Criteria for Assessment of Plus Oak Stands

Abstract

In the Voronezh region the share of seed plantations is less than half of the area of oak forests. Therefore, the regeneration of high-quality forests of seed origin with improved hereditary characteristics is a major challenge. In the production of seeds of improved breeding categories, plus stands play an important role. They produce improved seeds, if minus trees are removed. Moreover, permanent forest seed plots which were planted by the plus stand offspring, produce seeds of the required breeding category. Current laws and regulations do not provide specific recommendations on selection of plus stands. To address this issue and establish the criteria by which such forest stands should be selected we examined all the best stands containing plus trees in the Voronezh region (those that are candidates for plus stands). The frequency of occurrence of plus trees varies from 2 to 10 trees per 10 ha. We took the average value as the minimum to classify the forest plot as a plus stand. Marking forest stands as plus stands based on selection inventory data is recommended regardless of the time of the forest management fieldwork. Besides this, we performed a detailed inventory of the plus stand in the quadrant 41 of the Krasnoye divisional forestry area in the Vorontsovskoye forestry area on the area of 10.7 ha. The study was carried out on 10 trial plots (1 ha each), where a selection inventory was conducted, as well as an inventory of trees by technical assessment with a detailed description of each oak specimen by inventory characteristics, condition and the presence of flaws. The data obtained by selection inventory with identification of “good trees” (sum of plus and normally best trees) correlate with distribution of trees by technical assessment categories. The identified patterns can be used for selection inventory of oak plantations. We recommend to place stands in a category of plus stand if their forest density ranges from 0.7 to 0.9, more than 35 % of the trees have commercial wood and if this plot has at least one plus tree per two ha. Restoring oak forests with acorns harvested from plus stands will improve the quality of forest plantations.