Rehabilitating Slash Pile Burn Scars in Upper Montane Forests of the Colorado Front Range

Abstract

Slash pile burning is widely conducted by land managers to dispose of unwanted woody fuels, yet this practice typically has undesirable ecological impacts. Simple rehabilitation treatments may be effective at ameliorating some of the negative impacts of pile burning on plants and soils. Here, we investigated: (1) the impacts of slash pile burning on soil nitrogen and understory plant species richness and cover in Colorado Pinus contorta Douglas ex Louden and P. contorta — Populus tremuloides Michx. stands; (2) the effectiveness of woodchip mulch and soil scarification at reversing pile burning impacts on soil nitrogen; and (3) how mulching and scarifying, alone and in conjunction with native grass seeding, promote native plant establishment and discourage exotic invasion in burn scars. We found that pile burning diminished native richness and cover and increased soil nitrogen, particularly in the interior of burn scars where fire severity was greatest. Rehabilitation treatments appear to be useful tools for reversing pile burning impacts on soil and plants. Mulching dampened the increase in soil nitrogen; and scarifying, scarifying plus seeding, and mulching plus seeding were effective at encouraging native plant development while simultaneously minimizing exotic plant colonization.