Permalink : http://hdl.handle.net/2115/67943

KEYWORDS : global warming;Larix gmelinii;continuous permafrost;tree succession

Dahurian Larch, Larix gmelinii, grows as a tree in the continuous permafrost region of eastern Siberia. Along with other allied Larch species and/or subspecies (notably L. cajanderi), it can grow on continuous permafrost. The expected warming of the climate in Siberia from global warming will reduce the permanent permafrost area, and will have an effect on the reduction in distribution of the larch. We investigate the possible forest succession effects in the interactive system among larch, dark conifers and climate using a simple conceptual model. The basic variables are the larch biomass, BL, the dark conifer biomass, BD, and the water content in the active soil layer, W. External parameters include precipitation, P, and air temperature, Ta. We track three processes: biomass growth as a function of Ta and W; carbon losses on respiration and decay; competition within a species as well as between species that limit biomass growth. Analysis of evolution the equilibria of the model under current growing-season temperatures has a stable condition of larch forest that can became unstable, so that larch can be replaced by dark conifers. More increased temperatures produce a new non-trivial equilibrium with a coexistence of Larch with "dark conifers" (Pinus sibirica, Picea obovata and Abies sibirica). Further temperature increase leads to a stable state in which the Larch is fully displaced by the dark conifers.