Soil function can sensitively respond to different canopy composition of Crataegus and Berberis

Abstract

Mountainous sites can only grow a limited variety of vegetation types due to their fragile soil conditions. In the north of Iran, mountainous sites are commonly occupied by Crataegus and Berberis shrubs, which are natively distributed in Asia, Europe, North America and Africa. Despite the widespread distribution of these two species, the effect of pure and mixed canopy composition of these species on soil fertility and microbial activities (as soil function indicators) has not been considered. In this paper, five types of canopy composition have been studied for their effect on soil function; including pure Crataegus (PC), and pure Berberis (PB), as well as mixed Crataegus and Berberis with almost equal canopy cover (50C:50B), Crataegus-dominated stand (70C:30B), and Berberis-dominated stand (30C:70B). A total of 225 soil samples (5 plant types × 15 samples × 3 soil depths including 0–10 cm, 10–20 cm and 20–30 cm belowground) were taken from the field, transferred to the laboratory and analyzed. PCA results showed a difference in the soil characteristics between the canopy composition types, with the first and second axes justifying 46.67% and 14.12% of the total variance, respectively. The 50C:50B mixed canopy composition resulted in soils with higher values of soil organic matter fractions (i.e. particulate and dissolved C and N), C and nutrient (N, P, K, Ca and Mg) pools, and soil microbial (i.e. respiration and biomass) and enzyme (urease, acid phosphatase, arylsulfatase and invertase) activities, especially in the topsoil (0–10 cm). Soil function indicators decreased in ranked order of 70C:30B > 30C:70B > PC > PB plant types. As a conclusion, it can be stated that the equal ratio of Crataegus and Berberis can enhance soil function and create fertile islands in the high altitudes of natural ecosystems.