Although the BIOME3 and MAPSS models are capable of more detailed representation of vegetation types (eighteen and forty-five vegetation classifications, respectively), for the purposes of this study, vegetation classifications were aggregated into ten common biome classifications, so that the results of the two GVMs would be comparable (Table 1).
A comparison of BIOME2 (a precursor to BIOME3) and MAPSS over the conterminous United States determined that they were able to simulate current vegetation patterns with roughly equal success, but the structural differences in GVMs and their different responses to climate change in previous inter-comparison studies (Vegetation/Ecosystem Modeling and Analysis Project (VEMAP) Members 1995 and Neilson 1998) necessitated the use of the two GVMs in this analysis to better represent the range of assumptions and scientific uncertainties related to vegetation's response to climate change.
2005), the two major indicators utilised in this analysis are percentage of protected areas projected to change biome type and percentage change in representation of biomes projected under current and future vegetation simulations by the MAPSS and BIOME3 models.
The spatial distribution of potential vegetation as modelled by the MAPSS and BIOME3 GVMs under current climate (1961-1990) and future climate-change scenarios are presented in Figures 1 and 2 for comparison.
Under all four climate-change scenarios with the MAPSS GVM, Canada's national parks were projected to experience the greatest change in biome type compared with the other protected area designations.
Projections of biome change differed for protected area designations under the BIOME3 models when compared with MAPSS.
A comparison of the HadCM2 climate-change scenario, which was the only common climate-change scenario available for the MAPSS and BIOME3 GVMs, revealed that the BIOME3 consistently projected greater biome-type change compared with MAPSS.
Table 4 summarises how the representation of each of the ten biomes modelled was projected to change within Canada's existing protected area network under the MAPSS scenarios.