Using the UK as an example, Joseph W. Bull and  E.J. Milner‐Gulland join the BES Policy team and present their new model, designed to simulate prevention and cure tactics for decision makers. 

The UK Government’s Environment Bill sets out a decision to legally require most new economic development projects to achieve ‘Biodiversity Net Gain’ – that is, to leave the natural environment better off than when the project started. The way to do this is to work out what the biodiversity impacts of any given development are likely to be (e.g.  through the standard Environmental Impact Assessment process), and then find ways to either avoid those impacts in the first place or else compensate for them through for example, habitat restoration nearby.

Let’s imagine nature is our patient, and biodiversity loss is a malady. Avoiding impacts is analogous to preventing illness, whilst compensation is the cure for it. The important question, then, is which is preferable, prevention or cure? And under what circumstances? Deciding the answer to this could have ramifications across the UK, both on the design of development projects and on the overall approach to British nature conservation.

In our new article, we detail the model we constructed, which allows policymakers and others to simulate different mixtures of prevention and cure tactics for biodiversity losses associated with development. The model considers not only biodiversity trends, but also the behaviour of developers and the decisions taken by policymakers themselves. Using the model, we have generated some interesting results relating to the mitigation of wetland losses from development in the US; and the World Bank has already shown interest in using the model to evaluate its own Net Gain-type policies.

What we find is that, perhaps contrary to intuition, it is not always preferable from a conservation standpoint to prevent impacts. In some cases – particularly when the result is to lock land and/or resources into conservation interventions which otherwise would not have taken place – it is better to allow limited biodiversity losses and then fully ‘offset’ them elsewhere. Not only does such a finding (presuming sufficient evidence is available on likely outcomes) warn against an overly dogmatic interpretation of the mitigation hierarchy. It tells us as conservationists that it cannot necessarily be assumed avoiding impacts is the best outcome for nature overall, if there is some form of ‘net outcomes’ policy in place. Consequently, our work provides a basis for advising decision makers, particularly in the UK, about the best structure for the nascent Net Gain policy, given region-specific ecosystem recovery rates, development activity, legal compliance and uncertainties.

At a time of great uncertainty, let us at least try to put greater certainty on our efforts to retain and restore the natural environment – such that, however we leave the planet to future generations, we know it will at least be green and pleasant.

Read the full article, Choosing prevention or cure when mitigating biodiversity loss: trade‐offs under ‘no net loss’ policies, in Journal of Applied Ecology.