1Present address: Department of Geography and Environmental Science, Carleton University, Ottawa, ON, Canada K1S 5B6.
Experimental warming and burn severity alter soil CO2 flux and soil functional groups in a recently burned boreal forest
Article first published online: 2 DEC 2004
Global Change Biology
Volume 10, Issue 12, pages 1996–2004, December 2004
How to Cite
Bergner, B., Johnstone, J. and Treseder, K. K. (2004), Experimental warming and burn severity alter soil CO2 flux and soil functional groups in a recently burned boreal forest. Global Change Biology, 10: 1996–2004. doi: 10.1111/j.1365-2486.2004.00868.x
- Issue published online: 2 DEC 2004
- Article first published online: 2 DEC 2004
- Received 16 March 2004; revised version received 8 June 2004 and accepted 22 June 2004
Global warming is projected to be greatest in northern regions, where forest fires are also increasing in frequency. Thus, interactions between fire and temperature on soil respiration at high latitudes should be considered in determining feedbacks to climate. We tested the hypothesis that experimental warming will augment soil CO2 flux in a recently burned boreal forest by promoting microbial and root growth, but that this increase will be less apparent in more severely burned areas. We used open-top chambers to raise temperatures 0.4–0.9°C across two levels of burn severity in a fire scar in Alaskan black spruce forest. After 3 consecutive years of warming, soil respiration was measured through a portable gas exchange system. Abundance of active microbes was determined by using Biolog EcoPlates™ for bacteria and ergosterol analysis for fungi. Elevated temperatures increased soil CO2 flux by 20% and reduced root biomass, but had no effect on bacterial or fungal abundance or soil organic matter (SOM) content. Soil respiration, fungal abundance, SOM, and root biomass decreased with increasing burn severity. There were no significant interactions between temperature and burn severity with respect to any measurement. Higher soil respiration rates in the warmed plots may be because of higher metabolic activity of microbes or roots. All together, we found that postfire soils are a greater source of CO2 to the atmosphere under elevated temperatures even in severely burned areas, suggesting that global warming may produce a positive feedback to atmospheric CO2, even in young boreal ecosystems.