Long-term ecological consequences of forest fires in the continuous permafrost zone of Siberia

0524335 - ÚVGZ 2021 RIV GB eng J - Journal Article
Kirdyanov, A. - Saurer, M. - Siegwolf, R. - Knorre, A. A. - Prokushkin, A. S. - Churakova (Sidorova), O. - Fonti, M. - Büntgen, Ulf
Long-term ecological consequences of forest fires in the continuous permafrost zone of Siberia.
Environmental Research Letters. Roč. 15, č. 3 (2020), č. článku 034061. ISSN 1748-9326. E-ISSN 1748-9326
Institutional support: RVO:86652079
Keywords : water-use efficiency * tree-ring * larix-gmelinii * boreal forest * carbon isotopes * soil-water * larch * climate * delta-c-13 * wildfire * active soil layer * boreal forest * permafrost * Siberia * stable isotopes * tree rings * wildfire
OECD category: Meteorology and atmospheric sciences
Impact factor: 6.800, year: 2020
Method of publishing: Open access
https://iopscience.iop.org/article/10.1088/1748-9326/ab7469

Wildfires are an important factor in controlling forest ecosystem dynamics across the circumpolar boreal zone. An improved understanding of their direct and indirect, short- to long-term impacts on vegetation cover and permafrost-vegetation coupling is particularly important to predict changes in carbon, nutrient and water cycles under projected climate warming. Here, we apply dendrochronological techniques on a multi-parameter dataset to reconstruct the effect of wildfires on tree growth and seasonal permafrost thaw depth in Central Siberia. Based on annually-resolved and absolutely dated information from 19 Gmelin larch (Larix gmelinii (Rupr.) Rupr.) trees and active soil layer thickness measurements, we find substantial stand-level die-off, as well as the removal of ground vegetation and the organic layer following a major wildfire in 1896. Reduced stem growth coincides with increased delta C-13 in the cellulose of the surviving trees during the first decade after the wildfire, when stomatal conductance was reduced. The next six to seven decades are characterized by increased permafrost active soil layer thickness. During this period of post-wildfire ecosystem recovery, enhanced tree growth together with positive delta C-13 and negative delta O-18 trends are indicative of higher rates of photosynthesis and improved water supply. Afterwards, a thinner active soil layer leads to reduced growth because tree physiological processes become limited by summer temperature and water availability. Revealing long-term effects of forest fires on active soil layer thickness, ground vegetation composition and tree growth, this study demonstrates the importance of complex vegetation-permafrost interactions that modify the trajectory of post-fire forest recovery across much of the circumpolar boreal zone. To further quantify the influence of boreal wildfires on large-scale carbon cycle dynamics, future work should consider a wide range of tree species from different habitats in the high-northern latitudes.
Permanent Link: http://hdl.handle.net/11104/0308697