An integrodifference model that describes the spread of invading
species on a periodically fragmented environment is analyzed to derive
an asymptotic speed of range expansion. We consider the case that the
redistribution kernel is given by an exponentially damping function and
the population growth is subject to a Ricker function in which the
intrinsic growth rate is specified by a spatially periodic
step-function. We first derive a condition for successful invasion of a
small propagule, and then provide a mathematical formula for the rate
of spread. Based on the speeds calculated from the formula for various
combinations of parameter values, we discuss how the habitat
fragmentation influences the invasion speed. The speeds are also
compared with the corresponding speeds when the dispersal kernel is
replaced by a Gaussian.