Aim

A strong influence of climate on species’ range is often assumed, and forms the basis for projecting many future range shifts with changing climate. Particularly at poleward latitudinal or elevational edges, abiotic conditions are thought to play a major role in limiting distributions. We estimated the roles of climate and landscape features in shaping habitat at the northern distributional edge of a critically threatened mountain tree species.

Location

British Columbia and Alberta, Canada.

Taxon

Pinus albicaulis (Engelm.)

Methods

We used a hierarchical Bayesian model (HBM) to combine multiple scales, sources, qualities and types of species data. We jointly examined the climate influence on occupancy across scales, and on juvenile and adult abundance to quantify habitat quality at two life history stages.

Results

We found that cold temperature was the strongest predictor of whitebark pine occurrence at regional scales, with colder areas being better (i.e. the sign was negative). Occupancy at local scales was best predicted by low growing degree‐days and declining precipitation as snow. These relationships with occupancy across scales indicate that suitable climatic and topographic habitats currently exist beyond the northern edge of whitebark pine's current range. We found high adult abundance was predicted in sunny, cool habitats with little climatic drought, whereas high juvenile densities were associated with higher precipitation as snow and more climatic drought.

Main conclusions

The negative relationship to temperature and the ample suitable habitats predicted to exist poleward of the current species’ range limit indicates whitebark pine is not limited by cold temperatures. We suggest that not all species’ ranges are cold limited at high latitudes or elevations. For whitebark pine this means warming temperatures may not directly result in a northern range expansion as a result of warming habitat.

These data are only those collected by A.Clason. All other data used as part of this paper were collected by other researchers and organizations.