Comparison of regeneration and diversity of herbaceous species in created and natural gaps

In order to comparing the regeneration and diversity in natural and created gaps, all of the gaps in two compartments in Asalem forests were identified and divided into three categories: small gaps (2), medium gaps (200-500 m2), and large gaps (>500 m2). Seven plots with an area of 4m2 (2m×2m) were taken in each gap. The number of individuals of tree seedlings and saplings were recorded and coverage percent of herbaceous species were estimated in each plot based on extended Braun - Blanquet cover - abundance scale. In addition to counting the number of species, diversity indices including Simpson (1-D) and Shannon-Wiener (H') and Smith- Wilson’s evenness indices were calculated. The Kolomogrov-Smirnov test was used to study the normality of data and then one-way ANOVA test was performed using SAS software. Totally 38 natural and 30 created gaps were identified. The results revealed that mean of each gap size was 371 m2. There were no significant difference between the size of natural and created gaps but the number and total regeneration were significant differences among natural and created gaps. The least abundance of seedlings were obtained in the small gaps. Also diversity indices had maximum in the created gaps.