نتایج جستجو برای: vegetation
تعداد نتایج: 47633 فیلتر نتایج به سال:
Sagebrush (Artemisia spp.) communities constitute the largest temperate semidesert in North America and provide important rangelands for livestock and habitat for wildlife. Remote sensing methods might provide an efficient method to monitor sagebrush communities. This study used airborne LiDAR and field data to measure vegetation heights in five different community types at the Reynolds Creek E...
Knowledge and protection of natural plant assemblages are key objectives of the California Native Plant Society (CNPS). The CNPS Vegetation Program has a floristic classification system to define and map vegetation in the state, including rare and common vegetation. Rare vegetation represents important and distinctive assemblages of biodiversity, and over 60% of the described vegetation allianc...
To determine the suitable indices for vegetation cover and production assessment based on the remote sensing data, simultaneous digital data with field data belonging to the spring rangeland of the Semirom-Isfahan province were analyzed. During two years of monitoring the annual, grass, forb, and shrub vegetation cover and the total production data from 86 were collected. The Global Positioning...
The present study discusses a method used to produce updated information about vegetation cover in arid and semi-arid zones, using RS data and GIS technique. In this method, Landsat ETM+ data in 2002 was collected in an area of about 60000 ha in Nodoushan basin, Yazd, Iran. To collect the necessary ground data, 50 sites of different vegetation types were selected and the percentage of vegetatio...
As band widths are narrow and range of spectra is wide, subtle differences in spectral features can be extracted and used for mapping physical and chemical properties of bare substrate with imaging spectroscopy. However, the use of spectral characteristics of substrates is not accessible if substrate was covered by vegetation. In this study, we explored the feasibility of extracting karst ecoen...
To determine the suitable indices for vegetation cover and production assessment based on the remote sensing data, simultaneous digital data with field data belonging to the spring rangeland of the Semirom-Isfahan province were analyzed. During two years of monitoring the annual, grass, forb, and shrub vegetation cover and the total production data from 86 were collected. The Global Positioning...
Field surveys often show that high water turbidity limits cover of aquatic vegetation, while many small-scale experiments show that vegetation can reduce turbidity by decreasing water flow, stabilizing sediments, and competing with phytoplankton for nutrients. Here we bridged these two views by exploring the direction and strength of causal relationships between aquatic vegetation and turbidity...
In this study, to remove the effects of topography and surface roughness to observed spectrum initially, a method using the normalised reflectance (pseudoreflectance) was employed. Then, we examined the removal of the vegetation effects (such as green vegetation and dry vegetation) and a method to estimate soil pseudo-reflectance spectrum, because the ground surface shows the mixture of soil an...
Vegetation indices have been used extensively to estimate the vegetation density from satellite and airborne images for many years. In this paper we first focus on one of the most popular vegetation indices, the normalized difference vegetation index (NDVI ) [1] and introduce a statistical framework to analyze it. We propose a solution to the saturation problem of this index based on our statis...
.......................................................................................................................................... 1 Acknowledgements ......................................................................................................................... 2 Introduction .........................................................................................................
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