Roman Rosavec

Testing Vegetation Flammability: The Problem of Extremely Low Ignition Frequency and Overall Flammability Score

In the recent decades changes in fire regimes led to higher vulnerability of fire prone ecosystems, with vegetation being the only component influencing fire regime which can be managed in order to reduce probability of extreme fire events. For these management practices to be effective reliable information on the vegetation flammability is being crucial. Epiradiator based testing methods are one of the methods commonly used to investigate vegetation flammability and decrease in ignition frequency is always interpreted as a decrease in flammability. Furthermore, gathered information is often combined into a single flammability score. Here we present results of leaf litter testing which, together with previously conducted research on similar materials, show that material with very low ignition frequency under certain testing conditions can be extremely flammable if testing conditions are slightly changed. Additionally, our results indicate that combining measured information into one single flammability score, even though sometimes useful, is not always meaningful and should be performed with caution.

Pine reforestation of degraded sites on the island of Rab, Croatia

Abstract Degradation of forest sites on the island of Rab goes back several hundred years. The causes include in the first place negative anthropogenic impacts, followed by climatic conditions that are hostile to natural regeneration of climatozonal vegetation. In a part of the island, devastation has led to the disappearance of forests or the preservation of only degraded forms of the basic autochthonous forest vegetation, the forest of holm oak and manna ash (Fraxino orni‐Quercetum ilicis H‐ic/1956/1958). The beginning of the twentieth century saw intensive reforestation activities aimed at halting site degradation processes. The main task of the pines was to create site conditions for the return of climatozonal vegetation. The paper examines the correlation between pine cultures and the return of autochthonous vegetation. Differences were found among forest cultures of maritime (Pinus pinaster Aiton), black (Pinus nigra J.F.Arnold) and Aleppo pine (Pinus halepensis L.). Moreover, the results confirm the justifiability of reforesting degraded sites with pines, but they also reveal the absence of more pronounced effects on the sites. Today, there are about 1000 hectares of pine cultures on the island of Rab, yet climatozonal vegetation has been re‐established in only a small part of these forest cultures.