Interrelation of the Radial Increment of Trees with Various Factors

Abstract

Radial increment objectively reflects the quality of the assimilation apparatus of a woody plant. Its features indicate the influence of various anthropogenic, biotic and abiotic factors as well as the stability of the plant under stress. The aim of this study was to survey the long-term dynamics of the radial growth of six tree species: Betula pendula, Ulmus glabra, Quercus robur, Tilia cordata, Picea abies and Pinus silvestris, depending on the impact of creating a reservoir and the fluctuations of the water level in it. Additionally, another aim was to determine whether there is a dependence between the annual radial increment of these tree species and the change in the temperature factor during the growing season. We studied cores of trees growing in a park on the coast of the Sheksna river, the level of which is regulated by the water level in the Rybinsk Reservoir and changes along with it. This research presents the dynamics of the annual radial growth of Betula pendula over 59 years, Ulmus glabra over 50 years, Quercus robur over 59 years, Tilia cordata over 82 years, Picea abies over 128 years and Pinus silvestris over 125 years. The average annual radial growth decreases in the series Ulmus glabra > Betula pendula, Quercus robur > Tilia cordata > Picea abies > Pinus silvestris. The radial increase does not correlate with the annual water level in the Rybinsk Reservoir. However, years with extreme minimum and maximum reservoir filling affect the radial growth of Quercus robur (r = 0.56) and Tilia cordata (r = 0.52). It was found that after the creation of the reservoir, the radial increment of Picea abies was significantly reduced by 1.10 mm. The clearest dependence of ring width index was obtained for Picea abies on temperature in May (r = −0.30 at p ≤ 0.05) and for Pinus sylvestris on temperature in July (r = −0.25 at p ≤ 0.05). Similarly, a weak correlation of ring width index with temperature in some months was noted for deciduous trees. Picea abies is notable for its particular display of moderate inverse correlation to the radial growths of other trees.