Climatic signal in a radial growth of Canadian and Maximovich poplars in south-western Poland

ABSTRACT: The main goal set by researchers in this article was to gather knowledge on the structure of the basic biometric features of tree-rings of two species of poplars, belonging to different sections of Aegeiros – Populus xcanadensis and Tacamahaca – Populus maximowiczii, and to define and understand the correlation between weather and annual increment. A supplementary objective of the article was to determine pointer years of species found in individual populations. Our research used the standard methodology applied in dendroclimatology. In the analysis of correlation of the tree species studied, stronger statistically significant relationships were obtained in terms of precipitation-increment compared to temperature-increment. The annual increment in the Canadian poplar was enhanced by wet autumns and winters, especially by the rainfall in Oct and Dec in the previous year, as well as in Apr of this year. The tested Maximovich's poplars tested preferred rainfall during spring going into summer, especially in June of this year. Seven specific pointer years were determined for the Canadian poplar, comprising 4 positive (1987, 2008, 2010, 2012) and 3 negative years (2000, 2011, 2014). For P. maximowiczii, 11 pointer years were determined, i.e. 5 positive years (1987, 1991, 1999, 2009, 2012) and 6 negative (1984, 2000, 2002, 2010, 2013, 2015). In the pointer years, monthly sums of atmospheric precipitation and the average monthly air temperatures differed from the multi-year period. In the process of forming the secondary growth of the wood of the studied poplar species, the predominant role was played by atmospheric precipitation.