河北省优质米生产现状、存在问题与发展对策

河北省是华北地区重要的优质稻生产基地，常年水稻面积大约15万hm2。近年，受优质米市场需求的影响，优质稻面积在迅速扩大，目前累计推广面积达17万hm2，使我省优质米生产得到快速发展。但是，通过对优质米生产现状的分析，仍然存在品种单一、综合性状差，良种良法不配套，品牌意识不强，开发力度不足等问题。因此，必须采取加大新品种选育及引进力度，加强基地建设，优化栽培技术，提高加工水平，形成品牌优势等对策，推进我省优质米产业快速发展。     

试论河北省海岸带土壤开发利用

本文对河北省海岸带土壤开发利用的指导思想是:因地制宜,发挥优势,克服障碍,通过综合措施,争取最佳效益.并据此提出了四项基本原则:①多层次地利用土壤资源,提高开发利用的综合性和总体性;②多方面地满足市场需求;③多变化地适应土壤环境,增进生产建设的稳定性和抗逆力;④多途径地改善土壤条件,不断提高土壤肥力和生产力.对河北省海岸带开发利用进行了土壤区划,划分出:①山海关—滦河口棕壤、潮土、风沙土林果农渔旅游区;②滦河口—涧河口潮土、水稻土、盐土农牧渔盐区;③北排河—大口河潮土、沼泽土、盐土旱地农业牧渔盐区.分区提出了开发利用途径和主要措施.     

基于R2V和AutoCAD的树木年代学方法及其在冀北山地的初步应用

 综合应用AbleSoftwareR2V的矢量化功能和AutoCAD的测量功能,提出一种新的树木年轮测量方法,并用此方法测定了冀北山地广为分布的白榆地径年轮宽度,进而用来尝试过去气候序列的重建。结果表明:5—9月平均气温和总降雨量与年轮指数成正相关,相关系数分别为0.597(α<0.05)、0.695(α<0.05)。以此为基础,建立了5—9月平均气温、总降雨量的转换方程,重建了冀北山地1940—1955年共16年5—9月平均气温和总降雨量。     

GIS支持下小流域农林复合经营的侵蚀控制模拟——以冀西北青边口河小流域为例

根据张家口郭家梁试验场的小区资料 ,建立了小流域侵蚀产沙模型以及植物篱侵蚀控制模型 ;并在 GIS的支持下 ,从小流域数字高程模型 (DEM)中提取基于地块间水沙汇流网络 ,生成基于地块的水沙运移网络图 ,并将地块间的水沙汇流过程引入小流域侵蚀产沙的模拟中 ,实现了侵蚀产沙模型与地理信息系统 (GIS)的深层次耦合 ,模拟出坡面水沙在小流域的空间运动过程。1995～ 1999年青边口河小流域模拟结果表明 ,坡耕地、荒坡地、低覆盖的天然草地平均侵蚀模数最大 ,是侵蚀控制的重点土地利用类型。在坡耕地、荒坡地、低覆盖的天然草地配置面积占流域总面积的 18.2 %的植物篱—农作系统 (10 m带间距 2年生紫穗槐植物篱 ) ,利用次降雨资料计算模拟结果表明 ,对径流的控制效果在 8.1%～ 46 .2 %之间 ,对侵蚀模数的控制效果在 42 .9%～ 5 0 .2 %之间 ;养分流失的模拟分析表明 ,在现有条件下有机质的损失较大 ,而通过配置植物篱—农作系统可以有效地减少养分流失。     

河北省湿地退化分析及保护策略研究

湿地是地球上具有多种生态服务功能的生态系统,也是重要的自然资源。介绍了河北省丰富的湿地资源及比较齐全的湿地类型,在此基础之上通过实地调查与资料核查,分析了河北省湿地的生态系统结构及其在生态、经济等多方面功能,指出了当前河北省湿地退化等现存的主要问题,提出了湿地保护的对策,旨在形成人与湿地环境和谐相处的局面。     

陕北农牧交错带土地利用景观格局动态变化研究

利用1986年、1993年和2000年3期遥感资料,基于遥感和GIS技术,选取反映景观格局特征的指数,分析了陕北农牧交错带景观格局及动态变化的特征。结果表明,陕北农牧交错带土地利用景观整体多样性增加,整个景观正从单一景观向多样化的景观过渡,景观类型在空间上呈离散性分布趋势,结构复杂,景观斑块间离散度增大,形状变得较为不规则,整体破碎度逐渐增大。     

河北省农用水资源可持续利用若干问题的探讨

以农用水资源为研究对象，系统论述了农用水资源的组成、特性、调控及变化规律。在对河北省水资源状况进行分析的基础上，对河北省农用水资源的供、需平衡进行了初步研究，指出河北省对农用水资源的利用已经超过了其承载能力，且目前的利用方式是不可持续的，为了实现河北省农用水资源的可持续利用，必须进行包括农业结构调整在内的一系列工作。     

Disturbance effects on soil solution chemistry due to heating cable installation

Installation of heating cables for warming soil was used to evaluate the effect of disturbance on soil solution chemistry within a northern hardwood forest (Adirondack Mountains, New York). Differences in response among treatments suggested the importance of both the depth and timing of cable installation. There were increases (p>0.05) in many solutes within pilot study plots in which surrogate cable was installed at 15 cm depth. Most notably, mean nitrate concentrations for the 1st year following disturbance were 744 eq l^-1 at 15 cm depth compared to 7 eq l^-1 for the non-disturbed control. A comparison of pilot plots with 5 cm cable depth and an unheated soil-warming control plot with the same cable disturbance showed that the seasonality of soil disturbance may have a key role in response to disturbance. The soil solution response was diminished if installation occurred during the spring, a period of rapid uptake of nitrogen by vegetation. Mean nitrate concentrations were 176 eq l^-1 for 5-cm pilot plots (installed in fall 1991) versus 6 eq l^-1 for 5-cm, unheated soil-warming control plots (installed in spring 1992). Disturbance effects were attenuated over time and not generally apparent 1 year after installation.     

Are seedlings reasonable surrogates for trees? An analysis of ozone impacts on Quercus rubra

The appropriateness of using seedling responses to predict mature tree responses to ozone is questionable considering the long life span of trees. To determine if northern red oak (Quercus rubra L.) seedlings and mature trees respond similarly to ozone, 30-year-old trees and two-year-old seedlings were fumigated with subambient, ambient, and twice ambient concentrations of ozone for three growing seasons using an open-top chamber facility. Ozone reduced leaf physiological function of mature trees. However, stem diameter growth and leaf mass of mature trees were not significantly reduced by ozone. Photosynthesis in seedling leaves was slightly reduced by ozone, but seedling growth and biomass were unaffected. Mature tree fine-root biomass responded negatively to increasing ozone, while seedlings exhibited increases in biomass. Carbon retention was enhanced in leaves and branches of mature trees by ozone treatment, while seedlings were unresponsive. Differences in ozone uptake, recurrent flushing and carbon dynamics rather than microclimate may explain differences in ozone sensitivity between seedlings and mature trees. These results indicate that seedlings may not reflect the ozone sensitivity of larger more physiologically mature trees.     

Low genetic variation for Dendrobaena octaedra from Greenland compared to populations from Europe and North America: Refuge or selection?

The genetic relationship of 345 specimens of the parthenogenetic lumbricid Dendrobaena octaedra from Greenland, Canada and Europe were analysed by means of isozymes. The results showed that populations from Greenland were markedly different from Canadian and European populations, suggesting that dispersal between Greenland and the continents has been much more restricted in the past than dispersal between North America and Europe. This observation supports to the notion that Greenland populations have persisted for a long period and perhaps have survived the last glacial period in ice-free refugia. A highly significant positive correlation was seen between diversity measured either as mean haploid diversity or clonal diversity and mean temperature of the annual coldest month. These results indicate that temperature might cause selection in colder climates or that sexual processes in D. dendrobaena could have been active recently on an evolutionary time scale.