Learning and adaptation in the management of waterfowl harvests

A formal framework for the adaptive management of waterfowl harvests was adopted by the U.S. Fish and Wildlife Service in 1995. The process admits competing models of waterfowl population dynamics and harvest impacts, and relies on model averaging to compute optimal strategies for regulating harvest. Model weights, reflecting the relative ability of the alternative models to predict changes in population size, are used in the model averaging and are updated each year based on a comparison of model predictions and observations of population size. Since its inception the adaptive harvest program has focused principally on mallards (Anas platyrhynchos), which constitute a large portion of the U.S. waterfowl harvest. Four competing models, derived from a combination of two survival and two reproductive hypotheses, were originally assigned equal weights. In the last year of available information (2007), model weights favored the weakly density-dependent reproductive hypothesis over the strongly density-dependent one, and the additive mortality hypothesis over the compensatory one. The change in model weights led to a more conservative harvesting policy than what was in effect in the early years of the program. Adaptive harvest management has been successful in many ways, but nonetheless has exposed the difficulties in defining management objectives, in predicting and regulating harvests, and in coping with the tradeoffs inherent in managing multiple waterfowl stocks exposed to a common harvest. The key challenge now facing managers is whether adaptive harvest management as an institution can be sufficiently adaptive, and whether the knowledge and experience gained from the process can be reflected in higher-level policy decisions.     

工业级远程环境监测管理系统

针对一些工业生产发达地区污染源众多而且分散的特点,提出一套工业级远程环境监控管理系统,为环保执法人员提供了技术辅助手段.系统分为下位机和上位机两部分,适用于高温高粉尘的工业生产环境,满足稳定性和健壮性要求.系统已应用于佛山市南海区多家铝型材厂,取得良好的效果.     

How temperature and habitat quality affect parasitoid lifetime reproductive success—A simulation study

Adult parasitoid females lay their eggs in or on host insects. Most species are incapable of de novo lipogenesis as adults, and lipids accumulated during the larval stage are allocated either to egg production or to adult survival. Lipid consumption increases with distance covered by the parasitoids and thus with the distance between available hosts within a habitat. Temperature should affect parasitoid fitness because it changes the constraint imposed by a limited reserve of lipids and because it influences behaviour. Climate change involves both an increase in average temperature and an increased frequency of extreme weather such as heat waves. We investigated how the predicted increase of temperature will affect parasitoid fitness and how this depends on habitat parameters (spatial distribution of hosts and lipid cost of habitat exploitation). We studied optimal behaviour and calculated fitness at different temperatures and in different habitats using a stochastic dynamic programming model for pro-ovigenic parasitoids (which mature all their eggs before becoming adult). We show that an increase in temperature decreases fitness of parasitoids adapted to lower temperatures. This decrease in fitness depends on habitat quality. In field conditions (assuming small costs of intra-patch foraging), the loss of fitness should be larger in habitats with high inter-patch distance and in habitats with a more aggregated distribution of hosts. The foraging behaviour of parasitoids is also affected; at higher temperature we show that intra-patch foraging becomes less efficient, and patch residence times are longer.     

FEASIBILITY OF SEASONAL WATER PRICING CONSIDERING METERING COSTS1

ABSTRACT: Efficiency implications of seasonal pricing, uniform pricing, and optimal seasonal pricing with metering costs are analyzed qualitatively using classical optimization technique. The first two schemes are special cases of the last pricing scheme. A nonlinear-integer programming model is formulated for a case study application to Salt Lake City to examine the feasibility of seasonal pricing. The analysis indicates that uniform pricing is preferable unless metering costs are substantially lower than present levels.     

长江中游防洪减灾系统可持续性评价研究

长江中下游平原地区是我国经济发达地区，也是我国洪涝灾害最严重地区之一，根据长江流域可持续发展要求，提出两个问题，一是长江中下游平原区要走可持续发展之路，如何使区内社会经济发展与洪涝灾害相协调，这属于地区可持续发展问题，二是防洪减灾系统能否持久地发挥作用，为社会经济可持续发展提供保障，即防洪减灾系统可持续性评价问题，首先讨论了防洪减灾系统可持续性评价的基本涵义，提出了可持续性评价的5个准则，即功能持久性，风险最低性，经济可行性，环境可承受性及社会可接受性，其次，以长江中游平原分蓄洪工程为例，提出了相应的评价指标体系；最后，选择有效蓄洪量，蓄洪面积，围堤长度，耕地面积，区内人口，区内安全台面积等为指标，建立了分蓄洪工程可持续性评价模型－均衡规划模型，并进行了实例分析探讨。     

基于资源环境承载力的规划结构优化方法探讨

规划结构合理性以及规划结构优化是规划环境影响评价关注的核心问题之一。文章以某煤电、煤化工基地规划环评为例,探讨了以区域资源、环境承载力为约束条件,以经济效益最大化为规划目标,采用线性规划法优化煤电、煤化工基地规划结构的过程。线性规划模型以煤电、煤化工产品的规模作为变量;资源、环境约束条件包括水资源消耗量、煤炭资源消耗量、蒸汽消耗量、电能消耗量、SO2排放量和CO2排放量。通过线性规划模型对煤电、煤化工产品的规模进行优化,在增加煤电、煤化工基地的经济效益的同时,减小了区域资源消耗和污染物排放水平。     

佛山水道引水对环境容量影响研究

采用污染负荷优化分配的线性规划方法,通过感潮河网水环境数学模型模拟得出污染贡献率。求取不同引水方案时佛山水道的环境容量,并建立引水量与环境容量的回归方程。研究结果表明,环境容量与引水量呈线性递增关系。根据回归方程可反推得出引水方案或削污方案,为引水与截污的实施提供了数据支持,并且对佛山水道综合整治的优化决策具有指导意义。     

基于阶次序列与凸规划的铀尾矿库监测定位算法

在铀尾矿库放射性核素泄露污染WSN监测中,针对凸规划定位精度低的问题,提出一种基于阶次序列的凸规划定位算法。通过划分子区域缩小未知节点几何约束范围,建立各子区域的重心坐标到锚节点的阶次序列表,计算未知节点序列与序列表的相关度,并以最大相关度的子区域重心坐标为定位结果。使该改进算法满足低密度条件的定位并能减少其计算量提高定位精度。经过仿真,新算法较凸规划算法在定位精度上提高了14%。     

Livestock mortality in pastoralist herds in Ethiopia and implications for drought response

Participatory epidemiology methods were employed retrospectively in three pastoralist regions of Ethiopia to estimate the specific causes of excess livestock mortality during drought. The results showed that starvation/dehydration accounted for between 61.5 and 100 per cent of excess livestock mortality during drought, whereas disease‐related mortality accounted for between 0 and 28.1 per cent of excess mortality. Field observations indicate that, in livestock, disease risks and mortality increase in the immediate post‐drought period, during rain. The design of livelihoods‐based drought response programmes should include protection of core livestock assets, and it should take account of the specific causes of excess livestock mortality during drought and immediately afterwards. This study shows that, when comparing livestock feed supplementation and veterinary support, relatively more aid should be directed at the former if the objective is to protect core livestock during drought. Veterinary support should consider disease‐related mortality in the immediate post‐drought period, and tailor inputs accordingly.