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71.
This paper presents a method for characterizing the complexity of landscape boundaries by remote sensing. This characterization is supported by a new boundary typology, that takes into account points where three or more landcovers converge (i.e., convergency points or coverts). Landscape boundary richness and diversity indices were proposed and calculated over 19 landscapes in South-East Brazil. Results showed that landscape boundaries, especially convergency points, provided an enrichment in landscape pattern analysis. Landcover boundary diversities were significantly related to landcover shape: elongated riparian units had the highest values for boundary diversity and coverts proportion indices. On the other hand, landscape analysis showed that indices of shape, richness, diversity and coverts proportion provided an additional evaluation of landcover spatial distribution within the landscape. 相似文献
72.
应用高光谱数据定量反演查干湖水质参数研究 总被引:2,自引:0,他引:2
湖泊水质下降和富营养化问题日益严重,传统监测方法已经日益不能满足水质监测的需要。该文通过野外高光谱仪器测定查干湖水体反射光谱,分析研究水体反射光谱特征与水质参数叶绿素a含量、透明度和浊度之间的关系,运用多种半经验算法建立反演模型。结果表明:单波段光谱反射率与叶绿素a和浊度的相关系数较小,但与透明度相关系数较高;光谱反射率通过对数、比值转换,可以有效的提高叶绿素a和浊度估测模型的精度,却对透明度作用不大。总体来说,叶绿素a和浊度估测模型效果较好,透明度高光谱估测模型相对较差,需进一步研究。 相似文献
73.
In mountainous Mediterranean regions, land abandonment processes in past decades are hypothesized to trigger secondary vegetal
succession and homogenization, which in recent years has increased the size of burned areas. We conducted an analysis of temporal
changes in landscape vegetal spatial pattern over a 15-year period (1984–1998) in a rural area of 672.3 km2 in Eastern Spain to investigate the relationship between local landscape heterogeneity and wildfire occurrence. Heterogeneity
was analyzed from textural metrics derived from non-classified remote sensing data at several periods, and was related to
wildfire history in the study area. Several neural network models found significant relationships between local spatial pattern
and future fire occurrence. In this study, sensitivity analysis of the texture variables suggested that fire occurrence, estimated
as probability of burning in the near future, increased where local homogeneity was higher. 相似文献
74.
地面高光谱和低空遥感监测小麦白粉病初探 总被引:4,自引:1,他引:4
利用手持式高光谱仪和基于数字技术的低空遥感系统,对不同严重度小麦白粉病冠层光谱反射率进行了测定,同时调查病情指数,分析不同时期地面平台光谱反射率与病情指数及低空遥感平台反射率与病情指数(disease index,DI)、归一化植被指数(normalized difference vegetable index,NDVI)相关性。结果表明,地面光谱测量冠层光谱反射率和低空遥感数字图像反射率与小麦白粉病病情指数在灌浆期有显著的相关关系,就地面测量结果而言,近红外波段的相关性高于绿光波段,相关系数分别为0.79和0.54;低空遥感数字图像红、绿、蓝三波段中,相关性依次降低,相关系数分别为0.79、0.75和0.62;而且低空遥感图像与归一化植被指数也存在较好的相关关系,蓝、红、绿波段,相关系数依次为0.70、0.68和0.54。这表明利用遥感非破坏性监测小麦白粉痛有着良好的应用前景,对于小麦白粉病发生面积监测有重要意义。 相似文献
75.
Regional land-cover change affects biodiversity, hydrology, and biogeochemical cycles at local, watershed, and landscape scales.
Developing countries are experiencing rapid land cover change, but assessment is often restricted by limited financial resources,
accessibility, and historical data. The assessment of regional land cover patterns is often the first step in developing conservation
and management plans. This study used remotely sensed land cover and topographic data (Landsat and Shuttle Radar Topography
Mission), supervised classification techniques, and spectral mixture analysis to characterize current landscape patterns and
quantify land cover change from 1985 to 2003 in the Altiplano (2535–4671 m) and Intermediate Valley (Mountain) (1491–4623 m)
physiographic zones in the Southeastern Bolivian Andes. Current land cover was mapped into six classes with an overall accuracy
of 88% using traditional classification techniques and limited field data. The land cover change analysis showed that extensive
deforestation, desertification, and agricultural expansion at a regional scale occurred in the last 20 years (17.3% of the
Mountain Zone and 7.2% of the Altiplano). Spectral mixture analysis (SMA) indicated that communal rangeland degradation has
also occurred, with increases in soil and non-photosynthetic vegetation fractions in most cover classes. SMA also identified
local areas with intensive management activities that are changing differently from the overall region (e.g., localized areas
of increased green vegetation). This indicates that actions of local communities, governments, and environmental managers
can moderate the potentially severe future changes implied by the results of this study. 相似文献
76.
利用遥感技术监测锡林郭勒天然草原利用强度方法初探 总被引:1,自引:0,他引:1
利用多时相的遥感数据,对2005年锡林郭勒天然草原生长期放牧利用强度进行了信息提取、监测和制图。结果表明:在牧草生长季节,天然草原各旬度的利用强度与植被指数旬度变动系数成反比,并与降雨和植被长势时空分布格局相一致;放牧初期旬度变动系数下降4%左右,利用强度较轻,处于轻度过牧状态;6月中旬以后,旬度变动系数下降12%~20%之间,利用强度加重,处于中度超载过牧状态;8月下旬后植物生长停止,旬度变动系数下降27%左右,利用强度最重,处于重度超载过牧状态。遥感监测结果经过地面同步采集数据验证,监测精度达到79.6%。 相似文献
77.
Urban forests are unique and highly valued resources. However, trees in urban forests are often under greater stress than those in rural or undeveloped areas due to soil compaction, restricted growing spaces, high temperatures, and exposure to air and water pollution. In addition, conditions change more quickly in urban as opposed to rural and undeveloped settings. Subsequently, proactive management of urban forests can be challenging and requires the availability of current and comprehensive information. Geospatial tools, such as, geographic information systems (GIS), global positioning systems (GPS) and remote sensing, work extremely well together for gathering, analyzing, and reporting information. Many urban forest management questions could be quickly and effectively addressed using geospatial methods and tools. The geospatial tools can provide timely and extensive spatial data from which urban forest attributes can be derived, such as land cover, forest structure, species composition and condition, heat island effects, and carbon storage. Emerging geospatial tools that could be adapted for urban forest applications include data fusion, virtual reality, three-dimensional visualization, Internet delivery, modeling, and emergency response. 相似文献
78.
79.
80.
Reliable information on weed abundance and distribution within fields is essential for weed management in agricultural systems. Such information is necessary to adopt localized and variable rates of herbicide spraying, thus reducing chemical waste, crop damage, and environmental pollution. This paper examined the potential of airborne multispectral imagery to discriminate and map weed infestations in an experimental citrus orchard in Japan. Using an airborne digital sensor, multispectral imagery was acquired over the study site on 10 April 2003. The obtained reflectance imagery was analyzed using an image object-based approach in eCognition. After creating image objects on the image, the spectral information for weeds and citrus, represented by corresponding selected sample image objects, was extracted. Significant differences in the spectral characteristics between weeds and citrus were observed in each of the red, green, and blue wavebands. The simple average values of these wavebands were used to classify image objects with the nearest neighbor algorithm. Maps were generated with different classes or levels of class groups. A subsequent accuracy assessment demonstrated that the weeds were successfully discriminated from other image objects with a classification accuracy of 99.07%. Therefore, maps generated based on the classification result could provide valuable information for developing a site-specific weed management program for the study orchard. 相似文献