A time series of leachable dissolved organic carbon and total nitrogen in response to a wildfire at the Reynolds Creek Critical Zone Observatory, Idaho
Abstract
Wildfires are increasing in the intermountain west United States, and little is known about the timing and magnitude of carbon and nitrogen leached from soils after fire and how rapidly these elements recover. We collected soil samples from control and burned north- and south-facing aspects in sagebrush ecosystems at the Reynolds Creek Critical Zone Observatory over a 37-month time period after fire. We hypothesized that there would be lower dissolved organic carbon (DOC) leached after fire compared to controls on both north- and south-facing aspects because of reduced soil organic carbon (SOC) pools on both aspects. In contrast, we hypothesized an increase in leachable total nitrogen (TN) after immediately fire due to increased mineralization of soil organic nitrogen. We incubated 2, 3, 6, and 37-month post-fire and control soils in deionized water for three days in the dark, filtered them through pre-leached filters, and analyzed them for DOC and TN. In contrast to expectations, the mean leachable DOC on the north-facing aspect increased from 71.9∓9.8 to 118.3∓8.2 μg DOC/g soil in the first 2 months following fire, a 64.5% increase. However, the mean leachable DOC on the south-facing aspect declined from 84.3∓6.8 to 51.7∓4.5 μg DOC/g soil, a 38.7% decline, consistent with our expectations. By 6 months after the burn, the mean leachable DOC on the north- and south- facing aspects returned back to control levels. After 2 months, the mean leachable TN dramatically increased by almost 8 fold, especially on the north-facing aspect, from 24∓3.8 to 181∓12.2 μg TN/g soil. By 37 months, leachable TN had returned to control values. We conclude that leachable DOC decreased on the south-facing aspect and TN increased on both aspects in the first two months after fire. However, leachable DOC increased on the north-aspect suggesting wildfire may make carbon initially more soluble on this aspect. Both DOC and TN returned back to control levels by 37 months suggesting that these systems are relatively resilient to wildfires.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH087.0001L
- Keywords:
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- 1815 Erosion;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 1871 Surface water quality;
- HYDROLOGY;
- 1879 Watershed;
- HYDROLOGY