60-year Dynamics of the Upland Stands of Quercus Robur in the Southern Forest-Steppe in Connection with Thinning and Mass Decline

Abstract

Introduction. Current state of oak forests requires an assessment of risks of reduce of their productivity and mass decline and enhancing the sustainability in forestry practice. The aim of the paper is to analyze the influence of thinning and mass decline of oak on stability and productivity of the overstory stands. Three periods in dynamics of upland oak forests of natural origin were studied: thinnings (20 years), mass oak decline (10 years), and restoration (30 years). Results. During the first period, three modes of thinning were performed. In the first mode, both absolute and relative values of average-period increments and stock changes were offered, in the second mode – only relative ones, in the third mode – only relative increment tightly correlated with thinning intensities (r > 0.9). In the period of mass oak decline (1976-1985), the ranging of stands by their productivity was violated. The relative increment nega-tively depended on intensity of the dying off in 1976-1979. The increment of forest stands did not practi-cally decrease (in contrast to that of oak) for the expense of associate species. The share of oak in the dying off in the overstory was 90%