The needle percentage in the leafy shoot biomass of Scots pine in climate gradients of Eurasia

The efficiency of using photosynthetically active radiation by trees largely depends on the architecture of the assimilation apparatus in their crown. It is known that an increase in the level of atmospheric pollution is accompanied, on the one hand, by an increase in the foliage density on the leafy shoot length, and on the other hand, by an increase in the transparency of the crown due to the expansion of the leafless inner part of the crown. On this basis, we assume that the foliage percentage of leafy shoots (PL) is a sensitive indicator of changes in growing conditions not only due to environmental pollution, but also in broader ecological aspects, in particular, in the geographical or climatic gradients of Eurasia. For this purpose, a database of empirical data has been formed in the amount of 558 model trees of Scots pine of natural and artificial origin from 6 regions of Northern Eurasia with a measured percentage of needle in the leafy shoot biomass. A regression model has been designed, in which the contributions of mensuration variables (tree age and stem diameter), climatic variables (temperature and precipitation) and the origin of stands (natural and artificial) to explain the variability of the desired PL indicator are 15, 53 and 30 %, respectively. It is concluded that with a decrease in annual precipitation from 600 to 300 mm, there is an increase in PL by 0.2..0.3% for every 10 mm of annual precipitation, both in natural stands and in plantations. When the January temperature decreases from 0°C to -20 °C, PL increases by 0.8...1.0% for each 1°C. Thus, the foliage percentage of leafy shoots of Scots pine is an indicator of changes in growing conditions in the climate gradients of Eurasia

Biomass structure of Pinus sylvestris and Betula pendula forest ecosystems in pollution gradient near copper plant on the Southern Ural

In the gradient of pollution from the Karabash copper smelter in the Southern Urals (55° 29’ N, 60° 13’ E) in predominantly pure Scots pine and white birch stands, 12 and 34 sample plots are established, respectively, on which 42 and 56 model trees are taken, respectively, by stem diameter. The pollution gradient is expressed by the toxicity index suggested with a relative index of the content in the litter of three "technogenic" metals Cu, Pb и Fe. Regression analysis of the dependence of biomass and NPP of trees and stands from toxicity index is performed. There is a log-log-linear pattern of reduction of biomass and annual NPP of spruce-fir forest stands with increasing toxicity index in the direction to the source of pollution, but for the biomass of trees in the same gradient no consistent pattern is detected. The dry matter content (DMC) in all biomass components depends on the toxicity index and species at a statistically significant level: due to the increase in the toxicity index, it decreases in wood and bark, and increases in foliage and branches. At the same toxicity index, DMC in the branches and stem wood more in birch, but in the bark and foliage – in pine. In the wood and bark of a stem, this index is also related to the position in a stem: in the wood it decreases, and in the bark it increases in the direction from the bottom u

Geographic gradients of forest biomass of two nee-dled pines on the territory of Eurasia

On the basis of the compiled database in a number of 3020 sample plots with determinations of forest biomass of two-needled pines (subgenus Pinus) on theterritory ofEurasia fromGreat Britain to southernChina andJapan statistically significant transcontinental gradients of stem, roots, aboveground and total biomass are established. In the direction from North to South these biomass components change according to a bell-shaped curvewith a maximum in the third (the southern temperate) zonal belt, while the biomass of needles, branches and understory is monotonically increasing within this zonal gradient from subarctic to subequatorial zonal belts. In the direction from the Atlantic and Pacific coasts to the continentality pole inSiberia there is a biomass decrease as of all components of the wood story and the understory. The root: shoot ratio increases in the range between subarctic and southern temperate zone from 12 to 22% and then decreases to 16% in the subtropical zone, and within the southern temperate zone it monotonically increases from 20% on the oceanic coasts to 23% near continentality pole. The ratio of understory biomass to wood story biomass reduced from 4.0 to 2.5% ranging from subarctic to southern temperate zone and then rises to 3.5% in the subtropical zone, and within the south temperate zone it monotonically decreasing from the maximum value of 22% near Atlantic and Pacific coasts, approaching the level of 2-3% near the continentality pole. The results can be useful in the management of biosphere functions of forests undoubtedly

Modeling the additive stand biomass of Larix spp. for Eurasia

When using the unique in terms of the volumes of database on the level of a stand of the genus Larix Mill., the trans-Eurasian additive allometric models of biomass for Eurasian larch forests are developed for the first time, and thereby the combined problem of model additivity and generality is solved. The additive model of forest biomass of Larix is harmonized in two levels, one of which provides the principle of additivity of biomass components, and the second one is associated with the introduction of dummy independent variables localizing model for eco-regions of Eurasia. Comparative analysis of the biomass structure of larch stands of different ecoregions at the age of 100 years shows, that the greatest values of biomass (210-450 t/ha) correspond to the regions adjacent to the Atlantic and Pacific coasts, as well as to the regions, located at the southern limit of larch growing area and the lowest – to northern taiga regions of Siberia, where larch grows on permafrost. The biomass indices of different ecoregions differed not only in absolute value but also in biomass ratios of different components; for example, the proportion of needles in the aboveground biomass is maximum (5.0-7.3%) in the northern taiga of Central Siberia and the Far East on permafrost and is minimum (1.4-1.9%) in larch forests of upper productivity having biomass values 210-450 t/ha. The proposed model and corresponding tables for estimating stand biomass makes them possible to calculate larch stand biomass on Eurasian forests when using measuring taxation

Additive allometric model of Quercus spp. stand biomass for Eurasia

When using the unique in terms of the volume of database on the level of stand of the genus Quercus, the trans-Eurasian additive allometric models of biomass of stands for Eurasian Quercus forests are developed for the first time, and thereby the combined problem of model additivity and generality is solved. The additive model of forest biomass of Quercus is harmonized in two ways: it eliminated the internal contradictions of the component and the total biomass equations, and in addition, it takes into account regional differences of forest stands not only on total, aboveground and underground biomass, but also on its component structure, i.e. it reflects the regional peculiarities of the component structure of biomass

Augmentative Modelling: A Template for Populus spp. Stand Biomass in Eurasia Region

Today, estimating of biological productivity or carbon-depositing ability of forests is going on the global level, and its increase is one of the major factors of climate stabilization. In recent years, two trends in the harmonization of allometric models of tree biomass have been developing. The  first of them is related to ensuring the additivity of the biomass component composition, and the second one – to the search for the so-called generic model applicable to a wide range of environmental conditions. However, all "generic" models give significant biases in their application in local conditions. In our modeling, we adhere to the principle of biomass additivity, split "generic" model into regional variants by introducing dummy variables, and build the model at the transcontinental level for the first time. When using the unique in terms of the volume of database on the level of stand of the genus Populus spp. in a number of 212 sample plots, the trans-Eurasian additive allometric models of biomass of standsfor Eurasian Populus forests are developed, and thereby the combined problem of model additivity and generality is solved. The additive model of forest biomass of Populus is harmonized in two ways: it eliminated the internal contradictions of the component and the total biomass equations, and in addition, it takes into account regional differences of forest stands not only on total, aboveground and underground biomass, but also on its component structure, i.e. it reflects the regional peculiarities of the component structure of biomass. Keywords: genus Populus spp., biomass of forests, allometric models, sample plots, biological productivit

Additive biomass models for Larix spp. single-trees sensitive to temperature and precipitation in Eurasia

The analysis of the biomass of larch (genus Larix spp.) trees on the total component composition based on regression equations having the additive biomass structure. Two trends of changes in the tree biomass structure are revealed: due to the mean January temperature and due to the mean annual precipitation. It was shown for the first time that both trends are mutually determined: the intensity of biomass trend in relation to the temperature is changing when depending on the level of precipitation, and the intensity of biomass trend in relation to precipitation level is changing during to a transition from the cold zone to the warm one and vice versa

Географические особенности возобновления Pinus sibirica Du Tour

Одной из главных проблем лесной экологии является анализ закономерностей динамики численности природных ценопопуляций древесных растений на этапе их возобновления, влияющем на последующую структуру и развитие биогеоценоза. Процесс возобновления определяется как динамикой семеношения, так и особенностями распространения семян лесообразующих древесных видов. Возобновление пятихвойных сосен подсекции Cembrae с бескрылыми семенами обусловлено тесными трофическими связями с птицами рода Nucifraga sp., которые, создавая почвенные кормовые запасы, разносят семена. Цель исследования – выявление географических особенностей связи между семеношением и возобновлением сосны кедровой сибирской (Pinus sibirica Du Tour) при посредническом участии тонкоклювой кедровки (Nucifraga caryocatactes macrorhynchos Brehm C.L.). Исследование выполнено в 3 географических регионах произрастания кедровых лесов: в лесах Алданского нагорья в Южной Якутии (59º40´ с. ш. 125º24´ в. д.), Северного Урала в районе горного массива Денежкин Камень (60º25´ с. ш. 59º32´ в. д.) и горного хребта Хамар-Дабан в Юго-Восточном Прибайкалье (51º32´ с. ш. 103º32´ в. д.). Показано, что каждый регион ареала произрастания P. sibirica отличается динамикой и семеношения, и возобновления. Установлено, что в лесах Алданского нагорья обилие всходов P. sibirica положительно связано (R2 = 0,46) с урожаем шишек прошлого года. Количество всходов на Денежкином Камне и Хамар-Дабане отрицательно связано с урожаем прошлого года, но положительно (R2 = 0,48–0,49) – с урожаем позапрошлого года. Мы считаем, что всходы в любом случае появляются из семян урожая прошлого года, а видимая связь с урожаем позапрошлого года обусловлена деятельностью кедровки. В результате проведенных стационарных исследований на Северном Урале выявлена постоянная тесная (R2 = 0,81) положительная связь количества всходов P. sibirica с численностью кедровки в период запасания и разноса семян в августе–сентябре предыдущего года. Сделано предположение, что характер динамики урожая семян в регионе влияет на изменение численности кедровки в период заготовки ею семян, которая, в свою очередь, определяет обилие всходов P. sibirica следующего года. Это обуславливает выявленные различия в динамике возобновления P. sibirica и ее зависимости от урожаев шишек в рассматриваемых регионах. Для цитирования: Танцырев Н.В., Санников С.Н., Усольцев В.А. Географические особенности возобновления Pinus sibirica Du Tour // Изв. вузов. Лесн. журн. 2023. № 6. С. 44–56. https://doi.org/10.37482/0536-1036-2023-6-44-5

Quasi Two-dimensional Vortex Matter in ThH10_{10} Superhydride

A comprehensive study of the vortex phases and vortex dynamics is presented for a recently discovered high-temperature superconductor ThH$_{10}$ with $\textit{T}$$_C$ = 153 K at 170 GPa. The obtained results strongly suggest a quasi two-dimensional (2D) character of the vortex glass phase transition in ThH$_{10}$. The activation energy yields a logarithmic dependence $\textit{U}$$_0$ $\propto$ ln($\textit{H}$) on magnetic field in a low field region and a power law dependence $\textit{U}$$_0$ ~ $\textit{H}$$^{-1}$ in a high field region, signaling a crossover from 2D regime to 3D collective pinning regime, respectively. Additionally, a pinning force field dependence showcases dominance of surface-type pinning in the vicinity of $\textit{T}$$_C$. Thermal activation energy ($\textit{U}$$_0$), derived within thermally activated flux flow (TAFF) theory, takes very high values above 2$\times$10$^5$ K together with the Ginzburg number $\textit{Gi}$ = 0.039 - 0.085, which is lower only than those of BiSrCaCuO cuprates and 10-3-8 family of iron based superconductor. This indicates the enormous role of thermal fluctuations in the dynamics of the vortex lattice of superhydrides, the physics of which is similar to the physics of unconventional high-temperature superconductors

Forest stand biomass of Picea spp.: an additive model that may be related to climate and civilisational changes

Since ancient times, climate change has largely determined the fate of human civilisation, which was related mainly to changes in the structure and habitats of forest cover. In the context of current climate change, one must know the capabilities of forests to stabilise the climate by increasing biomass and carbon-depositing abilities. For this purpose, the authors compiled a database of harvest biomass (t/ha) in 900 spruce (Picea spp.) sample plots in the Eurasian area and used the methodology of multivariate regression analysis. The first attempt at modelling changes in the biomass additive component composition has been completed, according to the Trans-Eurasian hydrothermal gradients. It is found that the biomass of all components increases with the increase in the mean January temperature, regardless of mean annual precipitation. In warm zonal belts with increasing precipitation, the biomass of most of the components increases. In the process of transitioning from a warm zone to a cold one, the dependence of all biomass components upon precipitation is levelled, and at a mean January temperature of ˗30°C it becomes a weak negative trend. With an increase in temperature of 1°C in different ecoregions characterised by different values of temperature and precipitation, there is a general pattern of decrease in all biomass components. With an increase in precipitation of 100 mm in different ecoregions characterised by different values of temperature and precipitation, most of the components of biomass increase in warm zonal belts, and decrease in cold ones. The development of such models for the main forest-forming species of Eurasia will make it possible to predict changes in the productivity of the forest cover of Eurasia due to climate change