The effect of pure and mixed shrub cover of Crataegus on variability of soil characteristics and microbial respiration dynamic

The canopy of woody species is one of the most important components of rangeland ecosystems. The genus Crataegus spp. is the dominant shrub covers of rangeland habitats in the north of the country. From the habitat point of view, the presence of this plant in rangeland can be seen as an almost pure canopy or mixed with other shrub species. In the current study, the effect of different land covers [i.e. Crataegus melanocarpa M. B., Berberis integerrima Bunge., Ribes Uva – crispa L. and Prunus spinosa L. (CM-BI-RU-PS); Crataegus melanocarpa M. B., Berberis integerrima Bunge and Ribes Uva – crispa L. (CM-BI-RU); Crataegus melanocarpa M. B. and Berberis integerrima Bunge (CM-BI), and pure Crataegus melanocarpa M. B. (CM)] on variability of soil characteristics and microbial respiration dynamic, in the Kinj region of Mazandaran Province, was considered. In each of the land covers, 15 soil samples (0-10 cm depth) were collected and transferred to the laboratory. The amounts of soil organic matter, bulk and particle densities, texture, aggregate stability, coarse and fine root biomass were measured. In order to determine the changes in soil moisture, temperature and microbial respiration, sampling was carried out in the middle months of each season. The highest amount of soil organic matter was observed in CM-BI-RU-PS and CM-BI-RU habitats. Pure CM habitat had the highest value of bulk density, while the lowest value of this characteristic was assigned to CM-BI-RU-PS and CM-BI-RU habitats. CM-BI-RU-PS and CM-BI-RU habitats had the highest soil porosity. The CM-BI-RU-PS shrub cover has the most aggregate stability, and with the decrease in the diversity of shrub species, their stability decreased significantly. The highest amount of sand content was assigned to the pure CM habitat and the highest amount of clay was allocated to the CM-BI-RU-PS shrub cover. The highest coarse root biomass was observed in CM-BI-RU-PS and CM-BI-RU, while the fine root biomass was the highest in CM-BI-RU-PS. The characteristics of soil moisture, temperature and microbial respiration have shown statistically significant differences in different seasons of the year and also pure and mixed Crataegus covers. The highest soil moisture values were observed in the soil of CM-BI-RU-PS and CM-BI-RU habitats and winter season, while the highest soil temperature was assigned to the summer season and pure CM habitat. Soil microbial respiration was also higher in the summer season and CM-BI-RU-PS and CM-BI-RU habitats than other seasons and land covers. According to principal component analysis (PCA), the amount of organic matter, moisture content, and soil porosity in CM-BI-RU-PS and CM-BI-RU habitats have an effective role in soil microbial respiration of this type of land cover compared to other habitats. The results of this research confirm that the presence of species diversity in land cover can lead to the protection of soil quality indicators. In this regard, it is suggested to use other native shrub species in addition to Crataegus for the restoration of degraded rangeland in the study area as well as areas with similar ecological conditions.