COS 178-3 - Modeling future impacts of wildfire, Siberian silk moth, wind, and timber management on Siberian arctic and boreal ecosystems under climate change

Abstract: The Siberian arctic and boreal (taiga) ecosystems are experiencing warming about two to four times faster than the global average. This has grave implications for the extensive patchworks of carbon-storing permafrost and similar negative climate change feedback systems of Siberia. These rapidly increasing temperatures are modifying important disturbance regimes, causing unknown effects on species composition, permafrost, and albedo. We employed the spatially explicit landscape model, LANDIS-II, to investigate questions involving the timing and effects of vegetation tipping points of a large latitudinal gradient of central Siberian arctic and boreal ecosystems under climate change. We simulated wildfire, Siberian silk moth, wind, and timber management on four landscapes across the latitudinal gradient implementing LANDIS-II’s PnET-Succession, BFOLDS fire, BDA insect, and Biomass Harvest extensions as well as the newly developed albedo extension to project what these landscapes might look like under historical climate and climate change (CMIP6, RCP 8.5) conditions. Initial results show that under an increased climate warming scenario, fire and succession become near constant sources of mortality at all sites whereas under historical climate, they acted as more sporadic drivers of mortality. All four of the modeled landscapes experienced pronounced shifts in species compositions under increased warming with decreases in biomass and extent in each of the landscape’s respective dominant species classes. In the two southern-most sites, the southern taiga and middle-taiga, decreases in coniferous species were counterbalanced by an increase in deciduous species. The northern taiga experienced decreases in coniferous species as well but was replaced with an increase primarily in shrubs and wetland forest species. The northern-most site, the tundra, observed decreases in moss that were met with an encroachment of coniferous species. This movement of coniferous species out of southern latitudes and into the north affected permafrost, carbon storage and albedo. Understanding how the Siberian boreal and arctic landscapes are likely to respond to climate change and the effect of multiple disturbances will help guide global mitigation and management efforts to protect these vulnerable ecosystems.