Ascelin Gordon and his colleagues from Melbourne recently went through an interesting modelling exercise. They modelled the long-term effects, in both space and time, of different offset policies concerning urban development impacts on native grasslands around the city.
Their modelling explicitly included uncertainties , following the approach described by Langford et al. (2009). These uncertainties were both ecological (edge effects on conservation value, grassland response to management and offsetting, etc.) and political: which offset policy?
They compared five different offset policies:
Their conclusions are that offset policies that include spatial and temporal constraints on offsets give the best conservation outcomes. They also point out the obvious: the selection of the baseline is central to any assessment of policy outcomes.
whether (or when) [policies] achieve the objective of a “net gain” completely depends on the choice of baseline.
It might be obvious but it is certainly tricky when looking at policies that involve long-term ecological dynamics…
To find out more, check out their paper in Environmental Modelling & Software*. A pdf can be downloaded here.
* Gordon A., Langford W.T., Todd J.A., White M.D., Mullerworth D.W. & Bekessy S.A. (in press): Assessing the impacts of biodiversity offset policies. Environmental Modelling & Software, in press.
Tags: Australia, grassland restoration, habitat hectares, Modelling, strategic offsets