Life on the edge: Considering ecotonal habitat for the conservation of alpine reptile metacommunities

Abstract

Conservation planning focuses on core habitats, often overlooking ecotones, which can hold unrecognised potential for biodiversity conservation. This study focused on ecotonal habitat use in alpine reptile metacommunities, with emphasis on a grassland specialist, the critically endangered alpine she-oak skink, Cyclodomorphus praealtus. Survey transects in grasslands and woodlands in Kosciuszko National Park in the Australian Alps were used to investigate reptile occupancy and richness. Data was analysed using a multi-species occupancy model in relation to (1) distance from nearest grassland to assess grassland specialists' occupancy into woodland areas while accounting for imperfect detection, and (2) normalised difference vegetation index (NDVI) to assess the importance of high resource patches. Among the 11 reptile species detected, our hypothesis that grassland specialists would inhabit woodland ecotones was confirmed. The furthest occurrence of C. praealtus from the closest grassland was 41 m with a predicted occupancy of 0.06 (0.004 – 0.169 95 % Bayesian credible intervals) at 100 m. Contrary to conventional edge effect theories, our results revealed no increase in species richness nearer to the woodland ecotone from grasslands or with higher NDVI values. This study underscores the importance of including ecotonal buffers in ecological impact assessments and conservation plans for habitat specialists, that may still use ecotones of adjacent habitats. The findings emphasize the need for broader survey efforts beyond core habitats to capture the distribution of threatened species effectively. Incorporating ecotonal habitats into conservation strategies is crucial, particularly for specialist species whose dynamic use of ecotones may help safeguard them amidst predicted habitat transformation from anthropogenic influences and climate change.