نتایج جستجو برای: canopy cover

تعداد نتایج: 122030  

2002
Collin Homer Chengquan Huang Limin Yang Bruce K. Wylie Homer Collin Bruce Wylie

Multi-Resolution Land Characterization 2000 (MRLC 2000) is a second-generation federal consortium to create an updated pool of nation-wide Landsat 7 imagery, and derive a second-generation National Land Cover Database (NLCD 2000). This multi-layer, multisource database will include a suite of 30-meter resolution data that will serve as standardized ingredients for the production of land cover –...

2010
Yuri Knyazikhin Mitchell A. Schull Liang Xu Ranga B. Myneni Arindam Samanta

The concept of canopy spectral invariants expresses the observation that simple algebraic combinations of leaf and canopy spectral reflectance become wavelength independent and determine two canopy structure specific variables – the recollision and escape probabilities. These variables specify an accurate relationship between the spectral response of a vegetation canopy to incident solar radiat...

2010
David J. Nowak Eric J. Greenfield

The 2001 National Land Cover Database (NLCD) provides 30-m resolution estimates of percentage tree canopy and percentage impervious cover for the conterminous United States. Previous estimates that compared NLCD tree canopy and impervious cover estimates with photo-interpreted cover estimates within selected counties and places revealed that NLCD underestimates tree and impervious cover. Based ...

ژورنال: علوم آب و خاک 1997
بصیری, مهدی , خواجه الدین, سیدحمال الدین , وهابی, محمد رضا ,

Short-term changes (5 years) in canopy cover, species composition and forage production were studied under protection from grazing and grazed condition in 19 range sites in Fereydan region, Isfahan province. In this study, density, canopy cover and forage production data were obtained from quadrates inside and outside exclosures in the spring of 1983. These parameters were studied again in 1988...

The Nearest Individual Sampling Method is one of the distance sampling methods for estimating density, canopy cover and height of forest stands. Some distance sampling methods have more than one density estimator that may be skewed to the spatial pattern. Unless the stands of the trees under study have a random spatial pattern. Therefore, the purpose of this study was evaluating the effect of s...

The aim of this study was to investigate the role of species of Trifolium genus on the composition, diversity, forage value and quantitative vegetation parameters and interaction between Trifolium species and invasive species Leucanthemum vulgare Lam. in Fandoghlou rangelands in Ardabil province. In determining the sampling locations, six sites by systematic random method and due to the distrib...

2016
Glen L. Ritchie Esmaiel Malek Robert R. Gillies

Spectral reflectance of plant canopies provides an accurate indication of ground cover fraction, which is highly correlated with radiation capture. If nutrients and water do not limit growth, radiation capture is highly correlated with daily growth rate and ultimate yield. However, if nutrients and water limit growth, none of the common spectral indices are able to separate a more developed, st...

2008
Tim Whiteside Waqar Ahmad

Very high spatial resolution satellite imagery provides data that enables spatially detailed analysis of landscapes. The identification and extraction of information about tree crowns is one such use. Tree crown or canopy cover is one parameter of vegetation structural classification. The estimation of canopy cover has a wide range if uses related to management and policies. Tree crown extracti...

2011
Yuri Knyazikhin Mitchell A. Schull Liang Xu Ranga B. Myneni Arindam Samanta

The concept of canopy spectral invariants expresses the observation that simple algebraic combinations of leaf and canopy spectral reflectance become wavelength independent and determine two canopy structure specific variables – the recollision and escape probabilities. These variables specify an accurate relationship between the spectral response of a vegetation canopy to incident solar radiat...

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