World Congress of Soil Science Logo 18th World Congress of Soil Science
July 9-15, 2006 - Philadelphia, Pennsylvania, USA
International Union of Soil Sciences

Tuesday, 11 July 2006

This presentation is part of 28: 1.2A Spatial, Societal and Environmental Aspects of Pedodiversity - Theater

Investigation of Relationships between Soil Chemical and Physical Properties in Relation to Forest Types and Topographic Conditions in North of Iran.

Ali Salehi Sr., Guilan University, Somesara, 1144, Iran and Ghavamodin Zahedi Amiri Sr., Tehran Univ, Imam Hossein Street, Imam Khomeinee, Somesara, Iran.

The area of the study site is about 750 hectares and it is located in the north of Noshahr, Mazandaran province/the North of Iran. To determine of forest types, square plots of 50 * 50 m (2500 m2) were established and on each plot, all trees with more than 7.5 cm diameter at breast height (dbh: 1.3 m above the ground level) were measured. The basal area for each tree species in each sample was calculated and using these variables, classification of the samples was carried out by TWINSPAN (Two Ways Indicator Species Analysis). On the base of this method four tree groups or forest types were determined. In order to select sites for soil sampling, the forest was stratified into “landform units” based on differences in altitude, slope and aspect. In this way, 82 sample plots were selected for soil profiles from the original 325 tree plots. All of the soil profiles were described and pH, soil texture, bulk density, percentage of organic carbon, total of nitrogen, phosphorous and lime were analyzed in the soil laboratory. In order to determine the most important soil characteristics varied between soil profiles, Principle Component Analysis (PCA) was used. The soils were classified based on U.S.D.A. Soil Taxonomy (key of 1998). In order to study of relationships between soil properties and variations of trees composition and topographic conditions One-way ANOVA, Deternded Correspondence Analysis (DCA) was used. The results identified there are four main forest types in the study site. Carpinus-Quercus, Carpinus-Quercus with Alnus subcordata, Fagus-Carpinus and Fagus-Tilia are the most important forest types. Among soil properties, percentage of organic carbon, C/N ratio and phosphorus in A1 horizon, soil texture, soil bulk density in A1 horizon were the most significant factors varied between forest types. Percentage of organic carbon and C/N ratio has the highest amount in Fagus-Carpinus and is the lowest in Carpinus-Ouercus forest type. The heavy soils can be finding in Quercus-Carpinus type, as the lightest soils belong to Fagus-Carpinus forest type. The amount of Phosphorus was the highest on Fagus-Tilia and there is a significant difference between forest types of Fagus-Carpinus and Fagus-Tilia on the base of it. On the other hand the results showed altitude was the most important topographic factor varied in relation to distribution of Fagus orientalis and Carpinus betulus, and also in relation to the variations of percentage of organic carbon as well as C/N ratio in the study site. The results also showed there is a positive relationship between soil moisture and distribution of Alnus subcordata. Keywords: North of Iran, Physical and chemical soil properties, tree ecological groups (forest types), PCA, DCA, and ANOVA.

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