Mapping Land Cover and Estimating the Grassland Structure in a Priority Area of the Chihuahuan Desert

Abstract

Abstract:A field characterization of the grassland vegetation structure, represented by the coverage of grass canopy (CGC) and the grass height, was carried out during three years (2009)(2010)(2011) in a priority area for the conservation of grasslands of North America. Landsat Thematic Mapper (TM5) images were selected and the information of reflectance was obtained based on the geographical location of each field-sampling site. Linear models, constructed with field and satellite data, with high coefficients of determination for CGC (R 2 = 0.81, R 2 = 0.81 and R 2 = 0.72) and grass height (R 2 = 0.82, R 2 = 0.79 and R 2 = 0.73) were obtained. The maps showed a good level of CGC (>25%) and grass height (>25 cm), except for the year 2009, which presented the lowest values of grass height in the area. According to the Kappa Index, a moderate concordance among the three CGC maps was presented (0.49-0.59). Conversely, weak and moderate concordances were found among the grass height maps (0.36-0.59). It was observed that areas with a high CGC do not necessarily correspond to areas with greater grass height values. Based on the data analyzed in this study, the grassland areas are highly dynamic, structurally heterogeneous and the spatial distribution of the variables does not show a definite pattern. From the information generated, it is possible to determine those areas that are the most important for monitoring to then establish effective strategies for the conservation of these grasslands and the protection of threatened migratory bird species.

Atmospheric and Radiometric Correction Algorithms for the Multitemporal Assessment of Grasslands Productivity

“…It was observed that in the period when the scenes were taken, the spectral signature of the grassland varied along the years. This can be explained by the effects of density, weight, coverage, and shade, which are variable in grass communities [17,65].…”

“…These studies demonstrated the good relationships between the spectral information from the remote sensors and the biomass inventories in the field. Rodríguez-Maturino et al [17] correlated 3-year data from Landsat TM5 as well as field measurements of coverage of grass canopy and grass height, obtaining values of R 2 greater than 0.70.…”

Quantifying the Spatiotemporal Pattern of Urban Expansion and Hazard and Risk Area Identification in the Kaski District of Nepal

“…RS and GIS-based risk-area mapping is recognized as an imperative process to obtain effective hazard risk reduction and mitigation output [9]. Monitoring over-time changes requires consistency among maps, both ontologically and statistically [22], and time-series remote sensing data has made it possible to monitor changes in urban structure [32] and LULC [33,34]. Application, GIS, and remote sensing along with LULC modeling provides an wider understanding of human and environmental systems and improved knowledge of future changes cities are to confront [35,36].…”

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“…Las áreas de pastizal nativo y las áreas de pastoreo de otros tipos de vegetación se caracterizan por tener una cobertura de suelo en la que predominan especies herbáceas de la familia Poaceae, de las cuales existen en México 205 géneros que agrupan a 1,216 especies (Dávila et al, 2018). Diversas investigaciones han mostrado que los géneros con mayor presencia en estas áreas son: Bouteloua, Aristida, Andropogon, Muhlenbergia, Sporobolus y Heteropogon, entre otros, que tienen una cobertura del suelo entre el 7.3 % y 49.8 % de la superficie, en los estados de Chihuahua y Durango (Rodriguez-Maturino et al, 2017); así como Boteloua gracilis y Muhlenbergia rigida en el noreste de Jalisco, con cobertura entre 35 % y 40 % en áreas con pastoreo moderado y de 5 % y 10 % en áreas con sobrepastoreo (Delgado-Balbuena et al, 2013).…”