Сибирский лесной журнал (Jun 2016)
The problem of improvement birch stand productivity in forest steppe of Cis-Urals
Abstract
The article deals with birch stands of the forest steppes in Cis-Urals. It is pointed out that the latter are represented both by native and derivative stands formed in the place of native coniferous forest, for the most part pine stands. Birch stands, as a rule, have vegetative origin, low density (0.3–0.5) and deposit that does not exceed 130 m3/ha. As a silvicultural measure aimed at derivative birch stands’ productivity increasing, it is offered to create under the canopy preliminary forest crops of Scotch pine. The advantage of such crops is tending of plantations cutting and terms of technic mature wood growing. It has been determined that in investigated regions with low density birch stands on grey forest soil and chernozem, Scotch pine in preliminary forest crops develops surface roots which are branching in different directions from planting sites including in the direction of the brand stems. These roots are terminated among the interplacement mass of this mass of stiffened roots. In other words, on the first step of forest growing, preliminary crops do not experience considerable root competition as concerns birch stand. Based on the research data, high safe keeping of preliminary forest crops during the initial years after planting is proved. However, delay in birch stands harvesting can result in preliminary forest crops increment reduction and, in the long run, their destruction. Thus the mean height of the preliminary pine crops at the age of 11–12 years constitutes only 42–62 % as compared with pine crops of the same age that were formed on the cutover area if agrotechnical tending is systematically carried on in the latter. The positive role of birch stands in the initial 3–4 years after preliminary forest crops of Scotch pine forming has been proven experimentally. Then the birch woody canopy must be removed. Replacement of derivative birch stands for native pine stands by forming preliminary forest crops will make possible significantly increase stands’ productivity in forest-steppe of Cis-Urals, along with preserving stability of their protective environmental functions.
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