The Effect of Canopy Gaps on Biodiversity of Herbaceous Species in an Oriental Beech ( Fagus orienatlis Lipsky) Stand

摘要

This study was conducted to investigate the diversity of herbaceous species in harvest-created gaps and its comparison with the adjacent closed stands in beech forest of Alandan, compartment No. 3 and 4 (Mazandaran, Iran). To achieve this purpose, 16 gaps were selected including 4 classes of gap size with 4 replicates for each. In the centre of each gap and its cardinal points as well as the adjacent closed stands, sub-plots of 2/5x2/5 m size were placed and then the number of herbaceous species and beech seedlings was counted. Some features of overstory beech trees in the cardinal points of gap edge were measured. The results revealed that there was no significant difference between gaps in terms of diversity, richness and evenness indices. Moreover, the t-test indicated that there was no significant difference between gaps and the adjacent closed stand in terms of most diversity indices. The Pearson correlation results pointed that there is positive significant correlation between Simpson and Shanon-Wiener indices with crown radius toward gaps and also Margalef richness index with length of crown and crown radius toward gaps. In general, it can be stated that there is no difference among harvest- created gaps by single-tree selection method and its comparison with unharvested stand in regard to biodiversity indices of herbaceous species after 8 years of harvesting.