The Effect of Grey Heron Colonies on the Radial Growth of Trees in Pine Plantations

Abstract

Data on the influence that grey heron (Ardea cinerea L., 1758) colonies have on the dynamics of tree ring parameters in pine plantations are presented. It is shown that the beginning of the stands colonisation by the grey heron can be quite accurately determined by analysing the dynamics of the annual tree rings parameters, especially the width of their late layer and the optical density of wood (the values of the former are lower in the control stand, and of the latter one are higher there). Grey heron colonies begin to appear in pine forests as early as 10–12 years old, when the height of the trees reaches 5–6 m, and the diameter of the trunk at a height of 1.3 m from the soil surface is only 7–8 cm. In the first 15–20 years, they have a positive influence on the annual growth of trees, especially on the width of the late layer of wood and the thickness of the cell walls, but then the picture changes to the opposite. The total residence time of heron colonies in one place is about 35–40 years, after which they move to new places due to the forest stands coming into disarray or even facing complete destruction. To reduce the likelihood of the appearance of grey heron colonies, which in many cases have a negative impact on the state of forest biogeocoenoses, it is necessary to stop creating pure pine forests near water bodies, giving preference to spruce, birch, poplar, or linden-oak plantations.