Variations of Tree-Ring and Foliar δ~(13)C Values ofSabina przewalskii with Altitude

Since industrial revolution, a large amount of anthropogenic CO_2 from fossil fuel combustion and deforestation has been emitted into atmosphere, and thus, the atmospheric CO_2 concentration has increased rapidly, while the (δ~(13)C) in atmospheric CO_2 becomes lower and lower due to Suess effect. Therefore, prediction of (δ~(13)C) is crucial for studying global change. In order to make an accurate prediction, it is necessary to understand its historical variation. The dynamics of (δ~(13)C) in plants can sensitively reflect the variation. However, few studies are done of the stable carbon isotopes from high mountain regions, which are considered under ecological influence. In present paper, tree-ring and foliar (δ~(13)C) values at different altitudes, as well as photosynthetic pigments, soluble sugar and nitrogen contents, were measured. The results showed that no strong dependency of (d~(13)C) values on elevation was found both in tree rings and in leaves, but tree-ring (δ~(13)C) values were more negative than foliar (δ~(13)C) values. A significant negative relationship existed between foliar (δ~(13)C) values and photosynthetic pigments; however, foliar (δ~(13)C) values were not associated with leaf nitrogen and soluble sugar contents. During the past 50 years, tree-ring (δ~(13)C) values becomes lower and lower, although the rates of decrease in (δ~(13)C) values at different altitudes were different. The analysis showed thating (δ~(13)C) values, and the decreasing trend of tree-ring (δ~(13)C) values in the past 50 years was due to anthropological activities.