Investigating the impact of fire severity on tree recruitment, soil properties, and ecosystem carbon storage in a high latitude forest in the Yakutia region of Southeastern Siberia
Abstract
The intensity, frequency, and severity of forest fires is increasing across high latitude ecosystems with climate change. The eastern region of Siberia in Yakutia has been hit hard, representing 85% of the country's wildfires. Little is known how these forests will respond following fire and whether fire has changed the system enough to drive a conversion to shrub or grassland. In 2018, we sampled 23 plots within a fire scar that burned in 2002 near Yakutsk, Russia to investigate the changes in soil properties, tree recruitment, and ecosystem level carbon (C) storage following 10 years post-fire. For dead trees, we recorded a crown combustion index which ranged from 0 indicating a live tree and 3 indicating high combustion with most of the canopy combusted. These values were categorized into unburned, low, medium, and high burn severity. We recorded the number of recruits from the dominant conifer species to assess recruitment success. We measured soil moisture, bulk density, soil organic matter, soil C and nitrogen, and inorganic N in organic and mineral soil depths. Eighty five percent of the plots fell within the low to moderate burn severity. We found that tree recruitment was highly variable across plots and ranged from 0 to 39 individual saplings per m2 with a mean recruitment density of 11 (SD ± 12) but was not significantly different across burn severities (F4,21 = 1.3, p = 0.32). SOM across plots ranged from 2 to 67% with an average of 25% (SD ± 21) and did not differ across burn severity (F1,36 = 0.01, p = 0.9) but did differ between soil type where organic soil had higher SOM than mineral (F4,21 = 163.7, p < 0.0001). There was no significant difference among burn severity for any of the soil properties measured. However, organic and mineral soils consistently significantly differed in all soil properties. Our data show that low to moderate burn severity does not alter the environment enough to significantly change tree recruitment and soil properties suggesting that the forest most likely will not transition to another ecosystem type. Our next steps are to estimate pre-fire aboveground plant carbon using allometric equations relating diameter at breast height to tree biomass so that we can better understand how ecosystem level carbon storage may change with fire in this system.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.B52J0994D