The utilization of bryophytes in bioclimatic modeling: Predicted northwardmigration of peatlands in the Mackenzie River Basin, Canada, as a result of global warming

A bioclimatic model based on bryophyte species distribution and abundance r elative to climate was coupled with climatic and geographical data obtained from Leemans and Cramer (1991) and the Canadian Climate Center (CCC) Gener al Circulation model (GGM) at 1XCO(2) in order to reconstruct the present g eographical distribution of seven peatland types in the Mackenzie River Bas in. The geographical distribution of 195 peatlands previously identified by type were used to test the validity of the reconstructions. The rest revea led that the reconstruction using data from Leemans and Cramer was more acc urate than the reconstruction using the CCC GCM data. For this reason, the CCC 1XCO(2) data was subtracted from the CCC 2XCO(2) climatic data to produ ce an anomalies data set which was then added to the Leemans and Granter da ta to project the distribution of the seven types of peatlands at 2XCO(2). Results of this prediction were then compared to predictions using 2XCO(2) data obtained from the Geophysics Fluid Dynamics Laboratory (GFDL) GCM. The position. of the southern limits of peatland distribution was compared to past distributions resulting from a warming period in the early to mid Holo cene. Results of the predictions for the two climate change scenarios indic ated a northward migration of the southern boundary of peatland ecosystems of approximately 780 km in the central portion of the Mackenzie River Basin . The model also predicted that Mid-Boreal peatlands would be located along a diagonal running from southeast to northwest from 60 degrees longitude t o an area just south of the Mackenzie Delta far both scenarios. High-Boreal and Subarctic peatlands were located to the north of the diagonal, while L ow-Boreal peatlands were located to the south. However, the CCC anomalies Leemans and Cramer predictions did not clearly define the Low-Boreal since Low-Boreal indicators were only located in the Cordilleran Ecological Prov ince. Ecological diversity is anticipated to be maintained in the peatlands because all types were predicted to be found in the Basin at 2XCO(2) but a t different locations. Comparisons between the predicted position of the so uthern limits of peatland distribution and that during the early to mid Hol ocene indicate that the model's predictions were reasonable.