4. Changes in the state of health of stands in the years 1999-2003

Jerzy Wawrzoniak, Jadwiga Małachowska

Fig. 2. The level of damage to stands in 2003 estimated on the basis of the defoliation level on permanent observation plots using three defoliation classes

The data point out to the improvement tendency in the state of health of forest stands in Poland. The years 2002-2003 faced an impairment of the health of forest stands in Poland - Fig. 2 and 3. However in 2003, the value of the defoliation index for the monitored species taken together did not statistically differ from that in 2002 but was statistically higher than the value in the years 1999-2001. The monitored coniferous species did not reveal such a clear tendency. In 2003, the defoliation index value for all species taken together did not statistically differ from the value in the years 2002 and 2000, however it was significantly higher than in the years 1999 and 2001. The analysis of changes in the level of health of stands over the last five years can be done by comparing the shares of healthy

Fig. 3. Differences in the level of damage to stands between 2002 and 2003 on the basis of changes in the defoliation level of stands on permanent observation plots

and damaged trees in the monitored stands in subsequent years. Taking into consideration all monitored species taken together, the share of healthy trees ranged from10.97% in 1999 to 8.10% in 2003 revealing a declining trend in defoliation level. In coniferous stands this trend of changes was similar and ranged from 10.04% in 1999 to 7.79% in 2003. The broadleaved stands revealed a slightly elevated share of healthy trees oscillating from 13.96% in 1999 to 9.08% in 2003 however with a declining tendency. The share of damaged trees for all monitored species taken together over the same period ranged from 30.28% in 2001 to 34.17% in 2003.

In 2003, this share for the coniferous stands ranged from 30.05% in 2001 to 32.69%. The share of damaged trees in the broadleaved stands was on the slightly higher level and oscillated between 30.89% in 1999 and 38.92% in 2003. The broadleaved stands revealed the tendency to decrease in the share of healthy trees.

Fig. 4. Variation in the level of damage to stands (share in classes 2 and 3) in the natural-forest regions (older stands)

The level of healthiness of stands by natural-forest regions in 2003 indicated the tendency to increase the share of damaged trees in the majority of the regions. A decrease in the share of damaged trees in 2003 was found only in the regions representing the low level of healthiness such as the Sudeten and Silesian natural-forest regions. In other natural-forest regions there was an increase in the level of damage to stands when compared with the year 2002 (Fig. 4).




An increase in the level of damage to stands took in all monitored species. However, the defoliation index value in 2003 did not show significant differences when compared to 2002. In pine stands significant differences concerned the years 2001 and 1999, while in birch stands - to the years 2001, 2000 and 1999. The year 2003 saw a steady decline in the level of damage to stands in the Sudeten and Silesian natural-forest regions as compared to 2002, whereas it increased in the Mazowsze-Podlasie, Mazury-Podlasie, Wielkopolska-Pomerania, Carpathian and Małopolska regions.

  Raport 2003