Savo Rončević

Productivity of black locust (Robinia pseudoacacia L.) stands on chernozem in Vojvodina.

This paper presents the elements of growth of black locust trees and stands in 15 sample plots in Vojvodina, at the age of 21-68 years. In each sample plot, based on soil profile horizons the determined soil type was chernozem as well as its lower systematic units (subtype, variety and form), according to the Skoric et al. (1985) classification. On the basis of the mean stand heights (hL), the stands on the subtype of chernozem on loess and loesslike sediments belong to height classes I-IV, and stands on calcareous aeolian sand to classes II-V (according to R e d e i et al. 2014), which indicates their considerable variability with respect to productivity within the determined subtypes of chernozem. Significant differences at the level of chernozem subtypes were found between the mean heights (p = 0.032), but not between the mean diameters (p = 0.083). The mean diameters at breast height in the studied black locust stands were on average lower than the models of diameter growth for the appropriate height classes and determined by a larger number of trees per hectare than in the tables (R e d e i et al, 2014). The volume per hectare is higher than in the tables also being conditioned by the large number of trees per hectare. [Projekat Ministarstva nauke Republike Srbije, br. III43007: Istraživanje klimatskih promena na životnu sredinu: pracenje uticaja, adaptacija i ublažavanje]

Growth models of black poplar trees, section Aigeiros (Duby)

Different courses of tree growth in height and diameter in nursery and plantation, immediately after transplanting, cause the difficulties in adaptation of tree growth models. Tree growth models, which do not include the sudden transitions and specificities of nursery growth and in the first years after planting can show errors in the assessment of the values of current and average increment at the moment of culmination and at the age of maximum increment. This paper proposes the introduction of additional parameters in the models of diameter and height growth, e.g. the values of mean diameter at breast height and mean height immediately after planting. Compared to the models without additional parameters, the precision of diameter and height model is reflected in the lower standard error of regression (se) and in the more accurate assessment of current and average increment at the moment of culmination and at the age of culmination.