|RIJEČ GLAVNOGA UREDNIKA
|THE EDITORIAL BOARD AND THE AUTHORS OF THE ARTICLES IN “FORESTRY JOURNAL” RECEIVE SOME EXCELLENT NEWS
|In July 2008, the editor of “Forestry Journal” received a letter from Thompson Scientific, Philadelphia, USA, informing him that our journal was listed in Thomson Reuters Products and Information Services from the first 2008 double issue. Starting with Number 1–2/2008, “Forestry Journal” has been indexed and abstracted in the following:
Science Citation Index Expanded (also known as Sci Search), and
Journal Citation Reports/Science Edition
The letter goes on to say that in the future “Forestry Journal” will be evaluated and included in additional Thompson Reuters products and information services for the purpose of satisfying the needs of the scientific and academic research community.
The letter was signed by Ms Marian Hollingsworth, Director of Publisher Relations.
This exciting news is of outstanding importance for our editorial board, our publisher, the Croatian Forestry Association, and the authors of scientific articles in particular. Our journal has thus gained in reputation, while the authors, by their insertion in the SCI bibliographic base receive the highest possible grade for their published articles, which is counted towards their advancement.
On behalf of the Editorial Board and the Publisher, I would like to extend special thanks to Thompson Scientific for including “Forestry Journal” in the SCI bibliographic base, as well as on the evaluation and insertion in additional Thompson Reuters Products and Information Services.
Professor Branimir Prpić, PhD
PRPIĆ, Branimir ŠL
|IZVORNI ZNANSTVENI ČLANCI
|Seletković, A., R. Pernar, A. Jazbec, M. Ančić
|UDK 630* 587 + 588 (001)
|Accuracy Of High Spatial Resolution Satellite Images Classification For Forestry Needs
|Summary: Satellite images as a source of information are becoming more significant and more often used in Croatian forestry. Data in satellite images can be obtained in two ways – by visual and digital interpretation. Choice of adequate interpretation is dependant on set goals or, more precisely, on getting enough quality information needed for certain task. Main objective of this paper was to examine, compare and find the best way to interpret IKONOS high spatial resolution satellite images, that would be simple and acceptable for operational purposes. Research was conducted in Spačva forest basin area, where largest integral pedunculate oak (Quercus robur L) forest is situated. Interest array was defined with 1 IKONOS satellite image scene (11.3 x 11.3 km) and it covers the central part of Spačva forest complex, with four forest management units: Kragujna, Otočke šume, Slavir, Vrbanjske šume. The above mentioned shooting produced IKONOS satellite image of the Spačva basin area, 132 km2 large surface, in 5 spectral channels: PAN (1 x 1 m) and 4 MS Bundle (4 x 4 m).
Visual interpretation was conducted on the created colorcomposit with three chosen spectral channels (4, 3, 2), while digital interpretation was conducted through six different algorithms, on the IKONOS satellite image. For each algorithm of the supervised classification, as well as the visual interpretation, Kappa statistics and accuracy parameters of the classification were calculated. Reference data from field research was compared to results from different satellite image classification methods to determine the level of accuracy for each classification. From these comparisons, the error matrix, which represents the base for accuracy verification, was created. Three accuracy indexes were derived from the error matrix: total, producers and users index. Last two refer to each class individually. Apart from the mentioned indexes, error matrix was also used for calculating the parameters of Kappa statistics, which enabled data generalization.
Of all the conducted interpretations (classifications), visual interpretation produced best results – results obtained this way were the closest to the actual situation in the field (field research, data from forest management plans). Conducted methods of the IKONOS satellite image supervised classification determined that the most accurate method for operational application was the feature extraction classification with natural features recognition module, in which the unclassified areas are assigned to the most similar class. This research also confirmed the facts stated by Mas and Ramirez (1996) in their studies, concerning the claims that, besides being the most used, visual interpretation method also produced the most accurate results, primarily due to the human ability to identify objects/events of interest. On the other hand, process itself lasts relatively long, because each part of the image is analysed separately, which can significantly increase the time and the costs of the analysis.
Keywords: IKONOS satellite image, visual and digital interpretation, classification accuracy, Kappa statistics, accuracy index, Spačva
SELETKOVIĆ, Ante ŠL
PERNAR, FINTIĆ, Renata ŠL
Ančić, Mario ŠL
|Pernar, N., D. Bakšić, V. Bobić, I. Perković
|UDK 630* 114.2 + 116 (001)
|Soil Condition in Microdepressions of Žutica Forest
|Summary: This work is the result of research undertaken in a polyvalent forest ecosystem situated on the edge of Lonjsko Polje Nature Park in central Posavina. The forest of Žutica is a very valuable forest management complex. Being a retention area for high waters of the River Sava, its larger part is also an oil-gas field.
The last 30 to 40 years have seen physiological weakening and dieback of single trees and groups of trees and of pedunculate oak in particular. These phenomena, resulting from the disturbed ecological balance, are associated with intensive commercial activities in the area during the period mentioned above.
The basic hypothesis is that the ecosystem has undergone complex disturbance, which is associated with the following: oil well fluid spills in the past 40 years, hydrological changes resulting from a dense road network built to serve the needs of the oil-gas field and forest management. To a lesser extent, it is also linked with hydrological and microbiological changes associated with occasional retention of floodwater.
The purpose of our research was to identify some possible causes of these occurrences from the aspect of chemical and biological soil condition. We focused on the analysis and monitoring of chemical and biological properties of the surface soil in the lowest localities (microdepressions). Phosphorus and potassium concentrations and trace elements were investigated, and so were mineral oils and total lipoidal substances, as well as microbiological activity. The research is based on twice-yearly measurements of the above parameters in 14 points in those microdepressions whose location (e.g. in relation to some possible contamination with oil well fluids), as well as the occurrence of pedunculate oak dieback has led us to conclude that they represent micro-sites most exposed to the mentioned impacts.
Although the forest of Žutica is a homogeneous area in geographic and relief terms, the surface part of the soil in this forest has proved to be physiographically highly heterogeneous. With regard to oil carbohydrates, the soil is not contaminated over larger areas. Therefore, contamination as such is not considered responsible for tree dieback over larger areas.
Permanent sources of pollution at the level of very weak contamination are associated with restored mud ditch, but they are probably not reflected on the wider Žutica area. Microbiological parameters indicate populations of adapted micro-organisms which ar The concentration of trace elements in the soil is within geogenic values, whereas some occasional anomalies occur in the locations which have been recovered after oil well fluid spills.
Key words: forest soil; contamination soil; forest Žutica
PERNAR, Nikola ŠL
BAKŠIĆ, Darko ŠL
|UDK 630* 585 + 569 (001)
|Using Second order Histograms to Estimate Relative Stand Density
|Summary: The paper continues on past research into the application of digital stand scene processing and digital ortophoto processing for the needs of forest management. Black-and-white aerial photographs obtained during cyclic surveying of the Republic of Croatia were used for this purpose at an approximate scale 1:20,000 and 60 % overlap. Research was based on the example of the management unit “Jamaričko Brdo” of Lipovljani Forest Office.
The most commonly used parameter for quantitative stand descriptions is density. Since the application of digital processing techniques of stand scenes in the last ten years has resulted in the development of new methods of stand density evaluation, an additional possibility was investigated of cyclic photograph application by constructing second order histograms and establishing their relationship with three relative density categories.
First order histograms represent a graphic display of the proportion of some numerical values in the pixels of a digital photograph. Shades of gray ranging from 0 to 225 are found on the horizontal histogram axis, and the total number of pixels with these shades is found on the vertical axis.
Texture measures calculated only by means of the first order histogram data are deficient because they do not give information related to the relative relationship between the pixels themselves.
Texture may be described by measuring the smudginess (width) of a histogram around the main diagonal. Such type of textural data does not relate only to intensity distribution (gray scale) but also to the position of pixels with the same or similar values.
Namely, instead of only one point, any pair of picture points may be observed in a similar way, whose mutual position is determined with a relation. In this case, the assumed random experiment becomes two-dimensional, and evaluation or estimation of a probability density function is obtained from a second order histogram.
This is the reason that researchers in the field of remote sensing use data obtained from second order histograms to analyze texture and perform classifications. First order histograms are less frequently used. Texture features obtained with second order histograms are used in forestry remote sensing, especially for purposes of texture classification or segmentation, but are rarely used for stand parameter estimation.
This research indicates yet another possibility of applying digital image analysis to the assessment of relative density and stand condition. Second order histograms may be used to evaluate stand density. Three basic histogram shapes were constructed which can be associated with the related density categories.
Cyclic aerial photogrammetric survey of the Republic of Croatia is an exceptionally important project for space management. Hence, the application of second order histograms in remote sensing for the needs of forestry and for forest management in particular, shows continuity of research into the use of cyclic imaging in forestry. At the same time, it is yet another contribution of forestry to this project.
According to the available literature treating this issue, research in the past generally involved histogram analysis for the purpose of automatically recognizing crowns in the images during the vegetation period. Histogram analysis, especially in pictures obtained during vegetation dormancy, i.e. when vegetation is without leaves, is a relatively new approach.
Procedures of digital picture analysis are still imperfect and cannot fully replace classical procedures. Consequently, integrating digital and visual methods in decision making (with the goal of sustainable forest management) is considered appropriate.
Key words: cyclic records; density; first and second order histograms; digital ortophoto; texture
|Ballian, D., B. Giersberg, U. Tröber
|UDK 630* 165 (001)
|Genetic Variability of Common Yew (Taxus baccata L.) in Bosnia and Herzegovina
|Summary: By biochemical markers, we analyzed the molecular genetic structure of a part of natural populations of Common Yew (Taxus baccata L.) in Bosnia and Herzegovina.
For this analysis we used the material from 6 Yew populations. The genetic variability was analyzed by usage of 6 enzyme systems, and we successfully analyzed 6 gene loci who exhibited an adequate level of polymorphism. The analysis included a total of 16 allele.
The average number of allele per locus varied between 1,83 and 2,33. By the analysis we determined that the presence of significant variability within the populations, that showed a discontinued character. A potential genotype diversity varied between 162 and 1944, and the number of potential polymorphous genetic loci varied between 66, 6 % and 83, 3 %. Gen pool diversity varied between 1,208 and 1,564, and average real heterozygosis between 0,185 and 0,490, while the overall average realistic heterozygosis was 0,281 for all populations.
Based on the obtained results as a result we can make numerous remarks that are significant for carrying out the activities at protection of the autochthonous gene fund of the Yew.
Thus, by the analysis of 6 isoenzyme gene loci there was determined the existence of statistically significant differences among the studied populations, and variability of the Common Yew that was determined have indicated discontinued variability.
The differences were determined between the populations of Ozren and other populations, including significant differentiation among them, and their genetic distances were also considerable.
The results of the analysis of the Yew from Bosnia and Herzegovina indicated the existence of specific allele in the studied populations, as opposed to the larch from central and northern Europe, which means that our larch could not be too far from its glacial stand. The populations are thus more resistant and less susceptible to degradation and drying, than the populations from the west as they possess sufficient genetic variability.
Lower value of heterozygosis of the studied populations as opposed to the populations of the Yew from Central Europe show that the studied populations were under strong anthropogenic influence, however, they did not lose much of its adaptation genetic potential. If we analyze the heterozygosis of the gene loci 6-Pgdh – A, that is quite high, points at higher level of resistance of our Yew populations.
In order to preserve natural genetic resources of Common Yew in Bosnia and Herzegovina, it is necessary to establish gene banks in situ and ex situ, which are necessary for preservation of the genetic diversity.
In the activities with larch, and in its restoration, advantage should be given to its natural rejuvenation, with permanent monitoring of its genetic structure, in order to allow timely measures for preservation of optimal natural genetic structure that is typical for each separate population.
Key words: Taxus baccata L.; isoenzymes; variability