The use of incubation behavior to adjust avian reproductive costs after egg laying

Reproduction in birds requires the input of time and energy during discrete breeding phases leading to investment trade-offs between laying date, clutch size, body mass, and incubation constancy. We investigated costs during incubation by experimentally enlarging 25 clutches of white-tailed ptarmigan Lagopus leucurus. The experiment was conducted in 2 years, one with harsh weather that forced a natural delay in reproduction. When forced to delay egg-laying, females began incubation with poorer body condition and foraged more during incubation. Rates of mass loss during incubation were not affected by clutch enlargement, and did not differ between harsh and benign years; however, females that were heavier at the start of incubation lost more mass than lighter females. Clutch-enlarged females had reduced nest attendance compared to control birds in both years and incubation periods increased by up to 2 days relative to controls. In the harsh year, there was a trend for clutch-enlarged females to have lower nest success, but there was no effect on overwinter survival. Different behavioral responses by females in the 2 years showed that incubation costs may depend on other factors such as female quality, food supply, or weather conditions. Incubation is a dynamic period during which birds may adjust energy balances by varying body condition and food intake. Received: 28 March 2000 / Received in revised form: 18 August 2000 / Accepted: 2 July 2000     

Parental investment, adult sex ratios, and sexual selection in a socially monogamous seabird

Although most birds are monogamous, theory predicts that greater female parental investment and female-biased adult sex ratios will lower the polygyny threshold. This should result in polygynous mating, unless obligate biparental care or the spatial and temporal distribution of fertilizable females constrains a male’s ability to take advantage of a lowered polygyny threshold. Here we present data on the extent of male sexually dimorphic plumage, adult sex ratios and breeding season synchrony in three populations of a socially monogamous seabird, the brown booby Sula leucogaster. For one of these populations, San Pedro Mártir Island, we also present data on differences in male and female parental investment, mortality and probability of pairing. The extent of plumage dimorphism varied among populations. Sex ratios were female biased in all populations. On San Pedro Mártir Island, parental investment was female biased, females failed more often than males to find a mate, but there was no polygyny. We suggest that on San Pedro Mártir: (1) a period of obligate biparental care coupled with a relatively synchronous breeding season constrained the ability of males to take advantage of a high environmental polygamy potential and (2) the resulting socially monogamous mating system, in combination with the female-biased adult sex ratio, caused females to be limited by the availability of males despite their greater parental investment. Received: 18 November 1999 / Accepted: 24 January 2000     

农业生产对土壤盐渍化影响的经济分析

研究农业生产活动对土壤盐渍化的负面影响,有利于合理安排农业公共投资,促进生产与环境协调发展。在介绍我国土壤盐渍化概况的基础上,利用相关文献分析影响土壤盐渍化的不同因素,同时利用省级Panel数据和计量模型进一步探索农业生产活动对土壤盐渍化的影响。结果表明,灌溉程度、单位钾肥投入会对土壤盐渍化产生显著影响。单位耕地上灌溉面积越多,耕地发生盐渍化的概率也越高;同时单位面积上钾肥使用量越高,耕地发生盐渍化的概率也越高。此外,还在统计意义上发现排灌对抑制土壤盐渍化具有明显作用。因此,针对农业生产活动对农业生态环境可能造成的负面影响,进一步提出应该在增加农业公共投资的背景下,加强农业基础设施的建设,引导农户采用合理的农业生产方式,以协调我国农业生产与农业生态环境的和谐发展。     

环保投资效率实证与政策建议

对我国环保投资效率进行实证检验,发现每年我国的环保投资是不断增加的,但是相对于其自身的高速增长,环保投资所取得的治污效果是相当差的。尤其是本文在孙冬煜所构造的"环境保护投资优先增长模型"的基础上,对原模型中的假设进行了适度的修正,利用2000-2007年我国环保投资数据,对我国环保投资的效率进行了实证检验。我国的污染物排放量呈逐年上升趋势,且上升幅度较大。造成这种结果的原因,主要就是我国环保投资的效率低下。基于以上分析,作者还提出了完善公众监管措施、改进投融资机制、提高科技成果的转化能力、推动环保产业战略性调整与产业结构的优化、制定相关的财政激励措施等提升我国环保投资运行效率的政策建议。     

基于利益相关者分析的安全生产投资社会评价研究

在利益相关者分析基础上建立的评价模型指出安全生产投资利益相关者分析的范围、任务和原则,通过分析各利益相关者的损益及成本收益分担情况,指出安全生产投资利益调整的目的、方式以及政策建议。对安全生产投资社会评价的研究,不仅完善了安全生产投资的评价体系,也为制定安全生产经济政策、解决我国企业缺乏安全生产投资主动性及投资不足的问题提供依据。     

公路建设项目实施“代建制”管理模式探讨

在分析公路建设项目传统管理模式不足的基础上,结合我国公路建设工程实际情况,从工程管理体制改革、与国际管理体制接轨和公路建设项目公益性属性3方面阐述公路建设项目推行"代建制"管理模式的必要性。针对"代建制"管理模式在我国公路建设中存在缺乏法律法规的保障、缺乏职能定位依据、"代建制"机制不完善以及代建方管理水平较低等问题,提出从转变观念、完善法制建设、加强代建单位自我完善3个方面采取措施,推行和完善公路建设项目"代建制"管理模式,从而实现公路建设项目"质量、费用、进度和安全"目标的有效控制。     

高速公路水土保持生态服务功能价值评估浅析——以陕西省不同区域三条高速公路为例

以陕西省3个典型区域的3条高速公路为例,在构建高速公路水土保持生态服务功能价值评价体系并确定各评价指标计算方法的基础上,全面分析了高速公路水土保持的生态服务功能价值。旨在相互交流的基础上,为后期同类工程水土保持投资预算设计和资金管理使用提供理论依据。     

Insurance sector management of climate change adaptation in three Nordic countries: the influence of policy and market factors

The insurance industry is important for facilitating climate change adaptation. Insurance companies’ involvement is, however, influenced by national adaptation policy. The literature suggests that especially policy factors – government interventions, political priorities and public–private cooperation – and market factors – cost offset, cost mitigation, planning flexibility and business opportunities – shape private actor approaches. To increase the understanding of insurance company involvement in adaptation, this study examines how insurance companies’ approaches are influenced by policy and market factors in three countries: Denmark, Norway and Sweden. The study found that the policy factors tested significantly shaped the approaches of the companies assessed, while market factors currently appear less influential. This is likely due to the absence of climate risk and adaptation in political debates and among insurance policyholders. The study discusses the potential role of the insurance industry in adaptation governance and suggests how barriers facing insurance companies could be overcome.     

Local governments in the driving seat? A comparative analysis of public and private responsibilities for adaptation to climate change in European and North-American cities

The division of responsibilities between public and private actors has become a key governance issue for adaptation to climate change in urban areas. This paper offers a systematic, comparative analysis of three empirical studies which analysed how and why responsibilities were divided between public and private actors for the governance of local urban climate adaptation. For 20 governance arrangements in European and North-American cities, the divisions of responsibilities and the underlying rationales of actors for those divisions were analysed and compared. Data were gathered through content analysis of over 100 policy documents, 97 in-depth interviews and 2 multi-stakeholder workshops. The comparative analysis reveals that local public authorities are the key actors, as they bear the majority of responsibilities for climate proofing their cities. In this stage of policy emergence, local authorities are clearly in the driving seat. It is envisaged that local public authorities need to more actively engage the different private actors such as citizens, civil society and businesses through governance networks along with the maturation of the policy field and the expected acceleration of climate impacts in the coming decades.     

Mercury Levels in Pristine and Gold Mining Impacted Aquatic Ecosystems of Suriname, South America

Mercury levels in sediment and predatory fish were measured for 53 localities in Suriname. The average mercury level in bottom sediment surpassed the Canadian standard for sediment in most localities, except the coastal plains. Of the predatory fish, 41 % had a mercury level above the European Union standard for human consumption of 0.5 μg g⁻¹. Highest mercury levels were found in fish from the Brokopondo Reservoir and from the Upper Coppename River. High levels of mercury in fish in pristine areas are explained by atmospheric transportation of mercury with the northeastern trade winds followed by wet deposition. Contrary to gold mining areas, where mercury is bound to drifting sediments, in “pristine” areas the mercury is freely available for bio-accumulation and uptake. Impacts on piscivorous reptiles, birds, and mammals are unknown, but likely to be negative.