## 3 Results
### Isolation of Permanent Forest Areas  
During the comparison of forest cover areas that were present at different times in GIS program, constant forest cover areas were determined where a forest cover was without any interruptions during the period of 19 th-21 st centuries. This means that no economic-anthropogenic activity was ever carried out in those areas, and tree massifs grew there throughout the period. Layers of forest cover present at different time periods were uploaded into the ArcGIS software package and permanent forest areas were isolated using the polygon overlay method. The sizes of permanent areas of the area of the eldership (as percentages) are presented in Table 18.  
Figure 21: The ratio of forest cover/non-forest cover in slope ranges in elderships of Jurbarkas District: (**a**) 2 nd half of the 19 th century, (**b**) 1 st half of the 20 th century, (**c**) 2 nd half of the 20 th century. Figure 22: Distribution of forest cover/non-forest cover in Jurbarkas District: (**a**) 2 nd half of the 19 th century, (**b**) 1 st half of the 20 th century, (**c**) 2 nd half of the 20 th century. The permanent forest areas in the elderships make up 2.2-57.6% of the area of these elderships. Viesviles eldership has the largest area--57.6%, and the area in the rest of the elderships ranges from 2.2% to 23.1%. The average is 18.5%. Permanent forest areas make up 22.6% of the area throughout Jurbarkas District. The layer of permanent forest areas is divided into polygons according to the attribute data, the age of the trees, by overlaying the cadastral data layer with the use of the ArcGIS program. The applicable age ranges are the same as in Section 2.4. The area of these polygons was calculated (as a percentage) of the total area of permanent growth areas in the elderships (Table 19). \begin{table}
\begin{tabular}{c c} \hline
**Elderships** & **Area of Forest, \%** \\ \hline Erzvilkas & 11.5 \\ Girdziai & 23.1 \\ Juodaiciai & 2.2 \\ Jurbarkai & 36.6 \\ Jurbarkas city & 3.8 \\ Raudone & 11.0 \\ Seredzius & 12.2 \\ Skirsnemune & 16.0 \\ Smalininkai & 8.9 \\ Simkaiciai & 16.1 \\ Veliuona & 23.0 \\ Viesvile & 57.6 \\ Jurbarkas Distr. & 22.6 \\ \hline \end{tabular}
\end{table} 
Table 18: Permanent forest areas. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline
**Age of Trees, in Years** & **CrCriteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** & **Criteness** \\
20–39 & 20.4 & 31.2 & 19.7 & 19.7 & 0 & 24 & 16.1 & 3  
Analysis of the obtained data shows that an urbanized area--the City of Jurbarkas--stands out in the obtained results. It is dominated by areas of trees older than 80 years old in its permanent growth areas. This can be explained by the fact that mature trees were preserved in the city, but new areas were not planted, using city areas for other purposes. A fairly clear process of felling/planting of forest trees can be seen in the non-urbanized areas--trees 0-5 years old account for as much as 4.4-18.1% of the total area of growth areas. Bearing in mind that such changes took place over a period of 5 years, it can be said that quite intensive deforestation is taking place. If Viesvile eldership is eliminated from the research results, which, like the urbanized territory of the City of Jurbarkas, stands out from the general trends, the deforestation in the permanent growth areas over the last 5 years amounts to 7.4-18.1%. It is interesting that in the age group of 6-9 years, no such large areas of former logging were observed. The area of trees of this age is only 0.2-5.5%. Further examination of the distribution of forest areas according to the age of the trees growing in them shows that the largest areas of permanent forest cover are in age groups of 10-99 years. The areas of planted/grown trees make up 0-27.4% of the total forest cover area during these periods.