DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 13/2005 str. 31 <-- 31 --> PDF |
S. Matić, 1. Anić, M. Oršanić: SILV1CULTURAL TREATMENTS AIMED AT IMPROVING THE ANTI-EROSION ... Šumarski list SUPLEMRNT (2005), 17-30 FORESTS OF THE MI HTERRANEAN AREA In no other Croatian area is the issue of anti-erosion and water protection forest function as important as in the Mediterranean region. The forests in this area have for centuries been exposed to intensive anthropogenic influences. These influences commonly involve bad forest use, including, for example, irrational and uncontrolled felling for the purpose of obtaining raw timber material for a variety of needs, browsing and grazing, the removal of duff and leaf litter, slashing branches and pollarding, burning and clearing forests for agricultural areas, converting forests and forestland to meet the needs of infrastructure, tourism, viniculture, olive-growing and similar. In combination with fires, the specific climatic conditions and the erosive soils, these long-lasting influences have gradually led to the general degradation of Mediterranean forest ecosystems. The morphology and the silvicultural and structural characteristics of forest stands have been disturbed, and so have the vitality, stability, productivity, the ability of natural regeneration and the capacity of fulfilling all the functions expected from a Mediterranean forest ecosystem. The Croatian forest experts investigated and described different degradation forms of Mediterranean forests many years ago (Petračić 1942, 1938, Anić 1966, 1963, 1942, 1942a, Marčić 1955). The sequence of the Mediterranean forest ecosystems in the process of regression and progression, as well as their dynamics were also established (Anić 1959, Rauš 1987, Matić et al. 1997). Even more importantly, the answers to the question concerning the treatment of each degradation form aimed at changing their development into a progressive direction were provided by Matić et al. 1997, 1996, Matić and Rauš 1986. Mediterranean forests pose a permanent challenge to forestry, especially in terms of afforesting wasteland, garrigues, pseudogarrigues and scrub, tending and regenerating newly-established and the existing forest stands and actively protecting the degraded forest forms such as maquis, pseudomaquis and scrub. These are the most important silcivultural treatments which should be renewed in order to improve the anti-erosive and water- protective functions of the forests in this area. One of the crucial preparatory activities to be performed before the application of the above treatments is to draw up a management plan. A management plan is the first and the basic step in the management of Mediterranean forests and especially in the management of degraded forms of holm oak and pubescent oak forests (maquis, pseudomaquis, garrigues, pseudogarrigues, scrub, thickets, and mild and severe wasteland). Afforestation is a permanent activity; only by increasing the areas under forests is it possible to increase the non-commercial and commercial value of Mediter ranean forests. Preparatory activities have particular importance with regard to the fact that the area to be afforested in the Mediterranean karst in Croatia covers almost 400,000 ha (Matić andPrpić 1983). In order to perform these activities satisfactorily, it is necessary to plan the whole procedure carefully, select priority areas to be afforested, choose the time and the tree species for afforestation, prepare the soil, plan working techniques and control the quality of performance. Among others, priority in afforestation should be given to those forest areas in which the newly-established stands will have a distinctive anti-erosive and water- protective role. One of the best examples in Croatia is the project of afforesting and improving the torrential area of Senjska Draga (Ivančević 2003). In order to fulfil their commercial and non-commercial functions, the stands derived from afforestation or regeneration of old stands should not be allowed to develop spontaneously; on the contrary, they should be tended since their earliest youth. For example, some possible tending activities in young forest cultures may include ridging, fertilizing and mulching the soil around the young plants. In addition, protection measures against adverse abiotic (wind, fires, sun scorch and sea spray) and biotic (goats, sheep, fungi and pests) factors should be applied, as well as restocking, cleaning and thinning. Regeneration of Mediterranean forests usually comprises the following cases: 1. regenerating stands with climatogenic tree species 2. regenerating stands with pioneer tree species and simultaneous complete or partial replacement of a pioneer with a climatogenic tree species (complete or partial substitution of the stand form) 3. regenerating stands with pioneer tree species without substitution 4. indirect conversion of degraded forms 5. direct conversion of silvicultural forms. The first case is also the rarest. The holm oak forest of Kalifront (including the area of Dundo) on the island of Rab, covering approximately 1,000 ha, is probably the largest preserved complex of this size in the whole Mediterranean region. It is very rare to come across examples of regeneration of old holm oak stands. Past research in Croatia has shown that, with regard to susceptibility of holm oak seedlings to sudden changes in the light conditions and moisture in the regeneration area, regeneration should be accomplished with the shelterwood method and with gradual dosages of light in accordance with the needs of the seedlings and the young growth (M at i ć and Rauš 1986, Prpić 1986, Krejči andDubravac 2004). |