Natural Changes in Stand Structure in the Permanent plot of Hyrcanian forests (North of Iran)
By: M. Amini, K.H. Saghebtalebi, R. Amini, S.H. Amini
Key Words: Beech, Dead wood, Permanent sample plot, Stand, Structure.
J. Bio. Env. Sci. 8(5), 62-74, May 2016.
This research was aimed to investigate natural changes in stand structure of Hyrcanian forests. Forest structure, proportion of dead wood, and proportion of tree species were studied in 2006 and 2012. Results of the inventory of total 2375 trees in 2012, showed 3 layers and uneven-aged structure in a forest type of Fagus orientalis-Carpinus betulus. Other results are as following: mean tree number 389 ha-1, mean basal area 43 m2ha-1, mean stand volume 538 m3ha-1, and De’ Liocourt factor is 1.38. Dead trees were counted about 3.1% of the tree number and 5.7% of the stand volume. Comparison of the two inventories showed that beech trees are gaining more proportion among the tree species in almost all diameter classes, while hornbeam is losing more presence in the diameter classes. In DBH classes lower than 30 cm the proportion difference between beech and hornbeam is more obvious. Volume of damaged trees (broken, hollow, snag and log) was counted about 97 m3ha-1; while for dead woods was 30.6 m3ha-1. Within the six years of study, the hollow large trees have been fallen down. Dying of trees in DBH classes of lower than 50 cm provides a lot of scattered small gaps within the stand and caused establishment of younger individuals and cohorts. Almost 9.6 m3ha-1, comprising 1.6% of total volume, 28% of dead tree and 8.9% of damaged trees, was decomposed. In general view this forest is tending from the senility to juvenility in forest succession.