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161.
Economic analysis of optimal ecosystem management in the presence of a threshold has typically ignored the potential for induced behavioral responses. This paper contributes to the literature on non-convex ecosystem management by considering the implications of a particular behavioral response in a regional economy – that of amenity-led growth – to changes in ecosystem services generated by a lake ecosystem subject to a eutrophication threshold. The essential policy challenge is to achieve optimal levels of lake nutrients and urbanization given that improvements to water quality will induce additional migration and urbanization in the region with attendant ecological impacts. We show that policies that ignore the recursive relationship between urbanization and water quality unintentionally exacerbate boom-bust cycles of regional growth and decline and risk pushing the system towards long-run economic decline. In contrast, the optimal policy accounts for the behavioral feedbacks to improved ecosystem services, and balances regional growth and ecological degradation. 相似文献
162.
利用2008年6月1日~2009年5月31日在北京城区中国气象局(CMA),及其西南方向固城站(GCH)和东北方向上甸子本底站(SDZ)的近地面O3等观测数据,分析了O3的变化特征及其与其他污染物和气象要素的关系.结果表明,上甸子本底站近地面O3的季节变化和日变化规律与固城和北京城区站存在一定的差异,而固城站和北京城区站的O3变化特征差异较小.相关性分析显示,O3与NO、NO2、NOx、RH多呈负相关,且相关性冬季好于夏季,此外,O3与气温和风速呈正相关,其中北京城区站冬季和夏季O3与风速的相关性差异最明显.O3浓度与地面风向有一定关系,当风向为偏南时,O3浓度较高,当风向为东北时,O3浓度偏低. 相似文献
163.
We present how state-and-transition models (STMs) may be derived from image data, providing a graphical means of understanding how ecological dynamics are driven by complex interactions among ecosystem events. A temporal sequence of imagery of fine scale vegetation patterning was acquired from close range photogrammetry (CRP) of 1 m quadrats, in a long term monitoring project of Themeda triandra (Forsskal) grasslands in north western Australia. A principal components scaling of image metrics calculated on the imagery defined the state space of the STM, and thereby characterised the different patterns found in the imagery. Using the state space, we were able to relate key events (i.e. fire and rainfall) to both the image data and aboveground biomass, and identified distinct ecological ‘phases’ and ‘transitions’ of the system. The methodology objectively constructs a STM from imagery and, in principle, may be applied to any temporal sequence of imagery captured in any event-driven system. Our approach, by integrating image data, addresses the labour constraint limiting the extensive use of STMs in managing vegetation change in arid and semiarid rangelands. 相似文献
164.
The cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) is one of the most serious crop pests in northern China, calling for accurate prediction of pest outbreaks and strategies for pest control. A computer model is developed to simulate the population dynamics of H. armigera over a wide area in northern China. The area considered covers 12 provinces where serious outbreaks of H. armigera have been observed. In this model, pest development is driven by local ambient temperature, and adults migrate long distances between regions and select preferred hosts for oviposition within a region. Six types of host including cotton, wheat, corn, peanut, soybean and a single category composed of all other minor hosts are considered in this model. Survival rates of eggs and larvae are based on life-table data, and simulated as a function of host type, host phenology and temperature. The incidence of diapause depends on temperature and photoperiod experienced during the larval stage. Survival rate of non-diapause pupae is a nonlinear function of rainfall, and overwinter survival rate is a nonlinear function of temperature. Insecticide is applied when population density exceeds the economic threshold on a host crop within a region. Comparisons of model output with light-trap data indicate that our model reflects the pest population dynamics over a wide area, and could potentially be used for testing novel pest control strategies in northern China. 相似文献
165.
Hong Li Mijail Arias Anouk Blauw Arthur E. Mynett Steef Peters 《Ecological modelling》2010,221(20):2435-2446
Physically based numerical modelling follows from the basic understanding of the underlying mechanisms and is often represented by a set of (partial differential) equations. It is one of the main approaches in population dynamics modelling. The emphasis of the model introduced in this paper is on the simulation of short-term spatial and temporal dynamics of harmful algal bloom (HAB) events. Total suspended matter (TSM) concentration is one of the dominant factors for harmful algal bloom (HAB) prediction in North Sea. However, the modelling of suspended matter contains a high degree of uncertainty in this area. Therefore, this research aims to achieve a better estimation for the short-term prediction of harmful algal bloom development in both space and time by using spatially distributed TSM retrieved from remotely sensed images as physically based model inputs. In order to supply complete spatially covered datasets for the physically based model instrument: generic ecological model (GEM), this research retrieves TSM information from MERIS images by means of proper estimation techniques including biharmonic splines and self-learning cellular automata. A better estimation of HAB spatial pattern development is achieved by adding spatially distributed TSM data as inputs to original GEM model, and it proved that chlorophyll-a concentration in this area is very sensitive to TSM concentration. 相似文献
166.
Based on numerical experiments with a new physiologically structured population model we demonstrate that predator physiology under low food and under starving conditions can have substantial implications for population dynamics in predator-prey interactions. We focused on Daphnia-algae interactions as model system and developed a new dynamic energy budget (DEB) model for individual daphnids. This model integrates the κ-rule approach common to net assimilation models into a net-production model, but uses a fixed allocation of net-productive energy in juveniles. The new DEB-model agrees well with the results of life history experiments with Daphnia. Compared to a pure κ-rule model the new allocation scheme leads to significant earlier maturation at low food levels and thus is in better agreement with the data. Incorporation of the new DEB-model into a physiologically structured population model using a box-car elevator technique revealed that the dynamics of Daphnia-algae interactions are highly sensitive to the assumptions on the energy allocation of juveniles under low food conditions. Additionally we show that also other energy allocation rules of our DEB-model concerning decreasing food levels and starving conditions at the individual level have strong implications for Daphnia-algae interactions at the population level. With increasing carrying capacity of algae a stable equilibrium with coexistence of Daphnia occurs and algae shifts to limit cycles. The amplitudes of the limit cycles increase with increasing percentage of sustainable weight loss. If a κ-rule energy allocation is applied to juveniles, the stable equilibrium occurs for a much narrower range of algal carrying capacities, the algal concentration at equilibrium is about 2 times larger, and the range of algae carrying capacities at which daphnids become extinct extends to higher carrying capacities than in the new DEB-model. Because predator-prey dynamics are very sensitive to predator physiology under low food and starving conditions, empirical constraints of predator physiology under these conditions are essential when comparing model results with observations in laboratory experiments or in the field. 相似文献
167.
Global warming is the observed increase of the average temperature of the Earth. The primary cause of this phenomenon is the release of the greenhouse gases by burning of fossil fuels, land cleaning, agriculture, among others, leading to the increase of the so-called greenhouse effect. An approach to deal with this important problem is the time series analysis. In this regard, different techniques can be applied to evaluate the global warming dynamics. This kind of analysis allows one to make better predictions increasing our comprehension of the phenomenon. This article applies nonlinear tools to analyze temperature time series establishing state space reconstruction and prediction. Since noise contamination is unavoidable in data acquisition, it is important to employ robust techniques. The method of delay coordinates is employed for state space reconstruction and delay parameters are evaluated using the method of average mutual information and the method of false nearest neighbors. Afterwards, the simple nonlinear prediction method is employed to estimate temperatures of the future. Temperature time series from different places of the planet are used. Initially, the approach is verified considering known parts of the time series and afterwards, results are extrapolated for future values estimating temperature until 2028. Results show that these techniques are interesting to estimate temperature time history, presenting coherent estimations. 相似文献
168.
Lajos Izsó Miklós Antaiovits 《International journal of occupational safety and ergonomics》2013,19(3-4):173-189
An activity analysis method was developed for studying the structure and dynamics of control room operators’ activity during normal operation based on directly observable elements of the operators’ behavior. The method assesses current activity along three dimensions in each 5-min period of the shift. Intensity characterizes arousal level, direction shows whether the activity is directed predominantly at the process control task, at something else, or miscellaneous. Motivation reflects if the activity is driven by intrinsic or extrinsic motivation. A case study is presented, in which 3 morning, 3 afternoon, and 3 night shifts of a Nuclear Power Plant operator crew are involved. The obtained results gave a deeper understanding of the operators’ activity and also revealed an “arousal compensation” tendency. 相似文献
169.
地震应急避难需求的系统动力学研究 总被引:1,自引:0,他引:1
为定量研究地震应急避难人群的规模及变化规律,建立需求分析的系统动力学模型。该模型包括建筑物倒塌,断水和电梯停运3种因素造成的需求。参考汶川地震中板房建设速度和电梯修复速度,以及日本关于地震断水率的研究成果,建立非线性模型拟合各需求的变化规律。采用Vensim软件建立系统动力学模型,分析各需求的综合变化规律。采用上海市徐汇区的数据进行案例演算,并与其他研究方法对比分析仿真误差。仿真结果表明:建筑物损坏对人群数量的影响很大,但是灾后1个月内断水的影响最大;相对于工程技术因素,人因对需求有重要的影响。 相似文献
170.
Dynamics of the Coordination of Economy-Society and Resource-Environment in Shandong Peninsula,China
Han Rongqing 《中国人口.资源与环境(英文版)》2013,11(3):62-71
Abstract Shandong Peninsula, as a more developed region in Shandong Province even the east coast of China, is facing challenges from resources and environment pressures. This paper tried to track and assess the coordination status and the dynamic between resource-environment and economy-society systems in Shandong Peninsula during 2001—2008 in order to provide decision support for regional sustainability. An appraisal index system was built including five aspects of harmony degree (A), sustainability degree (B), opening degree (C), stability degree (D) and controllability degree (E). The results showed that: 1) The coordination level of resource-environment and economy-society in Shandong Peninsula has continuously grown, and it has undergone three stages: no coordinated degree (2001–2002), weak coordinated degree (2003–2006) and basically coordinated degree (2007– 2008). 2) Five indexes of criterion hierarchy also increased overall, but each index showed different trends. Harmony degree, sustainability degree and opening degree rose all the time, while stability degree and controllability degree alternately rose and fell. The improvement of controllability degree was the slowest. 3) The aggravating trend of environmental pollution was slowing down. The economic growth was driven by industrial growth and urbanization typically and investment was still the main force to pull the regional economic growth. At the same time, technology and education were becoming more and more important for economic growth. The level of foreign capital utility declined and the geographical advantage of Shandong Peninsula was exerted. Meanwhile some characteristics of knowledge economy were presenting. Water resources become the main constraint factor of fast development in Shandong Peninsula. It is necessary to further strengthen the coordination ability of government on regional sustainable development. 相似文献