A scientific study evaluating the impact of one of the first established biodiversity offsetting schemes on native vegetation found it was not possible to conclusively demonstrate the policy had resulted in a net biodiversity gain due to limited data and the lack of robust impact evaluations.
A group of scientists from British and Australian universities looked at the impact of biodiversity offsets set up under the region of Victoria in Australia’s “Native Vegetation Framework” from 2000 to 2013.
The framework was set up to prevent loss and degradation of existing vegetation and generate gains in vegetation extent and quality and included native vegetation offsetting.
In order to properly assess the outcomes, the report therefore looked at the impacts of completed 10-year-old offsets implemented within this system.
It concluded that the biodiversity offsets under the programme delivered “limited additionality and therefore had a limited impact on woody vegetation extent, and suggests that most losses of native vegetation were not counterbalanced”.
The paper highlighted the pressing need for “high-quality evidence demonstrating effectiveness” if biodiversity offsetting is used in policy and financial circles, and points to the lack of such evidence at present.
It concluded that offsetting systems around the world “consistently fail to achieve basic criteria for enabling a robust understanding of their actual impact,” and that data on ongoing monitoring is frequently disregarded.
The few existing reviews of offsetting suggest the latter works better in habitats that regenerate more quickly, such as wetlands, whereas outcomes are worse in slow-maturing habitats such as woodlands.
However, the paper underlined that this existing evidence is sparse and usually relies on weak study designs.
Some risks related to simplified assessment tools which can be easily applied by consultants are creating homogeneous habitats that don’t capture the biodiversity variety of a specific area, the report stated.
The report also highlighted the risk that biodiversity offsetting involves private actors that would have implemented nature-friendly management practices or would have not cleared existing native vegetation on their land even without being compensated for these activities through biodiversity offsetting.
This is what the paper calls “self-selection” bias and is a problem because biodiversity offsets can only be additional if they induce conservation actions that result in gains that would not have happened without the offset transaction.
Finally, the scientists said the study contributes to evidence that ecological gains from avoided losses are “consistently revealed to have been overestimated by ex-post impact evaluations,” joining a number of other studies that found the same in forest-based carbon and biodiversity offsetting systems.
By Rebecca Gualandi – rebecca@carbon-pulse.com
