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STRUCTURE AND PRODUCTIVITY OF THE FIR GROVES GENERATED FROM PRESERVATION UNDERGROWTH
N.M. Debkov (TSU, Tomsk, RF)
Структура и производительность ельников, сформировавшихся из сохраненного подроста.
Researches were carried out in the fir's forest formed from kept undergrowth, within a southern taiga of Tomsk region. It is established, that forest stands from undergrowth are characterised by the lowered consistence in comparison with normal fir's plantings.
The history of conservation of young growth of economic-valuable breeds spread the roots in the remote past - by the times of board of emperor Peter I (Shelgunov, 1859). Particulariy at this time principles of rationality and constancy of using one forests farming and shaped in I.T. Pososhkova, A.A. Nartova's works (Pisarenko, Strahov, 2004) within the limits of which there is an idea about savings of young generation of a wood at the timber cuttings, registered in the first forest instructions «About management of a wood part at mountain factories of a ridge Ural by rules of a wood science and a facilities», the published E.F. Kankrin in 1830 (Melehov, 1957). Further many domestic foresters addressed to a question of conservation of preliminary renewal, but we'll be limited only by this brief retrospective journey in history to show the importance for a forestry of Russia of a problem.
Lately by many generations of foresters has been shown, that, keeping undergrowth coniferous breeds, the period of cultivation of wood is reduced (Moiseyev, Volosevich, Dydicin, 1966; Derygin, Malyrov, 1989; Vyalykh, 2000; Clive, Brad, Hamish, 2002). Opinion of researchers differs only in occasion of timeframe to which the period maturation wood (from 15-20 till 50-60 years) is reduced. But it should not surprise, as «the forest is the phenomen geographical» (Morozov, 1949).
Productivity and quality of forest stands is considered to be the most important parameters of plantings, however, there is no much works about this problem (Nikonov, 1981; Sinkevich, 1982). In fact the matter is that the key factor in forestry - the factor of time, also is required certain timeframe for formation of plantings from undergrowth. Now a days these plantings in the majority are near to the age of ripeness, i.e. the most important taxation's characteristics were issued.
In the given work there was an attempt to shine a question on productivity of the fir groves which have generated from undergrowth on continuous cuttings of a southern subzone of a taiga of Tomsk region. Below the brief characteristic of the cut down plantings and applied technology of timber cuttings is showned.
As an experimental area has been chosen a place between rivers Ob and Tom which environment have predetermined approbation of technology of timber cuttings with conservation undergrowth in Tomsk area. The most part of the works begun since 1960th years, are lead in territory present Kaltaysky forestry. Here per 19691971 by continuous cabins on technology of «narrow tapes» is passed more than 3 thousand hectares. Undergrowth is kept on 64% of the area. In cutting ripe mainly
uneven-age coniferous-cedar forest stands of provisional structure 4S2F1C2B1A,
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mossy and grassy types of a wood with stocks of wood of 260-380 m /ha where up to cabin was 3-8 thousand pieces in hectares of young generation of coniferous breeds acted. The provisional structure uncanopy renewal would be 7S2F1C in different variations. After the forest exploitation, carried out by tractor TDT-40 draging for tops, it was kept 1,5-2,8 pieces thousand in hectares (Chitorkin, 2006).
The objects of research are middle-aged and premature fir groves of grassy and mossy types which have generated from kept at forest exploitationunder canopy of renewal of coniferous breeds (table 1).
Researches were carried out by a method of the temporary trial areas (TTA). Wile taping the trial areas conditions providing high reliability of received results were complied. On all trial areas the area providing availability of trees of the basic component of forest in quantity not less of 200, taxation by the way of continuous enumeration of a forest stand in absolute values to within 1 mm by means of a metal measured plug was made.
For studying productivity of forest stands on trial areas according to the metod proportional-step representation model trees were taken in quantity of 25-38 on the trial area. It has been cut and measured on a standard technique 117 model trees all over. The volume of a trunk was defined under the complex formula of median sections (complex formula Gubera). Processing of field data was conducted by the diversify-statistical methods accepted in forestry, with application of modern computer programs (Statistica 8.0).
Table 1 - Taxation structure of the fir groves which have generated from kept
Number TTA Composition Average height, M Average diameter, cm Average age, years Completeness Density, p/ha Type of forest Class of bondability
60F 15,7 15,9 62
11S 13,5 15,9 43
9 26B +C sp. L, P 17,4 9,7 15,9 12,1 17,1 12,8 43 42 18,6 0,64 815 grassy III.4
55F 14,3 16,4 65
13 15C 7S 23B 14,3 21.4 19.5 12,5 33 22,9 0,79 1000 grassy IV.0
47F 12,5 11,9 53
11L - 24,0 - 19,9 0,79
14 7C 10,3 10,7 46 1558 grassy III.9
31B 13,4 11,0 29
+S 10,9 10,1 53
15 41F 23P 15,4 20,7 18,2 24,9 66 81 25,4 0,79 888 mossy III.7
10S 19,6 22,4 73
18B 14,6 13,9 37
+C, 10,3 13,2 43
A - 18,2 -
sp. L - 7,8 -
Note:
- Fir - F; Spruce - S; Cedar - C; Pine - P; Larch - L; Birch - B; Aspen - A
The comparative analysis of productivity and others taxation parameters of studied forest stands is lead (table 2) under the general tables of growth of full (normal) fur-tree forest stands which are approved by Federal agency of a forestry and are recommended for use in practical forestry activity (Shvidenko and etc., 2008).
At the first approximation is visible, that plantings have arisen from undergrowth about 22-32 age, that proves to be true by earlier our researches, lead with attraction of materials forest inventory (Debkov, 2010). The analysis of growth of model trees has shown, that in the majority to this age interval conforms undergrowth of average and large altitude categories. Is to be noted, that in the majority the structure of undercanopy renewal repeats the structure of a parent forest stand therefore on cuttings plantings practically identical to cut down are formed.
As to conditions habitat (which could't change significally for so short time interval) which can be defined indirectly through bondability classes, making a start from dynamics of distribution of fir forests of Kaltaysky forestry where only 948 hectares (5,1%) plantings have a III bondability class and above III, and - IV and below, it is possible to approve 17458 hectares (94,9%) about some higher potential productivity. Actually the potential of productivity is not fully realising owing to, first of all, lowered density of a forest stand. It also influences, through absolute completeness, on a stock of a forest stand aside its reduction. In particular V.I. Kravchenko has come to a similar conclusion, studying influence of density of forest stands on their productivity in fir groves-bilberries (Kravchenko, 1963).
The purpuse of comparison of investigated plantings with full normal fur-tree forest stands was reception of the most informative comparative characteristics on the main taxation parameters (average height, average diameter, density, absolute completeness, stock). Thus by of the objective reasons (absence of initial data, of tables of course of growth put in basis, and thereof impossibility to find a mistake of an average, to apply to an assessment of reliability-unauthenticity of average values of our given and tabulared criterion Student's) revealing of reliability-unauthenticity of a difference of averages was carried out by means of a confidential interval at 5% a significance value.
Table 2 - The comparative analysis of productivity of fir groves from undergrowth and under tables of course of growth (TCG)_
Data Sources Average height, m Average diameter, cm Density, p/ha Completeness, M2/ha Stock, M3/ha
TTA №9 15,4+0,4 15,9+0,6 815,0 18,6 167,1+9,8
TCG 12,5 13,9 1835,4 29,2 194,5
Difference in % +23,5* +14,4* -55,6 -36,3 -14,1*
TTA №13 14,8+0,3 16,4+0,6 1000,0 22,9 221,6+21,0
TCG 11,5 12,8 1997,0 25,5 159,0
Difference in % +41,7* +28,1* -49,9 -10,2 +39,4*
TTA №14 12,6+0,2 11,9+0,4 1558,0 19,9 129,3+10,9
TCG 9,0 10,2 2761,0 22,5 119,1
Difference in % +40,0* +16,7* -43,6 -11,6 -8,6**
TTA № 15 15,7+0,5 18,2+1,0 888,0 25,4 249,5+29,3
TCG 12,4 14,0 1848,1 27,9 188,2
Difference in % +26,6* +30,0* -51,9 -9,0 +32,6*
Note: * - difference is significant at 5% significance level; ** - difference is not significant at the 5% significance level.
So, it is possible to characterize in brief studied plantings which have generated from kept at forest exploitation young growth of economic-valuable breeds, as rather sparse forest stands with the lowered completeness (concerning those normal forest stands). In a counterbalance to it, the trees completed investigated plantings, differ in greater heights and diameters. It predetermines that, despite of rather low density and completeness, on TTA №13 and 15 productivity is hier, than at normal plantings. However as given have shown TTA №9, decrease in absolute completeness up to 0,65, leads to authentic decrease in a root stock in comparison with normal plantings. Concerning TTA №14 meaningful differences in stocks is not present, all difference lays within the limits of definition of average value. As a result of the conclusion on earlier comeing of age of technical ripeness in plantings from undergrowth arises.
It is also an important fact, that formed plantings, in general, and the whole repeat formation's structure of the cut down forest stands, i.e. changes of breeds are not observed. Moreover, it is necessary to consider structure of these plantings as optimum with forestry point of view (the fraction of deciduous breeds makes 2-3 units in structure). Considering on planting where deciduous breeds, as a rule, are on the place of portage's, and coniferous - in apiaries, is possible to speak about greater stability to fires. In summary, we shall note, that (both on portage's, and on loading platforms) there is aftercutting generation of coniferous which will assist realization of potential productivity of plantings which have generated from undergrowth of economic-valuable breeds everywhere.
In summary it would be desirable to remind, that the comparative analysis is lead concerning normal (full) forest stands which are model. If to lead similar comparison to actual prevailing plantings (in wood valuation they have received the name modal) the general picture will be a little differ. Supposedly parameters of density and absolute completeness with respective alterations in size of a root stock will smooth out.
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