Original scientific paper
Structure, Texture and Regeneration of Dinaric Beech-fir Virgin forest of Čorkova Uvala
Igor Anić
; Šumarski fakultet Sveučilišta u Zagrebu
Stjepan Mikac
; Šumarski fakultet Sveučilišta u Zagrebu
Abstract
Not so very long ago (the end of the 19th century) a large part of the Dinaric Mountain range in Croatia was covered by beech-fir and beech virgin forests. These forests have since been gradually converted into natural managed forests (Prpić et al. 2001). Nevertheless, several Dinaric beech-fir virgin forests have remained until the present day, including Čorkova Uvala, Devčića Tavani, Nadžak-Bilo, Plješivička Uvala, Javorov Kal and Štirovača (Prpić et al. 2001, Vukelić and Tomljanović 2001). Their total area amounts to 360 ha.
The best investigated of these is Čorkova Uvala. The first scientific forest research in this forest dates back to 1957. Its structure has since been analyzed on several occasions: in a permanent sample plot of one hectare (Tikvić et al. 2006, 2004, Prpić and Seletković 1996, Prpić 1979, 1972), in 12 sample plots of 2,500 m2 each, systematically placed in the form of a network at a distance of 250 m from each other (Kramarić and Iuculano 1989) and in 153 sample plots, each sized 200 m2 and systematically set up in the central part of the old growth stand in the form of a network 50 m from one another (Mayer et al. 1980). In addition, several inventories have also been conducted as part of the management program for the management unit of Čorkova Uvala (1987), and the structure of a wider area of Čorkova Uvala – Čudinka reserve has been analyzed (Cestar et al. 1983). Most of these investigations and inventories provide an average picture of the old growth stand structure. Apart from the results of Mayer et al. (1980), there have been no in-depth analyses of its structure and regeneration.
More recently, research into natural regeneration in the old growth stand of Čorkova Uvala has been intensified and initial results have been published (Roženberger et al. 2007). This work presents the results of initial comparative research into the structure, texture and regeneration in the old growth stand of Čorkova Uvala.
This research was undertaken in the Dinaric beech-fir virgin forest of Čorkova Uvala in Plitvice Lakes National Park in the period 2004–2005. The research involved a systematic sample of 68 plots of 805 m2 each. The plots, set up in the form of a network, were placed 100 m from one another. The activities in each plot included measuring the terrain slope, describing the relief, assessing the canopy, identifying life stages of the virgin forest, measuring breast diameters on all trees (d1.30 > 3 cm) and classifying them by tree species. Dead trees were recorded separately. A height sample was measured in the plots and in their immediate proximity. The young growth was measured in each plot over an area of 80 m2 and classified by tree species and height.
Research provided the condition of the structure, texture and regeneration in the old growth stand extending over 80.50 ha. The old growth stand is made up of 440 trees per hectare on average. Common beech and other hardwoods (OHW) account for almost half of the trees (49 %). There are 45 % of fir trees (Abies alba Mill.) and 6 % of common spruces (Picea abies Karst.). The total tree number declines with an increase in breast diameters. The coefficient (q) of tree distribution by breast diameter is 1.20. Stand volume is 671.23 m2/ha, of which fir accounts for 52 %, broadleaves account for 42 %, and the remaining 6 % relates to spruce. 7.55 % of the total volume is accumulated among thinner trees with breast diameters up to 30 cm. Trees with mean breast diameters between 31 and 50 cm contain 19.92 % of the total stand volume. The remaining volume of 72.53 % is accumulated on trees with breast diameters above 50 cm. Different developmental stages have been identified, albeit over small areas, allowing us to conclude that the stand profile has the selection form. The initial developmental stage was determined in 9 % of the cases, the optimal stage in 18 % of the cases, the terminal stage in 65 % of the cases (ageing and decomposition), and the typical selection developmental stage in 8 % of the cases. The late optimal stage and the ageing stage are the most common due to the depression-like relief of Čorkova Uvala, which protects it from severe winds and allows mature and dead trees to remain standing for long periods. The decomposition stage occurs over small areas as a consequence of fall of singe trees or small groups of trees. In the area of the old growth stand the typical initial stage is relatively modest. It occurs in gaps but also under the canopy. The typical selection stage was found in the smallest number of cases. It is the densest (548 trees/ha), with a volume of 434.70 m3/ha and the highest participation of the silver fir. There are on average ten dead (dry and rotten) trees per one hectare of the old growth stand, of which seven are trees of silver fir. The highest number of dead fir trees was recorded in the 11–20 cm diameter class. The total abundance of the young growth was found in the localities in which a transitional initial/selection developmental stage was recorded. These localities are the least represented. There are 6,190 seedlings on average per one hectare of the old growth stand. Fir accounts for 60 %, beech for 28 %, spruce for 2 % and sycamore for 10 % of the total number of the young growth. Two thirds of the seedlings are up to 50 cm tall. On average, a fir taller than 50 cm is found on every 12 m2 of the area and one taller than 100 cm on every 30 m2 of the area. Unlike beech and sycamore, no fir taller than 300 cm was found up to the taxation limit. Of the total number of the young growth up to 100 cm in height, beech accounts for 15 %, spruce for 2 % and sycamore for 9 %. Beech and sycamore prevail in height classes above 100 cm. The young growth of spruce has a secondary role and occurs sporadically, reaching a height of up to 175 cm.
Keywords
beech-fir virgin forest; Croatia; Čorkova uvala; Plitvice Lakes; regeneration; structure; texture; virgin forest
Hrčak ID:
30704
URI
Publication date:
31.12.2008.
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