Frequency of tree micro-habitats in Persian ironwood- hornbeam forest at Bahramnia forestry plan (Gorgan)

In recent years the protection of biodiversity became an important goal in forest management and caused some conservative management approaches such as creating managed areas or areas in which no management has been implemented. In the past decade habitat trees came under focus. Micro-habitats are structures on dead or alive trees in the forest including changes such as wounds and fractures caused by biological process and provide places for forest living organisms. Nowadays the necessity of habitat trees protection has been emphasized in forest management and policy. This study aimed to assess the diversity and frequency of tree micro-habitats in Persian ironwood- hornbeam forest stands at Bahramnia Forestry Plan (Gorgan).

Therefore for assessing the trees’ micro-habitats 4 square sample plots each one with the area of 2500 m2 were selected and allometric characteristics (diameter and height) of all trees with the diameter more than 7.5 cm were recorded. Then according to an instruction the type and abundance of micro-habitats were assess and recorded for all trees. A binocular was used for assessing the micro-habitats located on top of the tree crown and their upper trunk. The habitat value as well as economic value of all trees have been calculated using Integrate+ software. Correlation test was used to assess relationship between occurrence and frequency of micro-habitat with quantitative characteristics of all trees.

The result showed that the studied stand is an uneven-aged stand and Persian-ironwood tree species is the most abundant tree species within it. The hornbeam trees have the highest average diameter and height, as well as the highest diversity and frequency of micro-habitats. The most frequent micro-habitats observed on the trees were EP, GR and CV. The result of correlation test showed a significant relationship between tree diameter and micro-habitats abundance. By increasing in the tree diameter the number of micro-habitats significantly increased.

Totally the results of this study show that there are different kinds of micro-habitats in the studied forest stands. Also the tree diameter is one of the factors that affects micro-habitats’ abundance. Therefore it is of importance to maintain some of the high diameter trees in the forest stand. Understanding the effective factors on occurrence and abundance of the micro-habitats can be an important help in protecting forest biodiversity. Studies on habitat trees in Iran’s forest ecosystems (particularly Hyrcanian Forests) is rather a new issue which can be an effective help for better understanding of the other functions of these ecosystems, especially ecosystem services and increasing biodiversity.