No abstract

No abstract

The study presents the large-scale assessment relating to the volume of coarse woody debris (CWD), i.e. standing dead trees, downed wood and stumps, in the forests of the Russian Federation. The results of the quantitative estimation of the stocks of snags, downed wood and stumps based on direct field measurements in 27,403 SFI (State Forest Inventory) permanent sample plots that are representative for 15 forest regions. The average total volume of woody detritus is estimated to be 29.22±9.7 m3/ha. The snags makes up 40.3%, downed wood – 55.3%, and stumps – 4.4% of the total CWD. The volume of above- and on-ground woody detritus to average live wood volume ratio is estimated to be 14.6±4.4%, including 5.82±1.8% for standing dead trees, 8.15±3.1% for downed wood and 0.67±0.4% for stumps. The highest volumes of woody detritus on average were found in the forest-steppe zone of European Russia, coniferous and broadleaved forests of the Far East and European Russia, and mountainous forests of South Siberia. The advantages of using the qualitatively new information acquired from SFI materials, for the more exact estimation of the volumes of the above - and on-ground woody detritus have revealed.

The authors have considered the feasibility of using the measurements of quality and quantity forest parameters on the State Forest Inventory (SFI) permanent sample plots (PSP) for estimating carbon stocks in forests in the preparation of the reports on the implementation of the national commitments under the Paris Agreement. The strengths and weaknesses of the SFI methods for estimating carbon stocks are revealed. The analytic assessment is demonstrated through the example of Khabarovsk Territory in which the SFI was completed in 2018. It is experimentally confirmed that significantly more accurate SFI data on the average growing stock volume, in combination with improved methods for estimating carbon assessment parameters, can increase the estimates of carbon stocks in the forest biomass approximately by +30%.

The article deals with the issues of the operational calculation of the breakdown voltages of drift n-p-n transistors in the inverse operating mode when calculating the parameters of their structure according to the given electrical parameters and characteristics. When calculating the parameters of the structure of a bipolar drift transistor, the concentrations at the collector-base (NCB) and emitter-base (NEB) p-n junctions are determined for a given avalanche breakdown voltage. The limitation of the minimum base thickness (WB.min) is determined by the given value of the voltage of the transistor base puncture and by a certain calculated impurity concentration between the concentrations of NCB and NEB. The calculated impurity concentrations in the base of the drift transistor in the forward and inverse modes of operation differ significantly. The technological experiment was carried out on silicon wafers with two different impurity concentrations in epitaxial structures and with different base thicknesses, as indicated by different values of the current amplification factors both in the direct and inverse connections. The concentration values were determined by calculating NCB and NEB according to the known boron diffusion mode to form the transistor base regions. The depths of p-n junctions were determined by the ball-thin section method. The electrical parameters of the transistors in direct and inverse connections were measured on an Л2-56 semiconductor device meter. Based on experimental data, the calculated impurity concentration in the base of the drift transistor is determined from the values of NCB and NEB. The resulting calculation expression can also be used to calculate the base voltage of drift n-p-n transistors in the inverse operating mode, the base voltage of switching transistors in I 2 L elements, as well as to calculate the area of the reverse gradient of ultra-sharp varicaps.