Effect of Stand Density and Diversity on the Tree Ratio of Height to Diameter Relationship in the Park Stands of Southern Ukr

The article investigated the influence of factors on the dependence of tree height on tree diameter in a park stand. The role of tree damage, density, and stand diversity as predictors in the dependence of tree height on its diameter was revealed. The hypothesis of the scale dependence of the influence of stand density on plant growth was tested. The number of plants that are within a radius of 3, 5, 7, 10 meters was determined for each of the recorded plant specimens. The diversity according Shannon of the plant community was estimated based on the information on the species composition of plants within a radius of 10 meters from the focal plant. The age of plants in the community was positively correlated with the diversity of vegetation in the surroundings of a particular plant. About 74.1% of the trees were found to have the signs of pathological damage. The best model to explain tree damage was a model that included as predictors plant species, its age, the diversity of the surrounding stand, and its density estimated from a 7-m radius sampling site. The GLM approach allowed to reveal that 83% of tree height variation can be explained by the information on tree and shrub species, plant condition (healthy plant or damaged one), its diameter and stand density. The stand density and the square of this index were found to be statistically significant predictors if the density was calculated for a sample area with a radius of 7 meters.