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| Pernar, N., Vukelić, J., Bakšić, D., Baričević, D. | UDK 630* 114.4 + 188 |
| An Insight Into Genesis and Properties of Soil in the Riparian Region of North-Eastern Baranja
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223 |
| Krpan, A. P. B., Poršinsky, T. | UDK 630* 363 |
| Efficiency of Mechanical Felling and Processing in Soft and Hardwood broadleaved stands – Part 2: Efficiency of harvesters in the culture of soft broadleaf trees
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233 |
| Zečić, Ž., Krpan, A. P. B., Poršinsky, T., Šušnjar, M. | UDK 630* 375 |
| Efficiency of tractors 8090 and 9078 in shelterwood fellings of stands in Požega mountains
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245 |
| Pilaš, I., Potočić, N. | UDK 630* 561 + 116 |
| Depedence of intraseasonal variations of tree stem diameter changes, electrical resistanee of cambial zone and groundwater in common oak stand (Q. robur L.)
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255 |
Summary: This paper presents research regarding the mutual relationship between intra-seasonal variations of tree stem diameter changes, changes of electrical resistance of cambial zone (ERCZ) and groundwater oscillations. Two groups consisting of ten common oak (Quercus robur L.) trees were selected, one group with crown damage status above (healthy trees) and the other below 40 % (damaged trees). Research was undertaken in the Pokupsko Basin area. The site was selected in forest type of pedunculate oak and common hornbeam, the soil was gleic luvisol. The groundwater regime on the site is characteristic for the wider area of the Posavina region with high groundwater levels during the winter and spring seasons and low levels in summer and autumn with minimal groundwater levels below 5 m. The measurements of stem diameter changes were made by the use of a simple point dendrometer. Differences were measured on a weekly basis by vernier caliper gauge. Electric resistance of cambial zone was monitored on average basis of four longitudinal measurements by Conditiometer. The groundwater data was collected from four piezometers at numerical depths of 0.5 m, 1.0 m 2.0 m and 7.0 m. The results of measurements were analyzed by Fast Fourier analysis i.e. similarities of cyclical patterns of data of respective variables were compared. Differences in stem diameter changes of two groups of trees were analyzed by cross correlation. The results of measurements showed that cumulative growth of healthy trees was two times larger than that of damaged ones i.e 3.88 mm versus 1.85 mm. Weakly tree stem changes were 0.14 mm of the healthy and 0.07 mm of the damaged group. Electric resistance of cambial zone was lower in the healthy group of trees (7,11 kW on average) than that of the damaged group (10,09 kW). The seasonal differences of stem diameter changes were most obvious in the first half of the growth season either in quantitative relations or in the existence of weekly time lag delay of stem changes of damaged trees in respect to healthy ones. Characteristic delay of stem diameter changes in the first part of the growth season vanished in the second part due to soil water deficiency caused by decreased groundwater level below rooting zone. The seasonal pattern of ERCZ showed that the difference between the two researched groups was constant during growth season. By use of FFT (Fast Fourier Transformation), from spectral density plots identical cyclical pattern of groundwater level measured on 2.0 m depth and stem diameter changes of healthy trees were most obvious. The identical peaks of spectral density plots showed that groundwater increase with cyclical behavior of 4.4 and 5.5 measurements influenced tree stem growth and changes of ERCZ what was confirmed by the existence of the same periodicity in these variables. This research showed that by use of easy measurable variables like stem diameter changes and electric resistance of cambial zone one can achieve a quite satisfactory evaluation of tree water status and health condition. Also, to some extent, the groundwater status can be monitored and this is useful for forestry practice in drought prevention and as a control of larger hydro technical activities in lowland common oak forests.
Key words: tree stem diameter changes; electrical resistance of cambial zone; groundwater; quercus robur; crown damage |
| Popijač, M., Seletković, I., Volner, M., Lovrenčić, I., Barišić, D., Kezić, N. | UDK 630* 160 + 161 |
| Dynamics of 137Cs and 40K Movement in Silver fir Trees on Sljeme Mountain
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269 |
| Posavec, S. | UDK 630* 652 |
| Specificy of Bussines Analyses Entities in Managing with Forest and Forest Land
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279 |
| Štorga, D. | UDK 630* 582 + 525 |
| Application of GIS in Stand Extraction According to Dendrometric Parameters
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287 |
