基于标准化土壤湿度指数的滦河流域农业干旱评价

干旱是造成农业生产损失的主要灾害之一,及时、准确地监测农业干旱对于降低作物生产损失具有重要意义.本研究基于土壤含水量历史时间序列数据构建了标准化土壤湿度指数,分析了滦河流域2002-2019年干旱时空分布变化规律,并对农业干旱进行定量评价.结果表明:研究期间,滦河流域内大部分栅格单元土壤含水量在时间上以正态分布为主,少...     

The effect of agricultural practices on the development of indigenous arbuscular mycorrhizal fungi. II. Studies in experimental microcosms

Two glasshouse experiments were performed to assess the development and metabolic activity of mycorrhizas formed by isolates of arbuscular mycorrhizal fungi (AMF) from three different genera, Acaulospora, Gigaspora and Glomus on Desmodium ovalifolium L. plants. In the first experiment the effect of disturbance of a pre-established extra-radical mycelium (ERM) was studied. In the second experiment the effect of phosphate addition as either organic matter (OM) or fertiliser was studied. Disturbance of a pre-established ERM reduced the formation of mycorrhizas by Gigaspora rosea (BEG111) and increased that by Glomus manihotis (BEG112) on D. ovalifolium plants. Acaulospora tuberculata (BEG41) failed to form mycorrhizas in the experiment. Either Gi. rosea (BEG111) or G. manihotis (BEG112) appeared to be the major component of the colonisation resulting from treatments with combinations of two or three of the AMF and determined the sensitivity of these treatments to disturbance of a pre-established ERM. The addition of phosphate fertiliser (10 mg P kg^-1) reduced mycorrhiza formation by each species of AMF compared with the addition of OM (10 mg P kg^-1). This work indicates that AMF from different genera respond differently to management by agricultural practices when in association with a tropical legume. Clearly, there is potential to alter the formation of mycorrhizas of AMF from different genera, through the use of agricultural practices. The significance of the development and metabolic activity of mycorrhizas formed by AMF from different genera for plant growth is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Early Utilization of Flood-Recession Soils as a Response to The Intensification of Fishing and Upland Agriculture: Resource-Use Dynamics in a Large Tikuna Community

The optimal use of Amazonian flood-recession soils in contexts of dense settlement is, according to many anthropologists, agronomists, and ecologists, the cultivation of proteinaceous cereals and legumes. Storable protein is thought to be necessary for nutritional security through the fish-poor season. Campo Alegre, a Tikuna floodplain community of over 1300 people, is one of the largest indigenous Amazonian communities in the contemporary ethnographic record. Furthermore, some two-thirds of its agricultural production is directed toward market sale. However, in the summers of 1994 and 1995, residents cultivated no proteinaceous crops on their extensive floodplain to store for later consumption. Their utilization of these soils, a relatively new resource for them, is best understood in relation to the intensification of two traditional resource bases—fisheries and upland soils, the resulting pressures on their production flows, and the desire to maintain them.     

<卡塔赫纳生物安全议定书>及其对转基因农产品国际贸易和生物技术发展的影响与对策

《生物多样性公约》缔约国,为了现代生物技术生产的活性转基因生物（ＬＭＯ）的安全转移和使用,保护人类健康和生物多样性,经过５年的艰苦谈判,于２０００年初通过了《卡塔赫纳生物安全议定书》,成为第一部有关ＬＭＯ的国际法。该《议定书》确认了预先防范原则,允许缔约方禁止或限制ＬＭＯ进境,并要求含有ＬＭＯ的货物附有标签。作者预测了《议定书》对转基因农产品国际贸易和生物技术发展的影响,并对我国应采取的对策提出了     

农田灌溉对印度区域气候的影响模拟

为满足人类对粮食的需求,全球灌溉农田面积迅速扩张,农田灌溉对区域气候的影响引起广泛地关注。利用区域环境系统集成模式(RIEMS2.0)和最新的土地利用变化资料,选取农田灌溉面积最大的印度区域作为研究区域,进行雨养农田和灌溉农田的对比试验,探讨农田灌溉对区域气候的影响。结果表明:(1)农田灌溉使得印度区域年平均气温降低1.4℃,年平均降水率增加0.35mm/d。农田灌溉对印度区域气候的影响存在明显的季节波动,季风前期及6月份该区域气候对下垫面变化的响应最为敏感;7-9月各气候要素变化较小。(2) 农田灌溉使得印度区域地表净辐射增加,且地表净辐射在潜热通量和感热通量之间的分配发生了较大的改变,潜热通量增加,感热通量减少;对地表起冷却作用;同时由于土壤湿度增加,蒸散作用增强,大气中水汽含量增加,潜热不稳定能量增加,导致对流性降水增加。     

农田土壤磷素淋溶及其预测

农田土壤磷的淋溶损失,不仅造成肥料利用率降低、农业生产成本上升,还能引起地下和地表水体富营养化。在综合大量中外文献的基础上,阐述了农田土壤磷素淋溶问题的提出、淋溶对水体富营养化的贡献、淋溶液中磷素的形态及其比例、影响土壤磷素淋溶的因子、淋溶机理、预测方法,并对农田土壤磷素淋溶及其预测作了展望。     

第2代杉木幼林生态系统水化学特征

对第 2代杉木幼林生态系统的降雨、穿透水、茎流、地表和地下径流等水文过程中 N、P、K、Ca、Mg、Cu、Fe、Zn和 Mn9种养分元素含量进行了连续 5 a的测定 ,结果表明 :降雨通过林冠后其化学特性发生明显变化 ,p H值出现酸化现象 ,穿透水中 Zn和 Org-N为负淋溶 ,其余各元素浓度有所增加。树干茎流的富集作用比穿透水强 ,其中 Zn为负 ,其它元素的浓度均比林外降雨的高。地表径流中 Zn>Org-N>NO3 -N,与降雨中含量相比较为淋失迁移型 ,Ca>K>Cu>Mg>P>NH4 -N>Mn>Fe为内贮型 ,p H值增大。地下径流中 Zn>Org-N>NH4 -N>K>Mn为淋失迁移型、Ca>Mg>Cu>NO3 -N>P>Fe为内贮型。该系统的水循环中 Ca>Mg>Fe>P为净损失、Zn>K>Org-N>NH4 -N>Mn>NO3 -N>Cu为净积累 ,与第 1代杉木林相比 ,第 2代杉木幼林水化学过滤与吸贮功能较差 ,系统稳定性也较弱 ,生态功能的恢复需要一定的时间     

中国农田土壤N2O排放通量分布格局研究

中国作为世界上一个重要农业大国,对全球大气中N2O浓度的影响正在引起人们的普遍关注。该研究采用针对农业土壤痕量气体排放估算建立的,基于N2O的产生、传输和消耗机理的反硝化分解（DNDC）模型,在建立了有关中国气候、农业土壤和农业生产的分县数据库基础上,估计了我国各县农业土壤N2O的排放通量,发现我国农田土壤N2O排放通量有较明显的地区差异,西北地区较低,东南地区较高。还发现无论温度升高,还是施肥量变化,对我国农田土壤N2O排放通量的影响,都存在区域差异,表现为东南地区的变化幅度较西北地区大,这可能与我国气候的干湿变化有较密切的关系。     

鼎湖山森林地表水水质状况分析

对鼎湖山生物圈保护区内两溪流水源水质状况进行了调查,结果发现：①鼎湖山地表水总体水质较好,符合地面水环境质量标准的I类水源水质标准。区内水体受污染程度低,绝大多数指标均符合饮用水卫生标准。②水体pH值较低,Al含量较高,总有机碳测定表现出整个水体受到一定程度的有机污染。水体中有害金属Mn和Pb含量略高,但都远低于饮用水卫生标准。③对地表水来源过程环节的水化学分析比较表明：大气降水、穿透水、土壤溶液（30cm层和80cm层）和地表水水样的pH值呈现“M”形变化。酸雨和土壤表层酸化是该区地表水pH值偏低的主要原因。地表水和30cm土壤溶液中的Al浓度分别是大气降水的5倍和8倍,地表水中的Al主要来源于酸雨对土壤的淋溶。地表水中的Na主要来源于大气降水。大气降水Pb浓度是地表水的17倍,林冠吸收富集和土壤固定吸附使地表水中的Pb大幅度降低。穿透水和土壤溶液中的Mn、K、Ca、Mg、Sr比大气降水和地表水浓度高,反映了元素被酸雨淋溶、活化和被植物、土壤吸收吸附的过程。从长远看,尽管在森林保存完好的地区,区域环境的恶化及酸雨对地表水水质的影响仍不容忽视。