STRUCTURAL AND DEVELOPMENTAL PATTERNS OF THE STAND IN THE SIBERIAN LARCH PLANTATIONS IN THE BOTTOMLAND ECOTOPE

Abstract

The rationale for the research is urged by the demand to enlarge the ecological and resource potential of territories due to establishing forest plantations. A Siberian larch, LarixsibiricaLed., can become one of the promising species for the set goal, as its yielding capacity is generally higher than that of natural indigenous stands. The research is aimed at finding out the patterns of the stand development and the principle of tree differentiation, in case they were evenly planted, in the Siberian larch artificial forest. The subject of research is axenic cultures of Siberian larch, established in 1959 by planting in the 2m x 2m layout in the bottomland eco-tope on the alluvial-meadow light clay soil rich in humus and exchangeable bases. Results. The paper introduces numerical information and mathematical models demonstrating the structural and developmental patterns of the stand in the Siberian larch plantations in the bottomland eco-tope. It is stated that Siberian larch trees in the research site greatly differ in sizes. As the stand develops, the amplitude between the minimal and maximal trunk diameter values and the row asymmetry ratio increase. The coefficient of excess increases up to 45 years, and after it - decreases. Though in the beginning the counting distribution of tree diameters was unimodel, gradually it became bimodal due to an uneven growth rate of the coenopopulation and the competition capacity of trees. The basal area of all the Kraft's Class 1 and Class 2 trees increased for 5.73 and 8.91 square meter per hectare, while the same parameter of the Class 4 and Class 5 trees decreased for 2.28 and 1.30 square meter per hectare due to waste of a growing forest. The average increment of the Class 4 trees was only 1.3 cm for 25 years of observation. Conclusion. It is considered to be appropriate to establish Siberian larch artificial forests in the bottomland ecotopes on unwooded territories in the Republic of Mari El, as they have a high yield capacity and significantly exceed the similar cultures in variable sites in their stumpage value. In order to increase the large timber share in an artificial forest it is necessary to perform cleaning cutting timely and to eliminate all Class 4-5 trees; or to arrange the initial density of cultures as a 4m x 4m layout. The optimal cutting period in the artificial forests should be 60 years, it will ensure the greatest increment of the stumpage value and reduce the damage due to root rot to the minimum.