Template-Type: ReDIF-Article 1.0
Author-Name: J. Novák
Author-Workplace-Name: Forestry and Game Management Research Institute, Research Station Opočno, Opočno, Czech Republic
Author-Name: M. Slodičák
Author-Workplace-Name: Forestry and Game Management Research Institute, Research Station Opočno, Opočno, Czech Republic
Title: Development of young substitute larch (Larix decidua Mill.) stands after first thinning
Abstract: European larch (Larix decidua Mill.) is one of the most important tree species in substitute stands of the Krušné hory Mts. (northern part of the Czech Republic). At present, young larch stands have dynamic height growth and their canopy is closing. Therefore, the proper forest treatment with respect to all functions of these stands is an urgent issue. The aim of the study is to recognise when it is possible to start with thinning and what types of thinning regimes are more suitable in larch stands with respect to their functions as substitute tree species stands. Research was conducted on experimental series Kalek established in a larch monoculture in 1999 (stand age of 12 years) at an elevation of 780 m above sea level in the category Piceeto-Fagetum oligo-mesotrophicum - Calamagrostis villosa. The presented analysis has two main parts: (a) effect of closing canopy on growth of larch - comparison of the groups of trees from border and inside rows and (b) effect of opening canopy on growth and development of young larch stands - comparison of two partial plots (500 m2 each): the one without thinning and the other with thinning (negative selection mainly from above at the age of 13 years). Comparative analyses of trees from border and inside rows showed high growth dynamics of these young larch stands, and therefore the first thinning is necessary in this stage (by 15 years of age). In spite of air pollution, the growth of experimental stands is supernormal and exceeds the data from growth tables, but 60% of individuals showed some malformations, mostly one-sided or two-sided stem curvature. Five years after the first thinning we found a significantly lower h/d ratio of mean stem on the thinned plot in comparison with the plot without thinning. On the other hand, the applied thinning had no effect (five years after realisation) on the h/d ratio of dominant trees (200 thickest trees per hectare).
Keywords: substitute forest stands, European larch, thinning, Krušné hory Mts., Czech Republic
Journal: Journal of Forest Science
Pages: 147-157
Volume: 52
Issue: 4
Year: 2006
DOI: 10.17221/4497-JFS
File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4497-JFS.html
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Handle: RePEc:caa:jnljfs:v:52:y:2006:i:4:id:4497-JFS

Template-Type: ReDIF-Article 1.0
Author-Name: J. Remeš
Author-Workplace-Name: Faculty of Forestry and Environment, Czech University of Agriculture in Prague, Prague, Czech Republic
Title: Transformation of even-aged spruce stands at the School Forest Enterprise Kostelec nad Černými lesy: Structure and final cutting of mature stand
Abstract: This paper deals with the transformation of pure even-aged forest stands to mixed and more uneven-aged stands on an example of selected even-aged Norway spruce stands in the School Forest Enterprise (SFE) in Kostelec nad Černými lesy. A forest stand where individual tree felling was used as the main method of forest stand regeneration was chosen as a conversion example. The main criterion of tree maturity is the culmination of mean volume increment of a single tree. The analyses confirmed a very high variability in the growth potential of individual trees. The potential and actual increment was strongly influenced by the stand position of tree and by crown release. These results show a high potential level of tree growth even at the age of 120 years. From 30% to 9% of all trees on particular experimental plots achieved felling maturity.
Keywords: even-aged stand, uneven-aged stand, single tree selection, final felling criteria, mean and current increment
Journal: Journal of Forest Science
Pages: 158-171
Volume: 52
Issue: 4
Year: 2006
DOI: 10.17221/4498-JFS
File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4498-JFS.html
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Handle: RePEc:caa:jnljfs:v:52:y:2006:i:4:id:4498-JFS

Template-Type: ReDIF-Article 1.0
Author-Name: R. Petráš
Author-Workplace-Name: National Forest Centre - Forest Research Institute, Zvolen, Slovak Republic
Author-Name: L. Brezina
Author-Workplace-Name: Faculty of Forestry, Technical University, Zvolen, Slovak Republic
Author-Name: J. Mecko
Author-Workplace-Name: National Forest Centre - Forest Research Institute, Zvolen, Slovak Republic
Title: Development of the primary values of yield tables of spruce in comparison with their development on permanent research plots
Abstract: Development of yield curves of mean and top height and development of mean diameter of the yield tables of spruce is compared with their development on 28 permanent research plots with 156 repeated measurements. The time gap of repeated measurements on research plots is in the range of 10-38 years. The agreement and differences in the development of model and empirical curves were examined by means of mathematical and statistical characteristics. The development of mean and top heights in the yield tables of spruce is consistent with their development on permanent research plots. Mean diameters of yield tables are systematically smaller by about 4%. Methodology of processing the concrete results is also presented.
Keywords: spruce, yield tables, yield curves, mean height, top height, mean diameter
Journal: Journal of Forest Science
Pages: 172-180
Volume: 52
Issue: 4
Year: 2006
DOI: 10.17221/4499-JFS
File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4499-JFS.html
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Template-Type: ReDIF-Article 1.0
Author-Name: F. Hájek
Author-Workplace-Name: Faculty of Forestry and Environment, Czech University of Agriculture in Prague, Prague, Czech Republic
Title: Object-oriented classification of Ikonos satellite data for the identification of tree species composition
Abstract: This paper describes the automated classification of tree species composition from Ikonos 4-meter imagery using an object-oriented approach. The image was acquired over a man-planted forest area with the proportion of various forest types (conifers, broadleaved, mixed) in the Krušné hory Mts., Czech Republic. In order to enlarge the class signature space, additional channels were calculated by low-pass filtering, IHS transformation and Haralick texture measures. Employing these layers, image segmentation and classification were conducted on several levels to create a hierarchical image object network. The higher level separated the image into smaller parts regarding the stand maturity and structure, the lower (detailed) level assigned individual tree clusters into classes for the main forest species. The classification accuracy was assessed by comparing the automated technique with the field inventory using Kappa coefficient. The study aimed to create a rule-base transferable to other datasets. Moreover, the appropriate scale of common image data and utilisation in forestry management are evaluated.
Keywords: automated image analysis, eCognition, median filters, texture, forestry management
Journal: Journal of Forest Science
Pages: 181-187
Volume: 52
Issue: 4
Year: 2006
DOI: 10.17221/4500-JFS
File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4500-JFS.html
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Template-Type: ReDIF-Article 1.0
Author-Name: Y. Lei
Author-Workplace-Name: Research Institute of Forest Resource Information and Techniques, Chinese Academy of Forestry, Beijing, China
Author-Name: S. Y. Zhang
Author-Workplace-Name: Resource Assessment and Utilization Group, Quebec, Canada
Title: Comparison and selection of growth models using the Schnute model
Abstract: Forestmodellers have long faced the problem of selecting an appropriate mathematical model to describe tree ontogenetic or size-shape empirical relationships for tree species. A common practice is to develop many models (or a model pool) that include different functional forms, and then to select the most appropriate one for a given data set. However, this process may impose subjective restrictions on the functional form. In this process, little attention is paid to the features (e.g. asymptote and inflection point rather than asymptote and nonasymptote) of different functional forms, and to the intrinsic curve of a given data set. In order to find a better way of comparing and selecting the growth models, this paper describes and analyses the characteristics of the Schnute model. This model has both flexibility and versatility that have not been used in forestry. In this study, the Schnute model was applied to different data sets of selected forest species to determine their functional forms. The results indicate that the model shows some desirable properties for the examined data sets, and allows for discerning the different intrinsic curve shapes such as sigmoid, concave and other curve shapes. Since no suitable functional form for a given data set is usually known prior to the comparison of candidate models, it is recommended that the Schnute model be used as the first step to determine an appropriate functional form of the data set under investigation in order to avoid using a functional form a priori.
Keywords: growth model, model selection, Schnute model, Meyer model, Bertalanffy-Richards model
Journal: Journal of Forest Science
Pages: 188-196
Volume: 52
Issue: 4
Year: 2006
DOI: 10.17221/4501-JFS
File-URL: http://jfs.agriculturejournals.cz/doi/10.17221/4501-JFS.html
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Handle: RePEc:caa:jnljfs:v:52:y:2006:i:4:id:4501-JFS