Stock of standing dead trees in boreal forests of Central Siberia

A significant part of carbon assimilated by forest is deposited in tree trunks. Growth and development of tree stands is accompanied by accumulation of standing dead trees (snags) due to natural tree mortality and as a result of the impact of exogenous factors. Carbon accumulated in these dead trunks is excluded from the fast turnover due to low rate of wood decomposition, so that snags can be considered as a pool of organic carbon with a slow rate of its return to the atmosphere. We estimated stock of snags on 54 sample plots, which represent the main types of forest ecosystems in the northern and middle taiga of Central Siberia. In the middle taiga, stock of snags varied from up to 7 m3 ha-1 in Siberian spruce forests to 20-42 m3 ha-1 in Scots pine forests. Larch forests in the northern taiga had the similar stock of snags as larch forests in the middle taiga despite significantly higher growing stock in the later. Snags contributed from 4 to 19% to the total stock of woody biomass in studied forests. This study indicated the significance of snags and can be used to estimate carbon budget of forest ecosystems of the region

Stimulation of processes of self-propagating high temperature synthesis in system Ti+Al at low temperatures by influence of [gamma]-quanta

In the present work, the influence of the irradiation with gamma-quanta 60Со upon the structural and phase state of the components of the mechanically activated powder composition of Ti+Al is investigated. The phase composition, structural parameters, and crystallinity are examined by means of X-ray diffractometry. It is found out that the irradiation with gamma-quanta changes the structure of the mechanically activated powder composition. The higher irradiation dose, the higher the structure crystallinity of both components with no change in phase state. At the same time, the parameters of Ti and Al crystal lattices approach to the initial parameters observed before the mechanical activation. The irradiation with gammaquanta leads to decrease of internal stresses in the mechanically activated powder composition while nanocrystallinity of the structure remains unchanged. Using of powder compositions exposed to the irradiation with gamma-quanta for the SH-synthesis helps to increase speed of the reaction, decrease the peak firing temperature and improve homogeneity, as well as the main phase of the produced material is TiAl

The density of pine stands under intensive forest growing

On permanent sample plots in young, middle-aged and mature, pure pine stands of the same age, the effectiveness of cuttings of different intensities was studied, to ensure intensive forest growing. Existing standards on the intensity of cutting and relative density do not fully provide the optimal parameters of stands after cutting. Meanwhile, the remaining part of the stand determines growth and productivity of the stand formed by the felling. The sample plots have been established in the «Pogorelsky Bor» experimental forest of V. N. Sukachev Institute of Forest SB RAS, territorially entering the Krasnoyarsk island forest-steppe. In the studied stands, the felling led to an increase in current radial increment, which depends on the area of the dominance square (Sod), which determines the amount of available resources for the tree after felling. Based on the analysis of the dynamics of radial growth and its relationship with the values of Sod for pine forest stands at different age stages and with different density, the optimum value of Sod is determined, which provides forming of trees of the 2–3rd Kraft classes of growth. Optimum values of the OD area were calculated depending on the values of the stem DBH and taking into account the habitat conditions. With a density that is lower than optimal, higher tree growth values can be obtained, but this does not mean achieving the maximum productivity of the stand as a whole. The studies allow, within the framework of the proposed approach, to provide intensive forest growing and formation of the stand structure that ensure the fulfillment of both economic and environmental functions of forests. The obtained data can be used in the development of recommendations for carrying out thinning in pine stands at different age stages of their formation

Dynamics of ground layers after experimental fires in pine forests

The influence of experimental burning on ground cover in pine forests of different age stands with dominated herbs and mosses in the Krasnoyarsk forest-steppe was studied. Experimental burning decreased species diversity, percent cover, and biomass of shrubs and herbs. Mosses degraded after fires. The species diversity and biomass of shrubs and herbs increased in 2 years after fire. The greatest species diversity of ground cover was in 60 year old pine forest in 2 years after fire (moderate intensity) (28 species). The percent cover of shrubs and herbs was below pre burning values in 110-years aged stand in 2 years after fire. The seedlings of Scotch pine Pinus sylvestris L. were 35.2 thousand units/ha in 60-years aged pine forest in 2 years after experimental burning. The seedlings of pine were 61.1 thousand units/ha and self-sowing was 14.8 thousand units/ha in the next year after fire. The number of pine shoots was high (51.1 thousand units/ha) and self-sowing was by 3.2 times more than in last year (47.0 thousand units/ha). Experimental burning of low intensity stimulated emergence of pine shoots in 110-years aged stand where their amount were 31.1 thousand units/ha in 3 month after fire. The reforestation was presented by pine shoots (31.5) and self-sowing (2.0 thousand units/ha) in next year after experimental burning. The number of pine shoots was 17.4 thousand units/ha and self-sowing increased by 11.0 times or 21.9 thousand units/ha in two years after burning

Critical conditions of forced ignition in Ni-Al, Ti-Al powder systems under solid-phase synthesis

A theoretical study of the critical conditions of forced solid-phase ignition in Ti-Al, Ni-Al systems was carried out. Based on the analysis of the non-stationary diffusion equation with moving boundaries, the critical powers of the heating source and the corresponding critical temperatures were determined during the formation of NiAl, TiAl3 intermetallic compounds using the state diagrams of these binary systems. The diffusion activation energies, frequency factors, particle sizes, and heat removal conditions were considered as variable parameters. The diagrams of critical parameters which relate the corresponding specific heating powers with the indicated values were constructed. It has been established that for the same values of the parameters and under identical synthesis conditions, the critical temperatures in these systems differ by more than one hundred degrees. The latter is associated with a significant difference in the width of the solubility region for the corresponding compounds of the composition NiAl, TiAl3. The performed analysis allows separating the modes of isothermal sintering and thermal explosion which makes it possible to control the thermal and diffusion modes of synthesis. The comparison of the calculation results with the experimental data showed their satisfactory agreement

Passive and Active Stokes Vector Measurements of Microwave Emission and Scattering by Precipitation

Passive und aktive Messungen des Stokesvektors, insbesondere seiner dritten Komponente, werden gezeigt und diskutiert. Aus den Messungen wird die Orientierung der Polarisationsebene und die mittlere Neigung von Regentropfen abgeleitet

Stokes- Radiometrie und Stokes-Radarmessungen

Die Messung aller vier Stokes-Parameter im Mikrowellenbereich mit aktiven und passiven Empfängern liefert zusätzlich neue und unabhängige Informationskanäle über den Atmosphärenzustand und erhöht die Genauigkeit der Niederschlagsbestimmung mittels Fernerkundungsmethoden. Das Design eines polarimetrischen Radiometers und erste experimentelle Ergebnisse aus Radar- und Radiometermessungen werden gezeigt

Radiolokatzionnije ismerinija polnogo vektora Stoksa echo-signala osadkov

Bodengestützte Messung der Radarrefektivität von Regen wurden mit dem meteorologischen polarimetrischen Radar POLDIRAD durchgeführt. Daraus abgeleitete Werte für die dritte und vierte Komponente des Stokesvectors und den Orientierungswinkel der Polarisationsellipse der Radarechosignale werden mit theoretischen Ergebnissen verglichen

Modeling and measurements of Stokes vector microwave emission and scattering for a precipitating atmosphere

Passive und aktive vollpolarimetrische Messungen von Regen wurden durchgeführt. Die Ergebnisse, insbesondere des dritten Stokes Parameters und des Orientierungswinkels der Polarizationellipse werden mit theoretischen Berechnungen verglichen. Das Meßprinzip und spezielle Eigenschaften des Radiometers und des Radars werden beschrieben