Estimation Of Leaf Area Index And Light Intercepted By Shrubs From Digital Videography

The development of digital videography has generated interest in the use of these instruments to estimate vegetation variables such as leaf area index (LAI) and light intercepted (f_IPAR) by shrubs in shrublands and open forest canopies. The objective of this study was to examine the relationships between the percentage of scene classified as foliage in color digital videography acquired in the field, and LAI and f_IPAR by canopies of two shrub species, bitterbrush (Purshia tridentata) and manzanita (Arctostaphylos patula). There was a positive linear relationship between the combined percentage of scene occupied by sunlit leaves, shaded leaves, and shaded background as the dependent variable, and f_IPAR (R² = 0.66 manzanita, and 0.61 bitterbrush). A logarithmic relationship was observed between the combined percentage f scene occupied by sunlit leaves, shaded leaves, and shaded background, and the independent variable LAI (R² = 0.88 manzanita, and 0.65 bitterbrush). A green/red ratio was useful for classification of video scene components into illuminated and shaded leaves, and illuminated and shaded background. This study demonstrates that color digital videography may be suitable for field estimates of f_IPAR and low LAIs in open shrublands.