نتایج جستجو برای: forest grass cover
تعداد نتایج: 227128 فیلتر نتایج به سال:
We estimated changes in forest cover between 1973 and 1995 in the southern part of the Western Ghats using satellite data. The study area of approximately 40,000 km showed a loss of 25.6% in forest cover over 22 years. The dense forest was reduced by 19.5% and open forest decreased by 33.2%. As a consequence, degraded forest increased by 26.64%. There has been a great deal of spatial variabilit...
Over the 150 year history of major agricultural activity in Iowa nearly all the native prairie (99.9%) and wetlands (95%) were lost as native plant communities were converted to row-crop agriculture. This major change from perennial to annual upland vegetation was accompanied by broad scale installation of tile drainage intended to remove moisture from saturated wetland soils, increasing availa...
An understanding of the processes governing natural afforestation over large spatial scales is vital for enhancing forest carbon sequestration. Models of tree species occurrence probability in non-forest vegetation could potentially identify the primary variables determining natural afforestation. However, inferring processes governing afforestation using tree species occurrence is potentially ...
This paper describes a combined remote sensing-GIS-logistic regression approach of merging extracted information from Landsat images with georeferenced biophysical and socio-economic datasets in the detection and analysis of the driving forces of forest cover change in Agusan del Norte (ADN) in Mindanao Island, Philippines, a province where forest resource use have been historically extensive. ...
Drought stress is a major contributing factor to plant mortality across the globe. effects are often studied at local scale, but recent advances in remote sensing allow for observations of water status broad geographic scales. The vegetation optical depth (VOD) derived from satellite-based surface microwave emission has been shown be sensitive canopy content, which increasingly recognized as an...
We present efficient multiscale approaches to the segmentation of natural clutter, specifically grass and forest, and to the enhancement of anomalies in synthetic aperture radar (SAR) imagery. The methods we propose exploit the coherent nature of SAR sensors. In particular, they take advantage of the characteristic statistical differences in imagery of different terrain types, as a function of ...
Theoretically, fire-tree cover feedbacks can maintain savanna and forest as alternative stable states. However, the global extent of fire-driven discontinuities in tree cover is unknown, especially accounting for seasonality and soils. We use tree cover, climate, fire, and soils data sets to show that tree cover is globally discontinuous. Climate influences tree cover globally but, at intermedi...
Deforestation rates in primary humid tropical forests of the Brazilian Legal Amazon (BLA) have declined significantly since the early 2000s. Brazil's national forest monitoring system provides extensive information for the BLA but lacks independent validation and systematic coverage outside of primary forests. We use a sample-based approach to consistently quantify 2000-2013 tree cover loss in ...
Forests are experiencing significant changes; studying geographic patterns in forests is critical in understanding the impact of forest dynamics to biodiversity, soil erosion, water chemistry and climate. Few studies have examined forest geographic pattern changes other than fragmentation; however, other spatial processes of forest dynamics are of equal importance. Here, we study forest attriti...
Land use change is one of the important aspects of the regional ecological restoration research. With remote sensing (RS) image in 2003, 2007 and 2012, using geographic information system (GIS) technologies, the land use pattern changes in Yimeng Mountain ecological restoration area in China and its driving force factors were studied. Results showed that: (1) Cultivated land constituted the lar...
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