Наукові праці Лісівничої академії наук України (Dec 2020)
Dynamics of litterfall in pine-beech stands and its changes under the influence of uniform shelterwood felling in the Lviv Roztocze region
Abstract
Quantitative and qualitative indicators of precipitation depend on many factors such as the composition of plant species, forestry activities, seasonal features of the year, climate and soil hydrological features in the region, etc. Of particular importance for the formation of litter-fall is the stand and its silvicultural and taxonomic features, which are the main component of the forest. In this work, the peculiarities of the annual dynamics of litterfall accumulation and its structural fractions are characterized (pine needles, beech leaves, leaves of accompanying breeds, branches, bark, pine cones, beechnuts, beechnut cupules, seeds of accompanying breeds) and their changes after the first methods of shelter wood felling of the main-use is unique in composition and limited in distribution pine-beech forests in Lviv Roztocze region. It was found that, depending on the biometric indicators of mature pine-beech stands, the annual rainfall is usually 5-6 t / ha in a dehydrated state. The largest share of litterfall in the annual cycle is beech leaves (29.5-36.8%) and much smaller pine needles (20.8-25.6%). Quite significant in the composition of the precipitation is the mass of branches (12.4-14.7%), pine cones (10.5-11.7%), tree bark (6.6-9.0%), and beechnut cupules (3,6-10.6%). A small share of litterfall is represented by beech nuts (1.7-4.3%) and leaves of accompanying breeds (0.4-1.7%) and the smallest by seeds of accompanying breeds (0.01-0.13%). The largest mass of litterfall is formed in October (35.6-44.6%) due to defoliation, mainly beech. A significant amount of dead phytomass also falls in September (14.1-16.2%) and in the autumn-winter-spring period (November - March, 19.3-19.7%). A small increase in litterfall accumulation in the pine-beech stands of Lviv Roztocze is also typical in May (8.4-14.3%). In September, the main share of litterfall is formed by pine needles and beech leaves, and in fruitful years it is also represented by beech nuts and beechnut cupules; in the autumn-winter-spring period - branches, pine needles, the bark of beech and beechnut cupules; in May - pine branches and cones. The lowest amount of phytomass falls in April (about 2.0 %). During this period, the main components of litterfall are represented by pine branches, bark, cones, and pine needles. A small share of litterfall is also observed in July (2.9-3,7%) and August (2.7-3.7%), formed mainly by the fall of cones, bark and pine needles. In general, in pine-beech stands of Lviv Roztocze, about 60% of organic matter falls in autumn, in winter, and spring up to 15% and in summer – 11.0-13.0%. The annual dynamics of accumulation of individual litterfall fractions in pine-beech forests are ambiguous. It depends on the functioning and role of the relevant organs in the life of trees. The largest mass of pine needles falls in September (29.0-33.2%) or in October (26.4-40.2%), beech leaves and accompanying breeds in October (84.5-87.4 and 81.0-81.2% respectively), branches in winter (38.9-63.6%) or in May (13.1-45.3%), bark in winter (39.7-43.1%), pine cones in May and June (26.7-38.0 and 28.7-38.8% respectively), beech nuts in September (54.2-58.7%), beechnut cupules in September and winter (17.9-23.2 and 40.7-53.0% respectively), seeds of accompanying breeds in October (57.1-70.7%). The smallest amount of litterfall of different fractions of trees phytomass also occurs in different periods of the annual cycle. Pine needles, beech leaves and accompanying breeds fall at a minimum amount in April, branches - in August, tree bark - in April, August and October, pine cones - in October, beech nuts - from April to July, beechnut cupules - in June and July, the seeds of accompanying breeds - from April to August. The most identical and close to the total mass of litterfall's annual accumulation patterns are the annual dynamics of pine needle litter, beech leaves, and leaves of accompanying breeds. The annual dynamics of litterfall of beech branches, bark and nuts, and seeds of accompanying breeds are similar. The annual dynamics of pine cones and beechnut cupules are different, both among themselves and other fractions. The impact of shelterwood feelings of the main-use on the litterfall accumulation is closely related to their organizational and technical indicators, particularly the intensity of feeling. After the first stage of shelterwood uniform felling, the annual mass of litterfall decreased to 44.3%, and group-shelterwood felling – to 62.1% compared to the control, while the annual dynamics of litterfall and its fractions after felling did not change significantly. Simultaneously, it should be noted that felling improves the light supply of deciduous species, which form mainly the second layer of trees and stimulate their fruiting. As a result, in the section of shelterwood uniform felling, the share of beech nuts in the total mass of litterfall, compared with the control, increased 1.3 times, and the beechnut cupules – 1.1 times. In the group- shelterwood felling section, the number of beechnuts and beechnut cupules increased 2.1 times, and the number of seeds of accompanying breeds – 2.9 times compared to the control values.
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