An evaluation of the pesera soil erosion model and its application to a case study in Zakynthos, Greece

Abstract. The Pan‐European Soil Erosion Risk Assessment (pesera ) model was evaluated using existing soil erosion data collected under various types of climate, vegetation, landscape and soil conditions. The data used represent a variety of typical Mediterranean land uses such as winter wheat, vines, olives and bare, stony land prevailing in hilly areas. Using this data, the model was calibrated for sediment transport by overland flow and results compared to measured soil erosion values from runoff plots and a watershed on a monthly basis. The performance of the model was assessed statistically, showing that it can be satisfactorily used for predicting soil erosion rates under the conditions included in the study. The overall model estimate including all the available experimental data was 0.69 t ha^?1 yr^?1 with a maximum error of 1.49 t ha^?1 yr^?1. After validation, the model was applied to a small watershed (60 ha) of great ecological importance for the sea turtle Caretta caretta. For this purpose, soil and vegetation maps were compiled from all the necessary data for applying the model. The model was run for three years using daily data from an existing nearby meteorological station. The predicted and measured soil erosion rates for a 7‐month period were 0.31 t and 0.18 t, respectively. Application of the model to each mapping unit showed the over‐riding importance of land use for sediment generation under the given climatic conditions. Bare land, occupying 5.5% of the watershed area, generated up to 69% of the total sediments estimated for the watershed. It is concluded that the pesera model can be used as a regional diagnostic tool under a range of soil, topographic and climatic conditions for identifying the best land use type and vegetation cover to protect hilly areas from soil erosion. The calculated overall root mean square error for the model is 0.06 t ha^?1 yr^?1, compared to a soil erosion rate of 0.04 t ha^?1 yr^?1, which can be tolerated for protecting the area for the sea turtle.     

对耕地保护的认识和思考

耕地保护的落实关系到我国的粮食安全,经济安全,生态安全。为了能够对耕地保护有一个更好的认识,文章从耕地保护的提出、目标、意义、主体、策略等方面来再次的认识耕地保护,耕地保护需要政府、农民以及其他非耕地使用者的共同参与,并提出了进一步建立和完善耕地保护的经济补偿机制,充分调动农民对保护耕地的积极性,明确耕地产权的耕地保护策略。     

陕西省生猪规模养殖成本调查分析

通过对陕西省生猪规模养殖场户生产数据的分析,研究生猪规模养殖成本的构成,对控制生猪养殖成本提供依据,从成本投入的角度分析陕西适宜的生猪养殖规模,揭示规模化和专业化是生猪养殖的发展方向,提出推进规模化养殖的建议.     

Privatization of Veterinary Services in Developing Countries: A Review

Increasing fiscal constraints on the government, a lackadaisical performance by public sector animal health and breeding services and pressure from donor partners have prompted the governments of various developing countries to rethink the role of the public sector in the provision of veterinary services. Various countries have started to implement, or have already implemented, privatization of some veterinary services. The results are mixed. It is established that private provision alone is not optimal, and a blend of private and public sector veterinary services is required to utilize the virtues of both.The privatization process has also begun in India. Certain state governments in India are pursuing a cost recovery approach and are encouraging private practitioners to cope with the financial constraints and to deliver broad and effective animal health and breeding services. This paper considers the global aspects of the privatization of veterinary services as well as the scenario in India, so as to gain an insight into the very complex and debatable issue of privatization of veterinary services.     

大通县长宁镇退耕还林(草)后续产业探讨

分析了退耕还林(草)现状,结果表明,退耕还林草的后续产业发展不足,提出发展退耕还林草的后续产业对策。     

基于[火用]方法的空调冷热源系统优化决策

结合方法和热经济学原理建立了空调冷热源系统的分析模型,阐述了产品成本是评价冷热源系统方案优劣的关键因素.采用多目标模糊决策方法,综合考虑了单位产品成本、初投资、技术先进性、安装面积、运行安全可靠性、维护管理难易程度和环保性等多种影响因素,基于方法的冷热源优化决策算法.通过应用实例,说明了此新优化决策算法相比工程中传统决策方法,可靠性更高,使各决策方案间优劣区分度更加明显。     

广西城市土地综合承载力时空差异分析

城市土地综合承载力能够反映城市土地承载的资源水平、经济规模、社会发展、环境压力等.从资源、经济、社会、环境等4个方面,构建城市土地综合承载力评价指标体系,采用主成分分析法、聚类分析法对广西全区及其14个市2005-2014年城市土地综合承载力进行评价,分析其时空特征及驱动因素,为提高城市土地综合承载力提供参考.结果表明,2005-2014年广西城市土地综合承载力整体呈上升趋势;2005-2014年广西城市土地综合承载力空间分布差异显著,柳州、桂林、南宁等市属于高承载区,北海、玉林、梧州等市属于较高承载区,其他市承载力随时间变化处于不同等级;经济发达程度是影响城市土地综合承载力的重要因素,但并不能直接代表城市土地综合承载力水平.     

一次浸提技术对提高速溶绿茶品质的作用

为了提高速溶绿茶品质,改善产品的溶解性能,研究了不同浸提次数对速溶绿茶主要滋味成分含量、茶汤色差及感官品质的影响．结果表明：第一次浸提固形物的得率是第二次浸提的4—5倍,第一次浸提产品的茶汤色泽、感官品质,特别是溶解性方面均明显优于第二次浸提的．采用一次浸提技术可提高生产效率,降低生产成本,并获得优质速溶绿茶产品．     

层次分析法在退耕还林生态效益评价指标体系建立中的应用

退耕还林生态效益评价是当今研究的热点问题之一,构建评价指标是评价工作的前提和基础。笔者根据退耕还林生态效益的主要影响因子,在设定多层次指标体系的基础上,采用AHP法计算各指标权重,以确定影响退耕还林生态效益的主要因素。结果表明:退耕还林生态效益指标体系19个指标中,所占比重最大的5个指标依次为:土壤的侵蚀模数、地表径流量、土壤容重、枯落物层厚度和林草的覆盖率等。     

The role of agroforestry in the farming systems in Rwanda with special reference to the Bugesera-Gisaka-Migongo (BGM) region

The Rwandan farmers, faced with a perpetual land shortage, have evolved certain intensive systems of organic agriculture. These systems, particularly the homestead (compound) farming, involve the combination of food, fodder and tree crops. to a certain extent these systems can satisfy the multiple needs of the subsistence farmers living under several risks and constraints. However, they cannot cope with the expanding food demand of the rapidly increasing population. Some multipurpose, low-input technologies and agroforestry approaches have been designed to improve the productivity of these traditional systems; these include inter/mixed cropping systems and rotations, alley cropping with leguminous trees and shrubs, use of planted fallow, planting tree legumes on anti-erosive lines, mixed farming,community forestry and woodlots, and tree planting on farm/field boundaries. The essential aspects of these technologies are briefly discussed.ISAR-IITA FSR PROJECT, B.P. 629, Kigali RwandaISAR-Swiss Intercooperation, c/o Forestry Department, B.P. 617, Butare, Rwanda