Impacts of soil climate on distributions of forest-forming conifers in current and future climates

Introduction. Forests in Central Siberia represent a vast massif composed of six major conifers that shape the boreal forest: Siberian pine, Siberian fir, Siberian spruce, Scots pine, and two larches (Siberian larch on permafrost-free areas and Gmelin larch on permafrost). First, we built a bioclimatic model to predict major forest-forming conifer distributions based on atmospheric climate: warmth, water, and cold and soil permafrost. Our goal in this study is to supplement our model with soil climates: soil warmth and moisture and fertility resources.

Methods. For the mountain forests in southern Siberia (90-100 E and 52-56 N), a soil model was developed that related the forest composition to basic soil characteristics (warmth, moisture, texture composition, soil type, humus content, pH, C:N ratio etc.). Soil data (100 sites) were collected from the literature, which were accompanied by forest compositions from forest inventories and calculated climate data. The future climate was derived from the GCM INM-CM5-0 climate model for two scenarios, ssp126 and ssp585, at the mid-century.

Results and Conclusions. Soil properties were found to be important for conifer distributions over the mountains but less important than the atmospheric climates were. The genetic soil types and soil warmth and moisture appeared to be most important for the forest composition. The rest of the soil characteristics were much less important. Siberian larch and Siberian pine were found to be the most plastic conifers; Siberian fir was found to be the most demanding conifer. In the future climates, under additional warmth and plentiful rain across the mountains, as follows from the climate change scenarios, hydro-thermal conditions in soils would be favourable for the sustainability and productivity of coniferous forests.