ارتباط بين گروه هاي اكولوژيك گياهي در آشكوب علفي با عوامل رويشگاهي (مطالعه موردي : جنگل هاي ميان بند نكا)

Relationship Between Plant Ecological Groups in Herbal Layer and Forest Stand Factors(Case Study: Neka Forest, Iran)

In order to identify the plant ecological groups and to determine their distribution patterns in relation to soil physical and chemical characteristics and physiographical-features, vegetative elements and some soil properties were analyzed in submountain forest in north of Iran. This research was conducted in an area of 8 hectares at the altitiude of 690-800 meters above sea level in Neka forests. For identification and classification of vegetation cover, 214 grid plots of 100 m2 were chosen on the basis of Braun-Bianquet combined abundance-cover scale. Plant ecological groups were determined on the basis of vegetation data analysis (i.e., TWINSPAN) and ordination analysis (i.e., DCA) methods. Geographic information system (GIS) was used for mapping plant ecological groups and Digital Elevation Model (DEM). Comparison between plant ecological groups and slope, aspect and elevation maps showed that significant differences existed between plant groups and aspect, but there was not any significant relation between plant groups and slope or elevation. Ordination analysis was carried out using DCA in order to find out the floristic composition of ecological groups and samples. To investigate the relationship between ecological plant groups resulted from TWINSPAN method and physical-chemical characterizations, soil samples were selected from organic horizons and mineral layers. Soil characteristics including organic matter, moisture, lime) bulk density, C, N, P and K were used for analysis by PCA method. Results of PCA analysis indicated that the first group, namely Parrotia persica, Cerasus avium and Ficus carica, was related to soil physical properties. The second group, including Danae racemosa, Asplenlum adiantum-nigrum and Cardamine impatiens, corresponds to soil fertility, particularly soil chemical propeties. The third group, including Diospyrus lotus and Oplismenus undulatifolius and also the fourth group, Cyclamen coum, Lamium album and Galanthus transcaucasicus, were related to soil fertility.