tailieunhanh - Báo cáo lâm nghiệp: "Can 13C stable isotope record of Norway spruce tree rings display the effect of environmental conditions"

Tuyển tập những bài báo cáo nghiên cứu khoa học hay nhất được đăng trên tạp chí JOURNAL OF FOREST SCIENCE đề tài: Can 13C stable isotope record of Norway spruce tree rings display the effect of environmental conditions? | JOURNAL OF FOREST SCIENCE 54 2008 6 255-261 Can 13C stable isotope record of Norway spruce tree rings display the effect of environmental conditions L. Písová1 M. Svoboda1 J. Santrucek2 H. Santruckova2 1Faculty of Forestry and Wood Sciences Czech University of Life Sciences Prague Prague Czech Republic Faculty of Science University of South Bohemia in Ceské Budejovice Ceské Budejovice Czech Republic ABSTRACT The Bohemian Forest Mts. Sumava were exposed to heavy atmospheric pollution in the last century. A possible negative effect of atmospheric pollution on tree physiology has been studied using the isotopic composition A13C of tree rings. The wood is depleted of 13C relative to the air due to isotopic discrimination against 13C and preferred uptake of 12C during photosynthesis. The ratio 13C 12C A13C reflects the relative magnitudes of net assimilation and stomatal conductance that relate to demand and supply of CO2. Carbon-13 data are thus a useful index for assessing intrinsic water use efficiency mark period of drought or root system damages and also could indicate assimilation organ injure needle damage caused due to acid rain etc. . A decrease in A13C implies a negative effect of environmental conditions on tree physiology. Presumably changes in soil pH and aluminium content as an indirect effect of atmospheric pollution could have an impact on tree physiology. Our results showed that the isotopic signal varied around the average but the A13C signal was decreasing from the 1950s to 1980s and then increasing again starting in the 1990s. This trend is in accordance with the monitored atmospheric pollution and soil solution pH changes. Keywords A13C air pollution tree physiology Bohemian Forest Mts. soil pH aluminium soil acidification In the past the nutrient balance and development of trees in many areas of Central Europe were affected by acidification that occurred in this region Matzner Murach 1995 . The acidification of soils caused the loss of base cations

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