黄河流域农业持续发展中的生态环境问题   总被引：1，自引：1，他引：1  

罗其友  宫连英 《干旱区研究》1995,12(1):11-14

黄河流域大部分地区地处半干旱，半温润偏旱地带，生态环境十分脆弱，本文分析、评价了黄河流域农业持续发展中的主要生态环境问题及其建设成就，并讨论了良化生态环境的一些基本对策。  相似文献   

陕北黄土高原多沙粗沙区乡村聚落土壤水蚀定位观测研究     

岳大鹏  甘枝茂  甘锐  查小春 《干旱区资源与环境》2005,19(6):142-146

为研究乡村聚落的土壤侵蚀,在陕北榆林、绥德、延安建立观测站,于2003年对乡村聚落中的户间道路、户间空地、院落在降雨时的次径流泥沙含量、平均含沙量、次侵蚀强度及观测期降雨形成的总侵蚀强度,进行了观测与分析。其观测结果,均说明户间道路、户间空地径流平均含沙量较大,榆林为29.37g/L、29.96g/L,缓德为21.06g/L、17.53g/L、延安为54.6g/L2、9.18g/L,而院落平均径流含沙量较小,榆林、绥德、延安分别为9.47g/L、8.64g/L、14.87g/L。观测期降雨侵蚀总强度,三个观测站均以户间道路最大,分别为1142t/km2、2156.6t/km26、285.7t/km2;户间空地次之,分别为744.5t/km2、1192.6t/km2、1953.2t/km2;院落较小,分别为161.1t/km23、78.7t/km2、1274.3t/km2。说明乡村聚落土壤侵蚀不可忽视,应加强防治。  相似文献   

Bush cover and range condition assessments in relation to landscape and grazing in southern Ethiopia   总被引：6，自引：0，他引：6  

Oba  Gufu  Post  Eric  Syvertsen  P.O.  Stenseth  N.C. 《Landscape Ecology》2000,15(6):535-546

Progressive growth of bush cover in dry savannahs is responsible for declines in range conditions. In southern Ethiopia, the Booran pastoralists assisted our understanding of spatial patterns of bush cover and range conditions in 54 landscape patch types grouped into six landscape units within an area of 30000 km². The size of landscape patches sampled was 625 m². We assessed the relationships between bush cover, grass cover and bare soil and grazing pressure and soil erosion and changes in range condition. Externally, political conflicts and internally, break down of land use, and official bans on the use of fire promoted bush cover and the decline in range conditions. Bush cover was negatively correlated with grass cover, and positively correlated with bare soil. Grass cover was negatively correlated with bare soil and grazing pressure in most landscape patch types. Grazing pressure was not significantly correlated with bush cover or bare soil, while soil erosion was directly related to bare soil. Soil erosion was absent in 64% of the landscape patch types, and seemingly not a threat to the rangelands. The relationship between bush cover, grass cover, bare soil and soil erosion is complex and related to climate, landscape geology, and patterns of land use. Main threats to range conditions are bush climax, loss of grass cover and unpalatable forbs. Currently, >70% of the landscape patch types are in poor to fair range conditions. Decline in range conditions, unless reversed, will jeopardise the pastoral production system in southern Ethiopia.  相似文献   

人为干扰对典型草原土壤侵蚀影响的价值评价   总被引：1，自引：0，他引：1  

许中旗  赵盼茹  王英舜  许晴  李文华  闵庆文 《中国草地学报》2007,29(2):1-6

基于不同干扰条件下典型草原风洞试验的研究结果,计算了风蚀所造成的各种损失(养分、有机碳的损失及废弃地的形成等等),在此基础上,定量评价了人为干扰对土壤侵蚀过程的影响。研究结果表明,禁牧可以明显减小由风蚀所导致的草原生态系统的价值损失,而开垦和放牧则会增加其价值损失(包括速效养分、有机碳和废弃地形成)。总的来看,不同风速下不同生态系统的价值损失速率由大到小的排列顺序为:新开垦农田>农田>自由放牧草原>2003年禁牧草原>1987年禁牧草原;同时,风速越大不同干扰类型之间的价值损失差值越大。  相似文献   

Results of grid keratotomy, superficial keratectomy and debridement for the management of persistent corneal erosions in 92 dogs   总被引：2，自引：0，他引：2  

Stanley RG  Hardman C  Johnson BW 《Veterinary ophthalmology》1998,1(4):233-238

Ninety-two cases of persistent corneal erosions in dogs were analyzed for breed, gender, age and which eye was affected. The results of the treatment of 92 persistent corneal erosions in dogs by superficial keratectomy (SK), grid keratotomy (GK), or debridement with a sterile dry cotton swab are presented. These techniques gave better rates of healing than have been previously reported. All cases of persistent corneal erosions healed in this study. However, it must be noted that three cases treated with debridement only failed to heal after several treatments and were eventually treated with SK. After one procedure 80 out of 92 (87%) had healed. After one procedure, 63% of cases treated with debridement healed, 100% of cases treated with SK healed, and 85% of cases treated with GK healed. At the first postoperative visit, 88% (21/24 cases) of ulcers treated by SK had healed, and 75% (39/52 cases) of ulcers treated by GK had healed. Only 25% of the persistent corneal erosions had healed at the first visit after debridement. All 24 cases of persistent corneal erosions treated with SK healed after one treatment in a mean +/- SD of 9.3 +/- 3.9 days (median of 7 days). Fifty-two cases were managed with GK; 44 (83%) of these healed with one procedure and eight cases required a second GK procedure to resolve. A mean +/- SD of 13.4 +/- 5.1 days (median of 11.5 days) following GK was required for the persistent corneal erosions to heal. Nineteen cases were initially managed by debridement with a dry cotton swab under local anesthesia. Sixteen out of these 19 debridement cases healed (giving an overall healing rate of 84%) in a mean +/- SD time of 23.4 +/- 11.1 days (median 21.5). There were three cases that did not heal with debridement. These cases were debrided at 10-20 day intervals for 30-60 days, and were then treated with SK. Two of these cases healed within 7 days, the other case required 18 days to heal. Sixty-three per cent of persistent corneal erosions treated with debridement healed after one procedure; however, only four out of 19 cases (21%) were healed at the first revisit. Complications were rare: corneal edema occurred in two cases following multiple GK, and excessive granulation tissue in one case was managed with a SK. There was the occurrence of an ulcer adjacent to the surgery site in four cases, two cases following GK and two cases following SK.  相似文献   

沙漠地区农业种植技术初探   总被引：2，自引：1，他引：1  

翟志忠  阿腾格 《内蒙古林业科技》2000,(3):19-23

沙漠地区在没有造林或造林初期防护效益不显著情况下，农业种植受风沙危害比较严重，提高农业种植产量是我们面临的一道难题。本文对中国林科院沙漠林业实验中心井灌区第四实验场风沙环境和三年来的种植情况进行分析，得出农业防风害的措施有以下几个方面：农作物品种的选择；种植时间的调整；以增加起动风速为目的的各项抗风害措施的采用；以减小风沙流强度和目的的阻沙林和固沙工程的建造。这些措施能有效地减小和防止风沙灾害的发  相似文献   

Erosion rates obtained from check-dam sedimentation (SE Spain). A multi-method comparison     

A. Romero-Díaz  F. Alonso-SarriáM. Martínez-Lloris 《CATENA》2007

The main aims of this article are to calculate the erosion rates from sediments accumulated in the check dams and to compare the results with those of other methodologies.  相似文献   

林火对长白山自然保护区风灾区土壤性质的影响     

金慧  赵莹  赵伟  尹航  范宇光  秦立武  代玉红 《吉林林学院学报》2013,(6):698-703

以2012年长白山国家级自然保护区西坡风灾区森林火灾为研究背景，采用常规土壤分析方法研究了不同火烧强度下土壤理化性质的变化情况．结果表明：火烧后土壤容重和土壤含水率随火烧强度的增强显著下降；0～6cm土壤pH，土壤有机质，土壤全C、全N、速效P、速效K质量分数经轻度和中度火烧后均呈显著增加趋势；在火烧强度因子的控制下，对各养分质量分数进行的偏相关分析显示，除土壤pH外，其他各养分间存在显著的相关性．  相似文献   

Using the VS‐Fast methodology for soil degradation assessment: a case study from Senegal     

B. G. J. S. Sonneveld  D. Ndiaye 《Soil Use and Management》2012,28(4):625-634

Soil degradation threatens sustainable food production and accelerates global warming. Poorer countries, whose agricultural sectors are highly dependent on their natural resource bases, are hit particularly hard by declining soil productivity. Calls for soil‐quality monitoring are therefore, justified and this could inform decision‐makers on the preparation of appropriate interventions. However, the provision of monitoring methodologies is not an easy task. Soil degradation affects several soil characteristics that at larger scales cannot be evaluated with models or remote‐sensing techniques. Therefore, this study focuses on investigating the use of field‐based soil assessment methodologies to differentiate degrees of soil degradation. Specifically, we test the Visual Soil Field Assessment Tool (VS‐Fast) for detecting and monitoring soil degradation using a cross‐section of 71 sites in Senegal, the soil quality of which were classed by local experts. We found low correlation between VS‐Fast classes and expert assessments. By using an ordered logit model to quantify class boundaries, we show that experts categorized areas as ‘degraded’ for a wider range and higher VS‐Fast scores than the corresponding VS‐Fast class. Yet, from general linear models and analysis of variance procedures we found that areas classed by experts as ‘degraded’ had statistically significant lower VS‐Fast scores compared to those that were judged as ‘normal’ and ‘good’, while differences of the VS‐Fast scores between the latter two were negligible. It is remarkable that the visual assessment, the cheaper component of the VS‐Fast score, performs better in differentiating degradation status than its measured counterpart. The results support the need to investigate the applicability of other VSA methodologies that only use field observations and tactile methods.  相似文献   

水保林水源涵养与防止侵蚀效益评价信息系统     

冯秀兰  王礼先 《河北林果研究》1998,13(1):22-26

密云水库上游水源保持林水源涵养与防止土壤侵蚀效益评价信息系统是以管理信息系统理论为指导，按照信息系统的设计流程研制开发的，为水源保护林水源涵养与防止土壤侵蚀效益评价及预测的专题性系统。  相似文献