Fuel bed response to vegetation treatments in juniper-invaded sagebrush steppe

Christopher R Bernau,Eva K Strand,Stephen C Bunting

doi:10.1186/s42408-018-0002-z

Christopher R Bernau, Eva K Strand + Show 1 more

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https://doi.org/10.1186/s42408-018-0002-z

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Abstract

BackgroundExpansion of juniper (Juniperus spp. L.) and pinyon (Pinus spp. L.) into sagebrush steppe habitats has been occurring for over a century across western United States. Vegetation and fuel treatments, with the goal of increasing landscape diversity and herbaceous productivity, and reducing woody fuels are commonly implemented to mitigate effects of woodland encroachment in sagebrush ecosystems. This study was conducted in conjunction with the Sagebrush Steppe Treatment Evaluation Project (SageSTEP) and was designed to determine the impact of vegetation treatments on fuel variables two years post treatment in sagebrush steppe with an expanding juniper or pinyon −juniper woodland component. Ten locations that characterize common sagebrush steppe sites with an expanding woodland component in the Intermountain West were chosen for analysis. These woodland sites, covering a gradient of juniper development phases, were treated with mechanical (cut and leave) and prescribed fire treatments.ResultsTwo years post treatment, prescribed fire increased herbaceous biomass and reduced shrub biomass and down woody debris, but was not as effective in woodlands with higher juniper densities. Mechanical treatments increased herbaceous biomass and were effective in preserving the shrub biomass but increased down woody debris, which could lead to severe fire effects in the future.ConclusionsWe conclude that both prescribed fire and mechanical treatments are important management tools for maintenance and restoration of sagebrush steppe in areas that support juniper woodland expansion, but the differences in effects on shrub biomass and woody debris must be considered. A combination of the two treatments could lead to desirable effects in many areas.

Highlights

IntroductionThis study was conducted in conjunction with the Sagebrush Steppe Treatment Evaluation Project (SageSTEP) and was designed to determine the impact of vegetation treatments on fuel variables two years post treatment in sagebrush steppe with an expanding juniper or pinyon −juniper woodland component
The 10 sites impacted by the encroachment of juniper into sagebrush steppe were divided into three regions representing western juniper (J. occidentalis Hook.; 4 sites), Utah juniper (J. osteosperma [Torr.] Little; 4 sites), and a combination of Utah juniper and one-seed pinyon (Pinus monophylla Torr. & Frém.; 2 sites)
Site level analysis Differences in fuel loading responses at the site level were found between prescribed fire and mechanical treatment (Fig. 2) two years after the treatments

Summary

Introduction

This study was conducted in conjunction with the Sagebrush Steppe Treatment Evaluation Project (SageSTEP) and was designed to determine the impact of vegetation treatments on fuel variables two years post treatment in sagebrush steppe with an expanding juniper or pinyon −juniper woodland component. Ten locations that characterize common sagebrush steppe sites with an expanding woodland component in the Intermountain West were chosen for analysis. These woodland sites, covering a gradient of juniper development phases, were treated with mechanical (cut and leave) and prescribed fire treatments. L.) ecosystems in the western United States are contracting due to expansion of juniper Juniper and pinyon −juniper woodlands and savannas are native to the western United States, covering more than 30 million ha (West 1999). Over the past 130 to 150 years, there has been an increase in tree density within its historical extent, and an encroachment of juniper woodlands into adjacent vegetation types (Miller et al 2005, Miller et al 2008), primarily into the sagebrush steppe in the Great Basin

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