The Role of Erosion and Landform Position in Controlling the Fate of Pyrogenic Organic Matter
Abstract
Soil organic matter (SOM) is one of the largest stores of carbon on Earth, but it is sensitive to wildfire and erosion through a number of multifaceted and interactive processes. The formation of pyrogenic carbon (PyC) is one of the critical byproducts of incomplete combustion and an important component of SOM due to its relatively longer turnover times in soil. However, the role of erosion in controlling the redistribution and fate of PyC in soil needs further investigation. The erosion of SOM fractions was monitored after the Rim Fire, in Yosemite National Park, to investigate the effects of burn severity and slope on preferential erosion and SOM composition and storage throughout the landscape. Using a combination of spectroscopic, isotopic, and field techniques, we found evidence for preferential erosion of PyC and SOM post-fire and that erosion of PyC was mainly driven by differences in burn severity. To further investigate the fate of PyC post-erosion, we generated PyC by charring Pinus jeffreyi bark at three temperatures and incubated the PyC in soil from eroding and depositional landform positions. Throughout this incubation, microbial respiration was monitored via collection of CO2, and cumulative respiration was fitted using both single- and multi-pool exponential models. Overall, the lower temperature chars mixed with the soil from the depositional landform position had the highest decomposition rates, which suggests the role that landform position may play on the stability of pyrogenic carbon at the landscape scale. These results improve our understanding of the controls on PyC erosion and landscape-scale soil carbon stabilization, which is critical in light of ongoing climate change that is driving more frequent and severe wildfire regimes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H31H..07A
- Keywords:
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- 1813 Eco-hydrology;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1860 Streamflow;
- HYDROLOGY;
- 1871 Surface water quality;
- HYDROLOGY