[Determinación de las variables biofísicas usando técnicas de sensores remotos [índices de vegetación]]

Autor:Pérez C., Claudio

Institución:University of Nebraska. Graduate College

Monitoring rangeland characteristics is difficult because of the extensive nature of range, the biodiversity, variability of environments, and management practices. Remotely-sensed images provide an excellent tool to evaluate changes in environment over time, and allows us to construct decision making programs for different time frames. Empirical vegetation indices (VI) and canopy reflectance models have been used to extract and interpret information about biophysical variables from remotely-sensed vegetation canopies for the past 25 years. This study was conducted at the University of Nebraska Gudmundsen Sandhills Laboratory near Whitman, Neb. during June and August 1995 and 1996 to develop spectral reflectance curves and vegetation indices for grazed and ungrazed uplands and meadows in the Nebraska Sandhills. Canopy radiance of 128 quadrats (1 m2) located in the upland and meadow sites were measured with a Spectron SE 590 portable radiometer. Biophysical variables such as standing crop biomass, standing dead material, litter, leaf area index (LAI), percentage foliar cover, and soil moisture content also were estimated for each quadrat. Four vegetation indices, difference vegetation index, ratio vegetation index, normalized difference vegetation index and soil adjusted vegetation index, were calculated. The main objectives were (a) to determine the spectral characteristics of subirrigated range sites (meadows) and upland pastures dominated by the sands range site; b) to correlate the biophysical variables with the VIs; c) to identify a broad-band VI and/or a narrow-band VI; and d) to validate the Radiation Transport Program (RTP) in the Nebraska Sandhills, and in the controlled enviromnent of a growth chamber. Foliar cover had the highest number of significant correlations (p <0.05) with the different VIs; however, the VIs did not predict foliar cover, standing crop biomass, or LAI, reliably and consistently over time or space. None of the VIs tested was better than any of the others in predicting the measured values of the biophysical variables. Across the environmental used, RTP predicted foliar cover, standing crop biomass, chlorophyll content, and LAI more consistently than the VIs


Citar esta publicación:
Pérez C., Claudio (1998) [Determinación de las variables biofísicas usando técnicas de sensores remotos [índices de vegetación]] [en línea]. Nebraska, USA: Disponible en: https://biblioteca.inia.cl/handle/123456789/50483 (Consultado: ).