首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10篇
  免费   0篇
环保管理   1篇
综合类   1篇
基础理论   1篇
社会与环境   7篇
  2016年   1篇
  2014年   1篇
  2012年   1篇
  2011年   1篇
  2009年   1篇
  2007年   1篇
  2003年   1篇
  2002年   1篇
  1997年   1篇
  1993年   1篇
排序方式: 共有10条查询结果,搜索用时 31 毫秒
1
1.
The results are presented that have been obtained in studies on changes in the species composition, geobotanical characteristics, and productivity of natural vegetation in arid steppes of the Cisural region during the past few decades (1977–2012). Consideration is given to the significance of the soil factor in the processes of transformation of zonal vegetation. The increasing role of arid steppes as a natural barrier to desertification is demonstrated.  相似文献   
2.
An attempt has been made to make a comprehensive assessment of biological factors in the ecology of humus formation in forest-steppe and steppe chernozem soils of the Cisural region. Certain regional features in the effect of vegetation structure and composition and soil microbial and enzymatic activities on the humus state of zonal chernozem subtypes in virgin and plowed landscapes have been revealed.  相似文献   
3.
Data are presented that show the significance of the humus state of chernozem soils, their amphiphilic (hydrophobic-hydrophilic) components, and related physical properties (density, structural condition, and water permeability) for regeneration of natural vegetation and restoration of its species com-position in pasture ecosystems.  相似文献   
4.
Results are presented that have been obtained in studies on the effect of forests growing in the steppe zone on the conditions of formation and qualitative and quantitative composition of organic matter and on the properties of humus in chernozem soils of neighboring biogeocenoses.  相似文献   
5.
The influence of the Buzuluk Pine Forest on biodiversity of plants and soil properties in adjacent territories has been studied. The results show that in the immediate vicinity of the pine forest, under the influence of the relatively mild and humid mesoclimate, natural phytocenoses are dominated by mesophytic species. Biodiversity reaches a peak at a distance of 17–18 km from the forest, which is explained by the presence of both mesophytes and xerophytes in the same phytocenosis. The same zone is also characterized by the maximum diversity of soil properties and structural complexity of the soil cover. Grass communities on ordinary chernozems with a homogeneous soil cover, typical of the steppe zone, are formed at greater distances from the forest.  相似文献   
6.
The best groundwater resources in Finland are generally situated in glaciofluvial formations with thick sand and gravel deposits. The glaciofluvial formation of Jokkavaara, in northern Finland near the town of Rovaniemi, is important for both its groundwater reserves and its sand and gravel resources. The groundwater and mineral resources of Jokkavaara was studied to define their quantity and quality, and to develop a land-use plan which would help civil servants of the municipality to make the decisions necessary for exploiting sand and gravel. The land-use plan shows the areas where exploiting mineral resources is not allowed or recommended because of the risks of contamination of groundwater, or because of injurious effects on the environment caused by noise and dust from gravel pits, or by spoilt landscape. The size of Jokkavaara is 5 km2, and its mineral resources are about 53 million cubic metres. The sand and gravel deposits are at the most, 50 m thick. Risks of contamination by fallout are small, due to the thick sand and gravel deposits above groundwater level. Exploiting mineral resources have no effect on groundwater quality either. By the land-use plan and legislation, good groundwater can also be protected in the future. Legislation limits the exploitation of mineral resources especially in groundwater areas.  相似文献   
7.
Changes in the properties and ecological functions of soils under the effect of farming are considered. Evidence is provided that optimization of the structure of land inventory with regard to environmental conditions in a concrete region is a promising approach to the conservation and restoration of disturbed and degraded soils. A classification of soils with respect to their arability is proposed as a theoretical basis for reorganizing agricultural land use.  相似文献   
8.
Changes in the abundance and species compositions of the main groups of soil invertebrates have been analyzed in ecosystems long used as pastures and exposed to different degrees of grazing. The sum of the results makes it possible to conclude that the zoological method of indication of pasture ecosystems can be used in ecological monitoring of steppe landscapes.  相似文献   
9.
Samples of the slime mold Fuligo septica (L.) Wiggers were collected from an ecologically diverse selection of sites across the former USSR and in North Korea to determine their Zn concentrations. Plasmodia were collected from trees, rocks, soils, the walls of buildings and a variety of other materials and structures from 1990 to 1996. The biomass collected ranged from 305 to 968 mg, whereas Zn concentrations in plasmodia of F. septica ranged from 8400 to 23,000 mg kg(-1) dry wt. (mean and standard error = 14,200 +/- 860 mg kg(-1) dry wt.). No clear trend as to which areas produced F. septica with the highest Zn concentrations was discernable. Nor was it possible to identify any particular substrate on which F. septica grew that produced noticeably high Zn concentrations. For example, forest litter on which F. septica was found had Zn concentrations of only 25 to 130 mg kg(-1) dry wt. Our data confirm the only other study showing hyperaccumulation of Zn in F. septica, which was carried out in Finland. This ability seems to be unique to this species, but how or why it does this, or why such high Zn concentrations are not toxic to F. septica, are questions requiring future research.  相似文献   
10.
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号