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1.
盱眙县发掘资源优势,把龙虾作为特色产业,举办中国龙虾节,带动了一系列相关产业的发展,改变了当地的农业产业结构和就业结构,增加了就业和收入,增强了地方经济实力;并通过特色产业的品牌效应,带动了旅游等服务业的发展,吸引了外来投资,加速了工业化进程。通过总结盱眙县的经济发展实践,为落后地区的区域经济发展提供了参考和借鉴。  相似文献   
2.
通过对中国加入WTO后在粮食产业发展上面临的国内外形势的比较分析,指出了我国粮食产业发展在加入WTO的新形势下如何发展的问题,同时结合重庆市粮食生产情况,为重庆市粮食产业发展提出了一系列的建设性意见和对策,以应对加入WTO对我国及重庆市粮食产业带来的冲击,对把握重庆市粮食产业的发展方向有一定的指导意义。  相似文献   
3.
Forest fire management practices are highly dependent on the proper monitoring of the spatial distribution of the natural and man-made fuel complexes at landscape level. Spatial patterns of fuel types as well as the three-dimensional structure and state of the vegetation are essential for the assessment and prediction of forest fire risk and fire behaviour. A combination of the two remote sensing systems, imaging spectrometry and light detection and ranging (LiDAR), is well suited to map fuel types and properties, especially within the complex wildland–urban interface. LiDAR observations sample the spatial information dimension providing explicit geometric information about the structure of the Earth's surface and super-imposed objects. Imaging spectrometry on the other hand samples the spectral dimension, which is sensitive for discrimination of surface types. As a non-parametric classifier support vector machines (SVM) are particularly well adapted to classify data of high dimensionality and from multiple sources as proposed in this work. The presented approach achieves an improved land cover mapping adapted to forest fire management needs. The map is based on a single SVM classifier combining the spectral and spatial information dimensions provided by imaging spectrometry and LiDAR.  相似文献   
4.
The objectives of this study were to determine Global Positioning System (GPS) positional errors while moving under the forest canopy and to clarify the effects of polyline simplification on area and perimeter estimations. We used the Pathfinder Pro XR and GPSMAP 76S, which are categorized as “high-end mapping” and “general navigation” GPS receivers, respectively. The field tests were conducted in both natural and plantation forests. The results showed that the Pathfinder Pro XR, which has better multipath rejection technology, worked well, especially in the plantation forest under unfavorable conditions of higher stand density. We used analysis of variance to clarify the effects of the receiver type, positioning mode, stand type, and polyline simplification method on area and perimeter estimations. The receiver type and positioning mode were found to be significant factors that affected area estimation. The Pathfinder Pro XR estimated the area more accurately than the GPSMAP 76S, and differential GPS estimated the area more accurately than autonomous GPS. With respect to the perimeter, the receiver type, positioning mode, and polyline simplification method were found to be significant factors. The results showed that perimeter estimation was improved by using the velocity filter, and further improved by using the velocity filter and Douglas-Peucker algorithm, especially when the Pathfinder Pro XR was used. The GPSMAP 76S estimated the perimeter accurately without any filtering because its default speed filter worked well, even though the GPSMAP 76S is a general navigation GPS receiver.  相似文献   
5.
We used GIS on a regional scale to estimate and compare supply potentials and costs of small-scale logging systems, a mini-forwarder and a 4-ton truck operated by private logging contractors, and manual logging and a light truck operated by individual forest own- ers, with the mechanized operational system of the Forest Owners' Asso- ciation. Total potential yields of timber and logging residues were esti- mated as 418,895 m3 and 254,962 m3, respectively. The economic bal- ances were estimated and available amounts were projected as supply potentials from profitable sub-compartments. As a result, available amounts of timber and logging residues were estimated at 375,466 m3 (89.9%) and 203,850 m3 (80.0%), respectively. Because their transport expenses were lower than for other systems the most profitable sub-compartments were operated by private logging contractors who sold logging residues at a plant. The profitable sub-compartments operated by individual forest owners were few because the extracting distances were usually greater than 20 m. Raising logging residue prices from 3,000 yen·m-3 to 4,080 yen·m-3 or 6,800 yen·m-3, and establishing forest roads, which reduced some extracting distances to less than 20 m, increased the number and area of profitable sub*compartments, and increased available amounts of logging residues.  相似文献   
6.
    
The forests of Austrocedrus chilensis in southern Argentina suffer mortality from “mal del ciprés”, whose causes remain unknown. The purpose of this work was to establish the relation of soil features with the occurrence of the disease. In Río Grande Valley, Chubut Province, Argentina, 14 areas with “mal del ciprés” were selected for study. The spatial pattern of the decline varied among the different areas and was classified as aggregated and disaggregated. In each area, symptomatic and asymptomatic plots were established and characterized by 11 edaphic and topographic variables. Three forest areas where the disease was totally absent were also included. Site features were related to the occurrence of the decline using principal component analysis and cluster analysis. Results indicated that soil properties related to poor internal drainage, such as the proximity to water streams, non-allophanized soils of fine textures, and redoximorphic features, act as predisposing factors to the development of “mal del ciprés”. Poor soil drainage was strongly associated not only with the occurrence of the disease, but also with its spatial pattern. Symptomatic and asymptomatic plots presented similar edaphic features in areas with a disaggregated distribution of the decline and were grouped together in the multivariate analysis. This result suggests that large areas with such a pattern are prone to develop the decline.  相似文献   
7.
In 2011, a Diarrhetic Shellfish Poisoning (DSP) outbreak occurred in British Columbia (BC), Canada that was associated with cooked mussel consumption. This is the first reported DSP outbreak in BC. Investigation of ill individuals, traceback of product and laboratory testing for toxins were used in this investigation. Sixty-two illnesses were reported. Public health and food safety investigation identified a common food source and harvest area. Public health and regulatory agencies took actions to recall product and notify the public. Shellfish monitoring program changes were implemented after the outbreak. Improved response and understanding of toxin production will improve management of future DSP outbreaks.  相似文献   
8.
    
Changes to ecosystems caused by introduced herbivores can be predictable, stepwise transitions or unpredictable and even irreversible state changes. This study's objectives were to explore effects on forest succession and soil development 5 years after moose (Alces alces L.) were fenced out of areas within and adjacent to a national park in Newfoundland, Canada. Study plots spanned a range of understorey broadleaf plant associations with regenerating balsam fir (Abies balsamea (L.) Mill.), an important winter forage plant for moose and a dominant canopy tree throughout Newfoundland. After 5 years, height–diameter ratios were significantly larger for larger basal diameters of understorey balsam fir in unfenced, but not in fenced subplots, suggesting that growth of the conifer is compromised within the exclosure. In contrast, for most broadleaf trees and shrubs, moose removal by fencing results in greater heights and basal diameters than in control subplots. The competitive advantage of broadleaf trees and shrubs over balsam fir in the short-term may be a result of past sustained heavy moose browsing benefiting plants that are better at investing resources into below-ground growth or benefiting plants that have broader leaf canopies. It is not clear how long the broadleaf transition state we document will continue. Restorative actions intended to mimic usual patterns of forest regeneration in this region of Newfoundland might best consider moose removal with site preparation and/or planting to historic densities.  相似文献   
9.
  总被引:1,自引:0,他引:1  
During spring and summer 2003 severe drought-caused damage was observed in the park forests of the city of Helsinki; especially in barren site pine and spruce stands. The objectives of this study were to map and document the extent of the damage through the use of existing geographical information, digital aerial photography and field surveys and to examine the feasibility of assessing drought damage by visual interpretation of digital aerial photography. Our aim was also to assess the reasons for drought damage in Helsinki city park forests using geographic information system (GIS) analyses of existing interpretative and geographical data, i.e. digital aerial photographs, rainfall statistics and the compartmentwise GIS database of the park forest site and soil types.The total amount of area falling into serious damage classes represented approximately 25 ha (the total forested area in Helsinki is about 3700 ha). A majority of these areas were located on rocky sites having low stem volumes. The total proportion of damaged stock volume was estimated as 17 300 m3, which is 3.3% of the total stock volume in the study area. An accuracy assessment showed that visual interpretation of digital aerial photos is an excellent tool for assessing drought damage. The mean estimation error was 0.7 classes, and errors comprising 2 classes were found in all test grids. The overall correct percentage of photointerpretation was 46%, and estimation was unbiased (kappa 0.264). The forest site and soil type together with the tree species on site showed the greatest correlation with drought damage. The drier and more barren the site, the more likely that damage will occur. Roadside forests were in better condition than areas located further off the roads. Hills clearly impacted the condition of the trees through soil type and flow.  相似文献   
10.
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