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991.
The author studied the issues of the present-day status of forest resources and forest management of the Selenge River Basin on the transboundary territory of the Buryat Republic and Mongolia. It is necessary to establish a good policy for wood cutting of the main and secondary use and reforestation.  相似文献   
992.
In the framework of the VECTOR DIVCOST Project, a 2-year investigation was started in 2006, with the aim of testing the sensibility of microbial parameters to environmental changes and of assessing whether they can provide information about functional changes in the carbon cycle. The investigation was performed in the surface waters of two small brackish ponds (Ganzirri and Faro), located in the Cape Peloro transitional area (Sicily, Italy). The seasonal changes in both the microbial compartment [bacterioplankton, vibrios, exoenzymatic hydrolysis of proteins and polysaccharides, bacterial secondary production (HBP) and community respiration] and the trophic state of suspended matter [total suspended matter (TSM), particulate organic carbon (POC), particulate organic nitrogen (PON), C/N] were analysed in relation to the hydrological characteristics [temperature, salinity, oxygen, fluorescence, NH4, NO2, NO3, PO4]. Despite marked differences in the nutritional input and the diversification in both carbon budget and trophic level, the two ponds show similar trends in many of the investigated factors, hardly influenced by seasonal variations. Temporally coupled trends were observed for some parameters (enzyme activities, vibrios abundances, respiratory activity), whereas others (POC, PON, heterotrophic bacterial production, bacterioplankton) showed a seasonal shift between the two lakes. The different behaviour found for the some biotic parameters suggests that their response to environmental conditions may be modulated differently between the two lakes, which, despite their spatial proximity and reciprocal connection, do not always show contemporaneous functional processes.  相似文献   
993.
For decades, the scientific community has conducted essential background research and developed appropriate modeling tools in support of an ecosystem-based approach to natural resource management. Resource managers and the public, however, lack a clear roadmap for working with scientists to move beyond the traditional single-species approach. With current management processes so strongly focused on working in a species-by-species framework, there are entrenched cultural and institutional challenges to shifting those processes toward ecosystem-based management. We propose using the integrated ecosystem assessment process to both develop new management ideas for a particular ecosystem, and to help shift public policy processes and perceptions to embrace ecosystem approaches to management.  相似文献   
994.
概述了遥感技术在城市生态系统研究中的应用及其优越性。回顾了近 30年来国内外城市环境遥感的主要研究内容及成果。介绍了遥感技术在分析城市生态系统时的结构和模型 ,从而为研究不同城市生态系统的发展变化提供了有效的技术方法  相似文献   
995.
In an ecosystem approach to fisheries (EAF), management must draw on information of widely different types, and information addressing various scales. Knowledge-based systems assist in the decision-making process by summarising this information in a logical, transparent and reproducible way. Both rule-based Boolean and fuzzy-logic models have been used successfully as knowledge-based decision support tools. This study compares two such systems relevant to fisheries management in an EAF developed for the southern Benguela. The first is a rule-based system for the prediction of anchovy recruitment and the second is a fuzzy-logic tool to monitor implementation of an EAF in the sardine fishery. We construct a fuzzy-logic counterpart to the rule-based model, and a rule-based counterpart to the fuzzy-logic model, compare their results, and include feedback from potential users of these two decision support tools in our evaluation of the two approaches. With respect to the model objectives, no method clearly outperformed the other. The advantages of numerically processing continuous variables, and interpreting the final output, as in fuzzy-logic models, can be weighed up against the advantages of using a few, qualitative, easy-to-understand categories as in rule-based models. The natural language used in rule-based implementations is easily understood by, and communicated among, users of these systems. Users unfamiliar with fuzzy-set theory must “trust” the logic of the model. Graphical visualization of intermediate and end results is an important advantage of any system. Applying the two approaches in parallel improved our understanding of the model as well as of the underlying problems. Even for complex problems, small knowledge-based systems such as the ones explored here are worth developing and using. Their strengths lie in (i) synthesis of the problem in a logical and transparent framework, (ii) helping scientists to deliberate how to apply their science to transdisciplinary issues that are not purely scientific, and (iii) representing vehicles for delivering state-of-the-art science to those who need to use it. Possible applications of this approach for ecosystems of the Humboldt Current are discussed.  相似文献   
996.
Managed realignment (MR) is a ‘soft’ engineering technique that involves the deliberate landwards retreat of the existing line of coastal defence and subsequent tidal inundation of land. Managed realignment has been established worldwide for over 30 years and its goals may include habitat restoration, recovery of biodiversity and sustainable coastal defence. In southeast England in particular, an increasing number of MR sites (20–110 ha) have been commissioned in the last decade in response to increasing coastal habitat loss and sea-level rise. Following initial sea wall breaching and site flooding, monitoring of these sites is usually carried out for a period of 5 years and during this time changes in ecosystem structure can be easily observed. However, there is a poor understanding of the long-term effects of flooding on soil physicochemical parameters including sediment geochemistry and geochemical cycling, nutrient fluxes and soil maturation processes. Such physical and chemical changes may continue to take place over time-scales exceeding 5 years and therefore current monitoring practices may not be sufficient.  相似文献   
997.
The Land-Ocean Interactions in the Coastal Zone (LOICZ) biogeochemical model (LBM) was applied at different temporal and spatial scales in 17 Italian lagoons of the LaguNet network (http://www.dsa.unipr.it/lagunet). A series of alternative assumptions taking into account benthic vegetation and sedimentary fluxes were introduced and compared with the classical LBM approach at various time scales. The reliability of the LBM application to the seventeen Italian lagoons was tested by comparison to a pool of shallow coastal systems from the global LOICZ database with comparable depths and sizes. The nutrient loads of the Italian sites can be considered relatively low, particularly for dissolved inorganic phosphorus (DIP). Although the median values of estimated internal transformations (source-sink) of both dissolved inorganic phosphorous and nitrogen at the LaguNet sites were comparable with the selected LOICZ sites, the positive and negative extreme values were one order of magnitude lower. Overall, the LBM applications to the Italian sites gave good quality budgets for shallow systems subjected to relatively low nutrient inputs and with a wide range of primary producer communities, including seagrass, macroalgae and phytoplankton. Furthermore, stoichiometry of Carbon:Nitrogen:Phosphorous for the different primary producer groups allowed the integration of previous studies by identifying a series of relationships between nutrient loads and ecosystem functions.  相似文献   
998.
Carbon and Nitrogen stable isotopes and stomach contents analyses were used to investigate an estuarine fish food web and identify the contribution of these two methods to the knowledge and understanding of the food web's structure and its functioning. The nine most abundant fish species during the warm period in the Gironde estuary (southwest France, Europe) are examined. Observation of the stomach contents reflects a variety of feeding modes between fish species that consume a diverse assortment of prey, with limited dietary overlap. Nevertheless, when regarding the whole fish community, few prey species dominate the stomach contents. Nitrogen isotope ratios indicate a high intraspecific variability inducing an interspecific covering of the signatures. However, a tendency to δ15N enrichment according to the trophic position of the species studied was observed. Fish assemblages show a trend towards enrichment of their carbon isotopic signatures from the upper estuary (−20.8 ± 1.8‰) towards the lower estuary (−18.3 ± 1.6‰). But whatever the capture zone considered, most of the individual δ13C values for each fish analysed are comprised between −22 and −16‰. Only few specimens, belonging to migratory amphihaline species, have significantly lighter values.  相似文献   
999.
1000.
浙江省森林生态服务价值估算及其逐月变异分析   总被引:1,自引:0,他引:1  
森林生态服务价值的研究对构建绿色GDP核算体系、制定生态补偿标准、提高人类环境保护意识等有十分重要的意义。本文首先以卫星影像、地理空间数据、站点记录等资料,结合GIS、RS技术,估算了浙江省森林生态系统2010年的NPP、蒸散量、土壤保持量等;然后,采用能量替代法、机会成本法、影子工程法等估算了浙江省森林2010年的固碳释氧价值、有机物生产价值、水源涵养价值、营养物循环价值、水土保持价值;最后,对各种生态服务价值的逐月变异规律进行分析。结果表明:浙江省森林2010年的5种生态服务价值呈现明显的逐月变异规律;固碳释氧价值、有机物生产价值、营养物质循环价值、水土保持价值的逐月变异规律,均可用开口向下抛物线拟合;水源涵养价值的逐月变异规律,可用开口向上抛物线拟合。  相似文献   
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