摘要：Larch taiga, also known as Siberian boreal forest, plays an important role in global and
regional water–energy–carbon (WEC) cycles and in the climate system. Recent
in situ observations have suggested that larch-dominated taiga and permafrost
behave as a coupled eco-climate system across a broad boreal zone of Siberia.
However, neither field-based observations nor modeling experiments have clarified the
synthesized dynamics of this system. Here, using a new dynamic vegetation model
coupled with a permafrost model, we reveal the processes of interaction between the
taiga and permafrost. The model demonstrates that under the present climate
conditions in eastern Siberia, larch trees maintain permafrost by controlling the
seasonal thawing of permafrost, which in turn maintains the taiga by providing
sufficient water to the larch trees. The experiment without permafrost processes
showed that larch would decrease in biomass and be replaced by a dominance of
pine and other species that suffer drier hydroclimatic conditions. In the coupled
system, fire not only plays a destructive role in the forest, but also, in some cases,
preserves larch domination in forests. Climate warming sensitivity experiments
show that this coupled system cannot be maintained under warming of about
2 °C or more. Under such conditions, a forest with typical boreal tree species (dark conifer and
deciduous species) would become dominant, decoupled from the permafrost processes. This
study thus suggests that future global warming could drastically alter the larch-dominated
taiga–permafrost coupled system in Siberia, with associated changes of WEC processes and
feedback to climate.
