Social network analysis and valid Markov chain Monte Carlo tests of null models

Analyses of animal social networks derived from group-based associations often rely on randomisation methods developed in ecology (Manly, Ecology 76:1109–1115, 1995) and made available to the animal behaviour community through implementation of a pair-wise swapping algorithm by Bejder et al. (Anim Behav 56:719–725, 1998). We report a correctable flaw in this method and point the reader to a wider literature on the subject of null models in the ecology literature. We illustrate the importance of correcting the method using a toy network and use it to make a preliminary analysis of a network of associations among eagle rays.

气候变化背景下四川省单季稻水分盈亏的变化特征

研究利用四川稻区109 个气象台站1961-2010 年的地面气象资料和16 个农业气象站 1981-2010 年的单季稻生育期资料,计算了研究区水稻不同生育期的有效降水量和需水量,并探讨了水稻不同生育阶段内的缺水量和缺水率。结果表明,1961-2010 年四川水稻年均缺水率在孕穗到开花期最高,移栽到孕穗期次之,开花到成熟期最低。近50 a 来,水稻全生育期年有效降水量、需水量和缺水量总体表现为减少趋势,而缺水率在稻区中、西部总体呈升高趋势; 有效降水量在移栽到孕穗期和开花到成熟期以减小为主,而在孕穗到开花期总体呈升高趋势; 需水量在水稻不同生育期内总体均表现为减小趋势;缺水量和缺水率在孕穗到成熟期以减小为主,而在移栽到孕穗期稻区中、西部地区呈升高趋势。研究可为四川稻区的农业用水及合理灌溉提供依据。     

区域及全球尺度的NPP过程模型和NPP对全球变化的响应

植被净第一性生产力（NPP）不仅是表征植被活动和生态过程的关键参数,而且是判定生态系统碳汇和反映生态系统对全球变化响应的主要因子。当前,模型模拟成为大尺度NPP研究的主要手段,而在众多NPP估算模型中,过程模型逐渐趋于主导地位。虽然目前有关NPP的研究有很多,但还没有关注于大尺度上应用的过程模型及其模拟的NPP对全球变化的响应。因此本文主要侧重于 NPP 过程模型在区域及全球尺度上的应用,具体包含以下内容,①进一步将区域及全球尺度的NPP过程模型分为静态植被模型和动态植被模型。②阐明这些模型间存在的区别与联系。③归纳出NPP过程模型在区域及全球尺度上应用的3大挑战：时空尺度转换、多源数据的获取与融合以及模型模拟结果的验证与评价,并根据其解决方案总结出通用的模型应用框架。④从气候变化、大气成分变化和土地利用/土地覆盖变化3个方面探讨NPP对全球变化的响应机制,以期找到NPP变化的规律与模式。最后根据NPP模型的发展对未来区域及全球尺度的NPP过程模型进行展望,认为未来模型的综合性将更高,机理性也将更强,同时与全球变化研究结合得更加紧密,且基于多个已有模型的混合模型也是未来NPP模型发展的一个重要方向。此外,本文认为对NPP模拟结果的尺度效应研究也是未来NPP研究的热点之一。     

Willingness to pay for clean air in China

We use a residential sorting model incorporating migration disutility to recover the implicit value of clean air in China. The model is estimated using China Population Census Data along with PM2.5 satellite data. Our study provides new evidence on the willingness to pay for air quality improvements in developing countries and is the first application of an equilibrium sorting model to the valuation of non-market amenities in China. We employ two instrumental variables based on coal-fired electricity generation and wind direction to address the endogeneity of local air pollution. Results suggest important differences between the residential sorting model and a conventional hedonic model, highlighting the role of moving costs and the discreteness of the choice set. Our sorting results indicate that the economic value of air quality improvement associated with a one-unit decline in PM2.5 concentration is up to $8.83 billion for all Chinese households in 2005.     

Will Evolving Climate Conditions Increase the Risk of Floods of the Large U.S.‐Canada Transboundary Richelieu River Basin?

In spring 2011, an unprecedented flood hit the complex eastern United States (U.S.)–Canada transboundary Lake Champlain–Richelieu River (LCRR) Basin, destructing properties and inducing negative impacts on agriculture and fish habitats. The damages, covered by the Governments of Canada and the U.S., were estimated to C$90M. This natural disaster motivated the study of mitigation measures to prevent such disasters from reoccurring. When evaluating flood risks, long‐term evolving climate change should be taken into account to adopt mitigation measures that will remain relevant in the future. To assess the impacts of climate change on flood risks of the LCRR basin, three bias‐corrected multi‐resolution ensembles of climate projections for two greenhouse gas concentration scenarios were used to force a state‐of‐the‐art, high‐resolution, distributed hydrological model. The analysis of the hydrological simulations indicates that the 20‐year return period flood (corresponding to a medium flood) should decrease between 8% and 35% for the end of the 21st Century (2070–2099) time horizon and for the high‐emission scenario representative concentration pathway (RCP) 8.5. The reduction in flood risks is explained by a decrease in snow accumulation and an increase in evapotranspiration expected with the future warming of the region. Nevertheless, due to the large climate inter‐annual variability, short‐term flood probabilities should remain similar to those experienced in the recent past.     

Bridging gaps in demographic analysis with phylogenetic imputation

Phylogenetically informed imputation methods have rarely been applied to estimate missing values in demographic data but may be a powerful tool for reconstructing vital rates of survival, maturation, and fecundity for species of conservation concern. Imputed vital rates could be used to parameterize demographic models to explore how populations respond when vital rates are perturbed. We used standardized vital rate estimates for 50 bird species to assess the use of phylogenetic imputation to fill gaps in demographic data. We calculated imputation accuracy for vital rates of focal species excluded from the data set either singly or in combination and with and without phylogeny, body mass, and life-history trait data. We used imputed vital rates to calculate demographic metrics, including generation time, to validate the use of imputation in demographic analyses. Covariance among vital rates and other trait data provided a strong basis to guide imputation of missing vital rates in birds, even in the absence of phylogenetic information. Mean NRMSE for null and phylogenetic models differed by <0.01 except when no vital rates were available or for vital rates with high phylogenetic signal (Pagel's λ > 0.8). In these cases, including body mass and life-history trait data compensated for lack of phylogenetic information: mean normalized root mean square error (NRMSE) for null and phylogenetic models differed by <0.01 for adult survival and <0.04 for maturation rate. Estimates of demographic metrics were sensitive to the accuracy of imputed vital rates. For example, mean error in generation time doubled in response to inaccurate estimates of maturation time. Accurate demographic data and metrics, such as generation time, are needed to inform conservation planning processes, for example through International Union for Conservation of Nature Red List assessments and population viability analysis. Imputed vital rates could be useful in this context but, as for any estimated model parameters, awareness of the sensitivities of demographic model outputs to the imputed vital rates is essential.     

3MRA风险模型在铬渣整治项目制定过程中的应用

选用美国环境保护署现行废物风险评价模型(3MRA)对某铬渣整治项目进行环境风险评价.模拟了治理前后区域内环境风险情况.分析了污染物暴露途径及危害对象.通过模型对该项目预定处置方法可行性进行了验证.模拟结果显示,在95%受保护对象、95%置信水平条件下,铬渣堆存区域存在显著的环境风险,周边居民致癌风险在10-4数量级,水域生态风险危害商数>1.而在对铬渣进行解毒填埋处置后,环境风险将有效降低,验证了此项目处置方法的可行性.     

京杭大运河无锡段水质和土地利用的响应关系

以京杭大运河无锡段2003年7月和12月两景SPOT-5正射影像为数据源,结合断面水质数据,利用基于最小二乘法的多元回归方法,建立了枯水期和丰水期水质参数与土地利用的响应模型。结果表明:以监测断面为中心的缓冲区距离的空间变化与水质监测指标之间有很明显的响应关系,建立的模型显示,丰水期DO、CODMn、BOD5、TN和TP的最大响应宽度分别为100、100、300、200和100 m,枯水期的最大响应宽度则为500、200、300、400和200 m。运河的水质污染主要受离河岸较近的土地利用结构的影响,耕地上产生的农业污水、商业和工业中的废水以及大面积裸地上居民生活垃圾和建筑垃圾产生的污水是导致京杭大运河无锡段水质恶化的重要原因。     

澳大利亚职业安全健康统计体系及对我国借鉴研究

澳大利亚职业安全健康一直处于较好水平,其职业安全健康统计体系具有典型性。分析研究了澳大利亚的职业安全健康统计体系,包括统计相关法规,统计机构、统计指标、统计口径、统计方法和统计数据的公布等内容,总结了澳大利亚职业安全健康统计体系特点,并与我国安全生产统计现状进行比较,提出改进我国安全生产统计体系的建议,以期为我国安全生产统计体系的发展和变革提供参考。