对循环经济模式的思考

循环经济是一种资源闭环利用型经济。发展循环经济是缓解资源约事矛盾的根本出路，是从根本上减轻环境污染的有效途径，是提高经济效益的重要措施，是应对新贸易保护主义的迫切需要，是以人为本，实现可持续发展的本质要求。     

林权改革对集体林可持续经营的影响——以辽宁丹东为例

在创建集体林可持续经营评价体系基础上，采取定性要素赋值、数据标准化、层次分析法求权重等方法，计算出综合评价指标指数。再根据收集的数据，通过改革前后均值的显著性分析以及改革后综合评价指数、相关要素变化趋势分析，得出如下结果和结论：①林权改革对集体林可持续经营具有明显的促进作用，集体林可持续经营指数改革后比改革前上升了0．0454；②林权改革对集体林生态、经济、社会三个子系统可持续的影响程度有明显的差异，对集体林经济可持续影响最为显著，对集体林社会可持续的影响为其次，对集体林生态可持续的影响最小；③林权改革对集体林可持续经营的促进作用，随着时间的推移，越来越明显。     

云南山地民族刀耕火种生态学定位与山地森林资源可持续利用

通过对云南省永仁县直苴村刀耕火种农业的景观生态学研究，发现在一个相当长的时期内，正是刀耕火种使山地民族社区人和森林都实现了自身的可持续发展，并同时实现了二者的和谐发展，但随着人口、资源和环境的变化，刀耕火种存在的条件不断消失，刀耕火种也必然消失，这说明任何一种物质生产方式都有其时空尺度的局限性，都必须以一定的环境条件和资源条件为基础，以区域内生态系统的健康、持续性发展为前提，     

Oil Palm — Achievements and Potential

Abstract

Cultivation of the oil palm (Elaeis guineensis Jacq.) has expanded tremendously in recent years such that it is now second only to soybean as a major source of the world supply of oils and fats. Presently, Southeast Asia is the dominant region of production with Malaysia being the leading producer and exporter of palm oil. This paper reviews the various factors that have led to oil palm occupying its present position, including biological, technical, managerial, environmental, and socio-political aspects. Biological features recognised as critical to the high productivity of the crop are examined. These include its perennial and evergreen nature (giving a continuous year-round canopy cover intercepting a high proportion of incoming radiation), the year-round production of fruit bunches and the high partition of total assimilates into harvested product. Scientific and managerial aspects contributing to the success of the crop include the significant genetic improvements and production of high quality planting materials, the development and application of finely-tuned agronomic practices, the appropriate scale and efficient organisation of oil palm plantations and the continuous R&D and good infra-structural support provided in the main producing countries. The programmes of crop improvement through the utilisation of traditional breeding and selection methods, the development and benefits of vegetative propagation techniques using tissue culture and ongoing efforts to apply molecular and genetic engineering techniques to improve and modify oil composition, are reviewed. Finally, the nutritional qualities of palm oil as a healthy component of diet are briefly described.     

Population dynamics of tree species in southern Quebec,Canada: 1970–2005

Over the last few decades, several phenomena contributed to modify the structure and composition of the eastern North American forests. Along with forest management, disturbances such as insect defoliation, global environmental changes, acid deposition, and rising atmospheric CO₂ concentrations, have been identified as phenomena that could affect forest structure and composition. Currently, there is very little quantitative information on the resulting effect of multiple disturbances on the main parameters of forest dynamics (growth, mortality, and recruitment). Using available data from the Quebec permanent sample plots network, we analyzed the ecological response of tree species populations to the combined effect of contemporary global environmental changes, disturbance regimes, and forest management practices over the last 30 years in southern Quebec. The results indicate that the main parameters of forest dynamics changed considerably over the last three decades. The last spruce budworm outbreak initiated a successional change in coniferous stands. The basal area of Abies balsamea and Picea glauca, the most abundant coniferous species, decreased by 29.7%, while pioneer species abundance increased. For late successional deciduous species, observed changes in forest dynamics appear to be mainly associated with global environmental changes rather than with natural disturbances or forest harvesting. The results indicate that inferring responses of tree population dynamics to global environmental changes can be very complex or even misleading considering the confounding effects of other disturbance agents. The results also suggest that the ecosystem-based management approach promoted by forest ecologists, aimed at maintaining landscape stand composition and structures similar to those characterizing natural environments, will not be easily achieved. Forest ecosystems are highly dynamic and disturbances other than tree harvesting appear to have been the major factors affecting their pattern of change over the last three decades. Forest managers should consider adaptive management approaches that will consider the contemporary evolution of forest ecosystems in a changing environment.     

可持续发展理论的数学分析

运用Logistic曲线分析了系统的一般发展过程，根据其发展速度将发展过程分为起步、成长、成熟和饱和4个时期，并结合可持续发展的内涵与实质，提出了可持续发展理论的数学依据和数学实质。剖析了可持续发展实质上是在一定的约束条件下求某个泛函的最值问题     

弋阳县森林资源可持续发展的探讨

林业是我国国民经济的重要组成部分,笔者对弋阳县森林资源现状进行多方面的分析和评价,提出森林资源可持续发展对策。     

山区生态示范区建设的探索与实践——以四川省洪雅县为例

农村生态环境恶化、经济发展滞后一直是困扰山区可持续发展的难题。以洪雅县生态示范区为例,指出山区开展生态示范区建设存在的问题,结合山区的特点探讨了在山区建设生态示范区的途径。     

全球重要农业文化遗产-青田县稻鱼共生系统保护与可持续发展之思考

浙江青田县龙现村稻鱼共生系统作为全球重要农业文化遗产,其保护和可持续发展的问题现已引起了社会的关注。在调查研究的基础上,分析了青田县龙现村稻鱼共生系统得以长期延续的历史渊源、自然环境条件和人文社会因素等原因。同时,指出了这种稻鱼共生模式在当今市场经济条件下面临的挑战与问题,如市场问题、产业化问题、旅游业发展导致的环境问题、农业文化消失问题等。最后提出了一系列对策措施,如加强全村生态规划,建立稻鱼共生自然保护区,打造稻鱼生产品牌,适度发展农业生态旅游,建立多方参与机制等措施。     

有机肥产业化与我国农业的持续发展

农业的持续发展必须建立在土地肥力持续发展的基础上。长期单施偏施化肥和有机肥投入的减少,是造成土壤肥力下降、环境污染和农产品品质降低的重要原因。有机肥的产业化利用是解决环境污染问题,促进有机肥增施、提高农产品品质的新路子,也是农业持续发展的需要。本文提出了实施有机肥产业化的建议,以促进中国农业的持续发展。