黑龙江流域中俄保护区现状及展望   总被引：1，自引：0，他引：1  

汪凌峰  史蓉红  张明海 《野生动物》2006,27(6):11-13

黑龙江地处中俄边界，在流域内中俄积极开展保护合作。本文分析了中俄在黑龙江两侧的保护区类型、保护对象，结果表明黑龙江流域的众保护区具有共同的保护对象，保护区的类型也惊人的相似。这些相同相似之处对于中俄保护合作深入发展有重要义。  相似文献   

沙土区薄壁连拱护岸墙试验与应用     

张玉建  沈波 《排灌机械》2005,23(6):46-49

沙土区薄壁连拱护岸墙为悬臂式支撑、薄壁连拱无底板结构，拱板中间采用无砂砼排水孔的钢筋砼肋形预制板，冲沉法施工，造价低廉；外形美观，抗倾、抗滑性能强。该墙为平原沙土区河道水土保持及修复找到了一条经济合理、施工方便、简便易行的护坡办法，具有较高的实用价值和广阔的推广使用前景。  相似文献   

护坦与丁坝在林区沿河公路防护中的应用     

林炳淦 《福建林业科技》2005,32(4):167-169

研究分析了丁坝和护坦在沿河林区公路路基防护中的作用、防护原理、设置方法、应用条件和有效性问题。  相似文献   

从土地覆盖变化看塔里木河中下游天然草地的退化     

徐海量  宋郁东  陈亚宁 《中国草地学报》2003,25(4):21-24

通过GIS技术和1990～2000年的TM影像图,分析了塔里木河中下游近10年的土地覆盖动态变化,结果显示:在塔里木河中下游地区,天然草地退化严重,高、中覆盖草地大幅减少,低覆盖草地的数量虽然增加但主要是流域河岸胡杨林群落退化后向荒漠灌丛草地演化的结果;而在自然环境更加恶劣的塔里木河下游地区,随着断流和地下水位的下降,天然草地正在向裸地和沙地演变。通过分析,提出了恢复塔里木河中下游天然草地的治理建议。  相似文献   

Trends in NE Atlantic landings (southern Portugal): identifying the relative importance of fisheries and environmental variables   总被引：7，自引：1，他引：6  

KARIM ERZINI 《Fisheries Oceanography》2005,14(3):195-209

Time series of commercial landings from the Algarve (southern Portugal) from 1982 to 1999 were analyzed using min/max autocorrelation factor analysis (MAFA) and dynamic factor analysis (DFA). These techniques were used to identify trends and explore the relationships between the response variables (annual landings of 12 species) and explanatory variables [sea surface temperature, rainfall, an upwelling index, Guadiana river (south‐east Portugal) flow, the North Atlantic oscillation, the number of licensed fishing vessels and the number of commercial fishermen]. Landings were more highly correlated with non‐lagged environmental variables and in particular with Guadiana river flow. Both techniques gave coherent results, with the most important trend being a steady decline over time. A DFA model with two explanatory variables (Guadiana river flow and number of fishermen) and three common trends (smoothing functions over time) gave good fits to 10 of the 12 species. Results of other models indicated that river flow is the more important explanatory variable in this model. Changes in the mean flow and discharge regime of the Guadiana river resulting from the construction of the Alqueva dam, completed in 2002, are therefore likely to have a significant and deleterious impact on Algarve fisheries landings.  相似文献   

Some determinants of the spatio-temporal fire cycle in a mediterranean landscape (Corsica,France)     

Mouillot  Florent  Ratte  Jean-Pierre  Joffre  Richard  Moreno  Jose Manuel  Rambal  Serge 《Landscape Ecology》2003,18(7):665-674

Based on recent needs to accurately understand fire regimes and post-fire vegetation resilience at a supra-level for carbon cycle studies, this article focusses on the coupled history of fire and vegetation pattern for 40 years on a fire-prone area in central Corsica (France). This area has been submitted since the beginning of the 20^th century to land abandonment and the remaining land management has been largely controlled by frequent fires. Our objectives were to rebuild vegetation and fire maps in order to determine the factors which have driven the spatial and temporal distribution of fires on the area, what were the feed backs on the vegetation dynamics, and the long-term consequences of this inter-relationship. The results show a stable but high frequency of small fires, coupled with forest expansion over the study period. The results particularly illustrate the spatial distribution of fires according to topography and vegetation, leading to a strong contrast between areas never burnt and areas which have been burnt up to 7 times. Fires, when occuring, affect on average 9 to 12% of the S, SE and SW facing slopes (compared to only 2 to 5% for the N facing slopes), spread recurrently over ridge tops, affect all the vegetation types but reburn preferentially shrublands and grasslands. As these fire-proning parameters have also been shown to decrease the regeneration capacity of forests, this study highlights the needs in spatial studies (both in terms of fire spread and vegetation dynamic) to accurately apprehend vegetation dynamic and functionning in fire-prone areas.This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献   

黑河流域水资源开发利用现状及存在问题分析   总被引：7，自引：0，他引：7  

蓝永超  康尔泗  张济世  胡兴林 《干旱区资源与环境》2003,17(6):34-39

本文根据有关资料对黑河流域水资源的数量、分布与变化特征进行了较为详细的阐述 ,并且从可持续发展的内涵出发 ,分析了该地区水资源开发利用中出现的问题及对策。结果表明 ,黑河流域水资源开发利用中所出现的种种问题固然与西北内陆地区气候干旱等先天不利条件有很大的关系 ,但最主要的原因还是人类对水资源的开发利用不当所造成的。因此 ,必须改变传统的以牺牲生态环境为代价的经济发展模式 ,社会经济发展应充分考虑流域水资源的制约条件。  相似文献   

柴达木盆地家畜育肥饲草料营养成份分析     

任玉英  杜铁瑛 《青海草业》2005,14(2):27-31

对柴达木盆地地产育肥饲草料进行了营养成份分析，结果表明，柴达木盆地地产饲草料育肥家畜的日粮配方，与省内其他地区育肥家畜日粮配方的营养水平基本相当，只是磷含量较少，应适当增加磷比例。  相似文献   

A Comparison of Two Herbaceous Cover Sampling Methods to Assess Ecosystem Services in High-Shrub Rangelands: Photography-Based Grid Point Intercept (GPI) Versus Quadrat Sampling     

Kristin B. Hulvey  Katherine Thomas  Eric Thacker 《Herpetological Monographs》2018,40(5):152-159

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Food resources and cyprinid diet in permanent and temporary Mediterranean rivers with natural and regulated flow          下载免费PDF全文

Carlos M. Alexandre  Sabrina Sales  Maria Teresa Ferreira  Pedro R. Almeida 《Ecology of Freshwater Fish》2015,24(4):629-645

This study addresses the differences in food availability, diet and feeding activity of the Iberian barbel, between permanent and temporary nonregulated rivers, and the effect of flow regulation on feeding parameters. A total of 267 adult barbels were seasonally collected in four nonregulated and regulated rivers from permanent and temporary basins, and their gut content was analysed. Locally available food sources were evaluated across sites and seasons. Barbels from the permanent nonregulated river exhibit a more variable and diversified diet in which invertebrates assumed a large importance, especially during high flows. Barbels from the temporary nonregulated river presented a more uniform diet composed of plant material and detritus, particularly in drought seasons. Flow regulation affected different flow components in both systems, but the effects on food resources and barbels' diet were similar, resulting in an intra‐annual stabilisation of resource availability and fish diet, with a higher consumption of plants and detritus. Changes in fish diet and feeding activity in both nonregulated and regulated rivers were strongly associated with the seasonal variability of streamflow components, particularly between low‐ and high‐flow periods, and with the reduction in flow variability in the case of dam regulation. Results from this study can be used to improve guidelines for flow requirement implementation.  相似文献