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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.




ŠUMARSKI LIST 13/2005 str. 120     <-- 120 -->        PDF

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.


ŠUMARSKI LIST 13/2005 str. 121     <-- 121 -->        PDF

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.