. However, the annual operating hours or load increased, thereby leading to a decline in unit power generation incremental cost and unit pollutant abatement cost.