黄土高原沟坡地土地生产力评价的指标体系与评价方法

通过对渭北黄土高原地区沟坡地土壤理化性质的分析和对当地社会经济状况的调查研究,应用层次分析法对沟坡地上地自然生产力和现实生产力进行了分析和评价。在分析过程中,把当地主要造林树种根系垂直分布特征及其根系抗旱性特性纳入了分析评价体系。结果表明,嘴头村和西坡村不同树种沟坡地上刺槐(Robinia pseudoacacia)的自然生产力属于中等稍微偏上水平,而山杏(Prunus armeniacia var.ansu)、油松(Pinus tabulaeformis)和侧柏(Platycladus orientalis)的自然生产力水平则较低。两地沟坡地上的现实生产力计算结果则证明刺槐和山杏两个树种表现出了较高的水平,具有较好的发展前途;而油松和侧柏的现实生产力水平则较低,其发展推广受到了限制。群众对沟坡开发治理的态度和对开发方案的认可对沟坡开发的成功起到了重要作用。

气候变化和长白山岳桦树线树木年轮的关系(英文)

通过对生长在海拔1950m岳桦的树轮生长特征和气候关系的分析,评价了长白山树线对气候因子的敏感性。结果表明,长白山岳桦树线对气候因子有明显的敏感性,与其它研究不同的是,影响树线处岳桦生长的主要气候因子并不是当年夏季的温度,而是上年冬季的平均最低温度和当年3月的温度。尽管研究区降水量很大,但年轮宽度与上年冬季和当年春季的降水呈显著相关。另外,由于气候因子的年际变化对岳桦径向生长没有明显的影响,因此自20世纪80年代以来的年平均温度的升高并没有在年轮宽度上表现出持续的增加。图2表5参39。

土壤的年龄

通过文物考证,地质历史及14C测定的资料对多种土壤推断,大部分土壤形成的年龄约在二千年前到一万年之间,提出土壤来之不易,要爱惜土壤资源,保护和合理利用土壤资源。

乙草胺胁迫对土壤真菌拮抗功能和假单胞菌以及芽胞杆菌群落结构的影响

真菌拮抗功能是自然健康土壤对病原真菌所具有的免疫能力,这种能力与土壤中许多可分泌拮抗物质的细菌有关,而假单胞菌和芽胞杆菌是目前研究最多的具拮抗功能的种群。乙草胺是北方使用量最大的除草剂,目前它的施用对土壤真菌拮抗能力的影响还未见报道。本文通过室内模拟培养,考察不同浓度乙草胺(0、50、150、250mg·kg-1土)对土壤真菌拮抗能力的影响,并运用PCR-DGGE(变性梯度凝胶电泳)方法研究真菌拮抗功能逐渐下降的土壤样品中假单胞菌和芽胞杆菌群落结构变化情况。结果表明,在实验室微宇宙条件下,乙草胺的施用会降低土壤真菌拮抗能力,在处理第12d时可以得到土壤真菌拮抗功能差异显著的土壤样品。土壤芽胞杆菌多样性随乙草胺浓度的升高而下降,而假单胞菌多样性变化不大。乙草胺胁迫下芽胞杆菌和假单胞菌群落结构都发生明显改变,尤其是芽胞杆菌(处理土壤样品与对照的群落结构相似性为0.60),且施加浓度越高,群落结构组成偏离自然土壤越远。真菌拮抗能力的降低与假单胞菌和芽胞杆菌多样性和结构的改变相关。

中国灵芝科资源及其地理分布Ⅰ

　依据标本,列出了中国的灵芝科(灵芝属灵芝组)种名、同物异名及其地理分布和生境。并以海南岛为例,简述了灵芝科的生态分布特征。

我国北方农牧交错带生态经济型畜牧业发展对策:以河北省张北县试区为例

简析了北方农牧交错带区域主要畜种的生态、经济适应性,提出草畜一体化生产模式,即在沙化耕地、退化草滩发展以青刈莜麦为主的人工草地,舍饲圈养绒山羊。

干燥方式对粮食硒和氟含量的影响

目的　查明不同干燥方式对粮食硒、氟含量的影响,选择最佳的粮食干燥方法。方法　运用流行病学调查法分类采集大巴山区不同干燥方式下的粮食样品。硒的测定用DAN荧光分光光度法,氟的测定用氟离子选择电极法。结果　与日晒干燥方式相比,敞烧煤火熏烤可使粮食中的硒、氟含量同时成倍甚至成数百倍增加,降氟炉灶烘烤能有效降低粮食干燥后期的硒、氟污染。结论　在大巴山区应摒弃敞烧煤火熏烤的粮食干燥方法,推广使用降氟炉灶并倡导日晒干燥粮食法

Analysis of arable land loss and its impact on rural sustainability in Southern Jiangsu Province of China

Rapid urbanization and industrialization in southern Jiangsu Province have consumed a huge amount of arable land. Through comparative analysis of land cover maps derived from TM images in 1990, 2000 and 2006, we identified the trend of arable land loss. It is found that most arable land is lost to urbanization and rural settlements development. Urban settlements, rural settlements, and industrial park-mine-transport land increased, respectively, by 87 997 ha (174.65%), 81 041 ha (104.52%), and 12 692 ha (397.99%) from 1990 to 2006. Most of the source (e.g., change from) land covers are rice paddy fields and dryland. These two covers contributed to newly urbanized areas by 37.12% and 73.52% during 1990-2000, and 46.39% and 38.86% during 2000-2006. However, the loss of arable land is weakly correlated with ecological service value, per capita net income of farmers, but positively with grain yield for some counties. Most areas in the study site have a low arable land depletion rate and a high potential for sustainable development. More attention should be directed at those counties that have a high depletion rate but a low potential for sustainable development. Rural settlements should be controlled and rationalized through legislative measures to achieve harmonious development between urban and rural areas, and sustainable development for rural areas with a minimal impact on the ecoenvironment. (C) 2009 Elsevier Ltd. All rights reserved.

Structures and electrochemical characteristics of Ti0.26Zr0.07V0.24Mn0.1Ni0.33Mox (x=0-0.1) hydrogen storage alloys

Microstructures and electrochemical properties of Ti0.26Zr0.07V0.21Mn0.1Ni0.33Mox (x=0,0.025,0.05,0.075, 0.10) electrode alloys have been investigated. The results of XRD analysis show that the alloys are mainly composed of V-based solid solution phase with body centered cubic (bcc) structure and C14 Laves phase with hexagonal structure. The addition of Mo element can imp ove the activation characteristics, maximum discharge capacity and cyclic durability for the electrode alloys