attribute above average dense canopy 6.0 9.0 very dense canopy acronym scale_of loose canopy 4.0 5.0 average density canopy dense canopy 8.0 1.0 less dense canopy semi-loose canopy 3.0 2.0 moderately loose canopy moderately dense canopy 7.0 method_of entity variable_of 1-9 scale leaf density