Post-Fire Erosion Control Mulches Alter Belowground Processes and Nitrate Reductase Activity of a Perennial Forb, Heartleaf Arnica (Arnica cordifolia)

Berryman, E.M.; Morgan, P.; Robichaud, P.R.; Page-Dumroese, D. 2014. Post-fire erosion control mulches alter belowground processes and nitrate reductase activity of a perennial forb, heartleaf arnica (Arnica cordifolia). Res. Note RMRS-RN-69. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 10 p.

Keywords: soil rehabilitation, restoration, fire effects, respiration, nitrogen

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Abstract: Four years post-wildfire, we measured soil and plant properties on hillslopes treated with two different mulches (agricultural wheat straw and wood strands) and a control (unmulched, but burned). Soil total N was about 40% higher and microbial respiration of a standard wood substrate was nearly twice as high in the mulched plots compared to the unmulched plots. Greater respiration was tied to increased substrate moisture underneath mulch compared to bare soil. Nitrate reductase activity of a common forb (Arnica cordifolia) was about 30% higher on the wood strand plots than either the wheat straw or the unmulched plots. Mulch applications after wildfire may enhance N availability by increasing soil moisture, promoting microbial N mineralization, or by increasing biological nitrogen fixation. Because inference is limited for this case study, we call for additional replicated experiments investigating effects of mulch treatments on soil carbon and nitrogen cycling with links to plant regeneration.

Moscow FSL publication no. 2014a