13C discriminations of Pinus sylvestris vs. Pinus ponderosa at a dry site in Brandenburg (eastern Germany): 100-year growth comparison |
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Authors: | Ralf Wagner Bernhard Götz Sebastian Junge Tatjana Boettger |
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Affiliation: | 1. Department of Isotope Hydrology , Helmholtz Centre for Environmental Research – UFZ , Theodor-Lieser-Str. 4, 06120, Halle, Germany;2. Department of Forestry , Forest–Botanical Gardens, Eberswalde University of Applied Sciences , Am Zainhammer 5, 16225, Eberswalde, Germany |
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Abstract: | The carbon isotope composition (δ13C, ‰) and discrimination (Δ, ‰) of old grown North American Pinus ponderosa Dougl. Ex P. et C. Laws. and European Pinus sylvestris L. were determined using trees grown under almost identical growing conditions in a mixed stand in Bralitz, Northeast Germany. Single-tree δ13C analyses of tree-ring cellulose of both species were carried out at a yearly resolution for the period 1901–2001 and the results compared with growth (basal area increment). Annual mean δ13C values for P. ponderosa ranged from?21.6 ‰ to?25.2 ‰ and for P. sylvestris from?21.4 ‰ to?24.4 ‰. Accordingly, 13C discrimination (Δ) showed higher values for P. ponderosa throughout the investigation period. Five characteristic periods of Δ were identified for both the tree species, reflecting positive and negative influences of environmental factors. Good growing conditions such as after-thinning events had a positive effect on Δ, reflecting higher values, while poor conditions like aridity and air pollution had a negative influence, reflecting lower values. The dynamics of Δ were likewise reflected in the growth (basal area increment, BAI). Higher 13C discrimination values of P. ponderosa led to higher BAIs of P. ponderosa in comparison with P. sylvestris. Correlation function analyses confirmed that P. sylvestris was more dependent on precipitation than P. ponderosa, which showed a closer relationship with temperature. The results confirm that under predominantly dry growing conditions, P. ponderosa showed better growth performance than P. sylvestris, indicating better common intrinsic water-use efficiency and, therefore, higher rates of net photosynthesis at a given transpiration. In view of the prospect of climate change, the results are very significant for assessing both trees’ physiological properties and, hence, their potential for coping with future growing conditions. |
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Keywords: | Aridity Basal area increment Carbon isotope discrimination Carbon-13 Follow-up Growth Pinus sylvestris Pinus ponderosa Tree rings |
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