Analysis of understory plant composition in hardwoods and conifers plantations and their relation to soil characteristics

This study aims at analyzing the understory plant species composition in relation to soil characteristics in forest plantations. For this purpose, two plantations with coniferous (Cupressus arizonica and Biota orientalis) and broad-leaved species (Fraxinus rotundifolia and Robinia pseudoacacia) along with a nearby non-forested control area were selected in Gerizeh of Sanandaj, Kurdistan province, western Iran. Random systematic method with a network dimension of 75×50 m was used for collecting soil samples and vegetation data. Canonical Correspondence Analysis (CCA) differentiated the three sites in terms of soil and vegetation parameters. Results show that the majority of samples belonging to the hardwood plantation contained high values of OC, N, Mg, sand, silt and Ca which had a positive correlation with pH. The control area, showed significant correlation with clay and bulk density. Most samples of conifer plantation, however, had the lowest OC, P, N, Mg and pH. The most abundant understory species in the broadleaf plantation were Geranium tuberosum and Vicia michuuxii, in conifer plantation Erysium billardieri and Galium vernum, and in the control area Bromus tectorum and Euphorbia denticulata.