New Zealand Journal of Ecology (2023) 47(2): 3535

The conservation long game: Leiopelma species climate envelopes in New Zealand under a changing climate

Research Article
Jennifer M. Germano 1*
Richard Earl 2
Mandy Tocher 3
Petra Pearce 4
Jenny Christie 2
  1. Biodiversity Group, Department of Conservation, Private Bag 5, Nelson 7042, New Zealand
  2. Biodiversity Group, Department of Conservation, Private Bag 4715, Christchurch 8011, New Zealand
  3. LizardExpertNZ, P.O. Box 54, Port Chalmers, 9050
  4. National Institute of Water and Atmospheric Research, Private Bag 14901, Kilbirnie, Wellington 6241, New Zealand
*  Corresponding author

Amphibians are considered susceptible to a range of potential effects generated by climate change. We applied species distribution model (SDM) techniques to predict future areas of climatic suitability for Archey’s and Hochstetter’s frogs under two different climate change scenarios using climate variables derived from their existing geographic extent. For Hamilton’s frog their current range was too restricted to model future range, so we used past climate data from current strongholds to establish that these sites may not be suitable for this species in the long-term. Model projections for Archey’s frog showed the climatically suitable area expanded and extended south as greenhouse gas concentrations increased. Under the mid-range gas concentration scenario, suitable areas were similar in 2040 and 2090, and both had an 88% overlap with the current distribution. Under the high-end gas concentration scenario suitable areas for occupancy were similar to the mid-range concentrations by 2040 (84.6% overlap), but by 2090, while their currently occupied areas remain suitable for occupancy (85.5% overlap), the suitable area stretched south resulting in a large range expansion. For Hochstetter’s frog, the predicted climatically suitable area also moved south, but the proportion of their current range able to be occupied lessened as greenhouse gas concentrations increased. With the mid-range concentrations, less than half of their current areas were still suitable to occupy by 2040 and 2090 (46.1% and 35.7% respectively). The high-end greenhouse gas pathway produced a similar outcome by 2040 with only 47.3% of the current occupied area remaining suitable. Under this pathway, by 2090, suitable areas were much further south, and the northern North Island was no longer suitable for Hochstetter’s frog. We conclude that a shift from traditional conservation methods will be required to allow Leiopelma species to persist under a changing climate.