Dynamics of the tree species’ change in the field-protective forest belts of the Republic of Bashkortostan

The problem of changing tree species in protective afforestation remains poorly covered. The dynamics of species’ change in poplar (Populus L.) protective forest belt growing next to the forest crops of the Scotch pine (Рinus sylvestris L.) is discussed in the article. A forest belt 450 m long and 10 m wide grows in the steppe zone near the village of Shigaikulbash, Buzdyaksky District of the Republic of Bashkortostan. Accounting plots are laid every 50 m. Reliable pine undergrowth in the forest belt, poplar undergrowth was not found on any of the accounting plots. Comparative characteristics of pine undergrowth (density, average age, stem height, and diameter) and the condition of poplar trees were compared for 2008 and 2020. It was revealed that there was a change in the design of the forest belt from openwork to dense, there is a partial shrinkage of poplar, in some areas there is an exit of pine undergrowth to the first tier. For both periods, the highest density of pine (over 1.5 thousand trees/ha) was detected at a distance of up to 200 meters from pine forest crops, the lowest density (no more than 0.4 thousand trees/ha) – in the center of the forest belt. In 2020, the category of small undergrowth was not found, most of it is large undergrowth, some of which have entered the reproductive phase. The drying of poplar trees is observed. This was facilitated by a complex of reasons: the complete absence of agrotechnical care in the forest belts, a drought that has been recurring for several years and the maximum age of trees in the conditions of the steppe. There is no poplar undergrowth along the entire length of the forest strip. A similar pattern is observed in neighboring forest belts, which allows to make a conclusions about the actual change of balsam poplar (Populus balsamifera L.) to Scotch pine in protective forest belts, which should be accompanied by logging and agrotechnical tillage on the edges of forest belts, followed by the formation of a young pine tree stand of openwork design.