Lodgepole Pine Bole Wood Density and Decay Rate 1, 11, and 22 Years After Felling in Central Montana, United States

Duncan C Lutes,Colin C Hardy

doi:10.3389/ffgc.2021.687567

Abstract

Estimates of dead and down woody material (DWM) biomass are important for nutrient cycling, wildlife habitat assessment, fire effects and climate change science. Most methods used to sample woody material initially assess volume then estimates of wood density are used to convert volume to biomass. To assess initial wood density and decomposition rate, this study examined in situ wood density of lodgepole pine logs at the Tenderfoot Creek Experimental Forest (TCEF), central Montana, United States, 1, 11, and 22 years after felling. Mean wood density decreased from 0.39 to 0.27 g cm–3 over 22 years and the single exponential decay rate was k = 0.012 yr–1 1 and 11-years post-felling and 0.022 yr–1 11 and 22 years post-felling. A common 5-category decay classification system was evaluated for estimating wood density by decay class, which identified significant difference in three of four observed classes.

Highlights

Dead and down woody material (DWM) is an important ecological component in forested systems
Two samples collected in Yr11 had substantial heart rot and the wood density of the pieces was significantly lower than the 23 samples without heart rot [0.24 g cm−3 versus 0.34 g cm−3; t = 6.29; p(t) = < 0.0001] so those two samples were removed from further analysis
Wood density at years: 1999 (Yr1) was 0.39 g cm−3, which is within the range of sound lodgepole wood density reported by Maeglin and Wahlgren (1972) for eastern Montana (0.32–0.40 g cm−3) but greater than green lodgepole pine density of 0.38 g cm−3 published in the USDA Forest Service, Wood Handbook (Kretschmann, 2010), and lower than 0.41 g cm−3 published by Koch (1987) for entire stemwood of similar size and age lodgepole pine trees in the same latitudinal range

Summary

Introduction

Dead and down woody material (DWM) is an important ecological component in forested systems. DWM often comprises a large proportion of the total above ground biomass in forested systems, potentially 20%, or more (Grier and Logan, 1977; Harmon et al, 1986; Harmon and Hua, 1991). As dead wood decays carbon is transferred to the atmosphere through respiration, accounting for DWM is important for climate change science (Currie and Nadelhoffer, 2002; Weedon et al, 2009; Harmon et al, 2020). The importance and relative abundance of DWM necessitate an accurate accounting of its quantity

Methods

Results

Conclusion