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ŠUMARSKI LIST 9-10/2019 str. 9     <-- 9 -->        PDF

Microclimate differences in the degradation stages of holm oak (Quercus ilex L.) forests
Mikroklimatske različitosti degradacijskih stadija šuma hrasta crnike (Quercus ilex L.)
Damir Ugarković, Željko Španjol, Ivica Tikvić, Dražen Kapučija, Ivana Plišo Vusić
Maquis and garrigue are the most common degradation stages of Holm oak forests in Croatia. Disorganized and uncontrolled cutting degrades forests and changes their microclimates. Measurements were conducted in a Holm oak forest in the maquis and garrigue degradation stages, and in an Aleppo pine forest with Holm oak. The highest variations of microclimate elements were measured in the degradation stages of Holm oak. The average air and soil temperatures, precipitation, and potential evapotranspiration were highest in the garrigue stage and lowest in the maquis stage. The average volumetric soil water content was highest in the maquis stage (14.28%) and lowest in the garrigue stage (9.46%). The dry season water deficit was highest in the garrigue stage (-73.95 mm) and lowest in the maquis (-60.38 mm). Microclimate conditions in the garrigue degradation stage are less favorable for the growth and development of Holm oak than in high forest stands. The average values of microclimate elements in the Aleppo pine forest stand with Holm oak were within the average range of the microclimate elements of garrigue and maquis.
Key words: Forest microclimate, forest structure, Holm oak, degradation stages, Aleppo pine
In the Mediterranean region, forests have been exposed to intensive anthropogenic impacts for centuries. Examples of such impacts include uncontrolled cutting, grazing, removal of the litter layer, burning and clearing for expansion of agricultural lands, change of use of forests and forest lands for the purpose of developing infrastructure, tourism, raising of vineyards and olive groves, etc. Such long-term processes, in combination with fires, specific climatic conditions, and erosive soils, has gradually led to the general degradation of the Mediterranean forest ecosystems (Topić and Butorac 2011, Matić et al. 2011). Drought additionally supports a negative anthropogenic influence on these forests. High evaporative losses from forest cover could supply the critical moisture needed to trigger water condensation in ascending air masses as well as promoting rainfall (Millán et al. 1997).
The most important factor limiting the distribution, growth, and development of trees in the Mediterranean ecosystem is the lack of water during summer (Di Castri 1981, Ogaya & Penuelas 2006).