Estimates of downed woody debris decay class transitions for forests across the eastern United States

Technical Note: Linking climate change and downed woody debris decomposition across forests of the eastern United States

Biogeosciences ◽

10.5194/bg-11-6417-2014 ◽

2014 ◽

Vol 11 (22) ◽

pp. 6417-6425 ◽

Cited By ~ 16

Author(s):

M. B. Russell ◽

C. W. Woodall ◽

A. W. D'Amato ◽

S. Fraver ◽

J. B. Bradford

Keyword(s):

Climate Change ◽

United States ◽

Woody Debris ◽

Critical Role ◽

Future Climate Change ◽

Climate Change Scenarios ◽

Eastern United States ◽

Decomposition Rates ◽

Changing Climate ◽

Downed Woody Debris

Abstract. Forest ecosystems play a critical role in mitigating greenhouse gas emissions. Forest carbon (C) is stored through photosynthesis and released via decomposition and combustion. Relative to C fixation in biomass, much less is known about C depletion through decomposition of woody debris, particularly under a changing climate. It is assumed that the increased temperatures and longer growing seasons associated with projected climate change will increase the decomposition rates (i.e., more rapid C cycling) of downed woody debris (DWD); however, the magnitude of this increase has not been previously addressed. Using DWD measurements collected from a national forest inventory of the eastern United States, we show that the residence time of DWD may decrease (i.e., more rapid decomposition) by as much as 13% over the next 200 years, depending on various future climate change scenarios and forest types. Although existing dynamic global vegetation models account for the decomposition process, they typically do not include the effect of a changing climate on DWD decomposition rates. We expect that an increased understanding of decomposition rates, as presented in this current work, will be needed to adequately quantify the fate of woody detritus in future forests. Furthermore, we hope these results will lead to improved models that incorporate climate change scenarios for depicting future dead wood dynamics in addition to a traditional emphasis on live-tree demographics.

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Technical Note: Linking climate change and downed woody debris decomposition across forests of the eastern United States

Biogeosciences Discussions ◽

10.5194/bgd-11-9013-2014 ◽

2014 ◽

Vol 11 (6) ◽

pp. 9013-9034 ◽

Cited By ~ 1

Author(s):

M. B. Russell ◽

C. W. Woodall ◽

A. W. D'Amato ◽

S. Fraver ◽

J. B. Bradford

Keyword(s):

Climate Change ◽

United States ◽

Woody Debris ◽

Critical Role ◽

Future Climate Change ◽

Climate Change Scenarios ◽

Eastern United States ◽

Decomposition Rates ◽

Changing Climate ◽

Downed Woody Debris

Abstract. Forest ecosystems play a critical role in mitigating greenhouse gas emissions. Long-term forest carbon (C) storage is determined by the balance between C fixation into biomass through photosynthesis and C release via decomposition and combustion. Relative to C fixation in biomass, much less is known about C depletion through decomposition of woody debris, particularly under a changing climate. It is assumed that the increased temperatures and longer growing seasons associated with projected climate change will increase the decomposition rates (i.e., more rapid C cycling) of downed woody debris (DWD); however, the magnitude of this increase has not been previously addressed. Using DWD measurements collected from a national forest inventory of the eastern United States, we show that the residence time of DWD may decrease (i.e., more rapid decomposition) by as much as 13% over the next 200 years depending on various future climate change scenarios and forest types. Although existing dynamic global vegetation models account for the decomposition process, they typically do not include the effect of a changing climate on DWD decomposition rates. We expect that an increased understanding of decomposition rates, as presented in this current work, will be needed to adequately quantify the fate of woody detritus in future forests. Furthermore, we hope these results will lead to improved models that incorporate climate change scenarios for depicting future dead wood dynamics, in addition to a traditional emphasis on live tree demographics.

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Contrasting downed woody debris dynamics in managed and unmanaged northern hardwood stands

Canadian Journal of Forest Research ◽

10.1139/x08-130 ◽

2008 ◽

Vol 38 (11) ◽

pp. 2850-2861 ◽

Cited By ~ 28

Author(s):

Mark C. Vanderwel ◽

Hilary C. Thorpe ◽

Jennifer L. Shuter ◽

John P. Caspersen ◽

Sean C. Thomas

Keyword(s):

Matrix Model ◽

Woody Debris ◽

Fruiting Bodies ◽

Northern Hardwood ◽

Decay Class ◽

Species Type ◽

Downed Woody Debris ◽

Cut Surface ◽

Selection Silviculture

The reported effects of selection silviculture on downed woody debris (DWD) vary. To investigate the processes underlying potential management impacts on DWD stocks and fluxes, we conducted a repeated census of downed wood in selection-harvested, selectively harvested, and unmanaged (old-growth) stands in central Ontario. DWD was significantly more abundant in stands harvested within the last 20 years than in stands harvested earlier, and shifted towards more advanced decay classes over the first 20 years after harvest. These results are consistent with persistence of a harvest-related DWD pulse for up to two decades in managed stands. The transition of DWD from early and middle decay classes to more advanced decay classes proceeded more slowly in managed than unmanaged stands. Species type, identity of fungal fruiting bodies, presence of a cut surface, and plot moisture class were significant predictors of variation in decay dynamics within particular decay classes; however, these factors did not account for observed differences in decay-class transitions between managed and unmanaged stands. A decay class matrix model projected DWD half-lives of 19 years for unmanaged stands and 21 years for managed stands. Over the long term, slower decay dynamics may help somewhat in maintaining relatively high DWD abundances in stands managed under selection silviculture.

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Contributions of harvest slash to maintaining downed woody debris in selection-managed forests

Canadian Journal of Forest Research ◽

10.1139/x10-090 ◽

2010 ◽

Vol 40 (8) ◽

pp. 1680-1685 ◽

Cited By ~ 7

Author(s):

Mark C. Vanderwel ◽

Hilary C. Thorpe ◽

John P. Caspersen

Keyword(s):

Size Distribution ◽

Woody Debris ◽

Basal Area ◽

Managed Forests ◽

Projection Model ◽

Permanent Sample Plots ◽

Decay Class ◽

Class 1 ◽

Selection Harvesting ◽

Downed Woody Debris

Harvest slash can represent a major source of downed woody debris (DWD) in selection-managed forests. In this study, we analyze the volume, cover, size distribution, and decay-class distribution of DWD input by selection harvesting in central Ontario, Canada. Selection harvesting input 23.9 m3 DWD·ha–1 (0.013 m2 DWD·m–2), with cut basal area explaining 46% and 30% of the respective within-stand variation in cover and volume, respectively. The size distribution of the slash was similar to that of DWD in permanent sample plots (including old-growth stands and stands that have not been recently harvested), countering a common assumption that harvesting inputs only small-sized material. Harvest-origin DWD was bimodally distributed across decay classes, with the first peak (decay class 1) associated with fresh harvest slash and a second smaller peak (decay class 3) likely representing dead trees and branches that were felled or broken during harvest operations. A matrix projection model showed that slash can maintain DWD levels in managed, uneven-aged stands comparable with those in unmanaged stands, but the mean decay class increases steadily over a 20-year period after harvest. Our results underline the importance of harvest inputs for maintaining DWD pools in selection-managed forests and provide baseline information against which to compare forests managed with higher utilization standards.

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