نتایج جستجو برای: vegetation
تعداد نتایج: 47633 فیلتر نتایج به سال:
Model intercomparisons and evaluations against observations are essential for better understanding of models’ performance and for identifying the sources of uncertainty in their output. The terrestrial vegetation carbon simulated by 11 Earth system models (ESMs) involved in phase 5 of the Coupled Model Intercomparison Project (CMIP5) was evaluated in this study. The simulated vegetation carbonw...
Monitoring and tracking vegetation changes in vast and remote areas is a difficult task. Accurate extraction of existing vegetation is the primary step for better statistical assessment. An approach for vegetation mapping is proposed which automatically explores spectral characteristics of connected components in an image. Different frames of multi-spectral Indian Remote sensing IRS-1C LISS III...
Ecosystem response to disturbance is influenced by environmental conditions at a number of scales. Changes in climate have altered fire regimes across the western United States, and have also likely altered spatio-temporal patterns of post-fire vegetation regeneration. Fire occurrence data and a vegetation index (NDVI) derived from the NOAA Advanced Very High Resolution Radiometer (AVHRR) were ...
The role of naturally varying vegetation in influencing the climate variability in the West African Sahel is explored in a coupled atmosphere-land-vegetation model. The Sahel rainfall variability is influenced by sea-surface temperature variations in the oceans. Land-surface feedback is found to increase this variability both on interannual and interdecadal time scales. Interactive vegetation e...
Research has shown that soil moisture information can be retrieved by passive microwave remote sensing. This is even possible when there is a vegetation canopy present if the effects of the vegetation are corrected for. Vegetation correction algorithms must attempt to include all significant physical parameters, yet they must also only require data that can be readily obtained. Previous researc...
a r t i c l e i n f o Keywords: Band 4 Foliage-height diversity Horizontal vegetation structure Image texture Infrared air photo Landsat NDVI Wildlife habitat Ecologists commonly collect data on vegetation structure, which is an important attribute for characterizing habitat. However, measuring vegetation structure across large areas is logistically difficult. Our goal was to evaluate the degre...
Passive microwave remote sensing techniques can be used to monitor freeze/thaw at frozen soil surface. Researches found that the negative spectral gradient at 19GHz and 37GHz was a good criteria for decision of frozen soil[1]. At vegetated area, to make the algorithm simple, vegetation scattering were ignored, only their attenuation were considered, which were kept constant, regardless of veget...
Although considerable research has focused on the influences of logging debris treatments on soil and forest regeneration responses, few studies have identified whether debris effects are mediated by associated changes in competing vegetation abundance. At sites near Matlock, Washington, and Molalla, Oregon, studies were initiated after timber harvest to quantify the effects of three logging de...
Understanding the spatial and temporal dynamics of vegetation is essential in drylands. In this paper, we evaluated three vegetation indices, namely the Normalized Difference Vegetation Index (NDVI), the Soil-Adjusted Vegetation Index (SAVI) and the Enhanced Vegetation Index (EVI), derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) Surface-Reflectance Product in the Xinjiang...
This paper evaluated the capacity of SPOT VEGETATION time-series to monitor the vegetation biomass and water content in order to improve fire risk assessment in the savanna ecosystem of Kruger National Park in South Africa. First, the single date and integrated vegetation index approach, which quantify the amount of herbaceous biomass at the end of the rain season, were evaluated using in situ ...
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