Files
Abstract
Invasive species are significant threats to biodiversity, natural ecosystems and
agriculture leading to large worldwide economic and environmental damage. Spread
and control of invasive species are stochastic processes with important spatial
dimensions. Most economic studies of invasive species control ignore spatial and
stochastic aspects. This paper covers this gap in the previous studies by analysing a
spatially explicit dynamic process of controlling invasive species in a stochastic
setting. We show how stochasticity, spatial location of infestation and control can
influence the spread, control efficiency and optimal control strategies. The main aim
of this paper is to analyse the relationship between economic parameters and
stochastic spatial characteristics of infestation and control. In the model used, there
are two ways to control infestation: border control, under which the spread of
invasive species from any of its infested neighbouring cell is prevented, and cell
control, which removes the infestation from the existing cell. An integer optimisation
model is applied to find the optimal strategies to deal with invasive species. Results
show that it is optimal to eradicate or contain for a larger range of border control and
cell control costs when the invasion is in the corner or on the edge as compared to the
case where the initial infestation is in the middle of the landscape. Decrease in the
probability of successful border control makes containment an unfavourable control
option even for low border control costs. We show that decrease in the rate of spread
can result in switching optimal strategies from containment to abandonment of
control, or from eradication to containment. We also showed when the probability of
successful cell control decreases, a lower eradication cost is required for eradication
to remain the optimal strategy. In summary, this paper shows that in order to avoid
providing misleading recommendations to environmental managers, it is important to
include uncertainty in the spatial dynamic analysis of invasive species control.