Drivers of CO2 Emission Rates from Dead Wood Logs of 13 Tree Species in the Initial Decomposition Phase

Tiemo Kahl,Christian Wirth,Peter Otto,Kristin Baber,Jürgen Bauhus

doi:10.3390/f6072484

Tiemo Kahl, Christian Wirth + Show 3 more

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https://doi.org/10.3390/f6072484

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Abstract

Large dead wood is an important structural component of forest ecosystems and a main component of forest carbon cycles. CO2 emissions from dead wood can be used as a proxy for actual decomposition rates. The main drivers of CO2 emission rates for dead wood of temperate European tree species are largely unknown. We applied a novel, closed chamber measurement technique to 360 dead wood logs of 13 important tree species in three regions in Germany. We found that tree species identity was with 71% independent contribution to the model (R2 = 0.62) the most important driver of volume-based CO2 emission rates, with angiosperms having on average higher rates than conifers. Wood temperature and fungal species richness had a positive effect on CO2 emission rates, whereas wood density had a negative effect. This is the first time that positive fungal species richness—wood decomposition relationship in temperate forests was shown. Certain fungal species were associated with high or low CO2 emission rates. In addition, as indicated by separate models for each tree species, forest management intensity, study region, and the water content as well as C and N concentration of dead wood influenced CO2 emission rates.

Highlights

Large dead wood is an important structural component of forest ecosystems [1] and it influences a large number of ecosystem functions [2,3], of which the most relevant are carbon (C) storage [4,5], nutrient cycling [6], and provision of habitat for wood-dwelling organism and resource for xylophageous species [7]
Variance partitioning showed that the independent contribution of dead wood tree species was by far the most important (71%), whereas wood temperature (14%), fungal species richness (12%) and wood density (3%) contributed only a smaller proportion
We identified dead wood tree species, wood temperature, fungal species richness and wood density as the main drivers of CO2 emission rates in the initial phase of dead wood decomposition

Summary

Introduction

Large dead wood is an important structural component of forest ecosystems [1] and it influences a large number of ecosystem functions [2,3], of which the most relevant are carbon (C) storage [4,5], nutrient cycling [6], and provision of habitat for wood-dwelling organism and resource for xylophageous species [7]. The fungal phyla Ascomycota and Basidiomycota have the highest importance. Both differ considerably in their enzymatic spectra and cause characteristic rot types, e.g., soft-rot typical for Ascomycota, brown and white-rot for the latter. Dead wood CO2 emission rates depend on dead wood tree species identity [19] and on the fungal decomposer community [20]. They are controlled by environmental conditions that do affect the activity of fungal decomposers [21,22,23]

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