华北农业高产粮区地下水硝酸盐污染环境价值损失评估技术研究——以山东省桓台县为例

应用人力资本法、防护支出法和支付意愿调查法评估了华北高产粮区桓台县地下水农业面源硝酸盐污染的环境经济损失,并分析了不同评估技术对农业面源硝酸盐污染地下水环境价值损失评估的适用性,其适用性优先序为防护支出法的深井工程法>脱硝工程法≥人力资本法>支付意愿调查法。2 0 0 2年该县由农业地下水硝酸盐污染造成的年环境价值损失约为880万元(86 0 .8～1170 .1万元/浕) ,占当年农业总产值的1.1%～1.5 %。     

Water-table modelling to estimate irrigation losses: application to the Lower Durance, France

The consumption of water by irrigation in agriculture is very large and thus the effects of the management of irrigation systems on aquifers are very important. The basis of this preliminary study into the reduction of this consumption is to improve our understanding of the losses resulting from water transport and deep seepage inside the irrigated areas of cultivation (parcels) at the regional level (100 km) by studying water-table variations with reference to anthropogenic contributions. The use of a hydrodynamic model that incorporates adjustment of the quantity of irrigation water by a reduction coefficient enables actual water-table behaviour to be simulated. Losses can thus be deduced from the quantity of irrigation water flowing into the irrigation system and from hydrometeorological parameters.

Application of the technique in the Lower Durance (France) indicates that, in this region, 53% of the water remains in the irrigation network and 19% is lost by deep seepage, leaving only 28% of the water supplied for use by plants.     

农地承包经营权收益权的缺失及完善对策

分析了农地承包经营权收益权缺失的主要表现,体现在现行立法在农地征收中未对农地承包经营权设立单独的补偿项目;在征地补偿中缺乏对农地承包经营权预期收益和间接收益损失的补偿;对流转权利的不合理限制妨碍了农地承包经营权流转收益的实现。提出了完善农地承包经营权收益权的对策：应当在农地征收中设立农地承包经营权单独补偿项目;在征收补偿中包括对农地承包经营权预期收益和间接收益损失的补偿;取消对农地承包经营权流转权利的不合理限制。     

Economic implications of a virus prevention program in deciduous tree fruits in the US

Viral diseases in fruit trees present a potential danger that could injure the fruit industry, the planting stock industry (nurseries), and consumers in the United States and abroad. Currently, the US has a virus protection program (VPP) that serves to minimize the spread of viral diseases. This paper reports research estimating the economic consequences of the loss of the program on nurseries, growers and consumers. The potential economic losses are a measure of the value of the existing program. The paper focuses on apples, sweet cherries, and Clingstone peaches.

The effects of a loss of a VPP on nurseries would include direct and indirect losses from viral diseases in the form of lower quantity and quality of planting stocks. Fruit growers would be affected by reduced plant growth and fruit yield. Consumers would be affected by higher prices and reduced quantity of fruit.

We measured benefits of the virus prevention program as changes in consumer and producer surpluses. Empirical estimates were made using the method of avoided losses. Benefit estimates to three economic sectors—nurseries (avoided change in producer surplus), producers (avoided change in consumer and producer surpluses), and consumers (avoided change in consumer surplus)—were calculated. Total benefits for all three sectors were approximately $227.4 million a year, or more than 420 times the cost of the program. Our analysis utilizes a method that might be used to evaluate other programs that prevent the introduction of plant diseases.     

MAGPIE: A modelling framework for evaluating nitrate losses at national and catchment scales

Abstract. A national agri-environmental database and nitrate modelling system has been developed to support the UK government's nitrate policy development. The framework, 'MAGPIE', consists of a database and models linked within a Geographical Information System and provides a user interface which allows detailed spatial and statistical investigation of the current state (data and model output) and the impact of changes in conditions or agricultural practice. Data on crops and livestock numbers taken from the annual agricultural census were modified in relation to land cover data derived from remote sensing, and other sources. These data and data on climate, soils and altitude were interpolated to a 1 km grid. The models of nitrate loss were adapted to work with this data set while retaining as far as possible the salient features of the more detailed models and data from which they were derived. The resulting Policy Decision Support System was found to give estimates of mean annual flow and nitrate load for agricultural catchments which matched measured data closely. The system has contributed to work on a number of policy issues both within the UK and in the UK's contribution to international policy development on pollution derived from agriculture.     

The use of porous ceramic cup water samplers to measure solute leaching on chalk soils

Abstract. This paper reports results from a four year study to investigate the suitability of porous ceramic cups to measure solute leaching on shallow chalk soils. Measurements were carried out in one field following surface applications of nitrate and bromide tracers and in two fields after only bromide was applied. Soil water samples were collected from porous cups at 30,60 and 90cm depth after every 25 mm of drainage, and soil samples from 0–30, 30–60 and 60–90 cm were collected monthly eachwinter. Soil matric suctions andvolumetric moisture content were measured in one winter. Leaching losses, measured with ceramic cups were compared with those measured by soil analysis. Porous cups installed in chalk at 60 and 90 cm depth were only able to collect samples regularly when soil matric suctions were less than 15 kPa. Water held at such low suctions is likely to move quickly through relatively large fissures in the chalk. The slow rate of equilibration between solute concentrations in water moving in macrofissures and those in water moving through micropores of the chalk matrix, means that porous cups may not provide good estimates of leaching losses if they are installed in chalk rock.     

Patrolling with Livestock Guard Dogs: A Potential Method to Reduce Predation on Sheep

Patrolling with livestock guard dogs in mountain rangelands in Norway was evaluated as a method to prevent predation in areas with widely dispersed sheep. In contrast to guard dogs, patrol dogs are more socially bonded to people and follow a range inspector around. Range inspection was performed in 5 h bouts during three nights per week. The method was tested during three summer seasons in a total of eight sheep flocks grazing in three different mountain ranges. In total, three inspectors and four dogs were involved. Significant reductions in the number of sheep lost were achieved in one of the study areas. Lack of significance in the other areas was mainly due to the size of the area and qualities of the dogs: the range to be patrolled by one man dog unit should not exceed 10-12 km 2 , and the dogs should be experienced guard dogs which are properly socialized for this method.     

陇东地区主要农作物干旱灾损动态评估

[目的]为陇东地区旱灾动态监测及灾损评估提供依据。[方法]利用陇东冬小麦、春玉米的产量资料及其相应的生育期、土壤含水量和气象资料,计算作物的因旱减产率,分析不同时期水分亏缺率与作物因旱减产率之间的关系,并建立主要农作物的干旱灾损动态评估模型。[结果]冬小麦各类模型的误差值均小于春玉米,冬小麦累乘模型效果好于累加模型和简化模型,而春玉米累乘模型效果明显差于累加模型和简化模型,因此实际应用中要通过比较,因地制宜,选用适合的模型进行监测和评估。[结论]应用干旱灾损动态评估模型可及时了解陇东地区干旱对主要农作物产量影响的动态变化。     

“5·12”汶川特大地震灾害造成四川森林资源损失的评估研究

应用遥感技术、全球定位技术与地理信息系统,结合各类林业专题图及相关资料分析,研究＂5.12＂汶川特大地震灾害造成的四川森林资源损失情况。结果表明,重灾区受损林地面积共计32.87万hm2,导致该区域森林覆盖率下降1.87%,受灾活立木蓄积量1 958.25万m3,31个自然保护区不同程度受灾,其中以大熊猫为主要保护对象的自然保护区28个,占受灾保护区总数的71.00%,地震造成区域生态景观破碎化程度显著,系统斑块数量为震前的1.7倍,可能产生的孤岛效应,将使大熊猫等濒危动植物的濒危程度加剧;地震造成森林资源损毁的直接经济损失共达122.7亿元。该研究为灾后四川省森林植被恢复重建提供了重要依据。     

供求失衡生猪产业面临新调整

今年，生猪养殖陷入“猪周期”亏损困境，生猪价格一再创下近年新低、养殖重度亏损，市场表现出来的价格涨跌规律也与往年不同。为此，笔者专门采访了省内部分养殖、屠宰企业负责人，调查了解目前当前的生猪生产状况、市场变化产生原因，提出了养殖业在新的发展时期应该采取的对策。