Laboratory Assessment of Forest Soil Respiration Affected by Wildfires under Various Environments of Russia

Abstract

Pyrogenic carbon emission rates were estimated in the soils of three natural zones in Russia: forest-tundra, south-taiga, and foreststeppe. Postfire soils were found to be characterized by essential losses of soil C due to the combustion fire effect. Soils lost 3 or 5 parts of initial carbon content and showed an essential decrease in the C/N ratio during the fire effect. The pH values increased due to soil enrichment by ash during the fire events. CO 2 emission rates were highest in natural soil samples, because the amount of organic matter affected by mineralization in those soils was higher than in natural ones. Simultaneously, the total values of mineralized carbon were higher in postfire soils because the SOM quality and composition were altered due to the fire effect. The only exception was in forest-tundra soils, where a high portion of dissolved organic compounds was released during the surface fire. The quality of initial SOM and intensity of the wildfire play the most important roles in the fate of SOM in postfire environments. Further study of CO 2 emissions is needed to better characterize postfire SOM dynamics and develop an approach to model this process.

Effect of the Wildfires on Sandy Podzol Soils of Nadym Region, Yamalo-Nenets Autonomous District, Russia

“…e PCM (potential mineralizable carbon) values of the mature soil were essentially higher in superficial layers of mature soil than in lower ones. is was also an indicator of the fact that the deepness of fire effect in case of one-time surface fire is not high, and this effect is not pronounced in the deepest soil layers (see Figure 5) Data obtained are comparable with those obtained previously [16,17,39,40]. e total content of PAHs (see Figure 6) in fire-affected soil was higher than in control, and this is caused by pyrogenic factor.…”