How permafrost degradation threatens boreal forest growth on its southern margin?

Abstract

Boreal forests are adapted to cold climates and are thus especially sensitive and vulnerable to climate change. In this study, we chose 10 plots covering different topographies at the southern edge of a boreal forest. The annual ring widths of the 249 Dahurican larch (Larix gmelinii) tree cores from these plots were measured and used to calculate the basal area increment (BAI) and the interannual sensitivity (Sx). We found that forests in 10 plots showed a significant change in Sx consistently around 1980. The growth of slope forest was significantly correlated with increases in temperature and precipitation, while the wetland forests, including bogs and peatland plateaus, responded negatively to temperature. In terms of precipitation, there was no effect in the peatland plateaus, but a negative effect occurred in bogs. Our results imply that the depth of the frost table could lead to different soil waterlogging from surplus water from thawing permafrost, resulting in different responses of tree growth to climate change.

Keywords: Boreal forest; Climate warming; Frost table depth; Permafrost thawing; Topography; Waterlogging.