黄河流域耕地生态安全动态演进及时空异质性

耕地生态安全是粮食安全的基础。基于国家公顷生态足迹模型测算2000—2021年黄河流域耕地生态安全，采用标准差椭圆和时空地理加权回归模型，揭示黄河流域耕地生态安全的时空演进特征，识别其驱动因素的时空异质性。结果表明：黄河流域耕地生态安全总体呈现"N"型变动趋势，仍具有较大提升空间。从空间格局来看，黄河流域耕地生态安全呈现"东北—西南"方向收缩、"西北—东南"方向扩散态势，耕地生态安全差距变大。城镇化、财政支农及降水有利于提高黄河流域的耕地生态安全，农村居民收入及化肥施用强度则具有抑制作用，各影响因素存在明显的时空分异性。     

兰州市园林绿化用土及绿地土壤质量管理现状与对策

通过研究分析表明：兰州市园林绿化用土紧缺，绿地土壤存在密实度高、有机质含量低、污染严重、土源短缺、养护管理缺乏科学性等问题，必须提高土壤改良的科学性和管理的有效性，确保兰州市园林绿化事业的可持续发展。     

Effects of Clear Polymer Film on Emergence and Survival of Direct Sown Native Vegetation

Clear, degradable polymer films are used with agricultural crops to alter the germination and growing environment and extend the length of the growing season. The film acts like a greenhouse, elevating temperatures and improving soil water. We examined the potential of polymer film to improve emergence and persistence of direct‐seeded native vegetation. A seed mix comprising three tree species and two shrubs was sown in early August 2015, with and without polymer film. The effect of duration of polymer film (from 0–10 weeks) on emergence and persistence was tested, and the effects of polymer film on temperature and soil moisture were monitored. Our hypothesis that polymer film would improve emergence was partially supported, with between 6 and 10 weeks of polymer film coverage increasing emergence of small‐seeded species above the level of the Control. The polymer film increased temperatures by an average of 5 °C and volumetric water content by up to 10%, compared with ambient conditions, and reduced fluctuations in soil moisture, which may have contributed to the increased emergence observed. Emergence was low across all treatments (range 0·2–47%). Our hypothesis that polymer film would improve persistence was not supported, with seedling numbers declining rapidly following removal of the polymer film and no differences between treatments in percentage persistence by the end of the experiment. We concluded that polymer film is a potentially useful tool for improving emergence of smaller‐seeded species in direct seeding for land restoration, although provided no benefit for emergence of the larger‐seeded species. Copyright © 2017 John Wiley & Sons, Ltd.     

山区县耕地保护研究——以西林县为例

受自然条件的影响,山区的耕地保护工作难度加大。以广西西林县为例,运用主成分分析法分析发现,影响西林县耕地保护的主要因素是退耕还林,通过单对西林县标准分配面积的时空差异状况分析西林县耕地保护和生态保护存在的问题,提出了协调西林县耕地保护调控措施。     

Three decades following afforestation are sufficient to yield δ13C depth profiles

Vertical gradients in stable carbon isotope ratios (δ¹³C) in soil profiles can serve to approximate decomposition of organic matter under field conditions. This study tested the time (0, 30, and ≥ 150 y) required for the development of vertical δ¹³C profiles in topsoil by comparing arable, afforested and continuously forested sites, and showed that three decades following afforestation of former cropland are sufficient to develop distinct δ¹³C depth profiles.     

盐池沙地主要饲料灌木树种特性的观测

为了更好地提高灌木饲料林的经营管理水平,提高其利用率,在过去研究的基础上(李生宝等,1993,王　北等,1992),对饲料灌木树种的特性进行了研究。1　研究地区自然及社会经济概况研究地位于北纬37°47′～38°40′,东径106°42′～107°45′,为宁夏盐池县北部毛乌素沙地西南边缘。干旱少雨,风多沙大,光热资源丰富,年均气温77℃,1月平均气温-89℃,7月平均气温223℃,年温差312℃,≥10℃的积温29449℃,年日照时数28679ｈ,无霜期145ｄ,年降水量250～300ｍｍ,且主要集中在7、8、9几个月,约占全年降水量的60%以上,年变率大于30%,蒸发量是降水量的72倍…     

扶绥县蔗区耕地地力调查与发展对策

通过对广西扶绥县甘蔗种植的分布、生产情况以及当地耕作条件、耕地地力等情况进行调查,指出扶绥县甘蔗生产存在的主要问题,提出培肥耕地地力、加强灌溉设施建设、选用优良品种、推广机械化深耕深松技术、实行稻蔗轮作、推广甘蔗测土配方施肥技术、加强肥料市场监管力度等促进扶绥县甘蔗生产发展的对策。     

Impact of newly introduced perennial bioenergy crops on soil quality parameters at three different locations in W‐Germany

The land areas used for bioenergy crop cultivation are increasing across Europe. For several years now, various perennial crops have been cultivated, including Miscanthus , switchgrass and reed canary grass, and the newly introduced cup plant, giant knotweed, tall wheatgrass, virginia mallow, and wild plant mixtures. We investigated the impact that many of these perennial bioenergy crops (PECs) have on the soil organic C and N pools, microbial properties, and earthworm activity at three different study sites in W‐Germany with varying soil conditions after an experimental period of five years. Silage maize (Zea maize ) in rotation with green rye (Cecale cereale ) or Triticale was used for comparison (= annual energy crops; AEC). The overall intention of this study was to gain insights into the future trends of soil quality with changes in land‐use towards bioenergy production. Our results emphasized that in general, soil quality was improved through the cultivation of perennials. For example, after five years of investigation, the mean soil organic carbon contents increased, on average, by 1–2% at two of the three study sites, the soil microbial biomass increased from 13% (virginia mallow) to 27% (tall wheatgrass) (p < 0.05) compared to AEC treatment and the mean earthworm activity (cast production) was significantly improved in PECs compared to AEC. These trends were mainly found in silty to loamy soils, but the results were slightly different in sandy soils and dry climate conditions. We suggest that this might be traced back to unfavourable growing conditions for perennial crops during the first years of establishment. To our knowledge, this is the first comprehensive field investigation of the impact of these newly introduced perennial crops on soil quality indicators that considers various site‐ and soil‐specific growth conditions.     

新形势下热科院科研基地土地管理的对策研究

2006年初,中国热带农业科学院科研基地的院试验场下属的原宝岛公社5个单位的生产队(村)以多种方式要求退出试验场编制,严重影响了中国热带农业科学院科研事业的发展。院国有资产管理处经过一年多的详细调查,认真分析了中国热带农业科学院试验场土地管理中存在的问题,提出一些解决对策,以期探讨新形势下切实可行的科研基地管理模式。     

土地征用补偿分配过程中保护特殊群体权益的建议

土地征用补偿费分配不公、土地租赁款分配不公、同一情况村民不能得到同一标准补偿等问题已经成为涉农信访的主要问题,涉及到的人员主要是农村婚嫁妇女、小城镇户口人员等特殊群体,这些问题如果不能很好地解决将成为农村社会的不稳定因素。从特殊群体的介绍、侵害特殊群体利益的案例、问题产生的原因剖析以及可能的解决方法入手来阐释保护特殊群体利益的建议。