Template-Type: ReDIF-Article 1.0 Author-Name: M. Fabrika Author-Workplace-Name: Faculty of Forestry, Department of Forest Management and Geodesy, Technical University in Zvolen, Zvolen, Slovak Republic Author-Name: J. Ďurský Author-Workplace-Name: Faculty of Forestry, Department of Forest Management and Geodesy, Technical University in Zvolen, Zvolen, Slovak Republic Title: Algorithms and software solution of thinning models for SIBYLA growth simulator Abstract: 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 tree thinning, target diameter thinning, target frequency (equilibrium) curve thinning, clear cutting, and thinning by list (interactive thinning). A software solution of the algorithms, and an example of different thinning concepts for selected forest stands is presented at the end of the paper along with a discussion about the advantages and disadvantages of the thinning model compared to the SILVA 2.2 model. Keywords: tree growth models, thinning engine, thinning concepts, forest modeling Journal: Journal of Forest Science Pages: 431-445 Volume: 51 Issue: 10 Year: 2005 DOI: 10.17221/4577-JFS File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4577-JFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/jfs-200510-0001.txt Handle: RePEc:caa:jnljfs:v:51:y:2005:i:10:id:4577-JFS Template-Type: ReDIF-Article 1.0 Author-Name: L. DRÖßER Author-Workplace-Name: Institute of Silviculture, University of Göttingen, Göttingen, Germany Author-Name: B. Von Lüpke Author-Workplace-Name: Institute of Silviculture, University of Göttingen, Göttingen, Germany Title: Canopy gaps in two virgin beech forest reserves in Slovakia Abstract: 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 death of 80 trees over the last 40 years. Such large gaps are scarce. 85% of the gaps are smaller than 250 m2. A correction of the bias towards the over-abundance of large gaps by line-transect sampling was made by estimating the percentage area of gaps of different size from the percentage length along the transects. In Havešová an attempt was made to date the death of trees that were still visible in the gaps. 1/5 of the trees initiated gaps by their death, while 4/5 of the trees extended gaps. While uprooted trees dominate in Havešová, breakage is most common in Kyjov. Keywords: natural disturbance, gap size distribution, gap formation, European beech Journal: Journal of Forest Science Pages: 446-457 Volume: 51 Issue: 10 Year: 2005 DOI: 10.17221/4578-JFS File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4578-JFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/jfs-200510-0002.txt Handle: RePEc:caa:jnljfs:v:51:y:2005:i:10:id:4578-JFS Template-Type: ReDIF-Article 1.0 Author-Name: M. Barna Author-Workplace-Name: 2 Author-Name: J. Machava Title: Influence of stand density on Zn and Cu concentrations in beech leaves Abstract: 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 on the concentrations of the analysed elements, their total amounts (depending on the relevant amounts of leaves on the plots) and their amounts in leaves of unit trees. This paper is a continuation of the previous work focussed on Mn and Fe concentrations in beech leaves. Keywords: Fagus sylvatica L., leaf, concentration, zinc, copper, shelterwood cutting Journal: Journal of Forest Science Pages: 458-467 Volume: 51 Issue: 10 Year: 2005 DOI: 10.17221/4579-JFS File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4579-JFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/jfs-200510-0003.txt Handle: RePEc:caa:jnljfs:v:51:y:2005:i:10:id:4579-JFS Template-Type: ReDIF-Article 1.0 Author-Name: S. P. Sah Author-Workplace-Name: Department of Forest Ecology, University of Helsinki, Helsinki, Finland Title: 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 Abstract: 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) and this is explained by the presence of marked NO3- leaching at the Solling site. Although the annual trends (1990-1994) of N concentration in the foliage of spruce trees remained almost constant, their δ15N values significantly decreased with the increasing years of sampling. The 15N-depletion in spruce needle litter from 1990 to 1995 was by 2.0‰. This is explained by a slight decrease in N deposition at Solling site during this period. Keywords: N-deposition, 15N, nitrogen, spruce, soil Journal: Journal of Forest Science Pages: 468-475 Volume: 51 Issue: 10 Year: 2005 DOI: 10.17221/4580-JFS File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4580-JFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/jfs-200510-0004.txt Handle: RePEc:caa:jnljfs:v:51:y:2005:i:10:id:4580-JFS Template-Type: ReDIF-Article 1.0 Author-Name: D. Qiu Author-Workplace-Name: School of Life Science, Xiamen University, ADD TOWN, China Author-Workplace-Name: College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, China Author-Name: P. Lin Author-Workplace-Name: School of Life Science, Xiamen University, ADD TOWN, China Author-Name: J. Su Author-Workplace-Name: School of Life Science, Fujian Agriculture and Forestry University, Fuzhou, China Title: Relationship of leaf ultrastructure of mangrove Kandelia candel (L.) Druce to salt tolerance Abstract: 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 density of cells was lower than that in control plants. In plants treated with 50‰ salinity the nucleus collapsed and no structure of the nucleus could be observed. As far as chloroplasts in control plants were concerned, they were oblong with a typical arrangement of grana and stroma thylakoids and one or two grains of starch. However, the chloroplasts in plants treated with 25‰ salinity were swelling and usually contained more grains of starch and few plastoglobuli. Most chloroplasts had a reduced number of grana, particularly of thylakoids in grana as compared with control plants. The chloroplasts of plants treated with 50‰ salinity had a considerably reduced system of grana and stroma thylakoids, and sometimes they were even defor-med morphologically. They were mixed-up and contained more grains of starch and plastoglobuli. The indistinct structure of mitochondrial cristae was observed only in plants treated with 50‰ salinity. These showed that mitochondria are cell organs less sensitive to hypersaline conditions than chloroplasts and nucleus, and it was deduced that respiration was more conservative to an environment change than photosynthesis. Keywords: Kandelia candel (L.) Druce, salt stress, mesophyll cell, ultrastructure Journal: Journal of Forest Science Pages: 476-480 Volume: 51 Issue: 10 Year: 2005 DOI: 10.17221/4581-JFS File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4581-JFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/jfs-200510-0005.txt Handle: RePEc:caa:jnljfs:v:51:y:2005:i:10:id:4581-JFS