Larix Sibirica Ledeb Research Articles

Quality changes of cooked sausages influenced by the incorporation of a three-component natural antioxidant blend

The aim of this study was to evaluate the influence of triplicate blend of natural antioxidants on the sensorial, physicochemical and microbiological characteristics of cooked sausage. Three antioxidants: sodium L-ascorbate (x1), dihydroquercetin isolate from Larix sibirica Ledeb (x2) and lyophilized ethanol (30%) extract of dry distilled rose (Rosa damascena Mill) petals (x3) were studied in doses 0, 0.05 and 0.1 g/kg. The sensory characteristics, pH, primary products of lipid oxidation expressed by peroxide value and total viable count of the concentration of microorganisms were analysed. The studied parameters were measured on the first and the seventh day of the storage at 0-4°C. After 7 days of storage at 0-4°C it was found that the panel evaluated the highest sensory scores in design point 9 with addition of 0.05 g/kg of the three antioxidants and no difference was found compared to the control (without antioxidants). On the contrary, a minimum peroxide value of 2.88 ± 0.03 µeqO2/kg is achieved by the addition of 0.1 g/kg of the three antioxidants. The total viable count of microorganisms and pH values of the control samples were lower than those with the addition of antioxidants. Additional experiments are needed to optimize the three-component antioxidant blend.

СОСТОЯНИЕ ХВОЙНЫХ ИНТРОДУЦЕНТОВ В Г. НУР-СУЛТАНА

The article presents observational data on the survival, preservation and growth of introduced tree species created in the interstrip spaces of the green zone of the city of Nur-Sultan. The greatest preservation is characterized by Siberian spruce (Piceaobovata Ledeb.) (76.8%) and blue spruce (Piceapungens Engelm.) (58,9%). Black spruce (Piceamariana Mill.) and Siberian larch (Larixsibirica Ledeb.) have a preservation rate of an average of 44.5%. The lowest survival rate and preservation (16.4%) is distinguished by Siberian fi r (Abiessibirica Ledeb.). When comparing the method of planting forest crops with planting the material with an open and closed root system, it was revealed that the survival ability and preservation of seedlings with ORS was slightly higher than that of seedlings with CRS. The average survival ability of seedlings with ORS was 58.1%, for seedlings with CRS – 53.7%. Plants height corresponds to the biological characteristics of woody species. The highest average height was for Piceamariana Mill (184.1 cm), the smallest average height was for Piceaengelmannii Parry ex Engelm (143.4 cm). The most acclimatized species of woody plants – Piceaobovata Ledeb., Piceapungens Engelm. and Piceamariana Mill – have been identifi ed. These trees have a high capacity for survival, stable growth and decorative effect. These coniferous plants can be used to create green areas of settlements in Kazakhstan, similar in soil and climatic conditions to the city of Nur-Sultan.

Tree Rings Reveal the Impact of Soil Temperature on Larch Growth in the Forest-Steppe of Siberia

Dendroclimatology has focused mainly on the tree growth response to atmospheric variables. However, the roots of trees directly sense the “underground climate,” which can be expected to be no less important to tree growth. Data from two meteorological stations approximately 140 km apart in southern Siberia were applied to characterize the spatiotemporal dynamics of soil temperature and the statistical relationships of soil temperature to the aboveground climate and tree-ring width (TRW) chronologies of Larix sibirica Ledeb. from three forest–steppe stands. Correlation analysis revealed a depth-dependent delay in the maximum correlation of TRW with soil temperature. Temperatures of both the air and soil (depths 20–80 cm) were shown to have strong and temporally stable correlations between stations. The maximum air temperature is inferred to have the most substantial impact during July–September (R = −0.46–−0.64) and early winter (R = 0.39–0.52). Tree-ring indices reached a maximum correlation with soil temperature at a depth of 40 cm (R = −0.49–−0.59 at 40 cm) during April–August. High correlations are favored by similar soil characteristics at meteorological stations and tree-ring sites. Cluster analysis of climate correlations for individual trees based on the K-means revealed groupings of trees driven by microsite conditions, competition, and age. The results support a possible advantage of soil temperature over air temperature for dendroclimatic analysis of larch growth in semiarid conditions during specific seasons.

Radial growth patterns of Siberian larch in plantations of the Republic Mari El

Based on the measurements of 83 wood cores, the main patterns of changes in the width of the early and late zones in the annual ring of Siberian larch trees (Larix sibirica Ledeb.), as well as their total radial growth indices in the conditions of the Republic of Mari El were identified. It was found that the width of the early wood zone varies in trees from 0.15 to 11.3 mm, late wood – from 0.05 to 4.15 mm, the proportion of latewood – from 1.2 to 82.8 %, and the annual growth indices - from 13 to 423 %. The main factor in the variability of the total width of the annual rings and the layer of early wood is the age of the trees, and the contribution of weather conditions and other unaccounted factors (noise) to the overall variance of the annual growth parameters is no more than 20 %. The variability of the total width of the annual ring also depends on their genotypic features, which determine up to 42.7% of the total variance of the parameter in some cenopopulations. In the dynamics of the growth indices of larch trees, despite the existing specifics of each cenopopulation, the general sharp decline in their values after the droughts of 1972 and 2010, as well as the alternation of the periods of growth and decline, is clearly distinguished.

352 years long fire history of a Siberian boreal forest and its primary driving factor

Fire is a major disturbance agent in the boreal forest, affecting the structure, dynamics and biogeochemical cycles in this biome. In the Asian section of boreal forest, the records of long-term fire history are few that limits our understanding of factors forcing regional fire dynamics. We presented an annually-resolved 352-year (1666–2017) fire chronology based on fire scars of Scots pine ( Pinus sylvestris L.) and Siberian larch ( Larix sibirica Ledeb) from the Transbaikal area in the southeastern Siberia. Fire activity showed an increasing trend from 1720 to 1929 (R 2 = 0.80, P < 0.0001), and a significant decreasing trend from 1920 to 2010 (R 2 = 0.62, P < 0.001). We assessed the potential relationships between drought (as represented by the Palmer Drought Severity Index, PDSI, and the Monthly Drought Code, MDC), ocean-atmosphere circulation and forest fire by Superposed epoch analyses, cross-wavelet analysis and Granger causality analysis. Increased fire activity was associated with stronger drought from previous winter to current summer of fire event years and positive Arctic Oscillation (AO) before and during major fire season (February and April to May), as revealed by superposed epoch analysis. Granger causality pointed to the significant role of drought in driving forest fires. Our findings provide insights into the climate drivers of forest fire activity and its prediction in the Transbaikal region. • Fire history was reconstructed by fire scars in tree rings from 1666 to 2017 in southeastern Siberia. • Fire activity showed a significant increasing trend from 1720 to 1929 and a significant decreasing trend from 1920 to 2009. • Drought was the major climate driver of the fire. • Increased fire activity was associated with the positive Arctic Oscillation (AO) before and during the major fire season (February, April and May).

Изменчивость элементного состава годичных колец хвойных пород

Distribution of chemical elements in tree rings bears important information on various biogeochemical processes. In order to achieve a reliable interpretation of the information, it is necessary to know the degree of variation in the content of chemical elements both at the level of the entire species and at the level of individual trees. The research aims to determine which chemical elements have a stable distribution in the trunks of a number of conifers: Siberian spruce (Picea obovata Ledeb.), Scots pine (Pinus sylvestris L.), Siberian larch (Larix sibirica Ledeb.), and Siberian pine (Pinus sibirica Du Tour). The data for the analysis were obtained on the basis of the long-term experiment in forest growing. The experimental site was laid out in 1971–1972 in the vicinity of Krasnoyarsk by the staff of the Sukachev Institute of Forest of the Siberian Branch of the Russian Academy of Sciences. Before planting the seedlings, the soil ground was mechanically levelled, and thus, sufficiently equal growth conditions were created for all plantings. Cores with a diameter of 12 mm were sampled from three normally developing trees of each species and analyzed using modern X-ray fluorescence methods. Content relative values of elements (counts) were obtained with the Itrax Multiscanner (COX Analytical Systems). The content of elements in the tree rings was characterized by the concentration and reserve of elements. Concentration was calculated as the number of counts per 1 mm2 of the ring area; reserve was calculated as the number of counts over the entire ring area. Each of these variables was defined by the parameters of linear slope in the calendar year series and the standard deviation. The cluster analysis was performed in the 4-dimensional space of the obtained parameters. This allowed determining whether the series of element distributions from different trees and species are grouped. Three elements (Ca, Co, and P) show high stability of distribution parameters in tree rings with no regard to tree species. A number of other elements (Mn, Pb, Cl, Cr, Ni, Sr, and W) are stably grouped depending on the species. The results of the research enable to focus on the study of the elements stably distributed in the conifer trunks. For citation: Gavrikov V.L., Fertikov A.I., Sharafutdinov R.A., Vaganov E.A. Variability in Elemental Composition of Conifer Tree Rings. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 6, pp. 24–37. DOI: 10.37482/0536-1036-2021-6-24-37

Modeling of radial variations in wood properties and comparison of juvenile and mature wood of four common conifers in Mongolia

Abstract Pinus sylvestris L., Pinus sibirica Du Tour, Picea obovata Ledeb., and Larix sibirica Ledeb. are important forest tree species in Mongolia. The radial variations of wood anatomical characteristics, physical and mechanical properties were evaluated by linear or nonlinear mixed-effects models for effective wood utilization of those of conifers. Many of these wood properties either increased or decreased from the pith to the bark and then became nearly constant based on the selected models. The properties of mature wood were estimated by nonlinear mixed-effects models, suggesting that P. sylvestris and L. sibirica are suitable as structural lumber, P. sibirica can be used for furniture and other interior products, and P. obovata is suitable for structural lumber as well as for furniture or interior products.

Characteristics of the photosynthetic apparatus of Pinus sylvestris L. and Larix sibirica Ledeb. from different locations of the Irkutsk region (Eastern Siberia)

The characteristics of the photosynthetic apparatus of coniferous growing in various forest types and climatic conditions of the Irkutsk region (Taishet, Bratsk, Shelekhov, Irkutsk districts) have been explored. The content of photosynthetic pigments, total, free, and bound water in the needles of P. sylvestris and L. sibirica were studied. Using a pulse fluorimeter PAM 2500 (Waltz, Germany), the chlorophyll fluorescence in needles was measured based on such induction curve indices as Fv/Fm, Y(II), NPQ, and ETR. According to the chlorophyll fluorescence induction curve parameters of Scots pine and Siberian larch needles growing in different forest growth conditions, the most effective potential of primary photochemical processes in PSII was observed in Scots pine. While studying the pigment fund of Scots pine and Siberian larch needles, it was found that the highest values of the content of chlorophyll (Chl) a, b, and carotenoids were observed in P. sylvestris and L. sibirica growing in the climatic and forest growth conditions of the Shelekhov district. It is assumed that the revealed characteristics of the parameters reflect the processes of adaptation of the photosynthetic apparatus to various environmental conditions during vegetation development, as well as its high plasticity in different climatic growth conditions.

Experience In Creating Artificial Forest Plants In The Territory Of Belgorod Region

The experience of creating artificial forest plantations on the territory of the Belgorod region within the framework of the “Green Capital” project is considered. As part of the project, it was envisaged to create more than 100 thousand hectares of forest plantations on chalk slopes and erosion-hazardous areas of the region for 2010 - 2020, that is, bringing the forest cover of the region to 15% - the optimal value for the region. For the period 2010 - 2020 forest plantations were laid on the territory of more than 87.7 thousand hectares. For afforestation in the region, species are recommended that provide sustainable, durable and ecologically capacious afforestation: as the main species on chernozem soils: Quercus robur L., Q. rubra, Fraxinus excilsior L., Larix sibirica Ledeb .; on sandy soils - Pinus sylvestris L. Reforestation has been carried out since 2010 on the territory of 22 districts of the region. In 2016-2020 more than 6 thousand hectares of oak forests were created. As a result, the species Q. robur occupies an area of 22.2% of the area of artificial plantations; P. silvestris accounts for 13.2% of the area of artificial plantations in the oblast. Next in terms of planting volumes are such crops as A. hippocastanum, R. pseudoacacia and F. excélsior - 12.1%, 24.7% and 14.4%, respectively. The share of fruit crops, as well as B. pendula, A. platanoide, A. campestre, and U. laevis, is 11.7%.

Genetic Structure and Geographical Differentiation of Larix sibirica Ledeb. in the Urals

The Ural Mountains and the West Eurasian Taiga forests are one of the most important centers of genetic diversity for Larix sibirica Ledeb. Forest fragmentation negatively impacts forest ecosystems, especially due to the impact of their intensive use on the effects of climate change. For the preservation and rational use of forest genetic resources, it is necessary to carefully investigate the genetic diversity of the main forest-forming plant species. The Larix genus species are among the most widespread woody plants in the world. The Siberian larch (Larix sibirica, Pinaceae) is found in the forest, forest-tundra, tundra (Southern part), and forest-steppe zones of the North, Northeast, and partly East of the European part of Russia and in Western and Eastern Siberia; in the Urals, the Siberian larch is distributed fragmentarily. In this study, eight pairs of simple sequence repeat (SSR) primers were used to analyse the genetic diversity and population structure of 15 Siberian larch populations in the Urals. Natural populations in the Urals exhibit indicators of genetic diversity comparable to those of Siberia populations (expected heterozygosity, He = 0.623; expected number of alleles, Ne = 4017; observed heterozygosity, Ho = 0.461). Genetic structure analysis revealed that the examined populations are relatively highly differentiated (Fst = 0.089). Using various algorithms for determining the spatial genetic structure, the examined populations formed three groups according to geographical location. The data obtained are required for the development of species conservation and restoration programs, which are especially important in the Middle Urals, which is the region with strong forest fragmentation.

Euro-Siberian plant species on the western borders of their natural ranges in Nizhegorod region

It was investigation on distribution of seven Euro-Siberian plant species on the western borders of their natural ranges in Nizhegorod region. Amygdalus nana L., Cotoneaster melanocarpus Fisch. ex Blytt., Crataegus sanguinea Pall.,Spiraea crenata L. are on the north-west borders. Abies sibirica Ledeb., Larix sibirica Ledeb. et Lonicera caerulea L. are onthe south-west borders. It was ascertained, that Crataegus sanguinea, Larix sibirica et Lonicera caerulea enlarged its rangesat naturalization from cultivation and tinning of forests. Crataegus sanguinea moved on taiga and Larix sibirica moved onforest-steppe. This is analogous their ranges in Siberia. The ranges of Abies sibirica, Amygdalus nana, Cotoneaster melanocarpus and Spiraea crenata remained the same even under the conditions of cultivation. It was supposed, that the reasonof these differences is greater ecological tolerance of first third species. Anthropogenic factors promote reach their natural borders. Moreover, anthropogenic factors can create favorable phytocenotic conditions, but don´t can create favorablephysiographic conditions for others.

Modification of Arabinogalactan Isolated from Larix sibirica Ledeb. into Sulfated Derivatives with the Controlled Molecular Weights.

The process of sulfation of arabinogalactan—a natural polysaccharide from Larix sibirica Ledeb.—with sulfamic acid in 1,4-dioxane using different activators has been studied for the first time. The dynamics of the molecular weight of sulfated arabinogalactan upon variation in the temperature and time of sulfation of arabinogalactan with sulfamic acid in 1,4-dioxane has been investigated. It has been found that, as the sulfation time increases from 10 to 90 min, the molecular weights of the reaction products grow due to the introduction of sulfate groups without significant destruction of the initial polymer and sulfation products. Sulfation at 95 °C for 20 min yields the products with a higher molecular weight than in the case of sulfation at 85 °C, which is related to an increase in the sulfation rate; however, during the further process occurring under these conditions, sulfation is accompanied by the destruction and the molecular weight of the sulfated polymer decreases. The numerical optimization of arabinogalactan sulfation process has been performed. It has been shown that the optimal parameters for obtaining a product with a high sulfur content are a sulfamic acid amount of 20 mmol per 1 g of arabinogalactan, a process temperature of 85 °C, and a process time of 2.5 h.

ОПЫТ ПОСАДКИ КРУПНОМЕРНЫХ ХВОЙНЫХ ДРЕВЕСНЫХ РАСТЕНИЙ В ВЕСЕННЕ-ЛЕТНИЙ ПЕРИОД НА КРАЙНЕМ СЕВЕРЕ

The first experience of transplanting large-sized coniferous dendrointroducents (Picea glauca (Moench) Voss, Larix sibirica Ledeb.) in the spring-summer period without preliminary prepara-tion of the root system in the urban conditions of the Polar region was presented. Four specimens of middle-aged plants of both species were selected. The transplant was carried out with the max-imum use of mechanized equipment, which ensures good preservation of the lump and the tree it-self. There were four mutually related stages of work (preparatory, digging out plants, transporta-tion, planting), the quality of which depends on the success of plant survival. A brief description of the decorative qualities, morphometric parameters and the state of the experimental plants has been given. It has shown that due to the peculiarities of the soil and the location of the root system in coniferous introduced species, a clod of earth should be at least 60 cm thick, with a diameter of 110 to 130 cm. The main agrotechnical methods for the creation and care of plantings from large-sized plants were given.

Hydrological soil properties control tree regrowth after forest disturbance in the forest steppe of central Mongolia

Abstract. The central Mongolian forest steppe forms a transition between different ecozones and is as such particularly sensitive to environmental changes. It is commonly affected by disturbances such as logging and forest fires. Intensified drought events aggravate stress on the trees that are anyway at their drier limit in the forest steppe. Climate change increases evapotranspiration and reduces the distribution of discontinuous permafrost, which leads to drier soil conditions. The motivation for this study came about through our previous observation that forest stands show great differences with respect to their recovery after disturbance by fire or logging. Sometimes, no regrowth of trees takes place at all. As water availability is the main limiting factor of forest growth in this region, we hypothesised that differences in soil hydrology control the forest recovery pattern. To test this hypothesis, we analysed soil properties under forests, predominantly consisting of Siberian larch (Larix sibirica Ledeb.), in the forest steppe of the northern Khangai Mountains, central Mongolia. We distinguished the following four vegetation categories: (1) near-natural forest (FOR), (2) steppe close to the forest (STE), (3) disturbed forest with regrowth of trees (DWIR), and (4) disturbed forest showing no regrowth of trees (DNOR). A total of 54 soil profiles were described in the field and sampled for soil chemical, physical, and hydrological analysis. We found a significant difference in soil texture between soils under DWIR and DNOR. Sand generally dominated the soil texture, but soils under DWIR had more silt and clay compared to soils under DNOR. Soil pF curves showed that soils under DWIR had higher plant-available field capacity in their uppermost parts than soils under DNOR. In addition, hydraulic conductivity tended to be higher in the uppermost horizons of soils under DWIR compared to their counterparts under DNOR. Chemical properties of the soils under DWIR and DNOR showed no significant differences. We conclude that the differences in post-disturbance tree regrowth are mainly caused by different soil hydrology. High plant-available field capacity is the key factor for forest recovery under semi-arid conditions. High hydraulic conductivity in the uppermost soil horizons can further support tree regrowth because it reduces the evaporation loss and the competition of larch saplings with grasses and herbs for water. Another important factor is human impact, particularly grazing livestock on cleared forest sites, which often keeps seedlings from growing and, thus, inhibits forest recovery. None of the disturbed sites (DWIR and DNOR) had permafrost. We, thus, conclude that permafrost is no major factor for the post-disturbance tree regrowth pattern, although it generally supports tree growth in the forest steppe by preventing meltwater from seasonal ice from seeping below the root zone, thus increasing the water supply in summer.

Влияние расстояния от источников загрязнения до лесонасаждений на качество семян Larix sibirica Ledeb. в окрестных лесах города Улан-Батора (Монголия)

Seed quality and seed germination are the major indicators determining the success of regeneration and structure in natural forest ecosystems. This study focuses on problems associated with seed quality and seed germination under air pollution impacts in the surrounding forest ecosystems of Ulaanbaatar city of Mongolia. The objectives were to test whether there was any negative effect of air pollutants on the site index, and to analyze the relationship between seed quality and distance from the city center (maximum pollution). The study was carried out in natural larch forests (Larix sibirica Ledeb.) growing in the vicinity of the capital of Mongolia. A total of eight 100×100 m (1 ha) sample plots were laid out using completely randomized sampling design along the main wind direction. Remoteness from the city center was 10, 15, 20 and 30 km both to the north and to the south. Results showed a high variation in stand mean height (p &gt; 0.001) and diameter (p &gt; 0.001) among selected forest areas. In general, all sampled forests belonged to bonitet / quality classes III, IV and V, which are considered as relatively poor growing conditions in terms of site index. Therefore, greater site index and seed quality were observed in the most distant locations from the city center, and contrary, the poorest seed quality was detected in locations close to the city center. This emphasizes that forests growing close to pollution sources exist with a potential risk of degradation, and their reproductive organs are more sensitive to the effects of pollutants.

Accumulation of heavy metal pollution caused by traffic in forest trees in the park of Kerey and Janibek Khans of the city of Nur-Sultan, Kazakhstan

Air quality in Nur-Sultan, the fast-growing new capital city of Kazakhstan, has been poorly investigated. This research was carried in Kerey and Janibek Khans Park in Nur-Sultan, the capital city of Kazakhstan, which is affected by “different traffic density” on the roads. Three different categories of contamination (i) high pollution (distance from the main road 10–15 m), (ii) moderate pollution (distance from the side road 15–30 m), and (iii) low pollution (distance from the source of contamination 30–80 m) at different levels resulting from urban transportation were examined. The aim of the study is to determine the pollution accumulation amounts of Ni, Cd, Pb, Cr, Li, Co, Fe, and Zn in five different tree species: Norway spruce (Picea abies /L./ H. Karst.), blue spruce (Picea pungens Engelm.), Scots pine (Pinus sylvestris L.,), Siberian larch (Larix sibirica Ledeb.), and silver birch (Betula pendula Roth). Significant differences in Ni, Cd, Pb, Cr, Li, Co, Fe, and Zn accumulation amounts were determined between three different parts of the park exposed to different levels of contamination. Approximately twice higher Ni, 2.3 times Cd, 3.3 times Pb, 2.7 times Co, 1.6 times Zn accumulation were determined in the area exposed to high pollution than in the parts of the park exposed to low pollution. Cd deposition in the area exposed to high contamination was higher in silver birch than in Scots pine and Norway spruce, while Cr and Co deposition values were higher in Norway spruce than in birch and Scots pine.

Climate change and tree growth in the Khakass-Minusinsk Depression (South Siberia) impacted by large water reservoirs

Regional and local climate change depends on continentality, orography, and human activities. In particular, local climate modification by water reservoirs can reach far from shore and downstream. Among the possible ecological consequences are shifts in plant performance. Tree-ring width of affected trees can potentially be used as proxies for reservoir impact. Correlation analysis and t-tests were applied to climatic data and tree-ring chronologies of Pinus sylvestris L. and Larix sibirica Ledeb. from moisture-deficit habitats in the intermontane Khakass-Minusinsk Depression, to assess modification of climate and tree growth by the Krasnoyarsk and Sayano-Shushenskoe Reservoirs on the Yenisei River. Abrupt significant cooling in May–August and warming in September-March occurred after the launch of the turbines in dams, more pronounced near the Sayano-Shushenskoe dam (up to – 0.5 °C in summer and to + 3.5 °C in winter) than near the Krasnoyarsk Reservoir headwaters (– 0.3 °C and + 1.4 °C). Significant lengthening of the warm season was also found for temperature thresholds 0–8 °C. Shifts of seasonality and intensity occurred in climatic responses of all tree-ring chronologies after development of water reservoirs. Patterns of these shifts, however, depended on species-specific sensitivity to climatic modification, distance from reservoirs, and physiographic regions. Mitigation of climate continentality and extremes by reservoirs appears to have offset possible negative effects of warming on tree growth.

FEATURES OF LARIX SIBIRICA LEDEB WOOD PROCESSING INTO HIGH YIELD FIBROUS SEMI-FINISHED PRODUCTS

About 40 % of the forest area in the Russian Federation is occupied by larch trees growing in the southern regions of Eastern Siberia and the Far East, where existing and reconstructed woodworking enterprises are located. In this regard, the use of larch wood in the production of fibrous semi-finished products is an urgent task for the Russian forest complex. As is known, larch wood contains a large number of extractive substances that have a significant impact on the process of its deep chemical processing. Therefore, it can be assumed that the production of wood (mechanical) pulp from larch wood, in particular chemical-thermomechanical pulp (CTMP), will be very effective, but with its own specific features. In this paper, it is proposed to modify the technology by using enzymes – protein catalysts of various reactions. The purpose of this study is to determine the potential of using larch wood enzymatic treatment in CTMP-technology, to evaluate the effect of enzymes on the physical and mechanical parameters of the fiber and the specific energy consumption during refining. Industrial samples of Larix sibirica Ledeb (Pinaceae) wood chips were used to obtain CTMP. Five commercially available enzymatic agents were used to treat wood chips. CTMP was obtained using laboratory equipment that simulates the industrial stages of production. Enzymatic treatment of larch wood has shown an improvement in the technological parameters of CTMP production, namely, a decrease in the specific energy consumption for refining and an increase in the quality of finished products.

Prospects of Using Tree-Ring Earlywood and Latewood Width for Reconstruction of Crops Yield on Example of South Siberia

Improvement of dendrochronological crops yield reconstruction by separate application of earlywood and latewood width chronologies succeeded in rain-fed semiarid region. (1) Background: Tree-ring width chronologies have been successfully applied for crops yield reconstruction models. We propose application of separated earlywood and latewood width chronologies as possible predictors improving the fitness of reconstruction models. (2) Methods: The generalized yield series of main crops (spring wheat, spring barley, oats) were investigated in rain-fed and irrigated areas in semiarid steppes of South Siberia. Chronologies of earlywood, latewood, and total ring width of Siberian larch (Larix sibirica Ledeb.) growing in forest-steppe in the middle of the study area were tested as predictors of yield reconstruction models. (3) Results: In the rain-fed territory, separation of earlywood and latewood allowed increasing variation of yield explained by reconstruction model from 17.4 to 20.5%, whereas total climatic-driven component of variation was 41.5%. However, both tree-ring based models explained only 7.7% of yield variation in the irrigated territory (climate inclusion increased it to 34.8%). Low temperature sensitivity of larch growth was the main limitation of the model. A 240-year (1780–2019) history of crop failures and yield variation dynamics were estimated from the actual data and the best reconstruction model. (4) Conclusions: Presently in the study region, breeding of the environment-resistant crops varieties compensates the increase of temperature in the yield dynamics, preventing severe harvest losses. Tree-ring based reconstructions may help to understand and forecast response of the crops to the climatic variability, and also the probability of crop failures, particularly in the rain-fed territories.

Dendrochronological Indication of Phyllophages’ Outbreaks by Larch Radial Growth in the Forest-steppe Zone of the Republic of Tyva

One of the possible consequences of climate change is a change in the demographic dynamics of phyllophagous insects. For a retrospective analysis of this dynamics, tree rings are used, especially in regions with limited documentary data. Due to the complex nature of the factors determining tree growth, in order to more clearly identify pest-induced defoliation in tree-ring chronologies one suppress the climatic signal expressed directly or indirectly (through chronologies of non-host tree species). However, in South Siberia, the choice of non-host species is hampered by the wide distribution of polyphages, like the gypsy moth (Lymantria dispar Linnaeus) and the Siberian silk moth (Dendrolimus sibiricus Tsch.). Therefore, the analysis of pest outbreaks in larch forests of the Republic of Tuva low mountains was started by removing the climatic response based on instrumental data, identifying depressions in the residual time-series of individual tree radial growth at several sites, and comparing them with available actual data on forest damage by phyllofages. Dendroclimatic analysis showed that the model including the precipitation-to-maximum-temperature ratio for June-September of the previous season and June of the current year, i.e. the degree of aridity during the previous and current growing season, describes 43.7% of the regional variation in the growth of Siberian larch (Larix sibirica Ledeb.). After removal of this component, several periods of larch growth depression were revealed during confirmed outbreaks of the Siberian silk moth, gypsy moth, and larch tortrix (Zeiraphera diniana Gn.). The use of documented data over 1998–2016 allowed to clarify the threshold values of the portion of affected trees for intensities of the growth depression ranging 1–1.5 standard deviations, providing the required reliability of the outbreak reconstruction. The dependence of the spatio-temporal patterns of growth depression on the pest species was revealed, reflecting their migration in the affected area. It has been shown that growth depressions may be delayed compared with the actual damage by pests due to the long recovery after recurrent defoliation.