Effect of Disturbance Intensity of Canopy Gap in Forest Stands on Seed Germination of Beech (Fagus orientalis) and Hornbeam (Carpinus betulus) Trees at Hyrcanian Forest

To understanding of effect of canopy gap disturbance on quantity and quality of seed germination of forest trees, seeds of two economic trees in Hyrcanian forest including Fagus orientalis and Carpinus betulus were collected from some canopy gaps with different sizes and their germination parameters were studied. In this regard, 48 canopy gaps were identified from a mixed Fagetum stand at Hajikola-Tirankli forestry plan from Tajan River watershed. In the following, the canopy gaps were classified to three difference size classes such as smaller than 150 (small), 150-350 (moderate) and 350-500 m2 (large) and the seeds of the Beech and Hornbeam were collected from inside and outside of the canopy gaps and seed germination test were done on the collected seeds. Seed germinant percent, germination speed and mean seed germination time were calculated and then statistically analyzed. Comparison of the collected data showed that there is no considerable difference between natural and artificial canopy gaps in aspect of seed germination parameters while for both species, collected seeds from moderate and large canopy gaps had higher seed germination and sometimes germination speed. It seems that optimal environmental condition such as moisture, temperature and light is better provided in canopy gaps bigger 150 m2 for seed germination of both species. Same research would be suggested on the other tree species.