Diameter growth models for mixed-species stands of Coastal British Columbia including thinning and fertilization effects

In this study, diameter growth models for three species growing in mixed-stands of Coastal British Columbia (BC), Canada, under a variety of silvicultural treatments were developed. The three species were: Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western redcedar (Thuja plicata Donn). A Box and Lucas model (1959) was initially fitted to the diameter growth series for each tree, as this model is very flexible and was based on processes reflective of the metabolic processes governing tree growth. Next, a random coefficients modelling approach (i.e., parameter prediction approach) was used to modify the estimated parameters for each species using functions of tree size and stage of development, site productivity, and inter-tree competition variables, while accounting for temporal correlation within trees. Impacts of fertilization on diameter growth were estimated by including the time since fertilization as an additional variable. Since state variables that are changed as a result of thinning were already in the model, accurate results post-thinning were obtained with no changes to the model. For the combined effects of thinning and fertilization, a two-step additive approach was used, where the state variables were changed following thinning and the diameter increment was modified for fertilization using the time since fertilization variable. Results indicated that multiple treatments sustain a change in growth for a longer time period following treatment than thinning or fertilization alone.     

刍议医疗设备管理的方法与实践应用

针对现代医疗仪器设备管理的新形势,从医疗器械的购置、验收、使用、维修保养、报废及计量检测六个方面阐述了完善医疗设备管理的方法与实践,以达到医疗设备科学化管理的目的.     

湘江沉积物镉和汞质量基准的建立及其应用

沉积物质量基准是保护底栖生物免受污染物危害的保护性临界水平,可用来评估与沉积物结合的污染物的影响,并为底栖生物保护和沉积物的科学管理提供依据.分析了湘江43个采样点沉积物、上覆水、间隙水和植物中Cd和Hg含量,选取钩虾做沉积物毒理实验,利用相平衡分配法、加标毒理实验法和背景值法确定湘江沉积物Cd和Hg质量基准低值(SQC-L)分别为1.89 mg·kg-1和0.13 mg·kg-1,基准高值(SQC-H)分别为28.32 mg·kg-1和0.79 mg·kg-1.经与国内外基准值比较,并与底栖生物监测数据和植物监测数据对比分析,表明确定的基准值合理.应用该基准值评价湘江沉积物质量现状发现,湘江沉积物Cd和Hg含量低于SQC-L和高于SQC-H的采样点所占比例较低,74.4%和76.7%的采样点沉积物Cd和Hg含量在SQC-L和SQC-H之间.     

Tidal river management in the south west Ganges-Brahmaputra delta in Bangladesh: Moving towards a transdisciplinary approach?

Due to both natural and anthropogenic forces, the south west part of the Ganges-Brahmaputra coastal area is facing diverse problems such as waterlogging, salinity, and loss of biodiversity. In order to address these challenges, local people have identified ‘tidal river management (TRM)’ as a comprehensive approach for sustainably managing this part of the Ganges-Brahmaputra Basin. However, due to institutional limitations, mismanagement and social conflicts, application of the TRM approach is not straightforward. In order to identify existing implementation barriers and to effectively apply the TRM approach, a transdisciplinary approach is examined for its potential to inform the re-shaping of TRM governing values and actions. It is argued that a thorough application of a transdisciplinary framework is essential, supported by the active involvement of key agencies and local stakeholders. The proposed transdisciplinary framework can potentially be applied to TRM projects for solving waterlogging and associated problems in order to achieve greater sustainability of the area.     

海洋灾害系统研究及预测预报

海洋灾害研究是一个庞大的系统工程,其研究领域绝不能局限于海洋,应该从地球整体乃至包括整个地球的宇宙空间去认识海洋灾害的发生、发展机制、各种灾害类型在全球变化中的位置,进而最大限度地达到预测、预报、预防的目的。     

灾害系统分类初探

本文在分析目前灾害分类中存在问题的基础上,以系统方法为指导,从地球表层系统出发,论述了灾害分类应考虑的五条原则,提出了一个采用同一、多级分类标志的新的灾害的系统分类,把各种灾害类型予以按某种标志划分明确的种类,使之能适应当前和一段时期灾害类型发展的需要,希望初步解决以往灾害分类中的不足之处。     

基于景观格局演变的城市湿地景观生态规划途径

 综述城市湿地景观格局演变研究和城市湿地景观生态规划研究进展,认为城市湿地对城市可持续发展有重要意义,必须对其进行具有前瞻性的景观生态规划。分析景观过程和景观格局相互关系,结合目前城市湿地景观生态规划多流于现状的局限,提出基于景观格局演变的城市湿地景观生态规划途径,将城市湿地景观格局演变研究和城市湿地景观生态规划研究结合起来,使城市湿地景观生态规划包含时、空二维信息。该途径提出的目的是使城市湿地景观生态规划更具前瞻性,对城市可持续发展起到更大作用,并对构建城市湿地景观生态规划研究理论框架有积极意义。     

基于逻辑框架法的自然资源用途管制路径与方法研究

统一用途管制是自然资源管理的宏观核心目标。目前自然资源用途管制中仍存在事权划分不清、管制指标维度不一、管制空间重叠、监督评价不足等问题,需从管制逻辑框架和系统构成的层面进行综合研究。逻辑框架法是一种从问题出发,将宏观目标转换为具体目标和措施的有效方法。借助逻辑框架法思路,在分析自然资源用途管制基本内涵的基础上,建立自然资源用途管制的“宏观目标—具体目标—问题提出—管制措施—评价监管”的逻辑框架关系,同时在自然资源用途管制具体措施和评价监督等方面提出相关建议。     

基于变异性范围法（RVA）的河流生态流量估算

河流生态系统的生物组成、结构和功能依赖于河流水流的天然动态变化特征,即河流水文情势。变异性范围法（Range of Variability Approach,RAV）被广泛应用于评估河流生态系统是否得到维护。将RVA法的思路扩展到生态流量的计算,提出了一种简便、立足整体河流水文情势的生态流量估算方法。该方法使用均值与RVA阈值差计算了生态流量值,为维持河流健康生态系统提供支持。将该方法应用于南水北调西线一期工程中泥曲河的生态流量估算,得到引水坝址仁达处年可调径流量为6.44亿m3,与其他生态需水估算方法的结论基本一致。另提出了可支配系数反映河流流量可调用状况。南水北调西线一期工程计划从泥曲调水8亿m3·a-1,从RVA法的理念来看,该方案对仁达至朱巴河段的生态系统将构成威胁,需谨慎实施。     

Connectivity Planning to Address Climate Change

As the climate changes, human land use may impede species from tracking areas with suitable climates. Maintaining connectivity between areas of different temperatures could allow organisms to move along temperature gradients and allow species to continue to occupy the same temperature space as the climate warms. We used a coarse‐filter approach to identify broad corridors for movement between areas where human influence is low while simultaneously routing the corridors along present‐day spatial gradients of temperature. We modified a cost–distance algorithm to model these corridors and tested the model with data on current land‐use and climate patterns in the Pacific Northwest of the United States. The resulting maps identified a network of patches and corridors across which species may move as climates change. The corridors are likely to be robust to uncertainty in the magnitude and direction of future climate change because they are derived from gradients and land‐use patterns. The assumptions we applied in our model simplified the stability of temperature gradients and species responses to climate change and land use, but the model is flexible enough to be tailored to specific regions by incorporating other climate variables or movement costs. When used at appropriate resolutions, our approach may be of value to local, regional, and continental conservation initiatives seeking to promote species movements in a changing climate. Planificación de Conectividad para Atender el Cambio Climático