Climatically Driven Stability in the Alpine/Moorland Boundary on Three Mountains in Southwest Lutruwita/Tasmania 1986–2020

ABSTRACT Questions Has the alpine ecotone shifted uphill from its historical position and has the vegetation composition on three highly maritime, mid‐latitude peaks in remote, natural areas changed between 1986 and 2020 in response to climate? Do the results support the null hypotheses that (1) the position of the alpine ecotone has not shifted upwards; (2) the richness of life forms better adapted to alpine conditions has not declined; and (3) there has been no decline in the frequency of alpine species or increase in lowland species in the vegetation between years? Location Mount Norold, Propsting Range and Mount Counsel in Southwest National Park, Tasmanian Wilderness World Heritage Area, Lutruwita/Tasmania, Australia. Methods Twelve 10 × 10 m quadrats were located along altitudinal transects across the alpine boundary on three mountains in 1986, 2010 and 2020. The cover‐abundance code data were used to calculate an alpine index. Presence/absence data were ordinated using global non‐metric multidimensional scaling and linear vectors fitted for sampling year, elevation and alpine index. Friedman's tests assessed the significance of richness changes in life forms and alpine species classes. Chi‐squared tests were used to assess significance of frequency changes for 32 taxa among years. Results Species composition showed a high degree of constancy between sampling years, although the richness of alpine species and the cushion life form increased between 1986 and 2020 when low cover species were filtered out of the data set. Four taxa varied significantly (increased) between years, two of which were cushion and two were sclerophyllous rhizomatous graminoids. A steepening of the relationship between the alpine index and altitude with time was also observed. Conclusions Our results indicate that vegetation at the alpine ecotone on three coastal mountains has remained spatially stable. Despite rising minimum temperatures at sea level, we detected no upward shift in the alpine boundary and no decline in alpine species. Instead, alpine species were retained with an increase in the cover of plants adapted to wind exposure. This pattern suggests that stronger winds may be buffering alpine communities against warming, helping maintain alpine conditions at the ecotone.