Using Aerial Photography and Image Analysis to Measure Changes in Giant Reed Populations

A study was conducted along the Rio Grande in southwest Texas to evaluate color-infrared aerial photography combined with supervised image analysis to quantify changes in giant reed (Arundo donax L.) populations over a 6-year period. Aerial photographs from 2002 and 2008 of the same seven fixed study sites were studied. Coverage of giant reed increased in all sites from 2002 to 2008, including increases ranging from 21.9 to 49.9% in six of the seven sites. Expansion of giant reed resulted primarily from its displacement of mixed herbaceous vegetation and encroachment on bare soil areas. These results indicate that color-infrared aerial photographs coupled with image analysis techniques can be useful tools to monitor and quantify changes in giant reed populations over time.