  We investigate spatially inhomogeneous versions of the stochastic
Lotka-Volterra model for predator-prey competition and coexistence by means of
Monte Carlo simulations on a two-dimensional lattice with periodic boundary
conditions. To study boundary effects for this paradigmatic population dynamics
system, we employ a simulation domain split into two patches: Upon setting the
predation rates at two distinct values, one half of the system resides in an
absorbing state where only the prey survives, while the other half attains a
stable coexistence state wherein both species remain active. At the domain
boundary, we observe a marked enhancement of the predator population density.
The predator correlation length displays a minimum at the boundary, before
reaching its asymptotic constant value deep in the active region. The frequency
of the population oscillations appears only very weakly affected by the
existence of two distinct domains, in contrast to their attenuation rate, which
assumes its largest value there. We also observe that boundary effects become
less prominent as the system is successively divided into subdomains in a
checkerboard pattern, with two different reaction rates assigned to neighboring
patches. When the domain size becomes reduced to the scale of the correlation
length, the mean population densities attain values that are very similar to
those in a disordered system with randomly assigned reaction rates drawn from a
bimodal distribution.
