Analysis of Spatial and Temporal Evolution of Vegetation Cover in the Spanish Central Pyrenees: Role of Human Management

A vegetation cover increase has been identified at global scales using satellite images and vegetation indices. This fact is usually explained by global climatic change processes such as CO₂ and temperature increases. Nevertheless, although these causes can be important, the role of socioeconomic transformations must be considered in some places, since in several areas of Northern Hemisphere an important change in management practices has been detected. Rural depopulation and land abandonment have reactivated the natural vegetation regeneration processes. This work analyses the vegetation evolution in the central Spanish Pyrenees from 1982 to 2000. The analysis has been done by using calibrated-NDVI temporal series from NOAA-AVHRR images. A positive and significant trend in NDVI data has been identified from 1982 to 2000 coinciding with a temperature increase in the study area. However, the spatial differences in magnitude and the sign of NDVI trends are significant. The role of land management changes in the 20th century is considered as a hypothesis to explain the spatial differences in NDVI trends. The role of land-cover and human land-uses on this process has been analyzed. The highest increment of NDVI is detected in lands affected by abandonment and human extensification. The importance of management changes in vegetation growth is discussed, and we indicate that although climate has great importance in vegetal evolution, land-management changes can not be neglected in our study area.     

Critical Evaluation of How the Rosgen Classification and Associated “Natural Channel Design” Methods Fail to Integrate and Quantify Fluvial Processes and Channel Response1

Abstract: Over the past 10 years the Rosgen classification system and its associated methods of “natural channel design” have become synonymous to some with the term “stream restoration” and the science of fluvial geomorphology. Since the mid 1990s, this classification approach has become widely adopted by governmental agencies, particularly those funding restoration projects. The purposes of this article are to present a critical review, highlight inconsistencies and identify technical problems of Rosgen’s “natural channel design” approach to stream restoration. This paper’s primary thesis is that alluvial streams are open systems that adjust to altered inputs of energy and materials, and that a form‐based system largely ignores this critical component. Problems with the use of the classification are encountered with identifying bankfull dimensions, particularly in incising channels and with the mixing of bed and bank sediment into a single population. Its use for engineering design and restoration may be flawed by ignoring some processes governed by force and resistance, and the imbalance between sediment supply and transporting power in unstable systems. An example of how C5 channels composed of different bank sediments adjust differently and to different equilibrium morphologies in response to an identical disturbance is shown. This contradicts the fundamental underpinning of “natural channel design” and the “reference‐reach approach.” The Rosgen classification is probably best applied as a communication tool to describe channel form but, in combination with “natural channel design” techniques, are not diagnostic of how to mitigate channel instability or predict equilibrium morphologies. For this, physically based, mechanistic approaches that rely on quantifying the driving and resisting forces that control active processes and ultimate channel morphology are better suited as the physics of erosion, transport, and deposition are the same regardless of the hydro‐physiographic province or stream type because of the uniformity of physical laws.     

纳米Al13的分离方法及混凝效果动态过程的研究

以相同Al13含量、不同浓度的PAC为原料,利用乙醇-丙酮混合溶剂法、SO4^2-／Ba^2 沉淀置换法以及柱层析法分离提纯纳米Al13形态,同时利用Al-Ferron逐时络合比色法、^27Al-NMR等多种现代分析手段进行分析鉴定,比较其分离效果,并采用烧杯实验法和透光率脉动检测技术对Al13形态以及PAC、AlCl3的絮凝效果及絮凝过程中絮集物形成和增长的变化差异作了对比性研究．实验结果表明,乙醇．丙酮混合溶剂法对Al13分离纯化效果最好,分离所得Al13平均粒径大,聚合程度高．柱层析法受柱体积的影响只对低浓度的PAC有较好的分离效果;SO4^2-／Ba^2 沉淀置换法虽具有较好的分离效果,但分离过程有其他杂质离子的加入,影响到产品品质．混凝效果和动态实验结果表明,Al13形态是在絮凝过程中起电中和作用的主要形态,具有较强的除浊及脱色能力,在混凝过程中当絮体受到剪切力的破坏时Al13形态比PAC和AlCl3具有更强重新絮凝的能力．     

日本森林管理的最新发展——以日本神奈川县林业政策过程为例

为了追求更好的森林管理效果，对相关森林政策的实施，不是仅仅停留在传统的狭义的行政管理部门上，同时还要涉厦到经营者、市民以及当地居民等利益相关者。使他们都要以相互协调的方式参与到森林管理当中来。它是建立在一定的森林价值观基础上，基于科学原理井突破以往的技术层面而对森林进行的一系列更加合理的管理措施体系。本文以日本神奈川县的林业政策形成过程为例对森林治理问题进行了讨论。     

理想弹塑性材料弯曲回弹分析及回弹弯矩计算

分析了弯曲回弹应力应变变化过程 ,推导了矩形截面杆回弹弯矩、回弹曲率的计算公式 (1 4 )、(1 1 ) ;发现经典纯弯曲理论确定回弹弯矩的方法与公式 (1 4 )比较存在较大理论误差     

A methodology for the life cycle and sustainability analysis of manufacturing processes

Life cycle assessment is emerging as a powerful tool in the evaluation of the environmental impact of manufacturing processes. This paper describes a general methodology for the life cycle analysis of manufacturing processes taking into account the flexibility and decision-making potential of knowledge base systems. Emphasis is placed on on-site waste minimisation and associated sustainability characteristics in relation to environmental impact assessment and process improvement. The ensuing software model is applied with some success to an initial study of pulp and paper manufacture.     

海洋碳的源与汇

通过对海洋碳源汇最近研究成果的分析,剖析了海洋碳源汇的内涵,提出了“表观碳源汇”与“实际碳源汇”的概念,对海洋碳源汇不确定性的原因进行分析,提出碳参数测定不淮确与其关键生物地球化学过程不清楚是其根本原因,继而提出了海洋碳源汇研究应特别注重陆架边缘海碳循环过程研究,提高碳参数测定的淮确性和应深入研究控制碳循环关键的海洋生物地球化学过程是其研究关键。     

Separating method and dynamic processes of Nano-Al13

In order to investigate the characteristics of pure Nano-Al₁₃, Nano-Al₁₃ was separated and purified from a series of poly-aluminum chloride (PAC) solutions which had the same Al₁₃ percentage but different total Al concentrations, by using column chromatography, ethanol-acetone resolving and SO²⁻ ₄/Ba²⁺ displacement. The Al₁₃ species yield was characterized by Al-ferron timed complexation spectrophotometry and ²⁷Al-NMR (nuclear magnetic resonance). The coagulation efficiency of Nano-Al₁₃, PAC and AlCl₃ in synthetic water was also investigated by Jar tests. The dynamic process and aggregation state of kaolin suspensions coagulating with Nano-Al₁₃, PAC and AlCl₃ were similarly investigated using a photometric dispersion analyzer 2000 (PDA2000). The experimental results indicated that the ethanol-acetone resolving method was simple and could separate the PAC solution at different concentrations, while column chromatography could separate PAC solutions at low concentrations. The SO₄ ²⁻/Ba²⁺ displacement method could separate PAC solutions at high concentrations. However, extra inorganic cation and anion could be added in the solution during separation. The coagulation efficiency and dynamic experimental results showed that Nano-Al₁₃ with high positive-charged species was effective in removing turbidity and color. The dynamic process results showed that Nano-Al₁₃ also had the best recovery capability after shearing compared with PAC and AlCl₃ because the Nano-Al₁₃ conformation is more effective in charge neutralization. Translated from Acta Scientiae Circumstantiae, 2005, 25(6): 767–772 [译自: 环境科学学报]