Effects of human disturbance on understory species diversity and soil physicochemical properties in Eucalyptus grandis plantation

The effects of human disturbance with different intensities (L: mild disturbance, M: moderate disturbance & H: severe disturbance) on species diversity and soil physical and chemical properties of Eucalyptus grandis plantation in Cangping Mountain Park, Ya'an, Sichuan Province were studied. The results showed that a total of 75 species of vascular plants were recorded, belonging to 52 families and 71 genera. There was no significant difference in species diversity index of shrub layer (P>0.05). With the increase of disturbance intensity, the species diversity index of shrub layer decreased first and then increased, and the species diversity index of herbaceous layer decreased first and then increased, and the contents of total nitrogen, available phosphorus, organic matter, available potassium and total potassium all decreased. The contents of pH values, total nitrogen, total phosphorus, available potassium and total potassium were closely related to the species diversity of the herbaceous layer. The diversity index of the shrub layer was significantly negatively correlated with water content.