Short description
(English)
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This project has the aim to investigate fluxes, pools, and turnover of C within the fine root sytems of individual trees over time and space. After the mapping of the fine root systems of genetically distinct tree individuals, a stable C isotope pulse will be applied to the canopies. The various forms of labelled C, from fine roots respired CO2 as well as non-structural and structural carbohydrates within the fine roots, will be recorded in dependency on time and distance to the stems. Projekt-Partner ETH Zürich
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Partners and International Organizations
(English)
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BE, CH, CZ, DE, EE, ES, FI, FR, GR, IE, IL, IT, LV, NL, NO, PL, PT, SE, SI, SK, TR, UK
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Abstract
(English)
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This project had the aim to investigate fluxes and pools of photosynthetically fixed carbon (C) within the fine root systems of individual Abies alba trees. Therefore, pulse-labellings with 13CO2 were applied to aboveground parts of trees in order to follow the 13C-label within the root systems. The various forms of labelled C within the fine roots, non-structural (starch) as well as structural carbohydrates (cellulose), were recorded in dependency on time. Relative 13C amounts (excess 13C) in the fine roots increased significantly after the 3rd day of labelling as 13C bulk and as 13C cellulose. Highest values were recorded 1 and 6 months after labelling. Highest 13C values were also recorded in the fine root diameter class 1.5-2.0 mm, whereas lowest values were in the fine roots diameter class <0.5 mm. A first 13C-signal in the soil was recorded in the dissolved organic carbon (DOC) after 1 month. In the soil organic matter (SOM), however, a first 13C-signal was observed only 12 months after the labelling. The label in the SOM occurred either in the floating SOM-particles after the water extraction or in the occluded and less dense fraction in the polytungstate. Applying the pulse-labelling either in spring, summer, or autumn, a clear seasonal effect was obvious by observing the incorporation of the 13C-label into the root systems mainly in summer and autumn. However, after the spring pulse-labelling, a stronger signal was observed for clipped plants compared to the control plants. Measuring the 13C-label in the starch of roots, it was obvious that the plants invested their photosynthetic products into root-starch mainly in the autumn. This highly labelled starch was mainly localised in the very young and newly formed fine roots.
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