Spatial variation in soil respiration is determined by forest canopy structure through soil water content in a mature beech forest

Spatial variation in soil respiration is determined by forest canopy structure through soil water content in a mature beech forest

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Spatial variation in soil respiration is determined by forest canopy structure through soil water content in a mature beech forest

Highlights

Soil respiration (SR) showed spatial variation with a coefficient of variation (CV) from 25 % to 28 % in a mature beech forest.

The spatial variation in SR was well related with soil water content (SWC) but not soil temperature.

Canopy openness indirectly explain the spatial variation in SR via SWC.

CV of SR in forest ecosystems around the world including our data varied widely from 14 % to 62 %.

Abstract

For accurate estimation of soil respiration (SR) in forest ecosystems, temporal and spatial variation in SR and the factors that control these variations must be considered. Although some of the factors underlying temporal variation in SR have been elucidated in recent decades, a large part of spatial variation in SR remains unexplained especially in forest ecosystems with complex structures. Our objectives were to demonstrate spatial variation in daily summed SR (SRdaily) and to examine if spatial variation in SRdaily can be explained by canopy openness which is one of the indexes of forest structure. We conducted simultaneous measurements of SRdaily, soil temperature (ST), and soil water content (SWC) at 121 points. We also measured canopy openness and some forest stand structure indexes in different seasons in 2012 and 2013. The coefficient of variation (CV) of SRdaily ranged from 25 % to 28 %, which was similar to that of SWC (21 % to 28 %). We also found that the spatial variation in SR in other forest ecosystems ranged widely (CV = 14 % to 62 %), and that in our site fell within the range. There was no significant relationship between ST and spatial variation in SRdaily; however, a significant relationship was observed between SWC and spatial variation in SRdaily (P < 0.01) excepted for the measurement conducted in June 2013. Multiple linear regression analysis indicated that canopy openness showed significant positive correlations with SWC during the growing season. And there was no significant relationships between SWC and forest stand structure indexes.

In this study, we found that canopy structure influenced SWC, which in turn determined the spatial variation in SR in this mature beech forest. The possible connections could give us new insight for adequate forest carbon management.

Keywords

Alkali absorption method

Canopy openness

Mature forest

Soil CO2 efflux

Soil moisture

Spatial heterogeneity

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© 2021 Elsevier B.V. All rights reserved.

Superforest

via ScienceDirect Publication: Forest Ecology and Management https://ift.tt/2zaqiu8

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