CANCELLED - Do peatlands have a role to play in future boreal upland forest dynamics?

Background/Question/Methods

The boreal forest is a fire-prone ecosystem where future changes in climate are predicted to increase the frequency and severity of wildfire. The current distribution of tree species is controlled by feedbacks between climate, vegetation, edaphic conditions, and fire frequency. Peatlands, which tend to have strong negative feedbacks that help to maintain saturated conditions, have the potential to modify local climate, store water to buffer against drought impacts, and affect fire behaviour. In the context of proposed oil sands mining and reclamation activities in northern Alberta, we investigated the potential role of peatlands–natural and reclaimed– to buffer against climate-mediated drought and increased fire frequency. Using a state-and-transition model, we used geospatial data for tree species, stand structure, soils, and moisture and nutrient regimes to simulate forest dynamics under contemporary and future climate change scenarios. Empirical relationships for forest succession and vegetation transitions were parameterized from provincial vegetation inventory data as well as literature sources. The local effects of peatlands on upland water availability and fire behaviour were based on conceptual models developed for northern Alberta and parameterized using new field research data. A two-factor scenario was evaluated for a natural versus reclamation landscape; and with and without peatlands.

Results/Conclusions

We present the spatially explicit model outputs of future predicted boreal forest distribution in northern Alberta, contrasting scenarios with and without peatlands. Overall, simulations show that peatlands have a small but significant ability to maintain current upland vegetation communities under moderate climate change scenarios. Moreover, the effect size tends to be greater in fine textured, low relief settings. While our simulations show that climate and fire have the biggest influence on the future vegetation states, peatlands have the ability to create local and landscape-level refugia. A global sensitivity analysis is also presented to highlight which model components are most influential in driving modelled vegetation dynamics and which parameters require better refinement to better constrain model predictions. Our spatially explicit simulations highlight the need to consider peatlands in forest management and reclamation activities where peatlands are prevalent.