Nurse effects of patch-canopy microhabitats promote herbs community establishment in sandy land

Seedling establishment mostly occurs beneath the canopies of shrubs which act as nurse plants. Nurse effects of patch-canopy soil microhabitats on seedling establishment of herbs were investigated by studying shrub patches in which the nurse species Artemisia ordosica was removed or kept in a comparative way. The results showed that keeping shrubs greatly increased soil moisture and soil organic carbon content, but greatly decreased soil temperature and soil bulk density. The herbs richness and individual numbers in patches with the canopy kept were significantly higher than those with the canopy removed (p < 0.05). Small shrub patches increased soil moisture and decreased the surface soil temperature more significantly than large shrub patches. Herbs richness and individual numbers in small shrub patches were significantly higher than those in large shrub patches (p < 0.05). The results suggested that small shrub patches, which acted as nurse plants, decreased soil temperature and soil bulk density, increased soil moisture, species richness and individual numbers under the canopies. Nurse plants can provide a favourable surface habitats for herbs in semi-arid sandy lands.