Roshan Sharma, Simon Jones, Lucy Bastin, Ascelin Gordon

Globally, private protected areas (PPAs) have become an important tool for
biodiversity conservation. While they are expanding in size and number, there is
limited evidence on their potential impact on avoiding biodiversity loss, and how this
impact compares to the public protected areas (PAs). The impact of protection is
measured as the actual biodiversity outcome within the area protected relative to the
hypothetical outcome without protection. To maximise this positive impact, PAs need
to be placed strategically on land that both harbours biodiversity and would be at risk
of losing some of the biodiversity if it were not protected. We evaluate and compare
the locations of PPAs and public PAs relative to random sites of similar governance
type, and a range of covariates that capture biodiversity and the risk of biodiversity
loss. We utilised data from a national PA database, and high-resolution data on
nationally significant threatened species and indicators that capture risk of biodiversity
loss at a continental scale in Australia. We find that PPAs tend to target areas of high
threatened species richness. However, on average, PPAs are placed in areas that
have lower risk of being cleared compared to randomly selected private land. We
observe that this bias towards unproductive land is more prominent in PPAs when
compared to public PAs. As nations work towards effectively conserving and
managing at least 30% of the world's lands by 2030 under the new Kunming-Montreal
Global Biodiversity Framework, it becomes essential to prioritise PAs and PPAs that
deliver impacts on avoiding biodiversity loss rather than solely focusing on areas that
represent biodiversity.