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ŠUMARSKI LIST 13/2005 str. 184     <-- 184 -->        PDF

B. Vrbek. I. Pilaš, T. Dubravac: LYSIMETRIC MONITORING OF SOIL WATER QUALITY IN THE FOREST ... Šumarski list - SUPLEMENT (2005), 165-1X5
ions (sodium and potassium - alkaline, calcium and ma- conductivity in uS/cm were measured in the field. The
gnesium - soil alkaline) were determined with the ato- methods are described in the WMO (1974), Standard
mic absorption spectrophotometric method (Perkin El- Methods (1975) and Mohler etal. (1975).
mer atomic spectr., model 603). The pH and electrical


DATA PROCESSING


Data obtained from the laboratory analyses were Access database in the Forestry Institute in Jastrebarprocessed
on a personal computer using Excel and Stasko.
The graphs were performed in Excel and Statistica
tistica 5.0 programmes. A separate part of statistics and the text was written in Word 7.0. The figures were
using Kruskal-Wallis tests was done in the Microsoft done in Correl.


TASK AND GOAL OF RESEARCH


Research was aimed at examining the impact of
precipitation on soil solution with lysimetric measurements.
To complete the task, the following parameters
had to be determined:


The quantity of more important cations and anions
and heavy metals in liquids at a depth of 10 cm below
the humus-accumulative horizon and at a depth
of 100 cm in the mineral part of the soil,


The quantity of investigated chemical elements in
kgha"1 deposited in the forest of pedunculate oak
and common hornbeam,


The chemical content of precipitation below oak


and hornbeam crowns,
The chemical content of precipitation in the control
sites,


The impact of the chemical precipitation content on
the chemical percolate content in the forest soil
using the accepted statistical methods.


RESULTS


In terms of cation and anion quantity in mgL"1, Tables
2, 3 and 4 manifested some differences in their
average values when all plots were compared. The
concentration of all ions was always the highest in the
area of Repaš, followed by Česma, Pokuplje and Šiljakovina.
The values show the average cation and anion
concentration in the observed vegetation period per
measuring points and areas.


Comparing the data obtained from below the
crowns per areas, the average cation and anion content
was found to be significantly lower in open spaces
unaffected by vegetation. The Repaš area again achieved
the highest anion values, whereas with regard to
average cation values for calcium and ammonia ions,
the highest values were recorded in the area of Pokuplje
and Siljakovina.


Lysimeter samples show changes in the picture of
the average ion content in mgL"1. The highest average
cation concentrations for calcium, potassium and magnesium
were found in the area of Repaš, while the highest
average concentrations for sodium were found in
the area of Pokupsko-Šiljakovina. Increased cation leaching
is due to the structure of the soil profile: most carbonates
occur in the lower part of the soils in Repaš.
Carbonate loess occurs in the lower part of the profile in
Česma. The situation is somewhat different with regard


to the average anion content in the lysimetric liquid. The
highest average anion concentrations were recorded in
the area of Česma, and then in the area of Repaš, with
the exception of chlorine, which was found in the area
of Pokupsko-Šiljakovina in approximately the same
amounts as in the lysimeters from the Česma area.
Increased amounts of chlorine in Pokupsko-Šiljakovina
are attributed to the presence of sodium. Most probably,
there is a local salinity source from lateral water discharge,
which requires more detailed research.


Cation and anion differences in lysimeters installed
at depths of 10 cm and 100 cm are shown in Figures
1 and 2. Calcium (Ca2 ) values in Repaš and sulphur
(S042~ -S) values are several times higher in lysimeters
placed at a depth of 100 cm in relation to other areas
and lysimeters. On average, lysimeters at a depth of
10 cm contain lower cation and anion concentrations
than lysimeters at a depth of 100 cm.


According to Table 10 and Figure 12, the average
deposition of all cations and anions in the forest ecosystem
(forest) is higher than in the control site (control
site) in the forest of pedunculate oak and common
hornbeam in northwest Croatia. This is yet another
proof that the biomass area of the forest ecosystem of
pedunculate oak and common hornbeam allows for
more dry deposition of matter, which is later percolated