Barčić Damir, PhD. Assis. Prof.

Open-air fires or forest fires are becoming a key factor in reducing the forest surface areas and
they are one of the major factors of devastation and degradation of forests and forest land and
their ecosystems in the Mediterranean, mainly in coastal karst. They cause extreme material
and economic damage, and they negatively affect biological and landscape diversity. After the
forest fire, significant quantities of fired trees are left behind, representing a significant amount
of lignocellulosic biomass available for conversion into a variety of biobased products. The
question arises as to what degree they are chemically degraded, or whether they still have the
properties required for further application in mechanical or chemical processing.
The main aim of this paper was to study the group chemical composition as a biomass chemical
property of the Aleppo pine (Pinus halepensis Mill.) sapwood before and after the impact
of low ground fire and high fire of the treetops at tree height of 0, 2 and 4 m. Therefore, the
impact of forest fires on the Allepo pine sapwood group chemical composition was studied in
terms of quality for further application in production of biorefinery products. In addition,
research results on group chemical composition of the same unfired and fired Aleppo pine wood
bark from previous study were used for comparison with sapwood from this study.
The obtained results show that the distribution of the main chemical components of Aleppo pine
unfired wood bark and sapwood is similar to the results of previous studies for different wood
species. That means that the bark contains a significantly higher content of ash, accessory materials
(extractives) and lignins, and a significantly lower content of polysaccharides cellulose and
polyoses (hemicellulose) than sapwood. The bark results from previous studies show a significant
difference in reduced ash, cellulose and lignin content, and in the increased accessory materials
and wood polyoses (hemicellulose) content between the unfired and fired wood. Furthermore, the
content of individual chemical components of fired bark at different forest fires heights of 0, 2 and
4 m for each sample did not differ significantly. Contrary to fired bark, no significant differences
have been observed in the chemical composition of sapwood between unfired and fired wood, not
even resulting from different forest fires heights. It can be concluded that the forest fire did not
have any effect on Aleppo pine sapwood, where the fired wood bark took over all the damage
caused by high temperature during the forest fire. In addition, the fired sapwood still retains the
chemical properties required for further application in biorefinery biobased products.

The Mediterranean forest region has been exposed to anthropogenic impacts for centuries, and the constant biotic and abiotic factors, together with increasing climate change, have hindered the proper management of forest ecosystems. This study presents the results of multiyear, systematic, specific and practical monitoring of the conversion of holm oak coppices using the principles of the shelterwood system. It also presents the growth and development dynamics of the stand on a permanent experimental plot from 1997 to 2017. The research was performed in the Eumediterranean vegetation zone of coniferous forest (Forest Management, Buzet branch, Pula Forestry Office, Magran Cuf management unit, compartment 83a). The plot has all the properties of a holm oak and manna ash forests (Orno-Quercetum ilicis H-ić/1956/1958). The basic elements of stand structure were monitored: diameter at breast height (DBH), tree height, horizontal crown projection, crown ground shading (light) and the appearance and abundance of all woody vegetation, with special emphasis on the growth and development of young generations of holm oak from seed. The paper also describes the threats limiting growth, development and survival of holm oak from seed (strong shooting tendencies of coppiced holm oak and bay laurel trees, excessive presence of shrubs). Forest management requires effective, timely and repeated tending to thin stands (already under the canopy), while also protecting young trees from wild game. The statistical method of interpolation determined the trends of stand development; trend equation with coefficient of determination (R2) is very high. This indicates the growth and development of the stand in the direction of renewal of holm oak stands. Shelterwood cutting, with regular and timely tending of young generations of trees through a seven-year regeneration period, resulted in a high quality young high forest of holm oak, the first of its kind in the broader Mediterranean area. The indigenous stands of holm oak, as the fundamental climatogenic coniferous species of the Mediterranean species, have multiple roles such as protection from erosion, resilience to biotic and abiotic factors and forest fires, tourism and landscape functions, and other general forest functions, and therefore deserve intensive and ongoing research. Holm oak stands also play a part in conserving genetic and biological diversity, the potential and persistence of forest ecosystems, improving stand structure, stability and resilience of forest ecosystems to climate change, and in the long-term increase the commercial value of forest stands in the Croatian Mediterranean.