نتایج جستجو برای: vegetation

تعداد نتایج: 47633  

Journal: :PloS one 2015
Sarah L Shafer Patrick J Bartlein Elizabeth M Gray Richard T Pelltier

Future climate change may significantly alter the distributions of many plant taxa. The effects of climate change may be particularly large in mountainous regions where climate can vary significantly with elevation. Understanding potential future vegetation changes in these regions requires methods that can resolve vegetation responses to climate change at fine spatial resolutions. We used LPJ,...

2014
S. Sampath Kumar

Agricultural drought is considered to be one of the man’s worst natural enemy. Its beginning is subtle, its progress is insidious and its effect can be devastating. In a country like India, drought is considered to be a major factor of uncertainty due to vagarious of monsoon. Once there was not effective drought assessment and monitoring system, but now remote sensing plays an important role an...

2007
Michael Lew - Smith

Question: How can the U.S. National Vegetation Classification (USNVC) serve as an effective tool for classifying and mapping vegetation, and inform assessments and monitoring? Location: Voyageurs National Park, northern Minnesota, U.S.A and environs. The park contains 54 243 ha of terrestrial habitat in the sub-boreal region of North America. Methods: We classified and mapped the natural vegeta...

2006
SERGIO M. VICENTE-SERRANO

This paper analyses monthly differences in drought impact on vegetation activity in a semi-arid region in the north-east of the Iberian Peninsula between 1987 and 2000. The study determines spatial differences in the effects of drought on the natural vegetation and agricultural crops by means of the joint use of vegetation indexes derived from AVHRR images, a drought index (standardized precipi...

Journal: :Remote Sensing 2016
Manuela Domínguez-Beisiegel Carmen Castañeda Bernard Mougenot Juan Herrero

Inland saline wetlands are complex systems undergoing continuous changes in moisture and salinity and are especially vulnerable to human pressures. Remote sensing is helpful to identify vegetation change in semi-arid wetlands and to assess wetland degradation. Remote sensing-based monitoring requires identification of the spectral characteristics of soils and vegetation and their correspondence...

2012
Anatoly A. Gitelson

Many algorithms have been developed for the remote estimation of vegetation fraction in terms of combinations of spectral bands, derivatives of reflectance spectra, neural networks, inversion of radiative transfer models, and several multi-spectral statistical approaches. The most widespread type of algorithm used is the mathematical combination of visible and near-infrared reflectance, in the ...

2015
Souleymane S. Traore Tobias Landmann Eric K. Forkuo Pierre C.S. Traore Kwame Nkrumah

Using time series of Normalized Difference Vegetation Index (NDVI) and rainfall data, we investigated historical vegetation productivity trends from 1982 to 2011 over the Bani River Basin in Mali. Statistical agreements between long-term trends in vegetation productivty, corresponding rainfall and rate of land cover change from Landsat time-series imagery was used to discern climate versus huma...

Journal: :Remote Sensing 2015
Yanxu Liu Yanglin Wang Jian Peng Yueyue Du Xianfeng Liu Shuangshuang Li Donghai Zhang

Changes in biodiversity owing to vegetation degradation resulting from widespread urbanization demands serious attention. However, the connection between vegetation degradation and urbanization appears to be complex and nonlinear, and deserves a series of long-term observations. On the basis of the Normalized Difference Vegetation Index (NDVI) and the image’s digital number (DN) in nighttime st...

Journal: :Remote Sensing 2012
Jose Raul Romo Leon Willem J. D. van Leeuwen Grant M. Casady

Post-fire vegetation response is influenced by the interaction of natural and anthropogenic factors such as topography, climate, vegetation type and restoration practices. Previous research has analyzed the relationship of some of these factors to vegetation response, but few have taken into account the effects of pre-fire restoration practices. We selected three wildfires that occurred in Band...

2008
David R. Bedford Eric E. Small

Spatial patterns of soil properties are linked to patchy vegetation in arid and semi-arid landscapes. The patterns of soil properties are generally assumed to be linked to the ecohydrological functioning of patchy dryland vegetation ecosystems. We studied the effects of vegetation canopy, its spatial pattern, and landforms on soil properties affecting overland flow and infiltration in shrubland...

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