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ŠUMARSKI LIST 13/2005 str. 119 <-- 119 --> PDF |
PRESENTATION AT THE INTERNATIONAL SYMPOSIUM Šumarski list - SUPLEMENT (2005). 110-119 BIOLOGICAL EROSION CONTROL IN THE WESTERN PART OF CROATIA Joso GRAČAN, Sanja PERIĆ, Mladen IVANKOVIĆ, Hrvoje MARJANOVTĆ´ SUMMARY: The paper presents research results of biological erosion control at the source of the river Una (Forest Administration Gospić, Forest Office Gračac) and in Istria (Forest Administration Buzet, Forest Office Labin). Research was initiated in 1972 and conducted by the Faculty of Forestry, University of Zagreb (Department of Forest Genetics and Dendrology) and the former Yugoslav Conifer Institute, Jastrebarsko (Department of Forest Tree Improvement). Research was financed by Karlovac Water Management Company and Rijeka Water Management Company and co-financed by the General Forestry Association of Croatia and the Republican Scientific Fund, Zagreb. Field experiments established in the spring covered an area of about 1.5 ha (Istria), while those established in the autumn (Lika) took up about 1 h. The experiments involved transplants of Austrian pine and hybrids of Austrian and Japanese red pine. The first research results were published when the plants reached 15 years of age (Lika) and 5 years of age (Istria). The average survival percentage in the field experiment in Lika was 59 % and the average height was 2.03 m. In Istria, the average survival percentage was 80.40% and the average height was 16.6 cm at the age of 5. As a rule, hybrids attained lower heights and survival percentages. Key words: Pinus nigra, P. densiflora, hybrids, erosion, biological control INTRODUCTION The erosion area at the source of the river Una exCentral Istria. Apart from the soil, erosion also affects tends over about 170 km2 and is among the most serithe lithological substrate (Komi eno vie etal. 1983). ously threatened in Croatia. Soil erosion control in the Soil protection against erosion and torrents has exceparea began in 1957 with the erection of civil engineetional economic, ecological and social importance in ring facilities. However, it soon became clear that the karst areas (Topic 2003). soil could not be protected against erosion with techni The paper presents research results of soil protec cal measures only, and that biological soil protection tion against erosion within the project "Biological ero was also required (Vidaković etal. 1986, Gračan sion control in Lika and Istria". The project was jointly et al. 1991, I v a n č e v i ć et al. 2003). This area con undertaken by the former Conifer Institute Jastrebar tains all erosion phenomena: surface, furrow and ditch sko (Department of Forest Tree Improvement) and the erosion (Radu 1 ovi ć 1972). According to Topic Faculty of Forestry, Zagreb (Department of Forest Ge (1997), the problem of karst and its afforestation has netics and Dendrology). Research was financed by the been treated by a number of Croatian authors. A cha Republican Scientific Fund (later the Ministry of racteristic example of flysch erosion, which is genera Science) and the Karlovac and Rijeka Water Manage lly not very common on flysch in Croatia, is found in ment Companies and co-financed by the General Fo the area of the rivers Botonega and Boljunšćica in restry Association (later Croatian Forests). The project involved both biological and technical-biological re Joso Gračan, Sanja Perić, Mladen Ivanković, Hrvoje Marjanović search in soil protection against erosion and runoff. Forest Research Institute, Jastrebarsko, Croatia Regrettably, the water management companies men tioned above have not even started the research yet. |
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J. Gračan, S. Pcrić. M. Ivankouć. II. Marjanović: BIOLOGICAL liROSION CONTROL ... Šumarski list SUPLKMLNT (2005). 110-11´) From the forestry standpoint, the basic task related experiments were established in Lika and Istria (Vito efficient area afforestation with the goal of reducing d a k o v i ć et al. 1981, G r a č a n et al. 1991, K o m 1 e erosion intensity. To accomplish the task, several field n o v i ć et al. 1992). MATERIAL AND METHODS The plants used in field experiments were raised in the nurseries of the Conifers Institute in Jastrebarsko (Department of Improvement) and the Department of Forest Genetics and Dendrology at the Faculty of Forestry in Zagreb. They were grown from sown seeds and maintained by tending and protection measures until the age of 2+0 and 1 + 1. Prior to establishing field experiments, the young plants were transplanted in plastic bags and "Jyffi" pots. Field experiments were established in the locality of "Belaj" (1.5 ha) in the spring and in "Lički Osrcdci" (1.0 ha) in the autumn of 1975. Different provenances of Austrian pine from Crna Gora (Kosanica and Crna Poda), Slovenia (Kranj), Macedonia (Berovo), Russia (Crimea), France (Corsica 4 and Corsica 5), Cyprus (1,2, 3) and Croatia (Supetar, Pelješac, Makarska, Senj, Vrhovine, Jastrebarsko), as well as hybrids of Austrian and Japanese red pine (Pinus nigra x P. densiflora) were transplanted in field experiments. In the "Lički Osredci" experiment, 2,863 plants (2,310 black pines, 553 hybrids) and in the "Belaj" experiment 2,597 plants (1,540 Austrian pines, 1,057 hybrids) were transplanted in gradones and in rows (Figures 1 and 2). The "Lički Osredci" experiment was established on an extremely inclined (30°-50°), skeletal and unfavourable terrain. The soil is excessively leached, and the whole plot is typical ditch erosion. The lithological composition of the wider area consists of Jurassic limestones and dolomites. There is a high percentage of skeletal soil, while genesis has reached the A-C form RESULTS AND The results of research entitled "Biological erosion control in Lika and Istria" relate to survival rates, measurements of heights and breast diameters and monitoring the growth and development of Austrian pine in field experiments established in Lički Osredci, Belaj and Zrmanja. A total of 18 different provenances of Austrian pine and 9 hybrid families of Austrian and Japanese red pine were transplanted in the experiments. Austrian pine is well known for its distinctly disjunct distribution range. It occurs naturally in the south of Europe, in the northwest of Africa and in Asia Minor. The results of plant survival (%), average heights (m and cm) and breast diameters (cm and mm) are shown in Tables 1, 2 and 3 and Figures 1, 2, and 3 for the field experiment in Lički Osrcdci and in Table 3 for the field experiment Belaj. (Gračan et al. 1991). According to Pel cer (1975), this is an area of montane beech forests (Fagetum montanum Ht.), forests of sessile oak with common hornbeam (Querceto-Carpinetum Ht.) and forests of pubescent oak and other oaks with hop hornbeam (Seslerio- Ostryetum Ht. et. H-ić). The average soil sample and eight samples of plant material were taken during the autumn of 1976, 1977, 1979, and 1988. The soil and plant material samples were analyzed with suitable methods in the Institute laboratory (Kom leno vi ć etal. 1992). The geological-lithological structure in the areas of Grimalda, Belaj and Kršlika - Glavica consists of Tertiary flysch deposits mainly composed of alternative marl and sandstone interlayers. Under recent conditions, this type of parent substrate is represented with over 80 % of shallow and moderately deep rendzinas. They are accompanied with regosols, colluvium and cambic rendzina arranged in a mosaic-like pattern (Martinović 1977, M artinović and Vrbek 1982, Martinović and Cestar 1984). The dominant community in the area is the forest of pubescent oak and oriental hornbeam (Orno-Carpinetum orientalis, B e rt o v i ć and L o v r i č 1987). The success of afforestation was monitored in 6 plots covering an area of about 20 ha in the "Zrmanja" experiment. The experiment was established in 1957 with seedlings of forest trees and fruits and with uncovered grass areas (C e s t a r etal. 1985). DISCUSSION Lički Osredci As seen in Tables 1 and 2, a total of 2,863 plants, of which 2,310 Austrian pines and 533 hybrids, were transplanted in the field experiment of Lički Osredci. The plant survival rate ranged from 17.20 % (Cypar 2) to 96.20 % (Berovo, Macedonia) in 1988, and from 17.20 % (Cypar 2) to 90.77 % (Pakline, Croatia) in 2004. The average height of Austrian pine was 2.03 m in 1988 and 5.75 m in 2004. In 1988, Cypar 1 attained the smallest average height of 1.18 m, while the plants of the Crni Pod provenance achieved the highest height of 2.74 m. In the autumn of 2004, the Cypar I provenance attained the smallest average height of 2.57 m, whereas the plants of the Berovo provenance (Macedonia) achieved the highest of 10.30 m. |
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J. Gračan, S. Perić, M. Ivanković, H. Marjanović: BIOLOGICAL EROSION CONTROL Šumarski list - SUPLEMENT (2005), 110-119 Comparison of growth and development of the plants of 18 Austrian pine provenances and 9 hybrid families of Austrian pine and Japanese red pine showed that hybrid plants had a relatively poor survival rate. At the age of 31 (autumn 2004), 138 plants out of 533 (1/4) survived and achieved an average height of 2.91 m. Clearly, not only was the survival rate of hybrid plants twice as low, but they also achieved lower heights. Research results indicate that the hybrids between Austrian pine and Japanese red pine are not suitable for biological erosion control at the source of the river Una and in Istria (Vidaković et al. 1986, Vidaković and Gračan 1973, Gračan etat. 1991). The average soil sample and eight samples of plant material were analyzed to show biogenic element concentrations in the needles of the plants, which mostly coincides with growth and appearance. Needle chlorosis was observed in the majority of the plants as a consequence of CaC03 concentration and nitrogen deficiency (Komlenović 1978,Gračan etal. 1991). Belaj Related to plant growth and development in this experiment, it should be stressed that the financing of this research was stopped in 1981. As mentioned earlier, the experiment was established in the spring of 1975, and survival and height measurements were performed in 1976. Heights and breast diameters were measured in the course of 1981 at plant age of 11 (Table 3). The average survival rate of all the plants in this experiment was 69.65 % in 1976, and the average height was 14.80 cm. The average hybrid survival rate was 80 % at the height of 16.75 cm. The survival of Austrian pines of different provenances was 59.30 %, with the average plant height of 12.80 cm. As expected, hybrid plants in the juvenile stage had higher survival percentages and average heights. The results of height and breast diameter measurements of all the plants in the 1981 experiment showed that the average heights of different provenances of Austrian pine were slightly higher (58.40 cm) compared to those of hybrids (54.25 cm). As for breast diameters, the ratio remained the same: the average dbh of Austrian pine was 29.62 mm and that of hybrids 25.27 mm. The average plant thickness in the experiment was 27.45 mm. The results of past research have shown that the soils in Istria in which the experiments were established are carbonate, of weakly alcalic reaction, well supplied with accessible calcium and poor in phosphorus. The humization condition and the total nitrogen supply are satisfactory. The soils have an ecologically favourable mechanical composition and belong predominantly to the textural classes of clayey loam and silty clay (Martinović 1977, Martinović and Vrbek 1982, Marti nović and Cestar 1987). CONCLUSION 1. Compared with hybrid plants, different provenances of Austrian pine dominate in terms of survival, height and diameter growth and development. 2. The average survival percentage (pondered) of these plants was 59.95 % in 2004. In the field experiment of Lički Osredci the average heights were 5.75 meters and breast diameter was 9.55 cm. 3. The hybrids between Austrian pine and Japanese red pine show nearly twice as low survival rate (25.14 %), height (2.03 m) and breast diameter (5.44 cm). 4. In the field experiment in Istria (Belaj), 8-year-old plants of different provenances show slightly better heights and breast diameters than hybrid plants. 5. From a forestry standpoint, biological erosion control achieved by planting seedlings of Austrian pine results in faster and more efficient afforestation of eroded areas. This considerably reduces the erosion intensity and enables the return of autochthonous vegetation. We take this opportunity to thank Mr Davor Zec, BSc, former manager of the Forest Office Gračac, and Mr Krunoslav Božičević, BSC, manager of the Forest Office Labin, on their invaluable help in plant measurements and finalization of this research. |