沙漠边缘地区苹果园节水栽培研究   总被引：3，自引：0，他引：3  

赵长增 《中国沙漠》1996,16(1):65-70

对沙漠边缘地区苹果园进行地面覆盖，可明显地减少水分蒸发和提高土壤水分的利用率，从而促进果树的生长发育．覆盖措施以地面覆草效果最好，可提高土壤含水量５０％，新梢生长量、单叶面积和叶绿素含量分别比对照高５７％、３０％和５９％，并提高了苹果的品质和产量。因此，覆盖是沙漠边缘地区果园重要的节水措施之一．  相似文献   

A Study on Soil Erosion in Pasighat Town (Arunachal Pradesh) India   总被引：1，自引：1，他引：1  

Tewari  Prakash 《Natural Hazards》2004,32(2):257-275

Pasighat which lies on the foothills of the Himalayas is one of the important townsof Arunachal Pradesh. A very turbulent river named Siang flows through the townand causes frequent flash floods, inundating the low-lying areas. This river and townis also under threat due to continuous soil erosion. This soil erosion affects theneighbouring state of Assam as well. Due to the soil erosion this river known asBrahmaputra in Assam is constantly changing its course making a large numberof water channels with sand bars thus inundating vast cultivable land every year.The study analyses the cause of the problem at Pasighat in the backdrop of theexisting river system, morphology and the geographical evolution of the TransHimalayas.  相似文献   

测绘专业高等专科毕业生动手能力的培养     

朱春晓 《测绘与空间地理信息》2002,25(2):48-封三

从高等专科教育培养目标与毕业生的基本要求出发 ,阐述专科毕业生动手能力培养的重要性 ;介绍工程测量专业毕业生必经掌握的基本操作技能与动手能力培养的方法和途径 ,阐述指导教师应具备的条件等  相似文献   

矿山测量应用型人才培养的实践与思考     

陈国良  顾和和  李钢  马昌忠 《测绘工程》2008,17(1):78-80

针对矿山测量人才培养的现状及存在的问题,从培养目标、能力体系、培养方案、课程体系优化等方面入手,探索应用型矿山测量人才的培养模式,提出了一系列具体措施。  相似文献   

Extreme climate events,migration for cultivation and policies:A case study in the early Qing Dynasty of China   总被引：6，自引：0，他引：6  

FANG XiuQi    YE Yu & ZENG ZaoZao School of Geography  Beijing Normal University  Beijing  China  Institute of Geographical Sciences  Natural Resources Research  Chinese Academy of Sciences  Beijing  China 《中国科学D辑(英文版)》2007,50(3):411-421

Based on the historical records of the annual increase in the workforce (men older than 16 years of age), the annual new taxed cropland in the Shengjing area (Northeast China), the extreme climate events in North China, and related management policies in Northeast China during 1661―1680, a case study has been conducted to investigate the relationship between the extreme climate events in North China and the migration to Northeast China for cultivation. This study has found that the migration to Northeast China for cultivation from 1661 to 1680 was a response to the drought events that occurred in North China. The upsurge of migration, which occurred in 1665―1680, was a response to the drought period during 1664―1680 in North China while the fewer disasters period in Northeast China. There were three migratory peaks during the upsurge of migration, which corresponded to the three drought events. The peaks of migration, however, often lagged behind the drought events about 1―2 years. The encourag-ing-migration policy, which was adopted to encourage cultivation in Northeast China, did not produce much migration into the region in the early Qing Dynasty. It did, however, provide a policy background, which ensured more than 10000 migrants per year to Northeast China when North China suffered from drought/flood disasters. As a response to the highest peak of migration induced by the severe droughts in North China during 1664―1667, a prohibiting-migration policy restricted further migration to Northeast China was carried out in 1668. Although the prohibiting-migration policy could not entirely stop the migrants fleeing from famine in North China to Northeast China, the migrants and cultivation were significantly reduced under the policy. The frequent changes of the policy on the years when taxation started after the land was cultivated were also related to climate events. The extreme climate events in North China, migration to Northeast China for cultivation, and the related management poli-cies showed an impact-response chain, which reflected the interaction among extreme climate events, human behavior, and policies.  相似文献   

豫北沙地油桃设施促早栽培技术研究     

张华  李晓云  荔克让 《中国沙漠》2000,20(Z2):141-145

油桃设施促早栽培是国内近年来兴起的一项高新农业技术,为了促进油桃设施栽培在豫北沙地的稳步发展,使之成为沙地高效开发的果产业之一,本文根据果树设施栽培环境因子的变化规律,借鉴国内油桃设施栽培的成功经验,结合豫北沙地自然、社会经济的状况,建立沙地油桃高效设施栽培模式,提出适宜的设施类型、结构,适栽品种,配置模式,栽植密度及配套栽培管理技术。  相似文献   

海藻栽培——传统方式及其改造途径   总被引：6，自引：1，他引：5  

费修绠  鲍鹰  卢山 《海洋与湖沼》2000,31(5):575-580

目前所有的海藻栽培技术和方法都是以在对藻类个体和群体的了解为基础的,这就是传统海藻栽培业的基础和出发点.现代生命科学和生物技术的进展和进步已使陆地的农业和医学大为受益,但传统的海藻栽培业还很少应用这些最新的科技成果.实际上自从建立以来最基本的栽培技术没有发生大的变化,这是因为在相当长时期内海藻栽培在技术上比较保守,有许多有待解决的问题,其中最主要的有六个方面.新的栽培种类需要增加,新的技术需要发展和应用,存在的问题需要得到解决和改进.本文就传统海藻栽培业中当前存在的主要问题,可能的改造途径以及它未来的发展方向进行了讨论.  相似文献   

A new method to characterize the spatial structure of soil macropore networks in effects of cultivation using computed tomography          下载免费PDF全文

Youbing Hu  Jie Feng  Tao Yang  Chao Wang 《水文研究》2014,28(9):3419-3431

Soil macropore networks are subsurface connected void spaces caused by processes such as fracture of soils, micro‐erosion and fauna burrows. Axial X‐ray computed tomography (CT) scanning provides a convenient means of recording the spatial structure of soil macropore networks. The objective of this study were to (1) based on CT technique and GIS digitized image method, construction a new technique for tracing, visualizing and measuring the soil macropore networks and (2) investigate the effects of farming activities on soil macropore networks characteristics. Our technique uses left‐turning and nine‐direction judgment methods, a combination of the layer‐by‐layer analysis method and the up‐down tracking algorithm. The characteristics for the overall structure patterns of macropores, the spatial distribution of the macropore networks and each single macropore network can be conveniently identified by our technique. Eight undisturbed soil columns from fields with two distinct land uses (under cultivation and not been cultivated) and four different depths (0–20, 20–40, 40–60 and 60–80 cm) were investigated. The soil columns were scanned using X‐ray CT at a voxel resolution of 0.075 × 0.075 × 3.000 mm. Results indicate that farming activities can destroy the initial structure of macropores, and those remaining are mainly small‐sized and medium‐sized networks with lower extension and hydraulic conductivity. The network properties show a significant difference between upper and lower layer. The results can provide beneficial reference to further research centered on non‐equilibrium flow prediction and chemical transport modeling in field soils. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Phytoremediation of heavy metal‐contaminated water and sediment by Eleocharis acicularis     

Masayuki Sakakibara  Yuko Ohmori  Nguyen Thi Hoang Ha  Sakae Sano  Koichiro Sera 《洁净——土壤、空气、水》2011,39(8):735-741

Phytoremediation is an environmental remediation technique that takes advantage of plant physiology and metabolism. The unique property of heavy metal hyperaccumulation by the macrophyte Eleocharis acicularis is of great significance in the phytoremediation of water and sediments contaminated by heavy metals at mine sites. In this study, a field cultivation experiment was performed to examine the applicability of E. acicularis to the remediation of water contaminated by heavy metals. The highest concentrations of heavy metals in the shoots of E. acicularis were 20 200 mg Cu/kg, 14 200 mg Zn/kg, 1740 mg As/kg, 894 mg Pb/kg, and 239 mg Cd/kg. The concentrations of Cu, Zn, As, Cd, and Pb in the shoots correlate with their concentrations in the soil in a log‐linear fashion. The bioconcentration factor for these elements decreases log‐linearly with increasing concentration in the soil. The results indicate the ability of E. acicularis to hyperaccumulate Cu, Zn, As, and Cd under natural conditions, making it a good candidate species for the phytoremediation of water contaminated by heavy metals.  相似文献   

从清代新疆屯垦政策角度谈屯田与生态环境的关系——以天山北路东部屯垦为中心     

刘超建 《干旱区地理》2015,38(2)

近年来,清代新疆屯田与生态环境的关系已成为研究热点。但多数只是从经济史或社会史的角度,作为研究的出发点,只注重了屯田对环境所造成的负面影响,对其正面影响多无涉及,得出屯田是造成土地沙漠化扩大的主要因素。事实上,这样的结论并不符合历史事实。为此,选取清代天山北路东部屯垦作为研究对象,运用历史农业地理的理论与方法,在小尺度的范围内,探求屯垦政策下所进行的农业开发与生态环境变化之间的互动性,以求对二者之间关系有个正确的定位。其主旨不是就清代屯田对生态环境影响进行的重新研究,而是从屯垦政策的角度,通过对清代移民人口、屯田规模、农业技术选择、土地权属及在屯田过程中所形成相关人文要素进行探讨,并由此所引起的屯田与生态环境的关系进行分析。结果表明屯田对生态环境影响主要表现在其积极的方面上,即戈壁变为绿洲,而不是所说的屯田引起沙漠化扩大,也就是说,其负面影响并不突出。这样就为我们能够正确认识清代新疆地区环境变迁提供了理论及事实上的支持。从而得出,自然本身、战争等其它要素,应该是环境变迁的主要因素。  相似文献