Caspian Coastal Forests: Arbuscular Mycorrhizal Fungi and Understory Vegetation

Moist and temperate Caspian forests are associated with a diversity of soil types and topography. Although, natural history and ecological attributes of the Caspian vegetation is well-documented, little is known about mycorrhizae of the Caspian (Hyrcanian) flora. Samples of herbaceous plant species were collected from 4 pre-determined altitudes (-13 upto about 1500m above sea level, approximately 500 m apart from three selected areas (Javaherdeh,J; Dalkhani,D; and Tonekabon,T) in Ooctober 2014. In addition, soil samples were collected from top 30 cm and analyzed for their physicochemical properties, mycorrhizal occurrence in roots and fungal spore density and diversity. Forty nine plant species from 30 families were sampled, identified and preserved. Brachypodium sylvaticum (Huds.) P. Beauv. and Polygonum mite Schrank. had the most frequent distribution in 4 and 6 of 11 stations, respectively. Results of this research revealed that plant species distribution in different forests varied in corresponding altitudes. However, within each forest, although plant species composition varied with increasing altitude and usually one species dominated in each forest, there were no clearcut ranges between habitats in altitudinal gradients studied here. AM fungal community composition, although unique to each rhizosphere, showed great variation between stations and amongst forests as was for the plant species. Results showed Shanon-Weaver diversity indiex for fungi generally followed the same pattern for plants. Pielou’s evenness indices of fungal species did not vary significantly, but differed within stations in each forest. There was no strong correlation between fungal density and soil elements as well as pH and EC except with contents of Na and clay at lower altitudes which correlated negatively with. We established the importance of mycorrhizal fungal community in development of understory herbaceous vegetation in Caspian forests, emphasizing the importance of elevation from sea level, sodium cation exchange capacity and soil texture in plant community development.