AVVIRK-2000: A Large-scale Forestry Scenario Model for Long-term Investment,Income and Harvest Analyses     

《Scandinavian Journal of Forest Research》2012,27(4):472-482

  相似文献   

Non-industrial Private Forest Owners' Risk Preferences     

《Scandinavian Journal of Forest Research》2012,27(6):651-660

A set of hypotheses was formulated on the basis of available knowledge about non-industrial private forest (NIPF) owners' risk preferences. The empirical material used for testing the hypotheses was gathered in telephone interviews with 130 randomly selected NIPF owners. The results confirm that direct economic risks such as price and cost changes are seen by this group as much more important than indirect economic risks such as biological damage. The forest owners regarded forest holdings as a safer investment than stocks or bank savings. The results on risk attitudes were ambiguous. However, when larger amounts of money were at stake, the forest owners could be considered risk averters and a decrease in absolute and relative risk aversion could be confirmed.  相似文献   

淡水养殖鱼类主要细菌性传染病快速诊断的研究——鱼病诊断箱的应用试验   总被引：2，自引：0，他引：2  

马家好  杨振国 《黑龙江畜牧兽医》1999,(8):4-5

应用以葡萄球菌Ａ蛋白协同凝集试验（ＳＰＡ－ＣＯＡ）为主要检测手段的鱼病诊断箱，于１９９５￣１９９７年在吉林，辽宁等７省进行现场检测试验。结果，６１个渔场１１个品种的５１６尾病鱼有菌生长的２８５尾，经ＳＰＡ－ＣＯＡ鉴定阳性数为２３９尾，占有菌生长的８３．８６％，１２个渔场５个品种１２１６尾假定健康鱼有菌生长的为２８尾，经ＳＰＡ－ＣＯＡ鉴定阳性数为２２尾，占有菌生长的７８．５７％，认为本诊断箱适用于基  相似文献   

冷季提高猪舍环境温度方式之效益分析     

付仕伦  谢宝元 《勤云标准版测试》2007,(8)

寻找温度与猪的生长之间关系的有关数据,得出在临界温度下,育成猪的生长随温度变化而变化的规律;总结了我国各地现有的各种养猪舍建筑形式;分析、探索了冷季提高、维持猪舍环境温度的各种方式;通过估算其成本和它们各自能带来的经济效益经行经济性比较得出全封闭式暖床保温。  相似文献   

不同紫花苜蓿品种引种试验研究     

姜义宝杨玉荣  王成章陈文 《勤云标准版测试》2007,(2)

引进了国外8个苜蓿品种,在2003年至2005年对其产量、株高、营养价值、越冬率、越夏性、抗倒伏和经济效益等方面进行了比较,结果表明这8个苜蓿品种在郑州地区均表现了良好的适应性,其中WL232和猎人河是推广的首选品种。  相似文献   

麦积山风景名胜区旅游环境容量分析     

郭玉刚  窦立宝  郑舒绮 《安徽农业科学》2009,35(19):9262-9263

从麦积山风景名胜区旅游者的旅游行为及麦积山风景名胜区自身的承受能力出发，以实地调查资料为依据，运用多种统计方法，测定麦积山风景名胜区的空间环境容量、经济容量、心理容量，并结合实际情况对计算结果进行误差修正，最终得出麦积山风景名胜区的合理空间容量及进入景区的速度。根据麦积山风景名胜区实际容纳游客人数与其合理空间容量的对比分析，发现麦积山风景名胜区全年空间容量处于未饱和状态。  相似文献   

多年生香豌豆的形态特征及经济性状研究     

文斌  王力  李凤霞  宁新红  师红玲 《青海草业》2004,13(2):2-6

多年生香豌豆是黄河水利委员会天水水土保持试验站引进的国外优良牧草品种。试验针对多年生香豌豆的形态特征、经济性状及其生长状况进行了试验研究，发现多年生香豌豆无论是作为牧草还是水土保持物种都具有极高的经济价值和生态价值，适于黄土高原及其与青藏高原结合部的气候条件下生长，对于解决上述地区牧草品种单一，植被退化及农村饲料短缺等实际问题，改善西北地区生态环境，促进农业产业结构调整，实现区域生态经济可持续发展等都具有重要的意义。  相似文献   

Weed control in conservation agriculture systems of Zimbabwe: Identifying economical best strategies     

《Crop Protection》2013

Weed management under conservation agriculture (CA), especially when manually controlled is one of the major setbacks for the widespread adoption of CA in southern Africa. This study was conducted at three on-station and three on-farm sites: CIMMYT-Harare, Domboshawa Training Centre and Henderson Research Station (on-station sites), Hereford farm, Madziva communal area and Shamva communal area (on-farm sites). The evaluation focused on the effect of initial herbicide application and succeeding manual weeding whenever weeds were 10 cm tall or 10 cm in length for grasses with stoloniferous–rhizomatous growth habit. Weeds counts, weeding time and grain yields were collected at all on-station sites. At the on-farm sites, weed counts were done before weeding and a number of farmers were timed during weeding. The results showed that herbicides use reduced the weed density and time taken on weeding at all sites. Combining herbicides e.g. atrazine, glyphosate and metalachlor had the lowest weed density and weeding time at all sites. However, the treatments had no effect on maize grain yields suggesting that appropriate and timely manual weeding reduced crop/weed competition. Herbicides treatments had higher input costs than manual weeding due to the additional cost of herbicide but the treatment with manual weeding only had more overall labour days compared to the mixture of three herbicides. In order to achieve economic benefits, smallholder farmers may use the time for value addition e.g. expand cropped land area, use time for value addition, or sell new products on the market. Herbicides use reduces the manual labour needed to control weeds and minimise total crop failure due to untimely weeding hence, herbicides are an important but not the only weed control option under CA systems in Zimbabwe.  相似文献   

鱼类与水环境间相互关系的研究回顾和设想   总被引：15，自引：1，他引：14  

刘恩生 《水产学报》2007,31(3):391-399

鱼类是湖泊生态系统中较高级的消费者，通过上行效应和下行效应与环境间存在着紧密的相互作用关系。湖泊环境等理化因子的变化通过上行效应改变鱼类群落结构和数量，而鱼类群落结构的变化通过营养级联和下行效应对水体的理化特征以及其它生物的组成、分布、丰度、生物量等水生态系统结构与功能的许多方面产生影响。[第一段]  相似文献   

高速公路的建设对沿线经济发展影响的研究——以赣粤高速公路江西段为例     

樊培军 《安徽农业科学》2007,35(5):1288-1289

以赣粤高速公路建设对江西省经济发展影响为例,阐明了高速公路对沿线经济发展的深刻影响.分析了高速公路建设对江西省区位优势改变、产业结构和产业布局的影响,从而提出了构建沿线经济带的设想.  相似文献