engleski

Forest crown condition and monitoring deposited matter in Gorski Kotar area in Croatia

Monitoring the state of crown damage in 2004 in the Republic of Croatia showed a further increase in the percentage of significant tree damage of all species. Compared to 2003 significant tree damage of all species increased by 3.6% ; from 23.2% to 26.8%. Significant damage to broadleaved trees, compared to last year, also increased by 3.5%, from 17.6% to 21.1%. In conifers the percentage of significant damage increased from 46.8% to 48.8%. The amount of damage to all species, in particular Silver fir, in the Gorski Kotar region, is worrying: Silver fir with 88.4% of singnificant damage is in a very poor condition, and beech is also of poor vitality with 20.1% significantly damaged trees. This high percentage of significant damage in the investigated area is a consequence of intensive dieback of fir. Monitoring of precipitation and liquid phase of the soil is also carried out on the experimental plot in the Gorski Kotar region. Plots are provided with rain-gauges for measuring amounts of precipitation and with funnels (bulks) for sampling of water (sedimentation of dry and wet deposition) as recommended by the ICP method (International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forest). Rain-gauges and funnels (bulks) are laid out in diagonal distribution in 9 units, each in a sub-plot area 30 x 30 m in size. At a control spot, without the influence of vegetation, funnels (bulks) and rain gauges were set up in a random distribution or circle. A zero-tension lysimeter was installed at a depth of 10-20 cm for measurement seepage water (percolate)in order to establish the quality. Sets of three rain-gauges and three funnels (bulks) were set up in the control areas, outside the influence of vegetation, i.e. in an open space. Data show that the annual introduction of nitrogeneous compounds/substances/for Gorski Kotar amounts to approximately 16-18 kgha-1. In the same way the investigated plot received approximately 8 kgha-1 chloride and about 9 kgha-1 sulphur. On average the lysimeters had a higher content of sedimentary substances than the values registered in the rain-gauges under the tree-crowns. This data points to the reason for lower pH values in lysimetric samples. Accumulation of depository substances on the soil surface and further transport through the soil profile into seepage and ground water is evident. Sedimentation matters effect the soil and the quality of seepage water. Lysimetric pedology enables determination of the degree of soil acidification due to dry and wet depositions and assessment of their buffer capacity. The kind of forest cover is an important factor in this process.

Gorski Kotar; Croatia; crown damage; monitoring; deposition

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