Windthrow Effects on Biodiversity of Natural forest Ecosystem in Local Scale

Windthrow in forest ecosystems is due to different microsites creation that can be effective on biodiversity of plant elements. Canopy gaps and pit- mounds (PMs) creation are the most common microsites. Current research was considered to investigate of the effect of these microsites on diversity, richness and evenness parameters. For this purpose, twenty hectare areas considered in the Tarbiat Modares University Experimental Forest Station that is located in Mazandaran province, northern Iran. Twenty one canopy gaps with thirty four uprooted trees were found in these areas. Line transect method was used for sampling and plant abundances were also recorded in canopy gaps. Circles plots with radius of 4 meter in intersection of PMs and 20-30 meter distance far from PM position were designed for recording cover percent of herbaceous plants. The diversity parameters were significantly different in canopy gaps areas. Biodiversity indices amounts had ascending trend with increasing of canopy gaps areas. PMs were significantly effective on diversity parameters also. Diversity and evenness indices showed significantly increasing on PMs position. Richness was increased on PMs, but no significant statistically difference was considered. The obtained results are indicating windthrow is effective on plant community's dynamics, which should be considered in forest management.