不同树种林分造林经济效益评价研究

以柳杉(Cryptomeria fortunei)、杉木(Cunninghamia lanceolata)和福建柏(Fokienia hodginsii)3个不同人工林分为研究对象,首先对3个林分蓄积量和出材量进行了分析讨论,接着应用净现值、内部收益率、收益成本比、土地期望值和净效益投资比等动态经济指标对3个林分的造林经济效果进行评价。结果表明,在3个林分中,杉木林分平均单株材积、蓄积量和经济材出材量最高,杉木林的NPV、IRR、LEV、B/C、N/K最大。     

马尾松人工林经营过程密度优化研究

马尾松是我国南方主要造林树种,在人工林中占有很大比例,但其林分经营过程的密度控制问题一直是未能很好解决的问题.在动态规划方法建立的马尾松人工林密度控制模型的基础上,以密度二次效应模型为基础、林分立木密度为目标函数,提出以净现值最大为标准,应用遗传算法优化马尾松人工林经营过程的间伐时间及其保留密度和主伐时间的最优组合方案.马尾松人工林经营过程的密度决策方案优化表明,遗传算法与经济评价相结合优化林分间伐时间及其保留密度和主伐时间决策组合效果很理想.马尾松人工林在地位指数10～18之间时,均以间伐两次为最优,第1次在11～12 a,第2次在16～17 a,而主伐年龄以22～25 a为最优.每一地位指数均优化得到其最优的营林措施组合方案,此时净现值最大且内部收益率大于12%.研究结果为马尾松人工林密度管理决策提供了理论参考.     

长白落叶松纸浆林培育模式

在定向培育纸浆林的基础上，综合长白落叶松纸浆林的工艺特性、林学特性和经济行性，确定出两个培育模式。实验表明：长白落叶松纸林最适宜在优良立地条件下培育。地位级越高、轮伐期越短，风险程度越小。Ｉ地位级２０００株／ｈｍ＾２密度下，轮伐期为１８ａ，内部收益率和净现值分别可达２４．１２％和５７１４．５６元／ｈｍ＾２。Ⅱ地位级２５００株／ｈｍ＾２密度下，轮伐期为２１ａ，内部收益率和净现值分别可达１９．５２％和     

多花黑麦草的应用研究进展

综述了国外对多花黑麦草(又名意大利黑麦草Lolium multiflorum)研究和利用现状,以及国内南方农区水田冬种多花黑麦草的主要生产利用模式。在国外,多花黑麦草除了被广泛应用于肉牛和奶牛的生产以外,还被应用于对磷污染土壤的生物修复。在国内,冬种黑麦草技术经过近20年的推广和应用,已经成为华南地区一种典型的生态农业种植模式,并发展形成了"稻-草-奶牛"、"稻-草-肉鹅"、"稻-草-猪"等一系列的黑麦草利用模式。探讨了生产黑麦草饲养草食畜禽在华南地区进一步推广应用的主要限制因子,以及今后需要重点研究的方向。     

意大利黑麦草应用于肉兔养殖的研究

试验的目的是探讨以意大利黑麦草和野生杂草作为青饲料代替部分精饲料饲喂肉兔对其增重、屠宰性状及兔肉品质的影响。经过40 d的分组饲喂试验发现,利用野生杂草或意大利黑麦草代替10%～50%的精饲料饲喂肉兔对其增重效果无显著影响（P〉0.05）;青饲料的引入在一定程度上增加了肉兔的屠宰率,还明显降低了兔肉中的脂肪含量,改善了兔肉的品质。     

质量提升型农业科研成果经济评价方法在专养雄蚕技术中的应用

应用农业科研投资动态评价系统DREAM,对蚕业界的重大高新技术--专养雄蚕技术进行了经济评价,并探讨了质量提升型农业科研成果的评价方法。研究结果表明：专养雄蚕技术的经济收益明显,投资回报显著,单产水平的变动对收益的影响要比蚕种费用、品种使用寿命和茧价差等因素的同幅变动更敏感;通过市场需求曲线的移动近似反映质量提高对经济收益的影响,可以更客观、全面的评价专养雄蚕技术的经济收益。     

Profitable small-scale sprinkle irrigation in Guatemala

A technically successful, small program of villiage level sprinkle irrigation system installations in Guatemala was studied to ascertain its apparent economic benefits. A simple variant of high technology irrigation (pressurized demand systems) combines otherwise under-used water supply sources with idle, small plots in steep terrain. When the program managers stayed within design boundaries or parameters, as originally conceived, economic benefits to villagers were judged to be positive or very positive. Therefore, there are identifiable situations where investment as well as maintenance costs can be kept under control and thereby make a genuine contribution to growth of the national economy.     

桉树与厚荚相思混交林经济效益分析

采用国际惯用的财务分析方法,对桉树与相思混交林进行了经济效益分析,结果表明∶尾叶桉（无性系ＭＬＡ）与厚荚相思行间混交纯利润最高达２１８８３．６２元／ｈｍ２,比带状混交提高４２．１％,比尾叶桉纯林提高３３．５％;行间混交、带状混交和纯林内部收益率分别为５１．９％,４９．４％和５１．６％;投资回收期行间混交为５．１年,其余为５．２年。雷林１号桉（实生苗）与厚荚相思混交,行间混交林纯利润最高,达１２００１．５８元／ｈｍ２,比带状混交林提高４６．４％,比纯林提高４９．３％;行间混交、带状混交、纯林的内部收益率分别为３９．４％,３８．２％和３７．７％;投资回收期均为５．３年。     

Financial analysis of shaded cocoa in Ghana

The cultivation of cocoa has been an important driver of tropical deforestation globally. Efforts to reverse this trend are focusing on the reintroduction of shade trees to cocoa plantations. Shade trees are valuable in enhancing biophysical conditions on cocoa (Theobroma cacao) fields and contribute to biodiversity and product diversification for smallholder producers. Participatory trials of cocoa agroforests planted with indigenous shade tree species were undertaken with farmers in the Atwima District of the Ashanti Region of Ghana, to increase tree volume on cocoa fields while improving rural livelihoods and enhancing environmental sustainability. An ex ante financial analysis of the technology was undertaken to assess its economic viability. Input–output data were collected from farmer experiments over three seasons and supplemented with data from traditional cocoa fields of varying rotation ages, and secondary data on production in later years of an eighty-year cocoa rotation. A discounted cash flow analysis was carried out to estimate the benefit-cost (B/C) ratio, net present value (NPV), internal rate of return (IRR) and land expectation value (LEV) as well as the sensitivity to a 20% decline in cocoa prices and additional chemical costs for various shade scenarios at a 10% discount rate. It was observed that cocoa production is, in general, profitable. The change from the traditional system to one with hybrid cocoa raised the IRR from 31% to 57% with planted shade and 67% without, although extra agrochemical costs would tend to reduce the profitability of unshaded hybrid cocoa in particular. The age of maximum LEV for the various scenarios suggests that the optimum economic rotation for the hybrid cocoa is between 18 and 29 years, much less than the traditional system.     

浙江省家蚕新品种选育科研投资收益的定量评价

引用农业科研投资收益计量模型,对浙江省1981-2005年家蚕新品种选育的科研投资收益进行定量评价。结果表明,浙江省在此期间对家蚕新品种选育研究投资所获得的经济收益达4 164.8万元(以1981年为基期),投资的内部收益率为35.09%,远高于全社会投资项目基准收益率8%,总体投资收益十分显著。然而在具体的投资收益流中,由于2000年以后没有选育出经济性状具有突破性改进的新品种在生产上推广应用,因而其投资收益逐年大幅下降,从2000年的197.02万元下降到2005年的64.83万元。根据评价结果,提出了加大科研投资力度、加快育种材料和育种手段与方法的创新、深化家蚕育种体制改革和激发育种人员积极性等政策性建议。