Šumarski list, Vol. 130 No. 11-12, 2006.
Izvorni znanstveni članak
Tannins and microelements in the cells of silver fir tree needles (Abies alba Mill.) and the microelements in bee honey as indicators of the silver fir forests condition in the area of Gorski Kotar
Jadranka Roša
; Hrvatske šume Zagreb
Sažetak
Air pollution has a great impact on the damage and the vitality decrease of fir trees (Abies alba Mill.). The damage of fir trees is largely visible in Gorski Kotar in the Risnjak National Park. More than 50 % of trees have significant crown damage. Their decline is connected with air pollution and the heavy metal elements found in the forest ground. The research on fir damage was carried out through structure analysis of the tannins in the cells of fir needles, in reference to the quantity of the microelements in the needles, and as to the kind and quantity of microelements in bee honey.
The research included one-year-old fir tree needles (Abies alba Mill.), which were collected in natural conditions in the years 2000 and 2001 on two locations. The first was Risnjak, which represented a polluted site of experimental type. The second was Donja Dobra, representing a clean site of a control or reference type. The needles were collected from the trees with various stage of damage, during three periods of time: May, July, and September of each sample year.
On the Risnjak site, the needles were collected from the crowns with significant damage. This means that these trees had over 20 % of needle loss. The trees with crown damage of 35 %, 45 %, 55 %, 75 % and 85 % were chosen on this site. The needles from the trees with slightly damaged crowns, between 5 % and 10 %, were collected on the site of Donja Dobra.
The needles used for the analysis of microelements were collected from the trees on both locations.
Bee honey, in this case honeydew honey, was collected at the end of vegetation season from the beehives near the location where the needles were collected.
The needles were moulded in paraffin wax and coloured using a special technique. The appearance of tannin, the shape and spreading, as well as the cell structure were analysed using a light microscope.
The analysis of the microelements in the needles was carried out for ten elements (Ca, Fe, Rb, Sr, Cu, Zn, Pb, Ni, Mn and Cr), the concentrations of which were determined by X-ray fluorescence using energetic dispersion, Energy Dispersive X-Ray Fluorescence, and the EDXRF method. The bee honey was analysed by the same method. In addition, the contents of radionuclides 7Be 137Cs and 40K were determined on the same sample by the method of gamma spectrometry.
The results collected were statistically processed by the computer program STATISTICA 6.0.
The analysis of the structure of tannins in fir-tree needles (Abies alba Mill.) showed the existence of significant differences between the sites of Risnjak and Donja Dobra. The changes in the tannin structure on Risnjak location were visible earlier than the ones on the Donja Dobra location, i.e. already in May. The biggest changes of the tannin structure were found in the epidermis, hypodermis and also in the mezzophyll and the central rib (xylem and phloem). A positive correlation between the site and stage of damage of the needles was established. The structural changes of the tannin are evident with the increase of the stage of needle damage. The differences are less significant between the years and the periods of sample on the individual locations.
The concentrations of microelements in the fir needles on Risnjak location statistically significantly differ from the one of the Donja Dobra location. All measured concentrations of the elements show higher values in the samples from the Donja Dobra location. The increase of Zn, Cu and Cr was by 1.2 times; Fe and Pb increased by 1.4 times, while the respective values of Ca and Rb were higher by 1.6 and 1.7 times. The biggest increase was found with Sr (4.2 times) and Mn (14.2 times). It can be concluded that the concentrations of manganese and strontium are best indicators for the degree of crown damage. The concentration of nutritive elements decreases proportionally with the increase of crown damage on Risnjak location. This correlation is mostly supported by Mn, Sr, Fe and Ca.
The concentration of the measured microelements in honeydew honey on both locations is approximately equal. The concentration of Pb and Cu is slightly bigger in the sample from the Risnjak location, but the concentration of other measured elements (Cr, Fe, Ni and Zn) is slightly bigger on the location Donja Dobra.
Based on the research, we can conclude that the tannins are good indicators for the observation of tree needles. Their morphological characteristics are correlated with the concentration of microelements and the stage of tree damage. The concentration of the microelements in honeydew honey did not show any significant differences between the different locations.
Ključne riječi
Hrčak ID:
21240
URI
Datum izdavanja:
31.12.2006.
Posjeta: 2.081 *