Data from: Incorporating existing thermal tolerance into projections of compositional turnover under climate change

Aim: Observed, realized niche space often underestimates species’
physiological tolerances due to interactions with other species, dispersal
constraints, and because some combinations of influential environmental
factors do not currently exist in the real world. Conversely, correlative
ecological niche models rely on the assumption that the range of
environmental conditions encompassed by a species’ geographic distribution
accurately reflects their environmental tolerances, including
community-level approaches like Generalised Dissimilarity Modelling (GDM).
We extend GDM to better understand what effect broader environmental
tolerances could have on compositional turnover under climate change.
Innovation: We show how GDM can be adjusted as a function of
best-available estimates of the average ratio between realized and
potential niche widths to modify projected temporal turnover. We
demonstrate this approach by using the estimated niche ratios of
Australian plant species (n=7184) relative to thermal extremes, and the
rate at which this ratio varied with temperature. The modified GDMs showed
existing thermal tolerance could reduce the turnover predicted by standard
models under climate change by up to 11%. We further show how the
reduction in expected turnover by 2090 will influence where a greater
proportion of the current community will persist in a region. Main
conclusions: We suggest that standard spatial GDMs and their modified
versions represent the extremes of ecological niche perspectives (i.e.
realized and potential) and the range of tolerance communities may have
when responding to environmental change. GDM projections therefore
identify the range of uncertainty associated with a critical model
assumption, and as climate change continues, ongoing community monitoring
could be used to validate the balance between the two possibilities.