Changes of Forests In Czechoslovakia V. PERINA Ministry of Agriculture, Prague, Czechoslovakia In the territory of Central Europe, and, consequently, because it did not take into consideration the biological in Czechoslovakia, there has occurred in the last two requirements of individual tree species. centuries a substantial change in the species composition A substantialchangeoftreespeciescomposition of the forests.This change was caused by an economic- occurred in the territory of Bohemia, situated, from the historical situation in this country. In the areas of relatively phytogeographical point of view, in the Hercynian range. dense population the timber consumption increasedpro- At the present time, the Norway spruce here covers over portionally with the development of industry, so that the 62,5%, and the Scotch pine over 19,7% of the total high timber resources in the forests were successively reduced. forest area. The broadleaved species cover only 13,2% Artificial regeneration was not regulated, and natural of the area. In the eastern part of Czechoslovakia, i.e., regeneration was, in those times, hindered to a great in Slovakia, which belongs to the Carpathian range, and degree by grazing. where industry was not developed to such a great extent Timber scarcity and the unfavorable state of forests as in Bohemia and timber consumption was less important, were such that various ways for the improvement of no substantial change of species composition occurred. forestry were sought, in order to ensure a sufficient quan- Here, high forests are composed primarily of broadleaved tity of timber. One of those ways was, especially at the species (54,8%), whereas conifers occupy only 45,2% close of the 18th and in the 19th century, the establish- of the area. The present tree species composition here ment of pure stands of Norway spruce (Picea excelsa L.) corresponds roughly to the natural conditions. On the and Scotch pine (Pinus sylvestris L.). In Central Europe other hand, in the western part of Czechoslovakia, i.e., in the Norway spruce is a native species in mountainranges, Bohemia, a great part of the spruce stands is situated while the Scotch pine is a species of the lowlands, grow- in unsuitable sites. The comparison of actual tree species ing there as an autochthonous species in the oak zone in representation in Bohemia with the ideal species composi- relatively poor and dry sites.Regarding climate, both tion corresponding to site conditions is given in the fol- species are,to a great degree, indifferent toit,thus lowing table: enabling them to be grown outside of their natural range. In the pure stands, the Scotch pine was grown first of (Cover of the total area (in %) all at low altitudes, later, in the oak stand zone (up to 600 Ideal meters above sea level), and finally, instead of in the oak (corresponding to forests, was mixed with the following species: Quercus, Species Actual site conditions) Carpinus, Fagus, Ulmus, etc. In the beech zone, ranging Picea excelsa L. 62,5 24,7 in Czechoslovakia at altitudes from 400 to 1,000 meters Pinus sylvestris L. 19,7 15,7 above sea level, mixed stands formed by the species Fagus Abies alba Mill. 2,8 10,0 silvatica L., Abies alba Mill., Picea excelsa L., Acer Larix decidua Mill. 1,6 4,1 pseudoplatanus L., etc., were changed to pure stands of Other conifers 0,2 Norway spruce. Fagus silvatica L. 5,0 18,1 The pure stands of Pinus sylvestris L., and especially Quercus robur L. 3,8 11,5 of Picea excelsa L., which were most favorable from the Fraxinus, Acer, Ulmus 1,1 4,7 economic point of view, successively extended and took Other hard broadleaved 2,1 2,1 over more and more areas, from which the autochthonous Other soft broadleaved 1,2 9,1 tree species were removed.In regeneration, a radical Total coniferous 86,8 54,5 methodclear-cutting, together with artificialregenera- Total broadleaved 13,2 45,5 tion by sowing and plantingwas used, and in thisway the original ecotypes suitable from the site point of view It is clear that in Bohemia a large area of spruce stands were destroyed.This management method caused the is situated on unsuitable sites, so that an important prob- establishment of pure, even-aged stands, characterized by lem arises here, viz, in which ways those pure stands may their regularity of cut areas and compartments. In the be replaced by mixed ones composed of species cones- history of Central European forests, this was the first and, ponding to the respective site conditions. The fact that to a great degree, accomplished planning, which ensured the spruce and pine stands in Bohemia occupy unsuitable a space arrangement in the forests and established a sites may be illustrated by a rough comparison with the simplicity and greater possibility in their management. site qualities of the stands situated in the eastern part of However,this method involved a number of errors, the Republic, i.e., in Slovakia, where the spruce and pine 476 Fifth World Forestry Congress Proceedings stands grow on much more favorable sites.The mean parts of Czechoslovakia to become considerably deterio- site qualities (by Schwappach's method) of Norway spruce rated. At the present time, only 11 % of the forests are and Scotch pine in Bohemia are 2,6 and 2,8 respectively, fully active from the hydrological point of view. In the and 1,4 and 2,2 in Slovakia. The same differences may residual forest area, the retention capacity of forest soils be found in regard to the mean aimual increment of coni- deteriorated 1-9 times. In view of the fact that a majority ferous and broadleaved tree species, averaging 3,4 cubic of Central European rivers rise in the territory of Czecho- meters and 2,5 cubic meters in Bohemia, and 4,9 cubic slovakia, this situation is very unsatisfactory. meters and 3,1 cubic meters in Slovakia, respectively. The above-mentioned unfavorable effects of pure stands The large-scale establishment of pure stands, especially accompanied by rough regeneration methods caused of Norway spruce, which was extended even to unsuitable forest science and practice to start, as early as at the close sites in Bohemia, brought about not only a decrease in of the 19th century and in the early 20th century, to solve timber production, but also a series of other unfavorable the problem of pure stands. Even at the present time, a features accompanying the pure stand management over great deal of attention is devoted to the change of pure the whole of Central Europe. stands in Czechoslovakia, both in research and in practice. The pure stands suffered heavily from various disasters In Central Europe the spruce and pine pure stands caused by both abiotic and biotic agents. The most dan- cover various geologic substrata and various soil types, and gerous abiotic factors were storm and snow. So, e.g., a occur in various climatic conditions.The difference great deal of timber, equaling two annual calculated cuts, between the given site conditions and those of the natural was damaged by gales in 1929, and by snow and rime in range of Norway spruce and Scotch pine forms, together the years 1930 to 1933. The last gales in 1955 destroyed with the economic conditions (growth, quality, resistance one-third of the annual calculated cut. The pure spruce of stands), the main criteria for the extent of changes. stands growing outside of their natural range suffered in Taking into account these points of view, the pure stands 1947 from drought, causing enormous financial losses. are divided into those with complete, prevailing, and In spite of the fact that forest management in Bohemia has partial changes.Because the greater part of Bohemian aimed at protecting the pure stands from storms and snow forests consists of managed forests (96%), the changes by various silvicultural measures (outer and inner space are not performed with the purpose of forming the arrangement, sequence of regeneration operations, tending natural associations of tree species which should replace of stands), at present, 11,5% of the total forest area is the present pure stands, but in order to form economically menaced by wind, 12,4% by snow, and 5,9% by drought. profitablestands. Insuchforeststheeconomically The disasters in pure stands caused by abiotic agents importantspecies,including the Norway spruce and affected outbreaks of harmful insects, inducing again Scotch pine, must be represented to a maximum degree. further biotic calamities. Of the great group of insects However, the site conditions (especially the soil condi- which attack the pure stands of Norway spruce, bark tions) and the safety of the forests must not be unfavor- beetles (Ips typographus L., Polygraphus polygraphus L., ably influenced. and Pityogenes chalcographus L.) are the most dangerous In order to determine the optimum species composition species, causing, in the years 1945-1947, timber destruc- and the silvicultural treatment aiming at the changes, it is tion equalling ¼ of the annual calculated cut. A very necessary to take into account the diversity of natural dangerous insect enemy of pure spruce and pine stands islargely is the nun moth (Lymantria monacha L.) which attacked conditions,and,therefore,foresttypology the forests of Bohemia several times. The most destruc- applied. Based upon the analysis of environmental factors, tive outbreak of this pest was in 1917-1919, when it of historical research results, and of economic considera- attacked the pure stands of Bohemia and Moravia, caus- tions, the determined typological units make it possible ing compulsory logging on 4% of the total forest area. to find not only the required species composition, but The establishment of pure stands also caused consider- also the techniques of changes (regeneration methods).