Physiological Parameters of the State of Pinus Pallasiana D. Don in different Forest-Growth Conditions in Ravine Viyskovyi

The influence of different forest-growth conditions on the ecological and physiological parameters of Pinus pallasiana D. Don plants growing in anti-erosion planting is investigated. The experimental sites are located in the thalweg (test area 1) and on the slope of southern exposure in the lower, middle, and upper parts (test areas 2–4) of Ravine Viyskovyi (steppe zone of Ukraine). Forest-growth conditions are clay-loam soil (CL₂) (mesophilic, fresh soil), СL_1–2 (xeromesophilic, rather fresh), СL1 (mesoxerophilic, somewhat dry or semi-arid), and СL_0–1 (xerophilic, arid) correspondently. It was shown that the growth rates of trees, the growth rate of lateral (scaffold) branches in length and thickness, needle-packing coefficient, and needle surface area of annual shoots are maximal in P. pallasianа in the thalweg in conditions of the best water supply and minimal in arid and semi-arid conditions of growth. The research revealed that the highest content of total water in the needles is characteristic of plants of fresh forest plant conditions and the smallest in arid and semi-arid areas (test areas 3 and 4), which is consistent with the forest-vegetation conditions.

Sufficient contents of potassium, calcium, and magnesium in all areas and phosphorus in three areas except the middle part of the slope were found in the needles of P. pallasianа. However, insufficient content of nitrogen was found in the needles, especially in the trees of the middle part of the slope, which, together with low water supply, could cause the most significant slowdown in the growth of P. pallasianа plants precisely on this experimental site. A correlation was established between the indices of plant growth and the content of water and nutrients.