Evaluation of Siberian Stone Pine Plantations at the End of the First Age Class

The 40-year-old plantations of Siberian stone pine laid out as a permanent seed plot have been studied. The research purpose is to study the integrity, state and main forest inventory parameters of the Siberian stone pine plantations on the southern line of the species range at the end of first age class; to determine the role of natural renewal of trees and shrubs on the development of the Siberian stone pine plantations; to improve process solutions for efficient renewal of high-value biological resources. The research uses the methods generally accepted in forestry, forest science and forest inventory. It is found that the integrity of Siberian stone pine on the site is about 31 % (678 pcs/ha), wherein 406 pcs/ha are without damage to the trunk. Only about 25 % of Siberian stone pine trees grow under low shade, the rest of them are constantly shaded by natural renewal and have varying degrees of suppression. No generative organs were found in 44-year-old Siberian stone pine trees. At the initial stage of plantations growth, the main factor negatively affecting the integrity and state of trees is the damaging of Siberian stone pine by moose. Traditional improvement thinning with leaving stumps that produce many shoots of deciduous species attracts moose to the site in winter, where they use young growth of deciduous species and the covered with needles part of Siberian stone pine as forage. Subsequently, in the absence of tending, natural renewal negatively affects the Siberian stone pine trees, inhibiting growth and formation. It is necessary to remove the negative influence in the mixed biocenosis in order to prevent further deterioration of the Siberian stone pine state. This requires completely different technological solutions for forestry activities such as ringing or injection of trees of natural renewal, causing drying at the root, which significantly reduces or eliminates the emergence of deciduous young growth. This will decrease the attractiveness of the site for moose and minimize their impact on Siberian stone pine. The clear drying of surrounding trees will enhance the illumination of Siberian stone pine crowns and improve their soil nutrition, ensuring good root, trunk, and crown growth and accelerating the beginning of the formation of generative organs. These technical solutions can be used throughout the forest zone for the artificial cultivation of the high-value species – Siberian stone pine. For citation: Terekhov G.G., Andreeva E.M., Stetsenko S.K. Evaluation of Siberian Stone Pine Plantations at the End of the First Age Class. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 6, pp. 56–68. DOI: 10.37482/0536-1036-2021-6-56-68

30-year cone production dynamics in Siberian stone pine (Pinus sibirica) in the southern boreal zone: a causal interpretation

Background and aims – Siberian stone pine is a keystone species for Siberia, and numerous studies have analyzed Siberian stone pine seeding dynamics in connection with the dynamics of weather conditions. However, all studies were based on observations before 1990. The aim of the study was to expand our knowledge about the balance of weather and climatic factors in the regulation of cone production to enable conclusions about the current reproductive function in Siberian stone pine.Material and methods – We monitored Siberian stone pine cone production in the southeastern region of the Western Siberian Plain, in association with climatic factors, over a period of 30 years. To analyze the relationship with weather conditions, we used the trait mature cone number per tree and weather data obtained from the weather station in Tomsk.Key results – During this period, cone production decreased by about one-third, mainly caused by the complete absence of high yields. The main factor negatively affecting cone production was late spring frost: severe frost occurring with a large accumulated sum of effective temperatures resulted in full cone loss, and light frost substantially reduced cone number. A less important but significant climatic factor was September temperature: as the temperature increased, the cone number decreased in the following year. Over the last 30 years, the sum of the effective temperatures at which the last spring frost occurs, as well as the average September temperature, increased considerably, resulting in reduced cone production.Conclusion – If the current climatic trend is maintained, and especially if it is strengthened, Siberian stone pine cone production in the southern boreal forest zone on the Western Siberian Plane is unlikely to provide for the effective renewal of the species.

An Agronomic Approach to Pine Nut Production by Grafting Stone Pine on Two Rootstocks

Stone pine (Pinus pinea) grows in natural stands within the Mediterranean basin and its nut is highly appreciated for its nutritional profile. Nevertheless, a decline in this species due to biotic and abiotic damages is currently being clearly observed. This situation has led to its development as a nut crop, to try to save its production and obtain regular harvests over the years. Under this agronomic scenario, the aim of this work was to compare the behavior of the stone pine grafted onto two rootstocks, P. pinea (PP) and P. halepensis (PH), by evaluating cone productivity, tree growth response, mast seeding patterns and pine nut composition. The field test was composed of 14 PH and 14 PP, randomly distributed into groups of 4–5 trees/rootstock. Data were from seven productive growing seasons. The results show higher growth and ripe cone production on PP rather than PH, although the productivity (cones/m2 canopy) was similar. Any effect of rootstock was observed on the mast seeding pattern and weight of cones, while the pine nut composition showed differences in the fatty acids content. The global quality of production was similar in PH and PP.

Study of the stem growth of heteroplastic grafts of stone pines in the Krasnoyarsk forest-steppe

Changes in the radial growth Pinus sibirica Du Tour and Pinus cembra L. grafts and Scots pine (Pinus sylvestris L.) rootstocks were observed in comparison with control (non-grafted) trees of the corresponding species, whichindicated the mutual influence of the grafting components on each other. The smaller width of the annual rings in Pinuscembra grafts compared to Siberian cedar grafts is due to their species features. In general, the phloem was more conservative in structure than the xylem and in the grafts union zone retained the species characteristics, sometimes manifestedin the form of jagged junction of two types of bark, while in the xylem in the union zone were cells with an intermediatestructure. The study of seasonal dynamics showed that, in comparison with the rootstocks of Scots pine (Pinus sylvestrisL.), the scions of Stone pine quickly passed to the process of maturation of tracheids, especially the scions of Pinus sibirica Du Tour, which also completed the development of xylem annual ring faster. The similarity of some parameters of theanatomical structure, reactions to climatic conditions, synchronization of the development of the annual ring in the scion of the P. cembra with the stock of the Scots pine explain the higher safety of grafts of the P. cembra in comparison withthe P. sibirica.