Climatic regions as an indicator of forest coarse and fine woody debris carbon stocks in the United States

Christopher W Woodall,Greg C Liknes

doi:10.1186/1750-0680-3-5

Abstract

BackgroundCoarse and fine woody debris are substantial forest ecosystem carbon stocks; however, there is a lack of understanding how these detrital carbon stocks vary across forested landscapes. Because forest woody detritus production and decay rates may partially depend on climatic conditions, the accumulation of coarse and fine woody debris carbon stocks in forests may be correlated with climate. This study used a nationwide inventory of coarse and fine woody debris in the United States to examine how these carbon stocks vary by climatic regions and variables.ResultsMean coarse and fine woody debris forest carbon stocks vary by Köppen's climatic regions across the United States. The highest carbon stocks were found in regions with cool summers while the lowest carbon stocks were found in arid desert/steppes or temperate humid regions. Coarse and fine woody debris carbon stocks were found to be positively correlated with available moisture and negatively correlated with maximum temperature.ConclusionIt was concluded with only medium confidence that coarse and fine woody debris carbon stocks may be at risk of becoming net emitter of carbon under a global climate warming scenario as increases in coarse or fine woody debris production (sinks) may be more than offset by increases in forest woody detritus decay rates (emission). Given the preliminary results of this study and the rather tenuous status of coarse and fine woody debris carbon stocks as either a source or sink of CO2, further research is suggested in the areas of forest detritus decay and production.

Highlights

Coarse and fine woody debris are substantial forest ecosystem carbon stocks; there is a lack of understanding how these detrital carbon stocks vary across forested landscapes
Coarse and fine woody debris carbon stocks vary by climatic region with the largest mean stocks found in dry/ cool climates such as "warm temperate with dry summer (Cs)" and "snow, fully humid, cool summer (Dfc)" where decay rates may be reduced (Table 1)
Climatic regions with the lowest mean coarse and fine woody debris carbon stocks were dry/hot climates such as "arid desert (BW)" or "warm temperate, fully humid (Cf)." Forest ecosystems associated with these climatic zones are southwestern deserts and steppes or southeastern mixed forests

Summary

Introduction

Coarse and fine woody debris are substantial forest ecosystem carbon stocks; there is a lack of understanding how these detrital carbon stocks vary across forested landscapes. This study used a nationwide inventory of coarse and fine woody debris in the United States to examine how these carbon stocks vary by climatic regions and variables. Estimation of carbon sequestration using large-scale forest inventory data has become important due to the link between possible climate change and the accumulation of greenhouse gases in the atmosphere [1,2]. Coarse woody debris is defined by the Forest Inventory and Analysis (FIA) program of the USDA Forest Service as down and dead woody material at least 7.62 cm in diameter [3]. Fine woody debris is defined by FIA as dead and down woody material with a diameter between 0.01 and 7.61 cm [3]. In the U.S, it has been estimated that 35 % of the total forest (page number not for citation purposes)

Objectives

Methods

Results

Discussion

Conclusion