Tsarev A. Tsarev V.A. Tsareva R.P.
Aspen – a forest weed or source of valuable raw materials
Reporter: Tsarev A.
The aspen (Populus tremula L.) is one of basic forest species of Russia. Its natural stands are good grow, enough unpretentious, has straight stems and beautiful renewal. Regrettably, it has a row defects. The most essential among them is high affection of heart decay (Fomes igniarius Fr.). Because of this forestry specialists are considered aspen as undesirable rubbish species. There are many recommendations directed on reduction of its areas. In spite of this, area of aspen stands in Russia for the last 50 years increased on 50% and reached 20.5 mln. ha, from which 7.8 mln. ha are found in European part and 12.8 mln. ha - in Asiatic part of country. But in the last decennials events all greater number of the researchers come to conclusion that aspen is very useful species and we must learn to raise its resistance to disease (A.S.Yablokov, S.P. Ivannikov, V.T.Bakulin, L.E.Mikhaylov, Y.Y. Smilga, M.M.Veresin and others).
One of the directions of the improvement of the species is a breeding, including selection, hybridization, polyploidy, transgenesis etc. Selection in Voronezh region has allowed revealing the high valuable plus stands of aspen, which in C2 soil conditions had great growth with wood stock of 340-490 m3/ha at 45 years age old and fullness, equal 1. The number of trees infected of heart decay did not exceed 6%. In the usual stands in similar conditions and the same age the number of infected trees was varied from 20% to 90%. Output of sound wood from plus stands was 67% -75% while at usual ones - varied from 2% to17%.
The wood of plus stands was also good. The density of wood was about 0.5 g/cm3, limit to toughness at compression along fibers - 355-359 kg/cm2, limit to toughness under steady-state bend - 655-673 kg/cm2, specific work under striking bend – 0.47 kg-m/см3, length of the fibers in 40-year layer on 1.3 m height reached 1.4 mm.
Else more impressive results are received at hybridization of the aspen. So, among hybrid offsprings of the aspen, breeded by V. P. Petruhnov, it was possible to select five best on productivity family. Two of them are received by crossbreeding of local plus trees and three - under remote hybridization ((P. tremuloides x P. tremula (local), P. tremuloides x P. bolleana and P. tremula (Obojanskaja) x P. canescens)). The average stock of steam wood determined by us in these families at 29 year ages, varied from 223 to 508 m3/ha. The sick trees in this age are not revealed. There are selected more than 60 perspective hybrids, height which in this age varied from 19 to 25 m, average diameter - from 25 to 40 cm, volume of the stem - from 0.4 to 1.1 m3. The dynamic of the growth of these hybrid shows that they did not reach quantitative ripeness (age of economic exploitability), and increase of them wood will be continue. Thereby, the hybrid aspen stands can supply about 500 m3/ha of wood already to 30 years old.
The analyzes of food value of aspen green masse show that it contents 0.14-0.35 food units in 1 kg depending on its composition (leaves, steams or branches) and moisture. The food value of lucerne varies from 0.24 (natural moisture) to 0.49 (hay) food units/kg.
The known that in many events cost aspen wood approaches to such on pine, but on some position of the using even exceeds, for instance: matches, bath-house panel, packing material for food-stuffs and others. Wood of aspen is broadly used for fabrication of the plywood; it is a valuable raw material for pulp industry, chemical industry at production of polymer, in fuel facilities, as well as food additives in stock-breeding and as medical raw material.
As a whole, the aspen presents the valuable resource of wood and other useful characteristic. Rational use of this potential of the aspen can bring in the essential contribution on transformation forest cultivation in high revenue branch of the country economy.
| Abstracts file: | Царев.doc |
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