Playbook for Urban Biodiversity

S3. Remove 'minimum patch size' rules for planning schemes and vegetation

Small patches of green space possess great value for biodiversity.

Research has shown that small patches of green space can harbour significant biodiversity – even accounting for the challenges of fragmentation and edge effects, many studies have discovered that multiple small patches of equivalent area to a single large green space had greater species diversity. This contradicts mainstream understandings that small patches of green space are less valuable than larger green spaces, which stimulates the importance to review the regulations and policies that protect vegetation and open space. Underestimating the contribution that small habitat patches can make towards urban nature can also result in the misunderstanding of the value of smaller revegetation or restoration interventions. Many studies have demonstrated the contribution of a single garden bed for urban biodiversity, including from within the City of Melbourne (Mata et al., 2023).

Consideration of key Victorian legislative instruments is warranted, in particular of the zones and overlays that are enforced in local government planning schemes, to identify biases or exemptions that enable the eradication of small patches. More challengingly, protection of small patches demands an examination of existing norms regarding the use of vegetation and biodiversity regulations set out in planning schemes in the assessment of developments on private land and in the management of public land. Due to the well-established myth that small habitats do not matter, local governments and state officers may currently be sympathetic to arguments that small patches are not significant enough to retain, protect or apply rigorous enforcement actions instances of non-compliance.