Melissa Thomas

Biosecurity activities primarily include pre-border and border quarantine, post-border surveillance and post-border eradication. Budget allocated to quarantine and surveillance activities ultimately influence the expenditure and success rate of eradication campaigns. Optimal portfolio allocation examined in previous research is susceptible to potential severe uncertainties existing in ecology and in the behaviour of invasive species itself. These uncertainties, together with a limited budget, make it difficult for decision makers to allocate the total management budget to each biosecurity activity in a robust manner.

Info-gap decision theory is applied to model the severe uncertainty in invasive species management, and robust optimize the total management cost.

This research shows that using a combination of pre-border and border quarantine (to reduce the incursion probability) and post-border surveillance (to enable early detection and rapid response), enables decision makers to be more robust to potential uncertainty.

Further, it is reported that investment in quarantine that is more cost-effective should outweigh that in surveillance, in line with precautionary principle.

Increasing the estimated population threshold for surveillance detection also gains more robustness.

Synthesis and applications: Portfolio allocation options developed in this research provide decision makers with a way to manage the invasive species spatially, cost-effectively, and confidently by allocating the total management budget in a robust manner. The methods outlined in this research can not only be applied to invasive species, but also the conservation of endangered species that are constrained by severe uncertainty in ecological modelling and limited resources.

Grassland alvar is a rare plant community that occurs throughout North America and northern Europe, and may require control of encroaching vegetation to be maintained or restored. We evaluated the hypothesis that restoration techniques used to restore the alvar ecosystem do not lead to declines in small mammal abundance. More specifically, we used a BACI design to compare how two methods of vegetation control, prescribed burns and mechanical removal, affected small mammal populations. The restoration was conducted beginning in 2019 on Pelee Island, Ontario, Canada. Live trapping of small mammals and associated vegetation sampling were conducted before and after on treatment and control locations. The only small mammal species to be caught during the study was the white-footed mouse (Peromyscus leucopus (Rafinesque, 1818)), which had an observed decrease across all treatment sites and the control site. Generalized linear mixed effects models demonstrated that the main effects of treatment and year best explained mouse abundance at the site level. Interannual variability appeared to explain more variation in mouse abundance than treatment effects. Our study did not provide strong evidence that the vegetation control measures we employed might limit white-footed mouse abundance.