The value of regrowth forests and woodlands for threatened fauna species

Whilst the loss of remnant ecosystems is a key driver of the biodiversity crisis, the loss of regrowth ecosystems is sometimes overlooked. The impact of regrowth vegetation loss on threatened fauna is not well understood, particularly relative to remnant vegetation loss. Here, we used structured expert elicitation to determine the minimum age at which regrowth vegetation is used by 33 threatened fauna species, and how quickly the habitat value of regrowth vegetation converges on that of remnant vegetation. Then, using remotely sensed data, we estimated the proportion of each species' current habitat that comprises regrowth vegetation. We conducted our analysis in Queensland, Australia, a jurisdiction with approximately 7.6 million hectares of regrowth woody vegetation (as of 2021) that can be cleared under exemption in state vegetation management laws. We found that the median minimum age of regrowth vegetation use for 33 focal species was 15 years (ranging from 3 to 68 years), while the median age at which regrowth vegetation provided 75 % of the relative value of remnant habitat was 36 years (ranging from 11 to 193 years). The variation in value of younger regrowth among species was driven by species-specific factors such as dependence on tree hollows, diet and breeding requirements. A median of 18 % of current potential habitat for the 33 focal species comprised regrowth vegetation. Most potential habitat for these species that had been cleared since 2018 was regrowth vegetation (71 %). We conclude that regrowth vegetation provides valuable threatened species habitat in Queensland from relatively young ages.