Grid based fragmentation analysis after Riitters et al. (2000).
(1) interior, if Density = 1.0
(2) undetermined, if Density > 0.6 and Density = Connectivity
(3) perforated, if Density > 0.6 and Density - Connectivity > 0
(4) edge, if Density > 0.6 and Density - Connectivity < 0
(5) transitional, if 0.4 < Density < 0.6
(6) patch, if Density < 0.4
References:
Riitters, K., Wickham, J., O'Neill, R., Jones, B., Smith, E. (2000):
Global-scale patterns of forest fragmentation. Conservation Ecology 4(2): 3
http://www.ecologyandsociety.org/vol4/iss2/art3/