Journal of Forest Science, 2005 (vol. 51), issue 10
Algorithms and software solution of thinning models for SIBYLA growth simulator
M. Fabrika, J. Ďurský
J. For. Sci., 2005, 51(10):431-445 | DOI: 10.17221/4577-JFS 
The paper deals with a proposal for a thinning model for the growth simulator SIBYLA. The model is based on an analytical-causal modeling approach. Some partial theorems are tested on experimental data from thinning sample plots. The model is composed of the following components: the model of bio-sociological tree status, the model for score of existence, the model for type of selection, the model for amount of thinning, and the aggregated model of the thinning concept. The appropriate combination of type and amount of thinning allows the user to perform the following thinning concepts: thinning from below, thinning from above, neutral thinning, crop...
Canopy gaps in two virgin beech forest reserves in Slovakia
L. DRÖßER, B. Von Lüpke
J. For. Sci., 2005, 51(10):446-457 | DOI: 10.17221/4578-JFS
The formation, size distribution and percentage of gaps in two virgin deciduous forests are presented in two case studies. Gaps are defined as openings in the canopy above 2/3 of stand height. These gaps comprise 16% of the forest area in Havešová Reserve and 14.6% of the forest area in Kyjov Reserve. The estimated turnover time is 220 years. More than half the gaps were caused by the death of one tree, and 80% of the gaps were due to the death of up to 3 trees. The largest gap in Havešová Reserve was 0.40 ha, resulting from the death of 56 trees over the last 40 years. The area of the largest gap in Kyjov Reserve was 0.44 ha. It was caused by the...
Influence of stand density on Zn and Cu concentrations in beech leaves
M. Barna, J. Machava
J. For. Sci., 2005, 51(10):458-467 | DOI: 10.17221/4579-JFS
The paper deals with the response of leaves in a beech stand to opening after shelterwood cutting of various intensity (stocking of 0.3, 0.5, 0.7, 0.9) performed in 1989. The research was running in 1996-1997, on dominant, codominant and subdominant sample trees representing the mean stand diameter on all the examined plots. The obtained data were compared separately for the leaves from the upper, medium and lower crown thirds. In some cases, there has been confirmed statistically significant influence of the cutting strength and other studied factors on Zn and Cu concentrations - at a significance level of α = 0.05. We found significant influence...
Isotope ratios and concentration of N in needles, roots and soils of Norway spruce (Picea abies [L.] Karst.) stands as influenced by atmospheric deposition of N
S. P. Sah
J. For. Sci., 2005, 51(10):468-475 | DOI: 10.17221/4580-JFS
This study aims to investigate the changes in isotope ratios in foliage and soils of two Norway spruce (Picea abies [L.] Karst.) forests greatly differing in their atmospheric N deposition and climatic conditions. As expected, both N concentrations and δ15N values in needles and roots were found to be significantly higher in the Solling stand (N-saturated) compared to the Hyytialä stand (N-poor). For both stands a typical vertical gradient of the soil 15N-enrichment was observed. As expected, the soil of N-polluted site (Solling) was 15N-enriched significantly more than that of N-limited site (Hyytialä)...
Relationship of leaf ultrastructure of mangrove Kandelia candel (L.) Druce to salt tolerance
D. Qiu, P. Lin, J. Su
J. For. Sci., 2005, 51(10):476-480 | DOI: 10.17221/4581-JFS
The leaf ultrastructure of mangrove Kandelia candel (L.) Druce planted in pots under different salinity conditions was compared under a transmission electron microscope (TEM). The results showed that the plasmalemma in plants grown in salinity conditions of 0‰ treatment (control) and 25‰ treatment was tightly combined, while in plants with salinity of 50‰ treatment, the plasmalemma crimpled remarkably and plasmolysis occurred. The nucleus and its two-layer membranes were obvious in control plants. In the case of 25‰ treatment, the membrane breakdown was observed, nucleoplasm dispersed in cytoplasm, and the electron...