Natural regeneration of alleppo pine (Pinus halepensis Mill.) forests after forest fires

U radu se istražuje problematika prirodne obnove opožarenih površina u sastojinama alepskog bora (Pinus halepensis Mill.) na tri trajne pokusne plohe. Rezultati se temelje na petogodišnjem sustavnom motrenju (2001.-2005.) u Šibeniku, trogodišnjem (2001.-2003.) u Splitu te dvogodišnjem (2002.-2003.) na Korčuli. Izmjerom je praćena prirodna obnova vegetacije po vrstama, brojnosti i visinskim klasama te učinci radova njege nakon požara. Istraživanja su obuhvatila pedološku obradu pokusnih ploha te kemijske i fizikalne karakteristike analiziranih uzoraka tla iz genetskih horizonata. Rezultati su pokazali prirodno, agresivno, gotovo korovsko širenje i regeneraciju alepskog bora na opožarenim površinama. Zavidan broj biljaka alepskog bora (ponika i pomlatka) na svim plohama ukazuje na uspješnu izrazito obilnu prirodnu obnovu, ali i problem izostanka autohtone vegetacije listača (osim na Korčuli). Izmjerenih 15.000-39.000 biljaka (Split), 56.000-105.000 biljaka (Korčula) te 106.000-121.000 biljaka po ha (Šibenik) pokazuje kako su mlade biljke alepskog bora brojnošću, visinom i preko 2,5m prerasle izgoreni materijal i u potpunosti prekrile izgorenu površinu. Pokusom se ukazuje na promjenu pristupa sanacije izgorenih površina izostavljanjem nepotrebnog, mukotrpnog, ali i skupog hrpanja ili slaganja preostalog opožarenog materijala na pruge. Tako visoko složen materijal na zraku se, u uvjetima mediteranske klime, izrazito sporo razgra|uje i dugo godina svojom masom povećava ionako stalno prisutnu opasnost od požara te narušava izgled krajolika. Preporuča se sanacija njegom i usitnjavanjem izgorenog materijala po površini motornom pilom tako da preostali materijal što više prijanja uz tlo. Vlaga iz tla i uvjeti mikroklime mlade sastojine alepskoga bora, u kojima će se tako obrađeni materijal naći, pridonijet će bržem razvoju mikroorganizama, razgradnji te bržoj humifikaciji. Alepski bor, kao pionirska vrsta drveća eumediterana, ima značajnu i nezamjenjivu pionirsku ulogu u ozelenjevanju opustošenih površina, ali i u pripremi stanišnih uvjeta za pridolazak autohtone vegetacije te hrasta crnike kao temeljnje vrste ovoga područja.This paper examines the problem of natural regeneration of burned (scorched) areas in stands of Aleppo pine (Pinus halepensis Mill.) on three experimental plots. Results are based on five-year systematic monitoring (2001- 2005) in [ibenik; three years (2001- 2003) in Split, and two years (2002-2003) in Kor~ula. The natural regeneration of vegetation was measured according to species, numbers and height classes, and the effects of tending interventions after the forest fire. Investigations covered pedological analysis of experimental plots, and chemical and physical characteristics of analysed soil samples from genetic horizons. The results showed natural, aggressive, almost like weed spreading and regeneration of Aleppo pine on the burnt areas. The considerable number of Aleppo pine plants (saplings and seedlings) on all plots demonstrated successful markedly abundant natural regeneration, but also the problem of the absence of autochthonous broad-leaved vegetation (with the exception of Kor~ula). The measured plants, 15 000 - 39 000 per ha (Split), 56 000 - 105 000 (Kor~ula), and 106 000 - 121 000 ([ibenik), demonstrates that young plants of Aleppo pine, by their number, height of over 2.5 m, overgrew the burnt, material and entirely covered the burnt area. The experiment indicates a change in the approach to treatment of burnt areas by omitting unnecessary, painstaking and expensive piling up and stacking of remaining scorched material in strips. In such highly complex way arranged material, exposed to air in Mediterranean Dinaric conditions, very slowly disintegrates, and its mass over the years increases already permanent danger of fire, and disrupts the landscape. Re-establishment is recommended by tending and fragmentation of scorched material over the surface by using a chain-saw, thus enabling the remaining material to adhere to the soil as much as possible. Moisture from the soil and micro-climate conditions of the young stand of Aleppo pine, containing the material treated in this way, will contribute to faster growth of micro-organisms, its disintegration and humification. As a pioneering tree species of the Eu-Mediterranean, Aleppo pine plays a significant and irreplaceable pioneering role in making the devastated area green again, and also in the preparation of stand conditions for the arrival of autochthonous vegetation - in particular Holm oak, which represents a basic climatogenic species of this region