Biometrics of tree-ring widths of (populus x canadensis moench) and their dependence on precipitation and air temperature in south-western poland
The aim of this study was to explore the structure of the basic biometric characteristics of Canadian poplar (Populus x canadensis Moench) growing on former farmland, and the influence of meteorological elements on the variability of tree-ring widths (TRW). The test was performed on stem discs. Measurements of TRW were made with the use of LINTABTM 6. The impact of meteorological conditions on the TRW of the examined poplars was determined using correlation analysis for the dependent variable – residual chronology and independent variables – rainfall and air temperature in the current year and the year preceding the formation of rings. The average TRW of the Canadian poplar was 6.70 mm, with a coefficient of variation of 45.6%. The average TRW in sapwood was 5.37 mm, 2.11 mm less than in heartwood. The site chronology represented the period 1967-2014 (48 years). Our study demonstrated a significant correlation between rainfall and temperature on TRW in Populus x canadensis. The greatest demand for water by the Canadian poplar was observed in April and September of the current year. In contrast, the effect of air temperature most negatively affected TRW in June-July of the previous year (especially July) and April-May of the current year. In the designated chronology we established 13 pointer years, 7 positive and 6 negative. Negative years were determined in the years in which the shortage of rainfall was up to 50% of the norm, and positive indicator years where precipitation was higher than in the multi-annual period, even >150%. Both the correlation analysis and the analysis of indicator years indicated rainfall as a factor determining the size of the tree-ring width in Canadian poplars. In recent years, Poland has seen a resurging interest in planting poplars, following a long-term global trend in forestry and the paper industry which requires fast-growing tree plantations. The authors of this study attempted to address the gap in knowledge about the impact of meteorological elements on the tree-ring widths of Populus x canadensis in the conditions of south-west Poland.