The effect of different canopy composition of shrublands on soil quality indicators in a semi-arid climate of Iran

Abstract

Mountain shrublands in semi-arid regions have a prominent role in regulating ecosystem services. Crataegus is a shrub distributed in wide areas of mountain semi-arid zones of the world. However, the effect of shrublands on soil quality indicators, especially fertility and biological activities, is poorly studied. In this study, the effect of various land covers with Crataegus melanocarpa M. B. (CM), Berberis integerrima Bunge. (BI), Ribes Uva – crispa L. (RU) and Prunus spinosa L. (PS) on soil quality indicators in Kinj region of northern Iran were investigated: 1) CM-BI-RU-PS; 2) CM-BI-RU; 3) CM-BI, and 4) pure CM. Soil samples were taken from 0 to 10 cm depth from each land cover as well as organic material (litter) and root samples. All samples were subjected to physical, chemical and biological analysis for soils and chemical analysis for litter and roots. The results showed that litter thickness under pure Crataegus (6.31 cm) was 4–53% higher than in mixed (2.95–6.05 cm) land covers. The soil fertility and biological characteristics were also lower by about 50% under the pure Crataegus than in the mixed shrublands. Based on principle component analysis (PCA), different land covers can be distinguished from each other based on litter, soil and root characteristics. In this regard, the first and second axes explained 36.86 and 16.40% of the total variance, respectively. PCA output showed that habitats with higher litter quality (i.e., higher values of N), and high soil fertility and biological activity belonged to CM-BI-RU-PS and CM-BI-RU land covers. Conversely, CM-BI and pure CM covers have poorer litter quality (i.e., higher values of C and C/N ratio) and lower levels of soil fertility indicators and biological activities. The results of this research indicate that the diversity of land cover in Crataegus ecosystems in semi-arid areas can maintain soil quality and create hotspots of soil quality indicators. Based on this, it is recommended to pay more attention to species diversity in order to restore degraded habitats in similar ecosystems, thus is important planting companion shrub species in addition to Crataegus.