Russian forest dynamics and response to changing climate: a simulation study

Russian boreal forests represent a significant portion of global terrestrial biomass, and are critical to understanding the Earth's response to climate change. Dynamic vegetation models are well suited to assess aboveground carbon storage in the boreal region and explore the impacts of climate change on boreal forests. An existing forest gap model was expanded from northern China and the Russian Far East to across all of Russia to test the limits of extrapolation from the area of initial development. The model was updated to include species range information and new species from western Siberia and European Russia. Model results were validated using independent forest inventory data from a representative sample of Russian forests. Correlations between model and forest inventory biomass are strong for several species. Operating at the landscape scale the model provides a realistic representation of biomass accumulation for dominant species, and predicts overall species composition. Age cohort data from forest inventory stations and model biomass was used to assess the difference in aboveground carbon biomass for the current state of forests, an even distribution of age cohorts, and a mature forest condition. The current and even age cohort distributions were not found to have significantly different biomass, but a transition to a mature forest condition would create significantly more biomass. The capacity for increased biomass is limited as a transition to a mature forest condition is unlikely to occur. Climate sensitivity analysis using temperature and precipitation change, as well as the introduction of the warm adapted Larix decidua as a mitigation attempt against vegetation shift showed that there is a different response in high and low diversity areas. The high diversity Russian Far East shows resilience to climate change, but the low diversity areas across Siberia are vulnerable to vegetation shifts under conditions of temperature increase. The system as a whole is primarily a low diversity system which is vulnerable to the effects of warming. The replacement of deciduous Larix spp. with evergreen conifers across Siberia as seen in response to warming has the potential to create a positive feedback due to the shift in albedo.