Effect of traditional conservation on woody and herbal species frequency in the mountain forests of northern Iran (Case Study: Poudeh village, Roodsar)

The aim of this study was to investigate the woody and herbal frequency and species diversity in the mountain forests of northern Iran, Poudeh village of Roodsar, over time and as a result of traditional exclosure of these forests.

The study area is located in the forests of Poudeh village, Roodsar, Guilan province. According to the traditions of the region, people protected the spots of the destroyed forest areas near their hazelnut gardens for flood prevention and personal exploitation. They do this by using stones and placing shrubs on it, or using wooden stems and barbed wires. In this area, there are many of exclosure forest spots that have been protected and enclosed by the native people. Three exclosure forest spots were selected for this study. For this purpose, plots with different conservation history including low-term enclosed forest area (Less than 40 years), middle-term enclosed forest area (More than 40 years) and reference forest area were selected and the indicators of relative frequency, relative ecological importance value and species diversity were calculated.

The results showed that with increasing the duration of forest protection, the relative abundance of beech in both strata levels increased the relative abundance of hornbeam and the amount of species diversity also decreased. The highest and lowest differences in relative abundance of beech between the two strata were observed in reference forest area and low-term enclosed forest area respectively. The ratio between the abundance of beech in the upper story to the understory for low-term enclosed forest area and middle-term enclosed forest area was 1.18 and 1.24, respectively. In the control area where the highest relative abundance of beech species (80%) was recorded in the upper floor (tree), there is a moderate relationship between the two floors (r = 0.61, p <0.001) and in short-term protection, this relationship is significant (r = 0.72, p <0.001). In the middle-term enclosed forest area (more than 40 years) with increasing the relative abundance of beech in the upper story, its relative abundance in the understory also increased significantly (r = 0.88, p<0.001).

The process of species change is a complex and time-consuming process. The results show in the evolution of the stand structure in the affected areas, medium-term protection can facilitate the formation of understory. It is recommended that middle-term enclosed forest area along with silvicultural treatment be applied to formation of understory.