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On the tree-root-soil-continuum - temporal and spatial coupling of the belowground carbon flux

Göttlicher, Sabine (2007). On the tree-root-soil-continuum - temporal and spatial coupling of the belowground carbon flux. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:43
ISBN 978-91-576-7342-8
[Doctoral thesis]

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The direct flux of current assimilates from the tree canopy to the belowground compartment drives roughly half of the soil respiratory activity in boreal forests. This thesis focuses on temporal and spatial aspects of the carbon (C) flux within the tree-root-soil continuum in temperate and boreal forests. I used the stable isotopes 13C and 15N to follow C from the canopy to the belowground compartment and the flow of nitrogen in the reverse direction. The C isotope composition of photosynthate varies diurnally, but such variations could not be observed in soil-respired CO2. Labelling of small (up to 4.5 m) Pinus sylvestris trees with 13CO2 showed that it took two days for the photosynthate to reach the soil. The velocity of the phloem flux was c. 0.1 m h-1. This flux of C is absolutely vital for the production of sporocarps by ectomycorrhizal fungi, as shown by their paucity in plots with girdled trees. It is also likely to be important for other soil microorganisms; addition of a labile 13C labelled C source revealed a lack of labile C substrates in girdled plots. The reduction in the abundance of ectomycorrhizal sporocarps from the edges to the centre of girdled plots and a 15N uptake experiment showed that lateral spread of ectomycorrhizal roots was on average 4 to 5 m from the trunks. Thus, it can be expected that an area of c. 60 m2 of soil is under the influence of direct flux of current assimilates from the tree canopy of a single tree. Areas of influence of several trees overlapped. I conclude that canopy and soil processes are coupled with time lags of a few days. The direct impact of plant photosynthate should be considered more often in studies of soil. The 13CO2 labelling study demonstrated that it is now possible to follow at a very high resolution the fate of this C into the belowground system.

Authors/Creators:Göttlicher, Sabine
Title:On the tree-root-soil-continuum - temporal and spatial coupling of the belowground carbon flux
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :April 2007
Number of Pages:55
ALLI. Göttlicher, S., Knohl, A., Wanek, W., Buchmann, N. & Richter, A. 2006. Short-term changes in carbon isotope composition of soluble carbohydrates and starch: from canopy leaves to the root system. Rapid Communications in Mass Spectrometry 20, 653-660. II. Betson, N.R., Göttlicher, S.G., Hall, M., Wallin, G., Richter, A. & Högberg, P. 2007. No diurnal variation in rate or carbon isotope composition of soil respiration in a boreal forest. Tree Physiology 27, 749-756. III. Högberg, P., Högberg, M.N. Göttlicher, S.G., Betson, N.R., Campbell, C., Schindlbacher, A., Hurry, V., Lundmark, T., Linder, S., Näsholm, T. 2007. High-resolution tracing of photosynthate carbon from the tree canopy to the forest soil microorganisms. Manuscript. IV. Göttlicher, S.G., Steinmann, K., Betson, N.R. & Högberg, P. 2006. The dependence of soil microbial activity on recent photosynthate from trees. Plant and Soil 287, 85-94. V. Göttlicher, S.G., Taylor A.F.S, Grip, H., Betson, N.R., Valinger, E., Högberg M.N., Högberg P. 2007. The lateral spread of tree root systems in boreal forests: estimates based on 15N uptake and distribution of sporocarps of ectomycorrhizal fungi. Manuscript.
Place of Publication:Umeå
ISBN for printed version:978-91-576-7342-8
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:boreal forests, forest soils, soil respiration, carbon cycle, mycorrhizae, girdling, roots, phloem, nitrogen, photosynthesis
Keywords:boreal forest, carbon, 13C labelling, ectomycorrhiza, girdling, tree roots, phloem, soil respiration, stable isotopes, substrate induced respiration
Permanent URL:
ID Code:1394
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: Sabine Göttlicher
Deposited On:17 Apr 2007 00:00
Metadata Last Modified:02 Dec 2014 10:11

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