δ¹³C AND INTRINSIC WATER USE EFFICIENCY FOR TREES IN VARIOUS HEALTH CONDITIONS – CASE STUDY FOR ŚWIERKLANIEC FOREST DISTRICT

The study included a comparative analysis of two Pinus sylvestris L. trees growing next to each other, but in a different health condition, and the reference trees growing in the same area in Poland. The declining tree, although it was a more difficult research material, was subjected to the same analyses as healthy trees, including: creating a ring width index (RWI) record, a δ¹³C record, an intrinsic water use efficiency (iWUE) record and checking for the following correlations: δ¹³C-temperature, δ¹³C-precipitation, δ¹³C-SO₂, and iWUE-SO₂. Our study found that trees with different health conditions may have comparable growth patterns, but different carbon isotopic compositions and iWUE. Differences between individual trees were also observed in sensitivity to changes in temperature and SO₂ emissions. The declining tree showed more significant correlations with summer temperatures, than the healthy tree and the reference trees, where significant correlations occurred in single months. Only in the instance of the declining tree, correlations were found between δ¹³C and SO₂. iWUE of all trees did not show sensitivity to SO₂ emitted in high concentrations; however, we observed the sensitivity of iWUE from the reference trees to low SO₂ concentrations.