نتایج جستجو برای: forest grass cover
تعداد نتایج: 227128 فیلتر نتایج به سال:
An automated method was developed for mapping forest cover change using satellite remote sensing data sets. This multi-temporal classification method consists of a training data automation (TDA) procedure and uses the advanced support vector machines (SVM) algorithm. The TDA procedure automatically generates training data using input satellite images and existing land cover products. The derive...
Human interventions in natural areas as a change in land use have led to a domino effect of anomalies and then environmental hazards. These extensive and cumulative changes in land cover and land use have manifested themselves in the form of anomalies such as the formation of severe runoff, soil erosion, the spread of desertification, and salinization of the soil. The main purpose of this study...
since density is considered as one of the most important numerical indices to explain quantitative values of a plant community by affecting on many aspects and activity of ecosystem, on the other hand, awareness about plants distribution pattern in environment is an essential preparation for measurement and study of vegetative cover, therefore, in this research determination of density and dist...
according to reports of forest range and watershed management organization of iran, hundreds of forest fires take place in our country every year. due to destroying forest and grass land in different parts of iran, especially in zagross and alborz mountain, it is necessary to develop new methods to reduce fire effects in these places. there are many parameters that increase probability of fire ...
Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness?
Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance b...
Traditionally Land Use Cover Change (LUCC) studies have focused on processes of negative land-cover change, primarily deforestation, partially because examples of positive land-cover change were not common. During the last two decades an outstanding tropical dry forest restoration process had taken place in the province of Guanacaste, Costa Rica, which has given us a unique opportunity to study...
As tropical regions are converted to agriculture, conservation of biodiversity will depend not only on the maintenance of protected forest areas, but also on the scope for conservation within the agricultural matrix in which they are embedded. Tree cover typically retained in agricultural landscapes in the neotropics may provide resources and habitats for animals, but little is known about the ...
Vegetation structure and density affect the dynamics of snow accumulation and ablation. Vegetation also affects our ability to estimate snow-covered area accurately from satellite-based sensors. The objective of this case study is to demonstrate how the angular pattern of reflectance from vegetation over snow can provide information on forest cover density. Imagery from the Multi-angle Imaging ...
Community structure and species’ abundances may be strongly correlated to patterns of forest cover, although such patterns are poorly known for tropical dry-forest birds, especially for those in Panamanian dry forests. Birds were distance-sampled during point counts in five dry-forest fragments in Panama. Distance from point count to forest edge and forest coverage at three spatial scales (500,...
In a recent issue of PNAS, Hansen et al. (1) did an excellent job of arguing for the need for a more consistent data set to investigate changes in global forest cover. The indicator they chose, gross forest cover loss (GFCL), marks an improvement both in reproducibility and comparability. However, it does so by using data that the authors themselves state “captures only part of the global fores...
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