The effect of woody plants on the understory soil parameters is different between grazed and ungrazed areas

Facilitative role of woody plants often modifies understory soil parameters. However, the effect of individual shrubs on soil qualitative parameters could be variable in the grasslands depending on the presence of grazing, and little is known about how facilitative interactions between woody plants and soil change with grazing. Therefore, in this study, we compared the conservative role of woody plant species on soil between grazed and ungrazed areas. Soil samples were collected beneath (patch) and outside (interpatch) of the canopy of Crataegus pseudomelanicarpa in grazed and ungrazed areas in the autumn. The content of total nitrogen (TN), total carbon (TC), particulate organic matter (POM), moisture and soil aggregate stability were compared between patch and interpatch in both grazed and ungrazed areas. Generally, the results showed that the main effects of the woody species were significant on the soil parameters (p < 0.05). The presence of the woody species in both grazed and ungrazed areas improved the values of all understory soil qualitative parameters. However, soil parameters such as POM, TC and TN were significantly higher in the patch (24.43 gr/kg, 1.53% and 0.20%, respectively) than in interpatch (15.41 gr/kg, 1.35 and 0.14%, respectively) in the grazed area, while in the ungrazed area, these differences were less pronounced or not significant between patch (26.00 gr/kg, 1.43 and 0.18%, respectively) and interpatch (19.10 gr/kg, 1.43 and 0.15%, respectively). We conclude that the nursing role of woody plants on soil in the degraded grasslands is more important when associated with grazing and should be considered in the restoration projects.