Aspen Restoration in the Eastern Sierra Nevada: Effectiveness of Prescribed Fire and Conifer Removal

Kevin D Krasnow,Anne S Halford,Scott L Stephens

doi:10.4996/fireecology.0803104

Kevin D Krasnow, Anne S Halford + Show 1 more

Open Access

https://doi.org/10.4996/fireecology.0803104

Copy DOI

Abstract

AbstractAspen (Populus tremuloidesMichx.) comprises only a small fraction (1 %) of the Sierra Nevada landscape, yet contributes significant biological diversity to this range. In an effort to rejuvenate declining aspen stands, the Bureau of Land Management conducted conifer removal in three sites (2004 to 2006) and prescribed fire in two sites (2007). The goal of this study was to evaluate the efficacy of these treatments. In each site, aspen densities in three regeneration size classes were measured in treated and untreated transects before and up to five years post-treatment. Five years after treatment, two of the three conifer removal sites showed significant improvement over controls in the density of total stems and two of three regeneration size classes. The third site did not show significant gains over controls in any size class and experienced significant aspen overstory mortality three years after treatment, which was attributed to sunscald and advanced age at the time of treatment. Three years after treatment, the two prescribed fire sites showed significant increases in total stem density and two regeneration size classes, but also exhibited significant stem mortality, which was likely due to a combination of herbivory and drought. Overall, both treatments can be effective, but future treatments should incorporate methods to reduce post-treatment mortality of residual aspen and new sprouts.

Highlights

Aspen (Populus tremuloides Michx.) is the most widely distributed tree in North America (Little 1971), yet comprises only a small fraction (1 %) of the Sierra Nevada landscape (Shepperd et al 2006)
Results from the conifer removal sites indicated that this is a viable means of stimulating aspen asexual regeneration in conifer-encroached stands (Shepperd et al 2001, Jones et al 2005)
Lack of treatment success in VC3 is likely due to a variety of factors that caused overstory death of the residual aspen stems after conifer removal

Summary

Introduction

Aspen (Populus tremuloides Michx.) is the most widely distributed tree in North America (Little 1971), yet comprises only a small fraction (1 %) of the Sierra Nevada landscape (Shepperd et al 2006). In the Rocky Mountains, rapid and widespread mortality, referred to as “Sudden Aspen Decline,” is occurring as a result of moisture stress and hydraulic impairment (Worrall et al 2010, Anderegg et al 2012). The historical extent of aspen in the Sierra Nevada is unknown, Rogers et al (2007) hypothesize that there was a large pulse of aspen regeneration in the late 1800s due to widespread fires, dam building, mining, and logging This may have been the last major window of regeneration for Sierran aspen, as the twentieth century marked the onset of fire suppression and reduced human disturbance. Of 542 aspen stands inventoried since 2002 in the Lake Tahoe Basin, 70 % of the stands have been classified as moderate to highest risk of being lost (Shepperd et al 2006)

Objectives

Methods

Results

Conclusion