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Abstract:
Hemi-boreal forests, which make up the transition from temperate deciduous forests to boreal forests in southern Siberia,
have experienced significant warming without any accompanying increase in precipitation during the last 80 years. This
climatic change could have a profound impact on tree growth and on the stability of forest ecosystems in this region, but at
present evidence for these impacts is lacking. In this study, we report a recent dramatic decline in the growth of hemi-boreal
forests, based on ring width measurements from three dominant tree-species (Pinus sylvestris, Larix sibirica and Larix
gmelinii), sampled from eight sites in the region. We found that regional tree growth has become increasingly limited by low
soil water content in the pre- and early-growing season (from October of the previous year to July of the current year) over
the past 80 years. A warming-induced reduction in soil water content has also increased the climate sensitivity of these
three tree species. Beginning in the mid-1980s, a clear decline in growth is evident for both the pine forests and the larch
forests, although there are increasing trends in the proxy of soil water use efficiencies. Our findings are consistent with
those from other parts of the world and provide valuable insights into the regional carbon cycle and vegetation dynamics,
and should be useful for devising adaptive forest management strategies.
