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ESTIMATING ROOT RESPIRATION IN SPRUCE AND BEECH: DECREASES IN SOIL RESPIRATION FOLLOWING GIRDLING
Citation:
Andersen, C P., I. Nikolova, P. Nikolova, K. H. Haberle, AND R. Matyssek. ESTIMATING ROOT RESPIRATION IN SPRUCE AND BEECH: DECREASES IN SOIL RESPIRATION FOLLOWING GIRDLING. Presented at Ecological Society of America meeting, Portland, OR, August 1-6, 2004.
Description:
A study was undertaken to follow seasonal fluxes of CO2 from soil and to estimate the contribution of autotrophic (root + mycorrhizal) to total soil respiration (SR) in a mixed stand of European beech (Fagus sylvatica) and Norway spruce (Picea abies) near Freising, Germany. Mature trees of each species were girdled to eliminate carbohydrate allocation to roots in August, 2002. SR was measured at distances of 0.5, 1.0, and 1.5/2.0 m from the bole of each tree at 1-2 wk intervals throughout the fall of 2002 and monthly during the spring and summer of 2003. Measurements of SR from the base of ungirdled trees of each species served as controls. SR decreased to levels below controls in beech within days of girdling, while spruce did not show a significant response until October 2002, six weeks after girdling. We estimate that beech root + mycorrhizal respiration represents nearly 50% of the total SR in this stand. Preliminary estimates of root respiration are less certain for spruce, although close to the bole root plus mycorrhizal respiration may comprise as much as 60% of total SR. SR decreased with soil temperature in the fall 2002 and increased again in 2003 as soils warmed. Temperature explained nearly 2/3 of the seasonal variation in SR in all treatments from August 2002 through May 2003. From June through September, 2003, temperature was unrelated to SR due to low precipitation. The results show that root respiration comprises a large fraction of total SR, and the rapid decline following girdling illustrates the importance of understanding tree level stresses that affect carbon allocation below ground.