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1.
政府渔业补助政策与博弈 总被引:1,自引:0,他引:1
渔业补助政策是政府为弥补市场经济缺陷而采取的重要措施,本文应用博弈论对政府与渔民的互动博弈展开研究,并确立了混合策略模型下的政府和渔民各自最佳选择概率,达到纳什均衡,这对于解释当前政府渔业补助政策内涵与指导修订补助政策有参考意义。 相似文献
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Nitrate leaching in a silage maize field under different irrigation and nitrogen fertilizer rates 总被引:4,自引:0,他引:4
Mahdi Gheysari Seyed Majid Mirlatifi Mehdi Homaee Gerrit Hoogenboom 《Agricultural Water Management》2009,96(6):946-954
Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO3) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO3-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189 kg N ha−1), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60 cm soil depths for all 36 experimental plots. Soil NO3-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO3-N leaching out of the 60-cm soil layer was 8.43 kg N ha−1, for the 142 kg N ha−1 and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO3 concentration at the 60 cm depth was 46 and 138 mg l−1, respectively. Based on our findings, it is possible to control NO3 leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management. 相似文献
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渔业公共资源管理既是一个国际性难题,也是我国渔业现代化和市场经济进程中,必须面对和妥善解决的渔业公共资源问题.本文重点分析了当前我国渔业公共资源存在的冲突矛盾,揭示其内在共性特征,总结了福建省渔业公共资源管理的经验和管理模式,结合渔业公共资源管理现状,提出了进一步完善我国渔业公共资源管理的制度设计思路和体制机制设计的原则,研究了适应我国社会主义市场经济条件下的渔业公共资源管理思路. 相似文献
5.
Luca Ceriola Paolo Accadia Piero Mannini Fabio Massa Nicoletta Milone Nicola Ungaro 《Fisheries Research》2008,92(2-3):255-267
The state of demersal fishery in the Southern Adriatic Sea (GFCM-GSA 18, Central Mediterranean), years 1996–2003, from a biological, social and economic point of view was analysed using 47 indicators: 22 biological indicators obtained from fishery-independent data through yearly experimental bottom trawl surveys (“Medits” Programme), and 25 socio-economic indicators estimated from fishery-dependent data, available from the monitoring system of the Italian Institute for Economic Research on Fisheries and Aquaculture (IREPA). Biological indicators were applied for “single-species” (Eledone cirrhosa, E. moschata, Illex coindetti, Merluccius merluccius, Mullus barbatus, Nephrops norvegicus, Parapenaeus longirostris, Raja clavata, Zeus faber) and for “multi-species” analysis. Economic indicators describing economic performance, productivity, costs and prices, and the overall economic sustainability of fishery were estimated. Social indicators and a general indicator summarising social sustainability were also considered. Indicators’ values were displayed using the Traffic Light system. Both fishery-independent and fishery-dependent indicators highlighted a progressive decline of the trawl fishery system in the GSA 18. This decline was mainly related to the ongoing depletion of the traditional fishery target species (mostly long-living, late-maturing species) partially replaced by the increase of traditional accessory species (generally short-living species), as well as to the reduction of productivity and increasing costs. The whole procedure was proposed as a contribution to the identification and applicability of bio-economic indicators for fishery management purposes. 相似文献
6.
Summary The use of N and P by mixed and by sole cropping (crop rotation) of maize and cowpeas were compared in a field experiment on an Alfisol at the Nyankpala Agricultural Experiment Station in the northern Guinea Savanna of Ghana, using two levels of N (0 and 80 kg N ha-1 year-1 as urea) and P application (0 and 60 kg P ha-1 year-1 as Volta phosphate rock). Maize grain yields were significantly reduced in the mixed cropping system. This yield difference became smaller with the application of N and P fertilizer. The N and P concentrations in maize ear leaves at silking indicated that a deficiency in N and P contributed to the maize yield depression in mixed cropping. Competition for soil and fertilizer N between maize and cowpeas was suggested by: (1) A similarity in total N uptake between the two cropping systems; (2) efficient use of soil nitrate by the cowpeas; and (3) low N2 fixation by the cowpeas, calculated with the aid of an extended-difference method. In general, N2 fixation was low, with the highest values in the sole cropping (53 kg ha-1) and a substantial reduction in the mixed cropping system. The application of N fertilizer further reduced N2 fixation. This was substantiated by nodule counts. The lower N2 fixation in the mixed cropping system was only partly explained by the lower density of cowpeas in this system. In addition, dry spells during the cropping season and shading by the maize component could have reduced the nodulation efficiency. No N transfer from the legume/rhizobium to the non-legume crop was observed. Impaired P nutrition in the mixed compared with the sole-cropped maize might have been due to less P mobility in the soil. This was indicated by lower soil moisture contents in the topsoil under mixed cropping, especially during the dry year of 1986. The results show that mixed cropping of maize and cowpeas did not lead to improved use of soil and fertilizer N and P or to an enhanced N2 fixation. On the contrary, an annual rotation of maize and cowpeas was clearly superior. 相似文献
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Kevin A. Hughes Kerstin Scherer Petra Rettberg Pete Convey 《Soil biology & biochemistry》2006,38(6):1488-1490
In the Arctic, seasonal ozone depletion is resulting in periods of enhanced UV-B radiation at ground level while regional climate change is associated with increasing temperatures. These changes are likely to alter plant distribution, biodiversity and morphology, which may have knock-on effects for microbially driven biogeochemical cycling and other soil processes. Our study examined the transmission of solar UV radiation through arctic tundra plants using a portable UV radiometer and the DLR-biofilm biological UV dosimeter. A strong negative correlation was found between vegetation cover and UV transmission to the soil surface. Penetration of UV to the soil beneath tundra plants varied depending upon plant morphology, being greater through low creeping plants than cushion plants, grasses or mosses. UV transmission to the soil surface beyond the foliage edge also varied with plant morphology and the presence of flowers. 相似文献
9.
介绍了位于环渤海经济圈中心地带的河北省海岸带和海洋经济概况,分析了河北省海洋生物资源的开发利用现状,并从政府管理、生态环境修复、加大海洋科技与教育投入、海洋生物资源摸底调查、海洋渔业产业结构的调整和海洋药用生物资源的开发等六个方面提出了保护和合理利用河北省海洋生物资源的对策,可为海洋生物资源的可持续利用提供参考依据。 相似文献
10.
总可捕量制度在我国的可行性分析 总被引:3,自引:0,他引:3
本文在论述总可捕量制度的定义、实施总可捕量制度需要具备的必要条件等内容的基础上,指出我国实施总可捕量制度的必然趋势及存在的困难。并提出了我国实施总可捕量制度的四点建议和设想:(1)大力实施减船措施,(2)加强渔业资源的调查与研究,(3)加强渔政执法,重视监督管理,(4)由点到面逐步实施TAC制度。 相似文献