Climate buffering effects of western Canadian boreal lakes: the effect of lake size and depth on shoreline and nearshore forests.

CONTEXT

Lakes can provide thermal refugia effects by buffering shoreline and inland temperatures, potentially delaying forest transitions. However, this effect has not been quantified for the majority of boreal Canada lakes, which are often excluded in general circulation model predictions of climate, thus potentially underestimating the effects of lake-mediated buffering.

OBJECTIVES

Here, we quantify the effects of varying lake morphometry on temperature buffering potential of 11 boreal lakes in central to western Canada. We aim to provide context for lake-mediated climate buffering in Canada's boreal forest.

METHODS

We established inland transects at 11 lakes in Ontario, Manitoba, Saskatchewan, Alberta, and the NWT of Canada, with temperature stations at 10 m, 100 m, 1 km, 10 km, and 100 km from shore. We predicted the effects of lake characteristics on mean July temperature anomaly, net ice-off period temperature anomaly, and the proportion of coniferous trees at sites.

RESULTS

July temperatures were coolest on the downwind side of lakes, within 10 km of shore, and at lakes with a high volume (Rc = 0.71), Near-shore sites were cooler than inland sites, particularly at a lower altitude above the lake and larger lake volumes (Rc = 0.66). Ice-off temperature anomalies were best predicted by the interaction between lake area and average lake depth (Rc = 0.55). Lastly, the proportion of coniferous trees at sites was best predicted by mean July temperature (Rc = 0.41).

CONCLUSIONS

We identified lakes across boreal Canada large enough to provide seasonal temperature buffering on their shoreline and nearshore forests, with an aim for inclusion in circulation models and to guide management and conservation efforts associated with lake-mediated climate refugia.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10980-025-02146-5.