نتایج جستجو برای: vegetation degradation

تعداد نتایج: 196873  

Journal: :مرتع و آبخیزداری 0
بهزاد رایگانی استادیار دانشکده علوم محیط زیست و منابع طبیعی، دانشگاه محیط زیست غلامرضا زهتابیان استاد دانشکده منابع طبیعی، دانشگاه تهران حسین آذرنیوند دانشیار دانشکده منابع طبیعی، دانشگاه تهران سید جمال الدین خواجه الدین استاد دانشکده منابع طبیعی، دانشگاه صنعتی اصفهان سید کاظم علوی پناه استاد دانشکده جغرافیا، دانشگاه تهران

arid and semi-arid areas, due to the sensitive, have variable ecosystems, so continuous assessment and monitoring of the environment is required for most of managerial and adjustment practices. vegetation is one of the most important assessment tools and used as a criterion for evaluation and monitoring of ecosystem functions. in this study, for the first time in the country, we have evaluated ...

Journal: :desert 0
h. azarnivand associate professor, faculty of natural resources, university of tehran, karaj, iran m.a. zare chahouki associate professor, faculty of natural resources, university of tehran, karaj, iran h. joneidi assistant professort, university of kurdestan, sanandaj, iran

one of the characteristics in iranian model of desertification potential assessment (imdpa) is vegetation. sincevegetation is very important factor in the degradation of land, so some indices were determined for this item in order toevaluate desertification potential of arid, semi arid and arid sub humid areas of iran. the indices included vegetationcondition, exploit and revegetation. to calib...

Journal: :Global change biology 2014
Thomas Hilker Enkhjargal Natsagdorj Richard H Waring Alexei Lyapustin Yujie Wang

The Mongolian Steppe is one of the largest remaining grassland ecosystems. Recent studies have reported widespread decline of vegetation across the steppe and about 70% of this ecosystem is now considered degraded. Among the scientific community there has been an active debate about whether the observed degradation is related to climate, or over-grazing, or both. Here, we employ a new atmospher...

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...

Mehrabi , Hamid , Zaferanieh , Saied ,

The estimate of the damage caused by the earthquake and other natural disasters in the first days after the occurrence of these events can provide a quick damages assessment and help to manage the crisis. Several methods are available to investigate the extent of earthquake’s damage. Optical remote sensing, photogrammetric methods (UAVs and LIDARs), radar interferometry (InSAR) and field observ...

2004
P. N. Macharia

A research study was conducted in Mashuru Division of Kajiado District, Kenya with the objective of analyzing the types of vegetation degradation, their causes and their influence on rangeland condition and trend. The study was conducted through remote sensing tools, ground truthing, interviews, community workshop and literature. The results of the study showed that excessive use of the woody s...

Journal: :Scientific reports 2016
L W Lehnert K Wesche K Trachte C Reudenbach J Bendix

The Tibetan Plateau (TP) is a globally important "water tower" that provides water for nearly 40% of the world's population. This supply function is claimed to be threatened by pasture degradation on the TP and the associated loss of water regulation functions. However, neither potential large scale degradation changes nor their drivers are known. Here, we analyse trends in a high-resolution da...

2000
M. JACOBA SALINAS GABRIEL BLANCA ANA T. ROMERO

Riparian vegetation is vulnerable to human impact worldwide, and this is especially so in arid areas, yet there have been few quantitative studies and this is especially so in Spain. The state of the riparian vegetation along three major rivers and seasonal watercourses of southeastern Spain was evaluated during 1992–93, using the species composition and community structure in watercourses of d...

2016
Lucien Wald L. Wald

A significant degradation in the responsivity of the AVHRR radiometers aboard the NOAA satellite series, affects the index vegetation (NDVI), which is an important source of information for monitoring vegetation conditions on regional and global scales. Many studies have been carried out which use the viewing Earth calibration approach in order to provide accurate calibration correction coeffic...

2012
Ayana Angassa

This article is based on comparative research conducted in three African countries—Mali, Botswana and Kenya—between 2006 and 2007. The research focuses on local perceptions of biodiversity loss and land degradation in grazing pastures as a result of anthropogenic activities. We show that land degradation can be motivated by climate change, while local overuse of indigenous vegetation can lead t...

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