Filters: Tags: NDVI (X) > Types: Citation (X)
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Locating meadow study sitesMeadow centers as recorded in the ‘Copy of sitecords_areaelev from Caruthers thesis.xls’ file delivered by Debinski in November 2012 were matched to polygons as recorded in files ‘teton97map_area.shp’ and ‘gallatin97map_area.shp’ both also delivered by Debinski in November 2012.In cases where the meadow center did not fall within a meadow polygon, if there was a meadow polygon of the same meadow TYPE nearby (judgment was used here), the meadow center was matched with the meadow polygon of same meadow TYPE. In total, 29 of 30 Gallatin meadow sites and 21 of 25 Teton meadow sites were positively located.Identifying meadow pixels for analysisThe native MODIS 250-meter grid was reprojected...
Categories: Data;
Types: Citation;
Tags: Greater Yellowstone Ecosystem,
MODIS,
NDVI,
North Central CASC,
Plants,
The capacity of ecosystems to provide services such as carbon storage, clean water, and forest products is determined not only by variations in ecosystem properties across landscapes, but also by ecosystem dynamics over time. ForWarn is a system developed by the U.S. Forest Service to monitor vegetation change using satellite imagery for the continental United States. It provides near real-time change maps that are updated every eight days, and summaries of these data also provide long-term change maps from 2000 to the present. Based on the detection of change in vegetation productivity, the ForWarn system monitors the effects of disturbances such as wildfires, insects, diseases, drought, and other effects of weather,...
Categories: Data;
Types: ArcGIS REST Map Service,
ArcGIS Service Definition,
Citation,
Downloadable,
Map Service;
Tags: Academics & scientific researchers,
AppLCC,
Appalachian,
Conservation NGOs,
Data,
Locating meadow study sitesMeadow centers as recorded in the ‘Copy of sitecords_areaelev from Caruthers thesis.xls’ file delivered by Debinski in November 2012 were matched to polygons as recorded in files ‘teton97map_area.shp’ and ‘gallatin97map_area.shp’ both also delivered by Debinski in November 2012.In cases where the meadow center did not fall within a meadow polygon, if there was a meadow polygon of the same meadow TYPE nearby (judgment was used here), the meadow center was matched with the meadow polygon of same meadow TYPE. In total, 29 of 30 Gallatin meadow sites and 21 of 25 Teton meadow sites were positively located.Identifying meadow pixels for analysisThe native MODIS 250-meter grid was reprojected...
Categories: Data;
Types: Citation;
Tags: Greater Yellowstone Ecosystem,
MODIS,
NDVI,
North Central CASC,
Plants,
Categories: Publication;
Types: Citation;
Tags: EVI,
Grasslands and Plains,
Greater Yellowstone Ecosystem,
Landscapes,
NDVI,
Water is a key driver of ecosystem processes in aridland ecosystems. Thus, changes in climate could have significant impacts on ecosystem structure and function. In the southwestern US, interactions among regional climate drivers (e.g., El Ni�o Southern Oscillation) and topographically controlled convective storms create a spatially and temporally variable precipitation regime that governs the rate and magnitude of ecosystem processes. We quantified the spatial and temporal distribution of reduced grassland greenness in response to seasonal and annual variation in precipitation at two scales at the Sevilleta Long Term Ecological Research site in central New Mexico, using Normalized Difference Vegetation Index (NDVI)...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: Aridland ecosystems,
Drought,
Grasslands,
Landscape Ecology,
NDVI,
Mapping salt-affected soils in remote rangelands is challenging. We used Landsat 7 ETM data to facilitate digital mapping of gypsic and natric soil areas in the upper Colorado River drainage. Optimum index factor band combinations were used to explore the scene. Normalized difference ratio models and threshold values were developed by comparing spectral signatures with gypsic and natric soil areas verifi ed in the fi eld. Gypsic soil areas were mapped using the normalized difference ratio of Bands 5 and 7 with a threshold >0.11, probably related to the spectral refl ectance of gypsum within a few centimeters of the surface. All sites predicted to be gypsic soil areas were determined to be gypsic by fi eld assessment,...
To assess the North American high-latitude vegetation response to the rising temperature, we derived NDVI trend for 91.2% of the non-water, non-snow land area of Canada and Alaska using the peak-summer Landsat surface reflectance data of 1984–2012. Our analysis indicated that 29.4% and 2.9% of the land area of Canada and Alaska showed statistically significant positive (greening) and negative (browning) trends respectively, at significance level p < 0.01, after burned forest areas were masked out. The area with greening trend dominated over that with browning trend for all land cover types. The greening occurred primarily in the tundra of western Alaska, along the north coast of Canada and in northeastern Canada;...
Normalized difference vegetation index (NDVI) is an indicator of vegetation health and density. High NDVI values generally correspond to dense vegetation and low NDVI values generally correspond to sparsely vegetated or barren areas. NDVI was calculated for pan-sharpened Landsat 8 Operational Land Imager images acquired on May 13, 2015 and May 15, 2016 for the region around Icy Bay, Alaska. NDVI results from 2015 were subtracted from results for 2016 to produce a change image. The change image can be used to assess changes in vegetation patterns resulting from a landslide that occurred near Tyndall Glacier in October, 2015 and generated a tsunami in Taan Fiord, an arm of Icy Bay. Positive change in NDVI generally...
Categories: Data;
Types: Citation,
Downloadable,
GeoTIFF,
Map Service,
Raster;
Tags: Alaska,
Icy Bay,
Icy Bay,
NDVI,
Taan Fiord,
Ambient-shade temperature was measured every 4 h with iButton thermochrons (Maxim Integrated Products, Inc., Sunnyville, CA, USA) placed at 1m above-ground level for a previous paper (Blake et al., 2012 – DOI 10.1111/1365-2656.12020). The Normalized Difference Vegetation Index (NDVI) of the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument (Huete et al. 2002 - http://dx.doi.org/10.1016/S0034-4257(02)00096-2) was used as an index of vegetation quantity. Monthly average NDVI values within the range of each tortoise population were derived based on grid sampling within the convex hull created by upland and lowland relocations of migratory individuals during their sedentary (non-migratory) phases of movement....
Types: Citation;
Tags: 24-hour clock,
Ecuador,
Espanola Island,
Galapagos Archipelago,
Galapagos Islands,
To assess the North American high-latitude vegetation response to the rising temperature, we derived NDVI trend for 91.2% of the non-water, non-snow land area of Canada and Alaska using the peak-summer Landsat surface reflectance data of 1984–2012. Our analysis indicated that 29.4% and 2.9% of the land area of Canada and Alaska showed statistically significant positive (greening) and negative (browning) trends respectively, at significance level p < 0.01, after burned forest areas were masked out. The area with greening trend dominated over that with browning trend for all land cover types. The greening occurred primarily in the tundra of western Alaska, along the north coast of Canada and in northeastern Canada;...
In this study we present a technique to discriminate between climate or human-induced dryland degradation, based on evaluations of AVHRR NDVI data and rainfall data. Since dryland areas typically have high inter-annual rainfall variations and rainfall has a dominant role in determining vegetation growth, minor biomass trends imposed by human influences are difficult to verify. By performing many linear regression calculations between different periods of accumulated precipitation and the annual NDVImax, we identify the rainfall period that is best related to the NDVImax and by this the proportion of biomass triggered by rainfall. Positive or negative deviations in biomass from this relationship, expressed in the...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: AVHRR,
Climate,
Degradation,
Desertification,
Dryland,
Groundwater dependent ecosystems (GDEs) rely on near-surface groundwater. These systems are receiving more attention with rising air temperature, prolonged drought, and where groundwater pumping captures natural groundwater discharge for anthropogenic use. Phreatophyte shrublands, meadows, and riparian areas are GDEs that provide critical habitat for many sensitive species, especially in arid and semi-arid environments. While GDEs are vital for ecosystem services and function, their long-term (i.e. ~ 30 years) spatial and temporal variability is poorly understood with respect to local and regional scale climate, groundwater, and rangeland management. In this work, we compute time series of NDVI derived from sensors...
Categories: Data,
Publication;
Types: Citation;
Tags: Complementary relationship,
Completed,
Cross-sensor,
EARTH SCIENCE > LAND SURFACE > LANDSCAPE,
Evaporative demand,
Landslide-generated tsunamis pose significant hazards, but developing models to assess these hazards presents unique challenges. George and others (2017) present a new methodology in which a depth-averaged two-phase landslide model (D-Claw) is used to simulate all stages of landslide dynamics and subsequent tsunami generation, propagation, and inundation. Because the model describes the evolution of solid and fluid volume fractions, it treats both landslides and tsunamis as special cases of a more general class of phenomena. Therefore, the landslide and tsunami can be seamlessly and efficiently simulated as a single-layer continuum with evolving solid-grain concentrations, and with wave generation via mass displacement...
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