DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 3-4/2008 str. 43 <-- 43 --> PDF |
S. Matić, D. Delač: UZGOJNI ZAHVATI KAO MJERA POVEĆANJA VRIJEDNOSTI PRIVATNIH ŠUMA ... wing stock in the stand. If the growing stock is higher than normal, cutting intensity should not exceed 30 %. If it is lower, cutting intensity may be reduced to 15 %. This is borderline intensity which should not be exceeded. This means that cutting should be postponed until another cutting cycle is over, in this case another 10 years. Higher or lower intensities could endanger the selection structure, i.e. the increment, regeneration and stability of the selection stand. Inappropriately applied intensities cannot maintain a selection stand in the optimal structural conditions which will ensure maximal production and optimal regeneration. Regrettably, this is one of the most serious current problems in selection management and selection forests. Beech and spruce stands which have officially been classified as uneven- aged stands and which have not been managed selectively but with selection cuts show a negative developmental trend. This kind of management results in decreased growing stock, absence of natural regeneration, reduced tree quality and lower increment. In such stands management based on regular principles should be organized over small areas (each structural unit – special silvicultural treatment) Silvicultural treatments are spatially divided over small areas. In other s structu words, ,, eac eaceach hh structural unit represents a special part of the stand which requisilvicu res a specia speciaspecial ll silvicultural treatment. They are spatially separated but temporally concentrated. Management with shelterwood cuts in small areas with a longer regenerachieve sp tion period achieves ss biologica biologicabiological ll diversit diversitdiversity yy o oof ff beec beecbeech hh an anand dd spruce forests. This type o gooof regeneration nn enables enablesenables, ,, ove oveover rr a aa longe longelonger rr tim timtime ee period periodperiod, ,, a aa good yield of seeds of the principal and other tree species and the survival of their young generation Regeneration in regular forests is generally done in 3 cuts (preparatory, seed and final) and less frequently in 4 or 5 cuts, where subsequent cuts are introduced. The preparatory cut is undertaken with 20 % intensity and the seed cut with 50 % intensity in a good seed year. The remaining wood volume is cut as needed, either with one or two subsequent cuts or, more frequently, with one final cut. Regular forests are tended throughout the life cycle of the stand, that is, until the shelterwood cuts are applied. Tending consists of the following stages: tending of the young growth after the final cut, cleaning in the developmental stage of the young growth and saplings, and tending with thinning. Tending of the young growth after the final cut is usually done once only, while cleaning or negative selection is done once or twice until the moment the stand reaches its maximal height increment. At this stage future trees are identified, which in beech and spruce forests takes place around the age of 30. At this age stands may be tended with thinning. Coppices of beech, pubescent oak and other hard broadleaves are regenerated with shelterwood cuts. The goal is to convert a coppice into the forest of high silvicultural form or seed forest. Regenerating a coppice with clearcutting and planting conifer species is a ifer serious mistake. Conifers ss may be planted in degraded forest soils which have a pr lost the properties that tt provide the parent climatogenic stand with optimal conditions for growth and development. Coppices should be tended throughout the rotation period. The tending stages in a coppice include reducing the number of poor quality and superfluous shoots on the stump, tending coppices with cleaning or negative selection, and tending coppices with thinning or positive selection. In the current economic and social conditions in Croatia arable areas are systematically being reduced and the size of abandoned agricultural land is Šumarski list br. 3–4, CXXXII (2008), 121-146 |