农产品补贴与可持续发展：欧盟的经验及对中国的启示

通过分析欧盟的共同农业政策的经验与改革，阐述了欧盟的农产品政府补贴与高成本农业以及环境保护之间的关系；并结合当前我国新农村建设中的农民增收和政府补贴问题，提出我国的政策选择。     

Food habits and marine survival of juvenile Chinook and coho salmon from marine waters of Southeast Alaska

Little is known about the food habits of juvenile Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon in marine environments of Alaska, or whether their diets may have contributed to extremely high marine survival rates for coho salmon from Southeast Alaska and much more modest survival rates for Southeast Alaskan Chinook salmon. To address these issues, we documented the spatial and temporal variability of diets of both species collected from marine waters of Southeast Alaska during summers of 1997–2000. Food habits were similar: major prey items of both species included fishes, crab larvae, hyperiid amphipods, insects, and euphausiids. Multivariate analyses of diet composition indicated that the most distinct groups were formed at the smallest spatial and temporal scales (the haul), although groups also formed at larger scales, such as by month or habitat type. Our expectations for how food habits would influence survival were only partially supported. As predicted, Southeast Alaskan coho salmon had more prey in their stomachs overall [1.8% of body weight (BW)] and proportionally far fewer empty stomachs (0.7%) than either Alaskan Chinook (1.4% BW, 5.1% empty) or coho salmon from other regions. However, contrary to our expectations, coho salmon diets contained surprisingly few fish (49% by weight). Apparently, Alaskan coho salmon achieved extremely high marine survival rates despite a diet consisting largely of small, less energetically‐efficient crustacean prey. Our results suggest that diet quantity (how much is eaten) rather than diet quality (what is eaten) is important to marine survival.     

基于PCA的农机购置补贴绩效评价研究

针对农机购置补贴绩效评价过程中存在的数据统计繁杂、人工处理耗费时间长、计算结果易出错、不能及时得到数据结果等问题,本文提出了一种基于PCA进行绩效评价的新方法,并与常用的因子分析法及图表比对法进行了结果比对。结果显示,该方法结果准确,且前三主分量累积比率达到83.16%接近85%(常用阈值),可用前三主分量代替整体研究失分率。经过在近两年的绩效考评工作中实践验证,该方法操作简便,结果简明,特别在数据量庞大情况下该法优势更加明显,适用于农机购置补贴绩效考核评价。     

新型城镇化进程中农业补贴制度效率提升研究

农业补贴是各国为促进农业健康持续发展而采用的政策工具，其效果受农业生产特点和宏观经济环境的双重影响。研究从影响农业补贴制度运行及其效率的宏观环境因素出发，分析了新型城镇化战略的实施对农业及其补贴政策的影响。在此基础上，分析了中国农业补贴制度的目标选择，明确了补贴政策工具选择的具体思路，最后提出了中国农业补贴制度效率提升的具体路径和保障机制。     

Geographical Distribution of African Mammals

This is a report of a marine predator (the white shark) being threatened by a member of the species on which it preys (a male Cape fur seal). Although these events may be rarely observed or occur infrequently, they may have important implications for the predator and its prey.We suggest that shark mobbing by adult male Cape fur seals is adaptive for the reduction of risk of predation by sharks. Mobbing of sharks is likely to alert conspecifics to the presence of a predator, and/or reduce the shark's hunting motivation near the mobbing site.     

膜肩网蝽的一种新天敌—异绒螨

异绒螨(Allotrombium sp.) 在北京、山东临沂地区每年发生一代,以成螨越冬。成螨和若螨可捕食膜肩网蝽(Hegesidemus habrus Drake)若虫,对膜肩网蝽种群数量有控制作用。异绒螨越冬前不产卵,翌年春产卵,幼螨营寄生生活。菜蚜是室内饲养异绒螨的好饲料,可缩短生活历期,有利于林间释放。在杨树幼林中,以若螨与膜肩网蝽1:50释放,膜肩网蝽虫口减退率达76.01％。人工助迁成螨,在林间亦易定居。     

暴猎蝽形态特征和生物学特性的研究*

据在四川省大邑县和北京室内饲养观察，暴猎蝽１ａ发生一代，以５龄若虫越冬。卵期２７．０８±１．００ｄ。若虫共５龄，历期３３４．７５±４．３０ｄ。成虫羽化后１６～１８ｄ交配，交配后１８～１９ｄ开始产卵。描述了各虫态形态特征。记述了生物学特性。试验表明该虫是舞毒蛾、杨扇舟蛾、春尺蠖、北京杨锉叶蜂、柳毒蛾、刺槐蚜等多种林木害虫的捕食性天故。     

基于聚类分析的农机购置补贴区域分类

为提高农机购置补贴效果,合理配置补贴资源,提出健全农机购置补贴政策应进行区域分类研究。该文提出粮食生产能力、经济水平、农民购买能力及自然条件是影响补贴区域分类的4个主要因素,并选取粮食产量、人均GDP、农民人均纯收入、丘陵山区所占比重作为衡量指标,利用Q-型系统聚类分析方法,对中国农机购置补贴进行区域分类,通过定性修正得出将31个省（市、区）分为4类区域的分类结果。针对各区域特征、农业机械化发展及投入现状,在补贴总量及结构、补贴机具、补贴标准等方面提出优化农机购置补贴的政策建议。     

Conservation and the scarecrow effect: Can human activity benefit threatened species by displacing predators?

Most wild animals show direct negative responses to human disturbance; however, disturbance may also have positive indirect effects by altering species interactions. In the Caribbean, introduced mongooses (Herpestes javanicus) are an important diurnal predator of the nests of critically endangered hawksbill sea turtles (Eretmochelys imbricata). We asked whether daytime visitor activity could benefit hawksbills by reducing mongoose activity in nesting habitat. We used track monitoring sites to measure how mongooses alter their space use in response to fluctuating human beach use and availability of hawksbill nests, and we estimated the indirect impact of human disturbance on nest predation for 5 years of hawksbill nesting. Human activity substantially decreased mongoose use of nesting habitat. Mongoose activity increased with abundance of nests and was lower at the edge than the interior of patches of beach vegetation, but neither factor altered relative sensitivity to disturbance. We estimated that, in addition to deterring mongooses from accessing nests on the open beach, human activity has the potential to reduce predation of nests in vegetation by up to 56% at our site, with the greatest per capita impact at low (<50) visitor numbers. Many forms of human activity negatively affect sea turtles, but our study indicates that there are positive aspects of daytime use of nesting beaches. Optimizing the trade-off between positive and negative impacts of disturbance could provide a useful approach for regulating tourist activity in critical habitat for threatened species.