نتایج جستجو برای: vegetation

تعداد نتایج: 47633  

Journal: :پژوهش های علوم و فناوری چوب و جنگل 0

identification of the best vegetation indices (vis) for use in quantitative analyzes of vegetation is one of the important issues for ecologists. the objective of this study was sensitivity evaluation of vegetation indices to a stand volume for identification of the best vegetation index (vi) in stand volume estimation using a statistical sensitivity method. also, another objective of this stud...

2008
Eric A. Davidson Gregory P. Asner Thomas A. Stone Christopher Neill Ricardo O. Figueiredo

[1] Degradation of cattle pastures is a management concern that influences future land use in Amazonia. However, ‘‘degradation’’ is poorly defined and has different meanings for ranchers, ecologists, and policy makers. Here we analyze pasture degradation using objective scalars of photosynthetic vegetation (PV), nonphotosynthetic vegetation (NPV), and exposed soil (S) derived from Landsat image...

1998
Christopher J. Kucharik John M. Norman Stith T. Gower

A new instrument called a Multiband Vegetation Imager (MVI) (Kucharik et al., 1997), which uses a 16-bit charge-coupled device (CCD) camera and ®lter exchange mechanism to capture 2-band (visible and near-infrared) image pairs of plant canopies, has been used to measure the light distribution over sunlit leaves and indirectly infer leaf area index (LAI), sunlit LAI and leaf angle distribution (...

Journal: :مرتع و آبخیزداری 0
محسن نقیلو کارشناس دانشکده منابع طبیعی، دانشگاه تهران، ایران محمد جعفری استاد دانشکده منابع طبیعی، دانشگاه تهران، ایران محمد طهمورث 3 کارشناس ارشد آبخیزداری، ایران اصغر کهندل استادیار جهاد دانشگاهی واحد تهران، ایران فریناز همدانیان 5 فارغ التحصیل کارشناس ارشد مرتعداری، ایران

the purpose of this research was to investigate the relationship between vegetation cover and soil characteristics in order to determine the most important soil factors which affect on quantitative variations and types of vegetation cover in the study area. the study area is located in west of tehran province and southeast of hashtgerd, next to najm-abad village. after field studies, the index ...

2009
Tayebeh Tabatabaie Fazel Amiri

SUMMARY Operational monitoring of vegetative cover by remote sensing currently involves the utilisation of vegetation indices. Vegetation indices are widely used for assessing and monitoring ecological variables such as vegetation cover, above-ground biomass and leaf area index. This study reviewed and evaluated different vegetation indices for estimating vegetation cover in rangelands in Cente...

ژورنال: مرتع 2021
Bagheri, Setareh, Jafari, Mohammad, Malekian, Arash, Peyrvand, Vahid, Tamartash, Reza, Tatian, Mohammadreza,

Using satellite imagery is a reasonable option to overcome the field visits problems and limitations to evaluate the vegetation cover over the years. The present research has conducted to specify the percentage of vegetation cover of rangelands using Geographic Information System (GIS) and vegetation indices. The study area is located in Qazvin plain rangelands, Iran. In this study, the MODIS s...

2008
MA Wei CHEN Yun-hao ZHOU Ji

Vegetation coverage has a significant influence on the land surface temperature (LST) distribution. In the field of urban heat islands (UHIs) based on remote sensing, vegetation indexes are widely used to estimate the LST-vegetation relationship. However, little evaluation work has been done on the comparison of the relationship between different vegetation indexes and LST. A Landsat Thematic M...

Determination of vegetation and soil interaction is necessary for sustainable use of rangeland ecosystem. Soil-vegetation interrelationships in galbanum (Ferula gummosa) habitats of Ataeeye and Shoorrud- Khorasan-e- Razavi Province, Iran were studied using multivariate analysis. The stratified- random system of sampling was employed to randomly collect vegetation and soil samples from 46 quadra...

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Gully erosion is one of the most significant erosion types. This type of erosion is one of the most important sources of sediment in different regions of the world. Gullies often have different dimensions and complex characteristics and these characteristics may affect the distribution of vegetation. Topographic characteristics of gullies provide complex ecosystem for vegetation establishment. ...

2010
A. Ono K. Kajiwara Y. Honda

For the analysis of vegetation areas using satellites, a variety of vegetation indexes such as NDVI and EVI have been developed. However, most indexes have weak response to grasping the type and quality (the growth state and situation) of vegetation. To grasp these vegetation characteristics, we have developed new vegetation indexes, i.e. shadow index (SI) and water stress trend (WST). We estim...

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