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.     

Starving the soil of plant inputs for 50 years reduces abundance but not diversity of soil bacterial communities

If soil communities rely on plant-derived carbon, is biodiversity lost when this primary source is removed? Soil microbial and mesofaunal communities at the Rothamsted Highfield site were compared under a mixed grass sward, arable rotation and a section maintained as a bare-fallow for the past 50 years by regular tillage. Organic matter reserves have been degraded and microbial and mesofaunal numbers and mite diversity have declined in this unique bare-fallow site, where fresh carbon inputs have been drastically reduced. However, it supports a species-rich metabolically active bacterial community of similar diversity to that in soil maintained as grass sward. Thus in contrast to soil mesofauna, bacterial diversity (but not abundance) is apparently independent of plant inputs.     

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.     

武功县耕地质量空间变异分析

为了弄清楚武功县耕地质量空间变异规律,应用地统计学方法,分别针对武功县耕地自然质量等指数、利用等指数和经济等指数各选取1000个分等单元样点,在保证样点为正态分布的前提下,应用GS+9.0软件进行对武功县耕地自然质量等指数、利用等指数和经济等指数的空间变异进行定量分析。结果表明:武功县耕地质量的空间变异是以结构性因素引起的为主,自然质量的空间变异在3270 m以内,利用质量的空间变异在11310 m以内,而经济质量的空间变异在14970 m以内。自然质量以南北方向和西北东南方向变异大,而东西方向变异小。利用质量和经济质量则以南北方向和西南东北方向变异大,东西方向变异最小。地统计学方法是定量研究耕地质量空间变异的有效方法,利用地统计学方法对耕地质量空间变异研究有利于认识耕地质量空间分异规律,也有利于有效选择耕地质量监测样点。     

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。     

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.     

北京市密云县耕地整理潜力调查分析

[目的]弄清密云县耕地整理潜力,为下一期整治规划服务。[方法]基于密云县2010年土地利用现状图、1∶50 000地形图以及密云县农用地分等定级数据库,用主成份分析、聚类分析、典型田块调查分析法分析密云县耕地整理潜力状况。[结果]全县耕地整理区面积21 286.23 hm2,通过耕地整理可增加有效耕地1 482.09 hm2,耕地利用率提高潜力为6.9%,其中一级潜力区主要分布在密云县的西南部,面积10 930.61 hm2;二级潜力区面积主要分布密云的西南和东北部,面积为6 479.97 hm2;三级潜力区面积为3 875.65 hm2。[结论]密云县耕地整理潜力较大,空间分布上以西南部为主。     

山西省太原市万柏林区农用地等级评价研究

以万柏林区为例,对农用地等级分别评定的方法进行了实证研究,结果表明:等级分别评定条件下,等的内涵为“农用地粮食生产能力的高低”,评价因素为土壤肥力因素,级的内涵为“农用地作为建设用地潜在收益能力的高低”,评价因素为自然环境因素和区位因素;应用等级分别评定方法得到的等级结果,可以表达出等级不分和等内定级所不能表达的信息;等级在不同比例尺条件下分别评定时,不能采用修正法定级。