Changes in soil quality indicators, in adjacent protected forest and deforested lands in central Iran.
Mohammad A. Hajabbasi1, Mehdi Sharifi2, and Mohsen Sheklabadi1. (1) Isfahan University of Technology, College of Agriculture, Isfahan, Iran, (2) Agriculture and Agri-Food Canada, Potato Research Centre, PO Box 20280, Fredericton, NB E3B 4Z7, Canada
Studying land degradation through soil quality approaches, which reveals soil functioning within the ecosystem, is necessary for sustainable management of land resources. A study was initiated is central Iran to understand the changes of soil functions, resulting from exploitive management, using some soil quality indicators. Adjacent undisturbed and disturbed sites were identified in each of three study areas, including two oak forest and a cypress forest in central Iran. Soils are derived from calcareous parent material with a slope of 30-40% and classified as Typic Calcixerolls or Typic Calcixerepts (Soil Survey Staff, 1999). Soil organic carbon (OC), particular organic matter (POM), total nitrogen (TN), mean weight diameter of aggregates (MWD), bulk density (ρb) and calcium carbonate (CaCO3) of the sites in 3 depths (0-5, 5-15 and 15-30 cm) were determined. The comparison of protected and disturbed forests for measured soil quality indicators showed that deforestation was affected soil quality indicators mostly in 15 cm of surface soil and changes of indices values in deeper layer were not significant except for OC and CaCO3. Deforestation followed by cultivation or overgrazing significantly decreased OC (157.1 and 134.1%), POM% (327.1 and 147.5%), (303.5 and 204.7%), TN (81.6 and 33.7%) and MWD (87.8 and 88.4%) in 0-5 and 5-15 cm soil depths. Differences of the indices in cypress were more limited compared to the oak forest regarding to lower density and type of vegetation. Overall, organic carbon, total nitrogen and aggregate stability can be considered as some of the most important soil quality indicators which can identify the degree of soil degradation in forest soils of central Iran. Forest soils in central Iran have a relatively large potential to store organic carbon and nitrogen. This study illustrates improvement of all soil quality indicators in protected forest and the success of conservative management in this region.