Negative patch-scale edge effects, where species are more common in
habitat interior than edge, are often used as evidence of negative
fragmentation effects. This is because, for a given total habitat area,
a more fragmented landscape contains less interior habitat. I tested
this cross-scale extrapolation by extracting from the literature a
sample of species showing negative or positive landscape-scale
fragmentation effects, and then for each species I searched for studies
from which I could calculated the slope of its patch-scale edge effect.
Species showing negative patch-scale edge effects were equally likely to
show negative or positive landscape-scale fragmentation effects, and
likewise for species showing positive patch-scale edge effects. Thus, a
species' patch-scale edge effect does reliably predict its response to
habitat fragmentation. Fragmentation effects, and the efficacy of
policies related to them, require evidence at a landscape scale,
comparing species' responses across landscapes with different levels of
fragmentation.