ANALYSIS OF SPECTRAL DATA FOR COMPARING RANGELAND AND CULTURAL PRACTICES IN SOUTHERN ALBERTA

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Abstract
Spectral reflectance characteristics of rangeland provide quantitative and qualitative information which can be useful for assessing range condition and phytomass. The data set in this study consisted of phytomass estimates and ground-based reflectance measurements in four wave bands between 0.5 and 1.1 μm taken from eight range improvement treatments near Lethbridge, Alberta from April through July in 1983 and 1984. The treatments consisted of subjecting native range to reseeding with grasses or legumes and fertilizer and herbicide additions. Spectral reflectance was highly correlated (R2 = 0.82 – 0.99) with the seasonal trajectory of phytomass production in spite of low amounts of green vegetation and high amounts of senescent vegetation. The data were analyzed by determining the relationship between accumulated phytomass and intercepted photosynthetically active radiation calculated from canopy reflectance. The regression coefficient of this relationship was an estimate of photochemical efficiency. The estimates of photochemical efficiency (1.09 and 0.76 g MJ−1 in 1983 and 1984, respectively) were lower than those reported in the literature (1.4 g MJ−1), presumably due to moisture stress in both years.Key words: Mixed prairie, short-grass, biomass, phytomass, remote sensing