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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.