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421.
M.T Arnaud J.P Chassany R Dejean J Ribart L Queno 《Journal of environmental management》1997,49(4):373-391
Based on an interdisciplinary study of nine localities, the authors analyse the role of human and local factors involved in the disappearance of chestnut groves. This analysis enables us to understand the significant elements involved, causes, restricting factors, potentialities which explain today's situation, and to hypothesise upon the evolution of the chestnut groves and the Southern Cevennes in the years to come. These hypotheses emphasise the necessary changes in attitudes and the extra research required to lead a positive future action in order to manage this territory in a rational way. 相似文献
422.
Zhuang Yahui Zhang Hongxun Wang Xiaoke & Li Changsheng Research Center for Eco-Environmental Sciences Chinese Academy of Sciences PO Box Beijing China Institute for the Study of Earth Oceans and Space University of New Hampshire Durham NH U.S.A. 《中国人口.资源与环境(英文版)》2004,(3)
The report summarizes surveys on carbon inventories and initiatives on sustainable carbon cycling taken by the Research Center for Eco-Environmental Sciences, where the authors work/worked. The first part of the report, which appeared in the preceding issue of this journal, deals with the concept of sustainable carbon cycling, the historic evolution of carbon cycling processes in China, carbon pool enhancement, value addition, carbon sequestration and carbon balance. This very paper, as the second part of the report, covers the results of carbon dynamics modeling, emission inventories of various carbon-containing greenhouse gases and their potential abatement measures. 相似文献
423.
Long-term stationary investigations in permanent plots have been performed in forests of different types growing in Greater Moscow. Their results have made it possible to reveal the trends essential to the dynamics of these forests and make a prognosis of their condition in the near future. Moreover, they suggest that it is necessary to review some long-standing concepts concerning the processes of forest formation, relationships between the main forest species, etc. 相似文献
424.
A comparative analysis of the dynamics of insular populations of terrestrial animals was performed. The stability of insular populations and the relationship between their viability and the type of dynamics are discussed. 相似文献
425.
西北干旱荒漠区生境严酷,物种贫乏,植被稀疏低矮,加上不合理的开发利用,致生境恶化。利用当地有限的水源来实现干旱荒漠区的植被恢复,防止流沙蔓延,可以从以下两方面入手:一方面,以裸地为立地条件,利用当地的关键种(keystone specics)或优势种(dominant species),选择合适的生境,采用人工种子库和幼苗移植等方法,促使已缺失的植物种在目的地重新定居;另一方面,利用灌丛效应选择合适物种加以配合,提高干旱荒漠区的植被盖度。研究表明:以上两种途径对实现干旱荒漠区的植被恢复和重建是可行的。 相似文献
426.
石油污染土壤的生物修复技术 总被引:22,自引:0,他引:22
石油污染土壤的生物修复技术具有高效、无二次污染和操作管理简便的优点,正逐步成为石油污染治理研究的一个重要领域。本从土壤中石油类物质降解了基本原理出发,总结了近年发展起来的强化生物降解效率的各种技术措施和工程方案及其适用条件,并在此基础上进一步分析了生物修复技术的发展方向和应用前景。中首先详细介绍了土壤中降解石油类物质的生物相组成及降解过程的基本生化原理,并指出影响微生物降解速率的因素主要有土壤pH值,温度、湿度、充氧量和各种营养物质及微量元素含量等。接着,重点重点阐述了石油污染土壤的非原位修复技术和原位修复技术并深入探讨了土地处理、生物堆积处理、堆肥处理等非原位修复技术和所采取的技术措施,主要包括应用高效降解微生物、投加氧化剂和表面活性剂等。最后,本还展望了石油类污染土壤生物治理的未来发展趋势。 相似文献
427.
Spartina alterniflora was transplanted into dieback areas of a salt marsh in southeast Louisiana at two elevations (ambient and +30 cm) with and
without macro- (N, P, and K) and micronutrient (Fe, Mn, Cu, and Zn) additions to determine if transplant success is dependent
on increasing elevation or nutrients.Spartina alterniflora transplanted into elevated plots had more than twice the above- and belowground biomass as compared to nonelevated plots
after three months of growth. Additionally, there was significantly more vegetative reproduction (greater culm density and
number of newly produced culms) in elevated plots as compared to plots at ambient elevation. Macronutrient additions increased
culm densities only in elevated plots.Spartina alterniflora transplanted into nonelevated plots had lower survival rates even when transplants received nutrient additions. These results
suggest thatS. alterniflora may be transplanted successfully into degraded salt-marsh areas if elevation is increased. The addition of nutrients without
a concomitant increase in elevation is not sufficient for transplant success. 相似文献
428.
Mark A. Ridgley Frank R. Rijsberman 《Journal of the American Water Resources Association》1992,28(6):1095-1110
ABSTRACT: As part of a major project to provide the Rhine delta protection from North Sea floods, the Dutch installed sluices at Haringvliet in the late 1960s and converted the Haringvliet-Hollandsch Diep-Biesbosch (HHB) estuary into a tidally-damped, fresh-water system. Two decades later, the Dutch Rijkswaterstaat commissioned a study of alternative policies for managing the sluices and removing contaminated bottom sediments, including policies which would at least partially restore estuarine conditions to the HHB. This paper describes the public policy analysis comprising that study, focusing on the role played by formal mullicriteria evaluation (MCE), including the Analytic Hierarchy Process. Through the tasks of value-tree structuring, impact measurement, and criterion prioritization, the MCE influenced the entire structure of the analysis, became an integral part of it, and, despite initial skepticism among the participants about the utility of multicriteria analysis, was subsequently accepted and viewed favorably by the majority of them. 相似文献
429.
Benoît Gabrielle Jeanne Da-Silveira Sabine Houot Joël Michelin 《Agriculture, ecosystems & environment》2005,110(3-4):289-299
Composting has emerged as a valuable route for the disposal of urban waste, with the prospect of applying composts on arable fields as organic amendments. Proper management of urban waste composts (UWC) requires a capacity to predict their impacts on carbon and nitrogen dynamics in the field, an issue in which simulation models are expected to play a prominent role.Here, we used a deterministic soil-crop model to simulate C–N dynamics in an arable field amended with three types of UWC (green waste and sludge, biodegradable waste, and solid waste), and a reference amendment (farmyard manure). The model is a version of CERES in which the soil C–N module was substituted with the NCSOIL model, whose microbiological parameters were determined from either laboratory incubation data or biochemical fractionation in a previous paper. CERES was tested against data from a field trial set up in 1998 in the Paris area, and managed as a maize (Zea mays L.)–wheat (Triticum aestivum L.) rotation. Comparison of observed and simulated data over the first 4 years of the field trial showed that CERES predicted the soil moisture and inorganic N dynamics reasonably well, as well as the variations in soil organic C. In particular, the parameterization of UWC organic matter from biochemical fractions achieved a similar fit as the parameterization based on incubation data. Wheat yields were also correctly predicted, but a systematic under-estimation of maize yields pointed at an under-estimation of spring and summer mineralization of N by CERES.Simulated N fluxes showed that the organic amendments induced an additional leaching ranging from 1 to 8 kg N ha−1 yr−1, which can be related to the initial mineral N content of the amendments. After 4 years, the composts had mineralized 3–8% of their initial organic N content, depending on their stability. Composts with slower N release had higher N availability for the crops. CERES could thus be used to aid in selecting the timing of compost application, in relation to its stability, based on both environmental and agronomical criteria. 相似文献
430.
IntroductionTheannelidPiscicolageometra(L)otherwiseknownasfishleechisacommonparasiteoffreshwaterfishes.Someareectoparasiticonpoikilothermicandhomoeothermicvertebratessuchasamphibians ,molluscs,andworms ,feedingontheirblood(Cheng ,1973;Duijn ,1973)causingconside… 相似文献