一次沈阳区域暴雨天气分析

对2009年8月19～20日沈阳地区出现的一次区域性暴雨天气进行分析,结果表明,此次降水的环流形势为典型的副热带高压与西风槽相迎合的暴雨天气形势;地面气旋发展的辐合作用和锋面的抬升作用是这次暴雨产生的触发机制;中低空急流的耦合配置为对流发展创造了有利条件,同时2支急流为这次暴雨天气提供了源源不断的水汽输送;K指数分布、500和700hPa的总温度场和假相当位温场对于降水量的预报有一定的指示意义;日本传真图和MM5对此次降水量预报把握较好。     

河北坝上地区土地荒漠化现状及生物对策研究

河北坝上地区属我国北方农牧交错带中脆弱生态环境的典型地区,沙化面积年递增率已达4.5,是我国土地沙漠化发展最快的地区.通过实地考察,对该区土地荒漠化现状的分析,指出应坚持"预防为主,保护优先"的治理思路,并从生物治理的角度,提出了综合整治措施.     

Forest carbon storage in the northeastern United States: Net effects of harvesting frequency,post-harvest retention,and wood products

Temperate forests are an important carbon sink, yet there is debate regarding the net effect of forest management practices on carbon storage. Few studies have investigated the effects of different silvicultural systems on forest carbon stocks, and the relative strength of in situ forest carbon versus wood products pools remains in question. Our research describes (1) the impact of harvesting frequency and proportion of post-harvest structural retention on carbon storage in northern hardwood-conifer forests, and (2) tests the significance of including harvested wood products in carbon accounting at the stand scale. We stratified Forest Inventory and Analysis (FIA) plots to control for environmental, forest structural and compositional variables, resulting in 32 FIA plots distributed throughout the northeastern U.S. We used the USDA Forest Service's Forest Vegetation Simulator to project stand development over a 160 year period under nine different forest management scenarios. Simulated treatments represented a gradient of increasing structural retention and decreasing harvesting frequencies, including a “no harvest” scenario. The simulations incorporated carbon flux between aboveground forest biomass (dead and live pools) and harvested wood products. Mean carbon storage over the simulation period was calculated for each silvicultural scenario. We investigated tradeoffs among scenarios using a factorial treatment design and two-way ANOVA. Mean carbon sequestration was significantly (α = 0.05) greater for “no management” compared to any of the active management scenarios. Of the harvest treatments, those favoring high levels of structural retention and decreased harvesting frequency stored the greatest amounts of carbon. Classification and regression tree analysis showed that management scenario was the strongest predictor of total carbon storage, though site-specific variables were important secondary predictors. In order to isolate the effect of in situ forest carbon storage and harvested wood products, we did not include the emissions benefits associated with substituting wood fiber for other construction materials or energy sources. Modeling results from this study show that harvesting frequency and structural retention significantly affect mean carbon storage. Our results illustrate the importance of both post-harvest forest structure and harvesting frequency in carbon storage, and are valuable to land owners interested in managing forests for carbon sequestration.     

河北省现代农业发展优先领域研究

采用特尔菲法，对河北省现代农业发展的现状、优先发展领域及领域内优先发展项目进行了调研，应用列联系数统计分析法分析了不同类别人员的差异。结果显示，目前河北省现代农业发展总体状况一般，必须采取有力措施加快发展。按照现代农业发展的6个重点领域，应依次优先突出发展科技支撑、产业体系、物质装备条件、市场体系、制度安排和农民素质。     

河北省苹果产业发展现状及对策

河北省苹果产量居全国第4位,苹果是河北省具有较强竞争力的优势产品。运用调查数据,系统分析了河北省苹果产业发展中取得的成就和存在的问题,并提出了河北省苹果产业发展的对策建议,如大力发展农民专业合作社、加大苹果的科技支撑力度、制定苹果商品的标准化管理体系、建立多级苹果批发市场、完善市场流通体系等。     

继往开来六十载 植保工作创辉煌——建国60a来河北植保工作发展与壮大

综述了建国60a来河北省植保工作的发展情况,总结了植保工作的成就和作用,旨为相关植保工作的开展提供借鉴。     

氮肥对北方超级稻茎蘖动态及产量的影响

以北方超级稻沈农265、吉粳88和龙粳14为试材,分析了不同氮素水平对水稻茎蘖动态及产量的影响。结果表明,在较高氮量水平下,沈农265、吉粳88能够提前进入茎蘖临界期,而龙粳14出现延迟现象;3个超级稻品种的最适施氮量都应该在150.5～207.0kg/hm2,在生产实际中农民可以适当降低惯用施氮量来优化产量结构,从而提高产量,达到更高的经济效益。     

廊坊市农产品质量安全管理现状研究

从廊坊市农产品质量安全的实际情况出发,针对其管理现状及成效,指出存在的问题,并对其原因进行具体分析,旨在推动该市农产品质量安全管理的发展。     

A participatory soil quality assessment in Northern Ethiopia's Mai-Negus catchment

Local communities often have substantial knowledge related to trends in soil quality and the associated limiting factors. Despite this, soil quality (SQ) degradation is a critical problem in Ethiopia and there is little or insufficient scientific information documenting local community experience in assessing SQ. This paper presents experiences of local communities in diagnosis of SQ and assesses the contribution of local knowledge as a strategy for sustainable development decision making within the Mai-Negus catchment of northern Ethiopia. Participatory transect-walks, group discussions and field observation which complemented by household interview were used to acquire data. Farmers identified SQ indicators e.g., crop yield, soil depth, erosion and sedimentation as their basis of categorizing the soils into high, medium and low SQ. They were also able to identify severely degraded areas (hotspots) and underlying causes. Significant variations (P ≤ 0.05) were shown between the proportions of farmers used certain SQ indicator and those who didn't while categorizing SQ. Local farmers involved in this study demonstrated their capability to suggest appropriate land management solutions for specific problems. This study demonstrates the benefit of involving local farmers in both problem identification and solution development so that anti-degradation technologies can easily be implemented and adopted.     

A new diagrammatic scale for the assessment of northern corn leaf blight

A diagrammatic scale was developed to assess the severity of northern corn leaf blight (NCLB), which is caused by the fungus Setosphaeria turcica. The validation of this new scale in relation to accuracy and precision was carried out by eight evaluators who estimated the severity of the infection on maize leaves showing NCLB symptoms, with and without the use of the scale. The new scale was also evaluated in relation to a published NCLB assessment scale. The precision and accuracy of the assessments were determined by linear regression, relating the estimated versus actual severity of NCLB as determined by image analysis. Using the new diagrammatic scale, evaluators were able to improve the precision and accuracy of NCLB assessments.