(Root Fungus and the Resistance of Coniferous Forests' Ecosystems. A Monograph)

Vilnius

1989

175 S.

18 Abb., 53 Tab., zahlr. Lit. Ang.

Serie

5-4200-0375-9

400084013

Detailed investigations of the root fungus Heterobasiion annosum (Fr.) Bref., as well as of the disease caused by it to coniferous trees, have been carried out since 1961. By now a considerable amount of data has been obtained on the distribution of the root fungus in the Republic, depending upon the forest type, age density and local growing conditions. Characteristic features of this disease and economic losses due to it have been studied. The main problems of fungus biology, as well as the possibilities of applying biological, chemical and forestry means against is, have been investigated. As a result of the investigations conducted, it was established that the distribution of the root fungus depends mainly on soil humidity and the previously used method of agricultural production. In pine forests, growing on old wood soils, this disease may be encountered comparatively seldom and cause little damage. The same may be said about stands growing on damp and wet soils. The infection rate of pines at any age does not exceed 5-10%. An opposite picture may be observed on arid and fresh soils (dry boron-A1, fresh boron-A2, fresh subboron-B2) after a long period of agricultural production. Under the above conditions of growing the root fungus is widely spread and causes great danager for the growing pine stands. In the 30-40-year pine stand massive shrinkage when growing on soils after long-term agricultural production and an vacant lands may be encountered on thousands of hectares in the Republic. Spruce forests may be considerably infected and destroyed by the root fungus even on typical forest soils. The tree damage rate depends on the local growing conditions of a forest, its age, density and stand composition. In the stands of equal age this disease is spread twice as much in fresh types of forests than in damp ones. With the increase of stand age the distribution of the root fungus increases, and this natural phenomenon is observed in spruce forests of different species composition and of different density. In spruce forests of 41-80 years, growing in fresh types of forest land (growing conditions B2, C2, D2), the damage of trees by the root fungus reaches, on the average, about 22-29 %, and in damp types of forest land (growing conditions B 3, C3, D3) the number of damaged trees reaches only 9-15 %. At the mature age (81-120 years) the average distribution of the root fungusin fresh types of forest land increases by 45-48 %, and on damp growing sites it only reaches up to 16-28 %. When spruce, included in the stand composition, makes up to 80-100 %, the damage increases by 3-14 % if compared with 50-70 % of spruce in the stand composition, and at a density of 0.8-1 the damage is g reater by 4-11 % than at a density of 0,5-0,7. Because of wood rot damage of the lower part of the trunk in spruce forests growing on fresh forest ......