RESEARCH OF FEATURES OF REPRODUCTION OF LARCHES IN NORTH-WEST OF RUSSIA

At present, when the question of the rational and sustainable forest management and forestation is open, larch  is quite simple and effective tool to solve these problems.

Larch is also one of the most valuable species for cultivation and for the planting of greenery in the North-West of Russia, because it has a number of valuable properties:

• It is the fastest growing out of all the conifers;

• Provides the most highly timber reserves in the North-West Russia;

• High quality wood – the maximum yield of industrial wood;

• The wood has a number of qualities:

 high density, abrasion resistance, so is used as ornamental material, it can be used for both internal and external structures; most often used for the manufacture of wooden structures and coverings exposed to abrasion (parquet floor, track, etc.).

 resistant to decay, so it can be used in places with high humidity – hydraulic structures, piles, shipyards, dams, locks

• Larch produces  sap from which made rosin, turpentine, α- and β-pinenes, healing balms, immersion oil, glue, paste paper sizing, repellents and others.

• It is of great interest in gardening: thanks to the annual discharge of the needles are the most stable in the landscaping of large industrial centers. It looks good in the alleys and miniature planting trees in public gardens and parks, in mixed groups of different types of larch. Colors of needles in spring and summer include all shades of green, from pale green to virid and bluish gray-green. Mixed groups of larch trees and rhododendrons, lilacs and  laburnum seem remarkably.

• fairly resistant to recreational load: has a deep tap root system, has a thick bark, which is difficult to cause mechanical damage, has a high regenerative capacity due to short shoots, that is relatively well tolerated pruning.

• hardy, smoke and gas resistance, moderately demanding  to soil wealth and moisture, so good for breeding in large cities.

Therefore, introduction of larches is worthy of widespread attention for artificial breeding industry, and for landscaping purposes. However, the possibility of a broad introduction is often limited by shortages of seed species and populations of larch, suitable for local conditions. Deficiency is associated with the lack of experience  and difficulties of harvesting seeds in local conditions.

Therefore, one of the real ways of eliminating the deficit is the use of local seeds reproduction, that is, from the local plants species and populations, showing high rates of growth and stability in the region.

Published materials about  the different types of seed larch in local conditions is very limited. Therefore, it is quite important to research features of seed of different types and forms of plantings in the park for the purpose of using them as a local seed source.

The aim of this work was to study the characteristics of seed and compare different species of larch in the North-West to the example plantation in the Botanical Garden of St. Petersburg State Forest Technical University and Okhta experimental base.

I studied 58 facilities, 23 of which are the most accessible selected for the study. Objects are represented by 7 species:

Siberian larch – Larix Sibirica;

Sukachev larch – Larix Sukaczewii;

European larch – Larix Decidua;

Polish larch – Larix Polonica;

Daurian larch – Larix Dahurica;

Coast larch – Larix Maritima;

Japanese larch – Larix Japonica.

They differ by age, the type of planting, forest assessment parameters and origin.

I studied the biological features and seed-larch, conducted the selection of sites and objects, the most suitable for the research, conducted the study sowing qualities of seeds were studied yield of cones and seeds, and a comparative analysis of the results.

Total of selected sites represented:

biogroups – 6;

Planting – 3;

2-row alleys – 4;

1-row alleys – 5;

Solitary tree – 5.

Chart  1 – Characteristic of sowing qualities of seeds

Our research confirmed the well-known thesis that the quality of seeds larches depend on ensuring the effectiveness of cross-pollination. Specificity pollination larch is that the pollen is heavy, and it is spread over a short distance, so cross-pollination is possible in group plantings. In single trees without providing cross-pollination (by self-pollination) crop quality is very low and does not exceed 3-12%. Moreover, efficiency of pollination depends on the amount of pollen produced than its more the higher vitality and seed germination. In turn, this also depends on age, light, crown size and local conditions. The highest marks were set at larch aged 90-160 years.

Indicators purity and germination studied species of larch in group planting in local conditions rather high and often surpass even the figures from the literature that are typical for the natural habitat.

It was revealed that the germination is directly related to vitality. Typically, seeds with formed embryo are viable.

Thus, for practical purposes on seed germination can be judged by the percentage of vitality. High quality of seeds is a criterion for the selection of objects for the planned picking of seed for practical purposes.

Chart  2 – Yield of cones and seeds

Evaluation of the yield and seed cones of larch at all objects made with binoculars. Harvesting cones made on available objects using secateurs,  fallen cones were taken from the ground, whipped by the wind, birds and squirrels.

From the research we can conclude that the maximum yield per tree is seen in European and Siberian larch ripe age because formed upper branches of tree large diameter and a decent height create the best  conditions for abundant crops.  The maximum yield of weight parameters shows Siberian and Sukachev larches,  minimum is Coast and Daurian larches.

In general, the harvest is very plentiful and can be obtained from a large number of tree seeds for efficient harvesting.

It was found the presence of a pronounced periodicity in seed-larch. Abundant average yield produced in a year, which is associated with the specific formation of generative buds on short shoots.

Research has shown that the studied species in the botanical garden of St. Petersburg State Forestry Technical University are characterized by abundant seed-bearing, the parameters of which are closely related to the species of larch, age, place of growth, soil conditions, lighting, physical parameters (height, stem diameter, length of the crown), planting density, the presence of neighboring trees, the sowing of indicators on the weight and size of the pollen.

Conclusion research is that the plantations of larches can serve as a reliable and inexpensive seed source.

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