Premium
Carbon isotope discrimination indicates improving water‐use efficiency of trees in northern Eurasia over the last 100 years
Author(s) -
Saurer Matthias,
Siegwolf Rolf T. W.,
Schweingruber Fritz H.
Publication year - 2004
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2004.00869.x
Subject(s) - transpiration , stomatal conductance , isotopes of carbon , environmental science , water use efficiency , atmosphere (unit) , carbon fibers , climate change , latitude , atmospheric sciences , photosynthesis , botany , chemistry , ecology , environmental chemistry , total organic carbon , biology , geology , geography , materials science , geodesy , meteorology , composite number , composite material
We investigated the response of conifer trees in northern Eurasia to climate change and increasing CO 2 over the last century by measuring the carbon isotope ratio in tree rings. Samples from Larix , Pinus and Picea trees growing at 26 high‐latitude sites (59–71°N) from Norway to Eastern Siberia were analysed. When comparing the periods 1861–1890 and 1961–1990, the isotope discrimination and the ratio of the intercellular to ambient CO 2 concentration ( c i / c a ) remained constant for trees growing in mild oceanic climate and under extremely cold and dry continental conditions. This shows a strong coordination of gas‐exchange processes, consisting in a biochemical acclimation and a reduction of the stomatal conductance. The correlation for c i / c a between the two investigated periods was particularly strong for Larix ( r 2 =0.90) and Pinus ( r 2 =0.94), but less pronounced for Picea ( r 2 =0.47). Constant c i / c a under increasing CO 2 in the atmosphere resulted in improved intrinsic water‐use efficiency ( W i ), the amount of water loss at the leaf level per unit carbon gain. We found that 125 out of 126 trees showed increasing W i from 1861 to 1890 to 1961 to 1990, with an average improvement of 19.2±0.9% (mean±SE). The adaptation in gas exchange and reduced transpiration of trees growing in this region must have had a strong impact on the water and energy budget, resulting in a drier and warmer surface air layer today than would exist without this vegetation–climate feedback.