Simulating spatio-temporal dynamics of tundra loss caused by the advancing latitudinal treeline in Siberia

Abstract:

The tundra-taiga transition zone in northern Siberia is expected to advance north in warming climates. However, it is largely unknown to what extent pristine tundra areas will be replaced by forests and where they may retreat during the upcoming warm centuries, ultimately enabling a possible recolonization when climate becomes cooler again.

To lower uncertainties in predictions that arise from time-lag effects from long life-cyles of involved tree species, we updated the individual-based spatially explicit vegetation simulation model LAVESI and applied it along the Siberian treeline (65-170° E). With this model, we track the development of the treeline in simulations forced with climate change scenarios based on RCP scenarios until the year 2300 and beyond.

We will focus with our analysis on the spatio-temporal dynamics of the treeline at five different focus regions from east to west: at the north of the Ural Mountains, the Taimyr Peninsula, the Buor Khaya Peninsula, along the Kolyma river, and, in Chukotka. This allows us to be able to estimate which types of tundra and the area that may be lost under the contrasting climate pathways. Based on these predictions, we can identify areas that may serve as refugia.

The results of this novel simulation approach will be discussed highlighting differences to other predictions based on models in which vegetation can quickly equilibrate with forcing climate, which is still the standard for dynamic global vegetation models.

Based on our findings, we will compile where tundra areas are most vulnerable and give recommendations where areas should be conserved to prevent or lower the risk of a total loss in Siberia.