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V delu smo raziskovali potek sukcesije po požarih v naravnih sestojih črnega bora (Pinus nigra Arnold). Izbrali smo požarišče v Trenti iz leta 2005 in požarišče nad Logom pod Mangartom, kjer se je poţar zgodil leta 1979. Postavili smo skupno 22 ploskev velikosti 10x10 m, na delih poţarišča z različno intenziteto poţara ter v ohranjenih sestojih. Na ploskvah smo opravili fitocenološke popise, popisali smo tudi pomladek drevesnih in grmovnih vrst ter sušice in leţeče drevje po stopnjah razkroja. Podatke smo analizirali s pomočjo hierarhične klasifikacije in analize glavnih koordinat. Vegetacijo smo analizirali tudi glede na rastlinske strategije po Grimeu (CSR). Ploskve z različnimi intenzitetami poţara smo primerjali glede na številčnost pomladka z neparametričnimi testi. Ugotavljali smo še korelacijo med odmrlo lesno maso in pomlajevanjem. Ugotovili smo jasne razlike med mlajšim poţariščem in ohranjenimi sestoji, starejše poţarišče pa je ohranjenim sestojem bolj podobno. Po poţaru se je spremenila pokrovnost dominantnih vrst zeliščne plasti (Erica carnea, Calamagrostis varia, Achnatherum calamagrostis), pojavile pa so se nekatere nove vrste, značilne za požarišča. Sukcesijo lahko prikažemo kot prehod od bolj stres-tolerantih vrst k vrstam s kompeticijsko strategijo, medtem ko ruderalna komponenta zaradi slabše produktivnosti rastišča ni izrazita. Na poţarišču so se uspešneje pomlajevale pionirske vrste, medtem ko pri značilnicah zdruţbe Fraxino orni-Pinetum nigrae ni razlik v obnovi med poţariščem in ohranjenimi sestoji. Pozitiven vpliv odmrle lesne mase na pomlajevanje smo ugotovili le v starejšem požarišču. The post-fire succession in natural black pine (Pinus nigra Arnold) stands was analysed. Our research was done in the Trenta valley, where a fire took place in 2005, and above Log pod Mangartom, where a fire burned in 1979. The species composition of 22 sample plots of 10x10 m in areas of different burn severity and in unburned stands was recorded. The seedlings and saplings of tree and shrub species were also counted, and the amount of snags and logs wasrecorded. Hierarchical aglomerative clustering methods and principle coordinate analysis were used. The vegetation was also analysed according to plant strategies sensu Grime (CSR). Differences in regeneration between burn severity sites were determined using nonparametric tests, and correlation between coarse woody debris and regeneration was analysed. Significant differences were found between the recent burned area and control sites, but the older burned area is very similar to non-burned sites. The cover of dominant herb species (Erica carnea, Calamagrostis varia, Achnatherum calamagrostis) changed after the fire, and some new species, typical for burned areas, appeared. The succession is a transition from stress-tolerators to more competitive species, while the ruderal component is not significant. Pioneer species regenerated successfully in burned areas, while there was no difference in the regeneration of typical Fraxino orni-Pinetum nigraespecies. Coarse woody debris was found to have a positive impact on regeneration in the older burned area. |
