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ŠUMARSKI LIST 13/2005 str. 186     <-- 186 -->        PDF

B. Vrbck, I. Pilaš, T. Dubravac: LYSIMETRIC MONITORING OF SOIL WAT LR QUALIFY IN THE FQRLST ... Šumarski list SUPLLMHNT (2005). 165-1X3
Nitrogen input via dry and wet deposition satisfies
the requirements of this forest ecosystem up to 100 %,
which may have both positive and negative consequences
on forest growth and development (Simončić
1996). The quantities of sulphur deposited in the forest
of pedunculate oak and common hornbeam during the
vegetation period are not high (4.73 kgha"´). One possible
reason for this may be attributed to a decrease in
sulphur emissions in the atmosphere in the last several
years, which is reflected in decreased sulphur depositions.
As a comparison, Simončić (1996) cites sulphur
depositions amounting to 13 kgha"1 in the open
and to 22 kgha"1 in a beech stand in the "Šoštanj" thermal
power plant. In a spruce culture the amount of sulphur
is 33 kgha"1. Data from 1993 for Slovenia
(Lešnjak and Rajh-Alatič 1993) show sulphur
depositions between 28 and 36 kgha"1 in urban areas,
and the amount of nitrogen of 15 kgha"´. For open alpine
areas in Austria Smidt (1993) gives the following
data: 7-15 kgha"´ of sulphur and 7-17.5 kgha"1 of nitrogen.
Führer (1993) in Hungary mentions sulphur
quantities of 16 kgha"´ and total nitrogen compounds of


12.5 kgha"´. For North America, sulphur quantities range
from 25 to 45 kgha"´ (Nash et al, 1992).
For Croatia, data vary in dependence on forest community,
altitude, sampling plot position, etc. Thus,
Komlenović et al. (1997) mention 23.77 kgha"´ of
sulphur (S04-S) and a total of 27.87 kgha"1 of nitrogen
(NO,-N + NH4-N) for Lividraga in Gorski Kotar. According
to some recent data collected during 1999
(Vrbek and Pilaš 2001), the quantity of sulphur
(SO4-S) varies from 5.2 kgha"´ in lowland forest ecosystems
of pedunculate oak and common hornbeam in
the area of Jastrebarsko and from 27.5 kgha"´ in the
area of Medvednica to 28.0 kgha"´ in the area of Zavižan
on Velebit. The highest quantity of 50.2 kgha"´
was recorded in the area of Lividraga. Data for total
nitrogen are even higher. A quantity of 15.2 kgha"´ was
recorded in the lowland area, 27.0 kgha"´ were recorded
in the area of Medvednica, about 26.0 kgha"´ were
recorded on Zavižan and as many as 74. 2 kgha"´ were
recorded in Lividraga, which is much higher than critical
contamination with nitrogen. Table 13 gives a survey
of sulphur and nitrogen quantities in different areas
in Europe in relation to the forest of pedunculate oak
and common hornbeam in northwest Croatia.


The data show decreased sulphur depositions in lowland
forest ecosystems of pedunculate oak and common
hornbeam in relation to the other areas in Croatia
and in the neighbouring countries. The input of NH4-N
and NO3-N is increased. Another 44 % were added in
the Table for the forest of pedunculate oak and common
hornbeam as the difference in precipitation for the
whole year, since monitoring was done during the ve


getation period. According to the reference data, depositions
may be higher in winter than in summer. High
nitrogen content means its better supply. The trees
show more luscious growth, higher vulnerability to
windthrows and increased susceptibility to fungi and
pest attacks, while the crowns break more easily.


The lysimeters showed the highest quantities of
ions in kgha"´, except for nitrates and ammonia, while
potassium quantities were lower. The quantities for Ca,
Mg and Na in kgha"´ were expected, because there is
constant leaching of these cations from the soil, especially
at lower pH values. Soils bind sulphate ions and
release basic cations (Komlenović 1988). Ca and K
leaching from the leaves is also increased. Data from
the control site show that the total cation and anion
quantities are regularly lower than the data referring to
those under the tree crowns, and even smaller in relation
to lysimetric liquid. These quantities coincide with
the data of the Hydrometeorological Office for the City
of Zagreb, where the quantities of chlorine (CI) reach


4.015 to 13.83 kgha"´, of sulphur 40 to 76 kgha"1, and
of nitrate compounds 2.7-9.1 kgha"´.
In the control rainfall gauges, the total CI quantity is


4.80 kgha"´, while the samples taken under the tree
crowns have a total value of 6.95 kgha"´. As seen in Table
5-9, other substances manifest the same increase.
The quantity of matter in the liquids collected from tree
crowns and stemflow changes in dependence on stand
age. Younger stands are much more threatened by depositions
than older stands, but this is also connected
with the quantities of liquids. Older stands have less
stemflow than younger ones. Another fact to be taken
into account is that the total soluble deposited matter
accounts for 38 % of the total deposited dust.
Lysimetric measurements were aimed at determining
the soil buffer capacity (in this case pseudogley and humofluvisol)
that supports the community of pedunculate
oak and common hornbeam. Ion difference shows that
acids have penetrated the forest soils in some places. Ion
difference in % is shown in Table 11 and in Figure 16 for
five main plots and for all measuring sites.


For the moment, the soils in the area of Repaš (plot
25) have a very good buffer capacity, although according
to the data from Table 11, negative results were
found on hornbeam and in the bulk gauge (marked
with yellow). Negative ion difference was also found
in the open space near the plots 15 and 36. Data for the
lysimeters at depths of 10 and 100 cm are very important.
The impact of acidification is seen in the samples
from the lysimeters at a depth of 10 cm (plots 6 - Čazma,
23 - Šiljakovina and 36 - Kupčina). The soils in
these areas show negative ion difference; in other
words, they indicate the process of soil acidification,
which has not yet reached far in depth. Deep lysimeters