欧美国家针叶树容器苗生产与启示

针叶树是芬兰、瑞典、挪威、美国、加拿大等欧美国家主要的商品林树种。容器苗是针叶树重要的育苗类型。与裸根苗比较,容器苗具有育苗周期更短、造林季节可延长、苗木适应性更广、苗木质量更一致的优点。因此,容器育苗成为精准林业发展的必然趋势。为了借鉴欧美容器育苗的技术方法,提高我国容器苗的质量,为我国针叶树容器苗发展提供参考,文中主要从4个方面综述了欧美国家检测与提高苗木质量的方法,即列举了针叶树常用的苗木质量检测指标,总结了育苗容器与育苗基质的改良进展,介绍了养分、水分、光照与温度等培养条件的优化手段,简要概述了容器苗病虫害防控的进展,提出了我国相关树种容器苗生产的启示与借鉴。     

《中越北部湾渔业合作协定》对我国南海各省（区）海洋渔业影响的初步分析

在初步分析了《中华人民共和国政府和越南社会主义共和国政府北部湾 渔业合作协定》的签定背景和主要内容的基础上，本文针对我国在北部湾业现状，由此可能产生的影响以及应采取的对策进行了初步探讨，认为划界后，南海区将有大批渔船湾西部渔场退出，造成经济损失约99．3亿元，同时渔民转产难度较大，会对近海渔业资源造成更大压力，增大机动渔船禁渔区和禁渔期等制度实施难度。此外，由于渔船的装备和渔民的水平等，难以确切把握北部湾的分界线，容易造成纠纷。本文据此对我国在北部渔业管理中应注意的问题提出几点看法；（1）扩大宣传，提高全社会保护渔业资源的理解；（2）降低捕捞强度，继续调整作业结构；（3）调查渔业资源，合理制定资源开发，利用方案；（4）成立专门机构，统一贯彻落实新规定。     

农机社会化服务对土地规模经营的影响——基于服务外包和供给的双重视角

为推动土地规模经营的进一步发展,助力小农户衔接大市场,兼顾农机服务供需两方面的研究必不可少。首先,从理论上分析农机服务外包与供给对于农户土地规模经营的作用机制;其次,运用OLS模型实证分析农机服务外包与农机服务供给对于农户土地规模经营的影响,为保证模型结果的可靠性,引入工具变量采用2SLS模型,做进一步分析;最后,选取家庭农机资产作为调节变量,建立调节效应模型,分析农户农机服务外包与供给二者间的关系。结果表明：农机服务外包对土地规模经营存在农户异质性影响,经营规模在(12.62 hm2,25.24 hm2］之间的农户户均农机服务外包环节数最高,达4.08,而经营规模在(0 hm2,12.62 hm2］、(25.24 hm2,37.86 hm2］以及大于37.86 hm2的农户户均农机服务外包环节数分别为3.48、2.29、1.45,表明随着农户经营规模的扩大,农机服务外包环节数呈现倒“U”趋势。农机服务供给对土地规模经营有正向促进作用,显著性系数为0.549;经营规模区间由低到高,其户均服务供给环节数分别为0.1、0.6、1.79和3.6,即随着经营规模的扩大,农户服务供给量也逐渐上升。家庭农机资产可以负向调节农机服务外包对土地规模经营的影响,自购农机与农机服务外包间存在替代关系。     

Improved milk production through PG–PL system by provision of in‐house shelter management in lactating Murrah buffaloes during winter season

Comprehensive information on the role of β‐casein and plasminogen–plasmin (PG–PL) system in milk secretion of Murrah buffaloes during winter season is lacking, although effects of cold stress can be ameliorated to an extent by altering microclimate at farm level. Hence, this study was aimed to determine the changes in productivity along with PG–PL system of milk, plasma hormones and metabolites of buffaloes during winter (December–January) season under two different management systems. Average minimum temperature and wind chill index during this season were 7.02 and 12.74 °C respectively. Buffaloes were divided in two groups of six animals each: control and treatment, where treatment group animals were placed in‐house with floor bedding of paddy straw and the control group animals in loose housing system without straw bedding. Physiological responses were recorded, and milk and blood samples were collected at weekly intervals for six‐week experimental period. Under in‐house management system, buffaloes experienced better comfort by alleviating environmental stress as their physiological responses such as respiration rate and pulse rate were significantly reduced (p < 0.01) as compared to the control, which subsequently resulted higher milk yield by 9.92% (p < 0.05). Analysis of milk samples revealed higher concentration of plasminogen (10.6 vs. 8.05 μg/ml; p < 0.01) and β‐casein (p < 0.05), and lower plasmin level (0.299 vs. 0.321 μg/ml; p < 0.05) in buffaloes under treatment group. It was also found that plasma cortisol, glucose and non‐esterified fatty acids levels were higher (p < 0.01) in control group as compared to the treatment animals by 13.6%, 8.14% and 12.6% respectively. However, milk composition, growth hormone, epinephrine and norepinephrine level in plasma were similar in both the groups. Hence, it may be concluded that provision of in‐house shelter management with floor bedding of paddy straw during winter was effective to minimize environmental stress and improved milk production through manipulation of PG–PL system in buffaloes.     

不同施氮水平对南方早稻氮素吸收利用及其产量和品质的影响

 在大田不同施氮条件下,研究了3个水稻品种的氮素吸收利用效率及其对产量和品质的影响。结果表明,施氮量增加,水稻氮素积累总量增加,而氮素的生产效率和收获指数下降。相同施氮量条件下提高穗肥比率,氮素积累量及其回收效率和运转效率增加,而氮素生产效率下降。不同施氮条件下水稻氮素吸收利用效率的变化对产量和品质性状产生重要影响,稻米蛋白质含量随氮素积累量增加而显著增加,随氮素生产效率提高而极显著下降;垩白米率及面积随氮素收获指数增加而显著提高。穗数随氮素积累量增加而显著增加,随氮素收获指数和氮素生产效率增加而显著下降;结     

基于粗糙集和WebGIS的农产品质量安全应急管理系统

针对农产品质量安全事件的特点,利用粗糙集方法,通过对10个样本案例进行属性分析与约简,确定了危害源毒性、影响范围、死亡人数、伤害人数和人口密度5个农产品质量安全事件等级综合评价指标,通过重要度分析得到各指标的权重分别为0.2、0.2、0.1、0.3和0.2.在此基础上构建了农产品质量安全事件等级评价模型;将模型计算语言化,以WebGIS为工具,设计与实现了农产品质量安全应急管理系统;通过模拟某次农产品质量安全事件表明,该系统能提高对事件的处置能力,也便于直观看到处置过程,为进行农产品质量安全应急管理提供参考.     

生态风景林研究进展

生态风景林是我国城市森林发展过程中形成的一个新林种.该文在对生态风景林营建技术及其效益评价相关研究成果进行概括的基础上,对当前重点研究方向进行了展望.     

Potential carbon stock in Japanese forest soils – simulated impact of forest management and climate change using the CENTURY model

Forest management and climate change may have a substantial impact on future soil organic carbon (SOC) stocks at the country scale. Potential SOC in Japanese forest soils was regionally estimated under nine forest managements and a climate change scenario using the CENTURY ecosystem model. Three rotations (30, 50, 100 yr) and three thinning regimes were tested: no‐thinning; 30% of the trees cut in the middle of the rotation (e.g. 15 year in a 30‐yr rotation) and thinned trees all left as litter or slash (ThinLef) and the trees from thinning removed from the forest (ThinRem). A climate change scenario was tested (ca. 3 °C increase in air temperature and 9% increase in precipitation). The model was run at 1 km resolution using climate, vegetation and soil databases. The estimated SOC stock ranged from 1600 to 1830 TgC (from 6800 to 7800 gC/m²), and the SOC stock was largest with the longest rotation and was largest under ThinLef with all three rotations. Despite an increase in net primary production, the SOC stock decreased by 5% under the climate change scenario.     

Effects of a plastic cover on soil moisture change in a Mediterranean climatic regime

Water deficit is a serious problem for most agricultural crops, especially in arid–semiarid regions, and limits sustainable development. Production can be improved by reducing evapotranspiration and loss of infiltrated water by the use of a plastic cover. We monitored soil moisture fortnightly over 1 yr using a neutron probe near four trees in an olive grove (Olea europaea, var. Arbequina), two of which had a plastic cover buried in the topsoil around them. These trees were monitored using three neutron probe access tubes per tree to compare the behaviour of soil moisture over time with two other identically instrumented and nearby trees with no cover. Analysis was based on the resultant moisture profiles. The plastic cover retained moisture and increased soil water residence time. During the dry season, the amount of water retained in the plots was at most 15–20% greater in the mid‐season and at least 5–6% greater at the end of season than in the central part of the plots near the trunk. The plastic cover was effective to ca. 50 cm with maximum water content near the soil surface. During the wet season, the cover did not affect soil water. Soil moisture was greater near the tree trunk as a result of stemflow and throughfall.     

修缮购置专项资金项目实施管理与成效

该文总结了2006年以来该所承担实施的27个修缮购置专项资金在实施过程中的管理情况及取得的初步成效,以期对修缮专项资金实施管理及进一步获得稳定支持以有益启示。