نتایج جستجو برای: canopy cover percentage
تعداد نتایج: 254028 فیلتر نتایج به سال:
In contrast to herbaceous canopies and forests, savannas are grassland ecosystems with sparsely distributed individual trees, so the canopy is spatially heterogeneous and open, whereas the woody cover in savannas, e.g., tree cover, adversely affects ecosystem structures and functions. Studies have shown that the dynamics of canopy structure are related to available water, climate, and human act...
Background and objective: Today, the use of predictive models of plant species distribution plays an important role in the assessment, restoration, protection and development of rangeland ecosystems. It is one of the important tools to obtain information about the causes of species distribution and habitat suitability for plant species. In this research, using multivariate analysis, the ecologi...
Windstorms are forest disturbances which generate canopy gaps. However, their effects on Mediterranean forests understudied. To fill that research gap, changes in tree, cover, growth and soil features Pinus halepensis sylvestris plantations affected by windthrows were quantified. In each plantation, trees soils closed-canopy stands gaps created the windthrow sampled. Changes tree cover radial a...
Overstory vegetation maps of species and canopy cover were developed from Landsat 7 Thematic Enhanced Thematic Mapper satellite imagery. Ecosystem Monitoring plot data, collected during the 1997-2001 field seasons, were used as training sites for the image classification. Sixty-two species classes and four canopy cover classes were mapped. The maps will be used to support a Joint Fire Science P...
For many natural and agricultural landscapes, vegetation partially covers the ground surface, resulting in significant variations in soil heat flux between interspace areas and underneath vegetation. This is particularly apparent in arid and semiarid regions where vegetation cover is low and clustered or ‘clumped’ with large areas of exposed soil. Surface heterogeneity presents significant chal...
In order to investigate the effect of different intensities on the quality and quantity of forage in the Bromus tomentellus Boiss species, mountain ranges in the northeastern part of the Delfan city were selected. Three zones with different grazing intensities were selected including the grazing area (reference), medium grazing (key) and heavy grazing (critical). In each region, sampling of sur...
Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a redu...
Rainfall interception losses from an agroforestry system in semi-arid Kenya comprising Grevillea robusta and maize were measured over a period of 33 months. These measurements showed that interception was slightly higher (10.2%) under trees with no maize understorey, than in the intercropped treatment (9.8%), and was directly related to the degree of tree canopy cover. Interception estimates us...
We used snow fences and small (1m) open-topped fiberglass chambers (OTCs) to study the effects of changes in winter snow cover and summer air temperatures on arctic tundra. In 1994, two 60m long, 2.8m high snow fences, one in moist and the other in dry tundra, were erected at Toolik Lake, Alaska. OTCs paired with unwarmed plots, were placed along each experimental snow gradient and in control a...
Monthly measurements of leaf area index (LAI) and the fraction of absorbed photosynthetically active radiation (fAPAR) taken at approximately monthly intervals were collected along three 750 m transects in a Kalahari woodland near Mongu in western Zambia. These data were compared with MODIS NDVI (MOD13, Collection 3) and MODIS LAI and fAPAR products (MOD15, Collection 3) over a 2 year period (2...
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