Selection Criteria for Elite Small-Number Forest Stands

The creation of new highly productive forest shelterbelts is associated with the use of appropriate seeding material. For this end, permanent forest seed base elements have to be allocated and created, including the elite stands. In difficult agricultural conditions, they often are represented by limited areas of small tree number, with no criteria for their allocation. The aim of this work is to develop criteria for allocating small elite stands in forest shelterbelts. The studies were conducted in forest shelterbelts of the five most common tree species in the North-West Caucasus: pedunculate oak (Quércus róbur L.), false acacia (Robinia pseudoacacia L.), lanceolate ash (Fraxinus lanceolata B.), common ash (Fraxinus excelsior L.), and honey locust (Gleditschia triacanthos L.). The age of the plants ranges from 42 to 57 years, the productivity class ranges from I to Ib. Overall, 35 trial plots (TP) with 30 individuals each were laid out. TP (5 in each field-protective belt) were located near each other, with selection assessment carried out on them separately in accordance with the Sukhorukikh-Biganova method. In laboratory, a data array was successively made up for each species by merging data from adjacent TPs until the sample size reached 150 individuals. It was revealed that the number of minus trees in the samples does not depend on the species composition (Pearson contingency coefficient is 0.065; Chi-square is 2.446; significance is 0.99), but changes in parallel with different selection options (T-parallelism is 0.1467; significance is 0.8827). A high statistical correlation was found between the number of minus trees and the overall number of individuals in the shelterbelt (R² = 0.9678 – 0.981). Adequate models for this dependence were calculated, and on their basis the ratio of minus trees was determined at different numbers of individuals in plus stands. For 30 overall trees it amounted to 20%, for 40 trees. – 22%, for 50–60 trees. – 23%, for 70 trees. – 24%, for 80–90 trees. – 25%, for 100–110 trees. – 26%, for 120–130 trees. – 27%, for 140 trees. – 28%, and finally, for 144 – 150 trees. – 29%.