Annual changes of oak decline in the forests of Kurdistan province

One of the environmental problems of the Zagros forests, is the occurrence of oak decline phenomenon in Zagros Forest. The intensity of oak decline in the North Zagros is slower than in the Middle and South Zagros. The purpose of this study was to investigate the trends of oak decline in forests of Baneh city from 2019 to 2020.Four sites including Belveh and Gandman (southern aspect) and Saraki and Mirhesam (northern aspect) were selected and 100 trees were evaluated in each site. Oak decline status was recorded during two years of research in five classes: healthy trees, dieback in crwon, dieback up to 50%, dieback more than 50% and standing dead tree. Wilcoxon and Friedman (non-parametric tests) were used to compare the decline codes at each site for two consecutive years and to compare the decline codes at four sites per year (separately). The results showed that the greatest change of oak decline class was in Saraki site (with 0.27 change). At all four sites, the trees were shifting to oak decline classes in the second year of the research, and the change in oak decline classes at each site for two consecutive years (Wilcoxon test) was statistically significant. Besides, the change of dieback trees (dieback and dieback up to 50%) from 24% of trees in 2019 to 44% of trees in 2020 had changed. Most oak decline was observed on the southern aspect. Overall, it is suggested that human intervention be controlled.