Investigation parametric diversity models in epiphytic corticolous mosses in relation to elevation changes in Caspian forests, south of Nowshahr (north of Iran)

In order to understand the distribution models of corticolous mosses (epiphytes growing on trees barks) and variations in the their abundance related to altitudinal gradients, southern forests of nowshahr were selected along a longitudinal transect from 0-2500 m.a.s.l. These forests consisted of three dominant forest types and within each type, 100 trees were selected as mosses substrata. By using parametercdiversity indices and a variety of abundance distribution models, the extent of species abundance variation and diversity of the species have been studied along the altitudinal gradient. Results showed that, in the middle layers of Hyrcanian forests, which has more precipitation, Fagus orientalis-Carpinus betulus forest types were significantly more diverse than other types including Parrotia persica-Carpinus betulus in the lower parts and Quercus macranthera-Carpinus orientalis in upper parts. The distribution model of two lower types were fitted in broken-stick model but Quercus macranthera-Carpinus orientalis which was in the upper parts was fitted in the logarithmic model.