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Structure of the Cenopopulations of Woody Plants in the Upland Oak Forests of Vegetative Origin of the Southern Part of the Volga Upland

Saratov State Agrarian University named after N. I. Vavilov, Teatralnaya Square, 1, Saratov, Russian Federation, 410012
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(Received : February 27, 2019; Accepted : April 24, 2019)


This paper reports on the age and vitality structure of upland low-stemmed oak forests through the example of oak woodlands in the southern part of the Volga Upland. Based on the data obtained for the three most common types of forest growth conditions, the dynamics of the age structure of tree species were analyzed. The data were obtained by complete enumeration on 15 test plots and determination of the age of each tree. The collected data covered five intervals of the age series : (1) 20-30 years, (2) 30-40 years, (3) 55-65 years, (4) 70-80 years and (5) 95-105 years. The age of all the trees in the sample plots was determined using coresamples taken by an increment borer at the level of the root collar. Further processing of the obtained cores and data analysis were carried out in laboratory conditions. The types of the timber stand age structure were determined according to the classification of Komin (1963). The following types of age structure were found in coppice oak forests of the southern part of the Volga Upland were felled from 24 to 112 years ago : relatively uneven-aged timber stand, uneven-aged timber stand with several clearly separated generations of two types (stepwise uneven-aged and cyclically uneven-aged). The variation coefficient values and the age range of mixed oak timber stood varied. The smallest age variation coefficient value of the mixed timber stand was 17%, the largest was 32%; the minimum age range was 23 years, the maximum range was 47 years. The age variation of the coppice oak in the coppice timber stand did not exceed 9%. It was established that the effect of the timber stand age (the amount of time that passed since the development of the stand after clear felling) on the age structure of the mixed timber stand was statistically significant. It was also established that the species composition of the timber stand and interaction of the species composition and age significantly affected the age structure. An analysis of the vitality structure of oak cenopopulations and the main associated species (Norway maple and small-leaved linden) showed that the diversification of the composition and structure of the timber stands as they grew and developed after a clear felling did not have a unidirectional effect on the cenopopulation vitality status of the oak and associated species. The vitality index of oak cenopopulation (calculated from the dimensional spectra of the individuals that comprised the cenopopulations) showed that the genetically determined growth potential of oak was better implemented in the cenopopulations of complex subors of transitional type (from dry to fresh). Based on the results of the research, a vitality scale for low-stemmed oak was developed for five age intervals.
Key words :Upland coppice oak forest, age structure, vitality structure, vital state, age structure dynamics, uneven-aged timber stands, age structure type, absolute age, pedunculate oak