Fire in lichen-rich subarctic tundra changes carbon and nitrogen cycling between ecosystem compartments but has minor effects on stocks

• Published in: Biogeosciences
• Main Authors: R. J. Heim, A. Yurtaev, A. Bucharova, W. Heim, V. Kutskir, K.-H. Knorr, C. Lampei, A. Pechkin, D. Schilling, F. Sulkarnaev, N. Hölzel
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2022
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Arctic; Climate change; Subarctic; Tundra
• Online Access: https://doi.org/10.5194/bg-19-2729-2022; https://doaj.org/article/db352fdd514c4227908078354cf45c60

Fires are predicted to increase in Arctic regions due to ongoing climate change. Tundra fires can alter carbon and nutrient cycling and release a substantial quantity of greenhouse gases with global consequences. Yet, the long-term effects of tundra fires on carbon (C) and nitrogen (N) stocks and cycling are still unclear. Here we used a space-for-time approach to investigate the long-term fire effects on C and N stocks and cycling in soil and aboveground living biomass. We collected data from three large fire scars ( >44 , 28, and 12 years old) and corresponding control areas and used linear mixed-effect models in a Bayesian framework to analyse long-term development of C and N stocks and cycling after fire. We found that tundra fires had no long-term effect on total C and N stocks because a major part of the stocks was located belowground in soils which were largely unaltered by fire. However, fire had a strong long-term effect on stocks in the aboveground vegetation, mainly due to the reduction in the lichen layer. Fire reduced N concentrations in graminoids and herbs on the younger fire scars, which affected respective <math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">C</mi><mo>/</mo><mi mathvariant="normal">N</mi></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="24pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="de4c857a5316d0d8e75c5f4965b9bc96"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-19-2729-2022-ie00001.svg" width="24pt" height="14pt" src="bg-19-2729-2022-ie00001.png"/></svg:svg> ratios and may indicate an increased post-fire competition between vascular plants. Aboveground plant biomass was depleted in 13 C in all three fire scars. In soil, the relative abundance of 13 C changed with time after fire. Our results indicate that in lichen-rich subarctic tundra ...