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Title: PRODUCTIVITY AND FORAGE QUALITY OF WARM SEASON GRASS PASTURES IN RELATION TO CANOPY REFLECTANCE IN ASTER WAVEBANDS

Author
item Starks, Patrick
item Zhao, Duli
item Phillips, William
item Brown, Michael
item Coleman, Samuel

Submitted to: American Society for Photogrammetry and Remote Sensing Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2005
Publication Date: 10/1/2005
Citation: Starks, P.J., Zhao, D., Phillips, W.A., Brown, M.A., Coleman, S.W. 2005. Productivity and forage quality of warm season grass pastures in relation to canopy reflectance in aster wavebands [abstract]. American Society for Photogrammetry and Remote Sensing. p. 14.

Interpretive Summary: Abstract Only.

Technical Abstract: Estimation of forage biomass production and quality parameters during the growing season is important for adjusting stocking rate and making pasture management decisions. Remotely sensed data collected from boom-, aircraft- or satellite platforms may be used to estimate rangeland productivity and forage quality. Experiments were conducted in the 2002 and 2003 growing seasons to determine the relationships of aboveground biomass, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP) concentration, and CP availability of five warm season grass pastures with canopy reflectance or reflectance ratios in wide wavebands. Canopy reflectance was measured periodically throughout the growing seasons using a portable, hyperspectral radiometer and converted to seven wide wavebands based on spectral ranges of the Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER). Forage NDF, ADF, and CP concentrations were quantified using standard laboratory chemical methods. Overall, CP content was highly and linearly correlated with the ratio of reflectance in NIR (780-860 nm) to Red (630-690 nm) with r2 = 0.554 (n = 414). Use of canopy reflectance or reflectance ratios in given wavebands explained 26, 55, and 51% of variances, respectively, for aboveground biomass, CP concentration, and CP availability (P < 0.0001). Pasture NDF and ADF had poor correlation with canopy reflectance compared to either CP or biomass. Our results suggest that remote sensing of canopy reflectance can be used for real-time and nondestructive prediction of CP concentration and biomass production in warm season grass pastures. The information from this study may also be useful for large scale monitoring of rangeland forage quality based on ASTER data.