上饶市城镇化建设中的耕地资源保护

在介绍了上饶市的城镇化发展基本情况后,就上饶市城镇化发展和耕地资源变化的相关关系进行了讨论,并运用统计学的相关知识,对城镇化水平与耕地变化之间的关系进行了数理分析及机制探讨,通过对上饶市城镇化发展过程中耕地资源流转潜力和耕地现实需求量的预测,明确了耕地保护数量质量目标,最后提出了城镇化进程中耕地保护的相应对策。     

The flora and structure of farmland hedges and hedgebanks near to pheasant release pens compared with other hedges

On farms where shooting takes place, hedgerows leading from woodlands with release pens are often used by pheasants as corridors for accessing game crops. We compared shrub and ground flora structure and species composition in hedges near to and away from release sites with a wide range of release sizes, at 109 game estates in four regions in England in 2002 and 2003. There was more bare ground, fewer stable perennial plant species, more weeds and fewer tree and shrub seedlings in hedges near to release sites compared to our controls, sometimes only when the nearby release exceeded a certain threshold. Alongside hedges there were more weeds on hedgebanks near to release sites, and depending on hedge size, fewer stable perennial species or fewer tree and shrub seedling species. While the woody structure of the hedge itself was not substantially different, shrub leafiness within hedges at 10-20 cm off the ground was reduced in all except very short hedges near to releases. We argue that the differences we observed were due to the presence of pheasants in those hedges during the late summer and autumn following release and not to pen siting or game management factors. We hypothesize that where larger accumulations of pheasants occur in hedges, the changes to ground flora species composition we observed were due to increased soil fertility and soil disturbance. The effects on mature shrub leafiness and woody seedlings were probably caused by direct pecking. Our study involved many sites and some of the effects identified were subtle. Our data on release size enables us to suggest how to minimise these effects where this is considered important, for example where hedgerows are recognized as particularly valuable or vulnerable.     

我国耕地生态保护问题与对策

耕地资源安全不仅关乎我国粮食安全,还关系到我国经济社会的可持续发展大计.近些年来,我国耕地生态保护中日益暴露出诸多问题,使耕地资源安全隐患非常突出.本文在阐述我国耕地资源数量与质量现状基础上,分析了耕地生态保护方面存在的主要问题,进而提出了进一步强化我国耕地生态保护的对策建议.     

西安市公众对耕地保护的认知程度调查

采用访谈问卷调查法探讨了西安市公众对耕地保护的认知程度,分析了公众对耕地资源各种功能及其外部效益的认识,为公众加强耕地保护工作提供借鉴。结果表明,①89.9%的受访者认为有必要加强耕地保护;70.6%的受访者认为耕地大量转为非农建设用地,可能导致农民大量失业;79.7%的受访者赞成耕地维持现状,耕地面积不减少。②耕地保护主要能提高城市郊区农民的生活质量,为农户提供就业保障和生存空间;保证农业生产的顺利进行;为子孙后代保留生存空间。③当前耕地保护工作面临最严峻问题是建设用地扩张占用大量优质耕地,致使耕地面积锐减;农民种田利益低下,致使农民不愿意种田,大量农民外地打工。④耕地外部效益功能主要有水源涵养,净化水质,保育水资源;同化城市和农村生活中产生废弃物;防止水土流失,保育土壤资源;提供娱乐、休闲旅游的空间。     

北京郊区土壤有机质含量的时空变异及其影响因素

【目的】揭示土壤有机质时空变化规律及其影响因素，为土壤肥力评价和管理提供指导。【方法】通过收集和实测北京南郊-大兴区1980、1990和2000年3个不同时期耕层土壤有机质含量的资料，应用地统计学方法对共进行分析。【结果】3个时期土壤有机质的平均含量分别为9.64、12.76和12.89 g·kg-1，它们的空间相关距离分别为80.5、59.2和49.0 km，呈递减趋势。大兴区土壤有机质含量空间分布呈北高南低之势。从1980年到2000年，有机质含量表现为由低向高逐级累积的规律，具体变化为有机质含量一级和二级的土地面积从无增加到分别占土地总面积的8.0%和14.3%，含量三级的土地面积从23.0%增加到37.1%，四级土地面积减少很少，约为2.19%，五级土地面积减少幅度最大，为50.4%。【结论】秸秆还田和施用有机肥是有机质含量普遍上升的原因，随着作物产量的不断提高，部分地区的有机质入不敷出，呈下降的趋势，应注意土壤的培肥管理。     

WTO与河北省耕地保护

本文阐述了河北省耕地资源变化趋势及特点,并对未来耕地需求作了分析,提出加入WTO后,河北省加强耕地保护的对策。     

四川省武胜县耕地撂荒问题研究

基于对四川省武胜县的调研,分析了武胜县耕地撂荒的现状及原因,研究发现造成四川省武胜县耕地撂荒的原因主要来自4个方面：自然环境因素、经济因素、政策制度因素和人为因素.在此基础上,提出了遏制耕地撂荒蔓延的对策建议.     

Factors Affecting Sampling Error of Nutrient Element Contents of Arable Fields

A sampling proficiency test is evaluated to analyze the influence of soil heterogeneity and sampling parameters on sampling error of nutrient contents. The influence of parameters on sampling error was assessed by multiple linear regression, regression tree analysis, and variance component analysis (VCA). Error was governed mainly by heterogeneity. Among sampling parameters, the number of increment samples had the largest influence. VCA revealed that the component between sampling repetitions was larger than the component between samplers. This suggests a predominance of heterogeneity for the influence on sampling error, increasing with field-scale heterogeneity. Sampling patterns of low complexity seemed sufficient for the homogeneous field, whereas sampling performance was enhanced by more complex sampling pattern on fields of intermediate and high heterogeneity. Overall, the results suggest that sampling error on arable fields sampled with simplified sampling schemes is often determined by soil heterogeneity and to a lesser degree by sampling parameters.     

不同年限全量玉米秸秆还田对玉米生长发育及土壤理化性状的影响

试验以未进行秸秆还田(H0,对照)、连续3年秸秆还田(H3,2007—2010年)、连续6年秸秆还田(H6,2005—2010年)及连续9年秸秆还田(H9,2002—2010年)的连作玉米农田为对象,通过测定土壤理化性状及玉米根系发育和地上产量性状的变化,探索不同秸秆还田年限对不同层次土壤改良效应及作物生长响应机理。结果表明:随着玉米全量秸秆连续还田,耕层0~30 cm土层土壤有机质、全氮、全磷含量大幅增加,速效氮、速效钾显著增加,而速效磷养分变化幅度较小,表明秸秆还田能够有效改善土壤养分状况;20~50 cm土层土壤容重随着秸秆还田年限增加较对照显著下降,表现H9相似文献   

武汉市耕地资源的时空变化及驱动力分析

基于武汉市1997~2006年的统计数据,从耕地资源变化的时间特征和空间差异入手,分析了武汉市耕地资源变化的规律与趋势,并运用因子分析和多元线性回归相结合的方法,定量分析了该市耕地资源变化的驱动因素。结果表明,武汉市耕地资源变化的时空特征明显,耕地资源呈现出减少的总体趋势;人口增长、经济发展和农业科技进步是影响武汉市耕地资源数量变化的3类因素。研究结论对武汉市合理利用耕地资源,实现地区农业的可持续发展具有重要意义。