Topographic Position Index and Ecological Land Type (warning
completely unrefined not quite Geologic dribble– with bad maps
:) …) Posted by smathermather on January 10, 2010 Warning. What
follows is somewhat informed, but I’m no geologist. I just play
one on wordpress. Understanding the basic underlying geology and
associated topography plus site history helps us achieve a basic
understanding of a sites ecological potential. At the most basic
level, we expect different wildlife and vegetation dynamics in a
floodplain vs. a mountain ridge. Classification of digital
elevation models can be done with a concept called topographic
position index (of which Jensen Enterprises has a pretty good
explanation). I’ve been playing with TPI for two areas in the
Allegheny Plateau in Ohio– one in an unglaciated portion, and
one in a glaciated portion. The Allegheny Plateau developed as
the once very tall Appalachians wore down to the nubs they are
today. That plateau has since eroded into little hill-like
remains, with strea