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DECLINE IN SOIL CO2 EFFLUX FOLLOWING TREE GIRTLING IN MATURE BEECH AND SPRUCE STANDS IN GERMANY
Citation:
Andersen, C P., K. H. Haberle, AND I. Nikolova. DECLINE IN SOIL CO2 EFFLUX FOLLOWING TREE GIRTLING IN MATURE BEECH AND SPRUCE STANDS IN GERMANY. Presented at 4th North American Forest Ecology Workshop, Corvallis, OR, June 16-20, 2003.
Description:
Studies were undertaken to estimate the contribution of autotrophic respiration to total soil CO2 efflux in stands of mature European beech (Fagus sylvatica) and Norway spruce (Picea abies) near Freising, Germany. Five mature trees of each species were girdled to eliminate carbohydrate allocation to roots in August, 2002. Soil CO2 efflux was measured at distances of 0.5, 1.0, and 1.5 m from the base of each beech, and 0.5, 1.0 and 2.0 m from the base of each spruce at approx. 1-2 wk intervals throughout the fall. Measurements of soil CO2 efflux from around five ungirdled trees of each species served as controls. Contribution of autotrophic to total CO2 efflux was estimated by the decrease in respiration around girdled compared to ungirdled trees, correcting for seasonal patterns evident in controls.
Highest rates of soil CO2 efflux in both beech and spruce were found at the 1.0 m distance from the bole. Within one week of girdling, soil CO2 efflux decreased to levels below controls in both species. By October, soil CO2 efflux had decreased in controls to nearly 50% the rates observed in August, while efflux around girdled trees was less than 25-30 % of initial rates in both species. Based on preliminary data, we estimate that autotrophic contribution to total soil CO2 efflux is at least 40-45% in these spruce and beech stands. Measurements will continue through a second growing season in conjunction with other measures of individual root respiration to further quantify the contribution of autotrophic to total CO2 flux in these stands.