about 20 % of the country (Udompitisap and Duangvichitkun 2006). A limitation of Point Asia images is
that they are not date stamped making it difficult to know
the exact year and season when the images were taken but,
according to Point Asia Dot Com Co., Ltd., all of the
images were taken in 2003–2007. The images employed in
this study were accessed from Point Asia (http://www.
pointasia.com) between 1 April and 31 August 2011.