Changes in soil properties under Eucalyptus relative to Pinus massoniana and natural broadleaved forests in South China

The ecological effects of eucalypt plantations (EPs) have garnered increasing attention. To understand their effect on soil quality at a landscape scale, and to determine whether soil quality parameters differ due to different stand types, we evaluated soil characteristics in twenty-one groups of EPs, Pinus massoniana Lamb. plantations (PMPs) and natural broadleaved forests (NBFs) across Guangdong Province, China. Both the physical characteristics of soil hydrology and the properties of soil nutrients in A and B horizons were determined. Results showed that, compared to NBFs, EPs and PMPs produced a shallower litter layer, reduced canopy density, higher soil bulk density, significantly lower total porosity, non-capillary porosity, total water volume, and hygroscopic water in the A horizon (P < 0.05). Moreover, total N, available K, and soil organic carbon (SOC) in EPs and PMPs were significantly lower than in NBFs. EPs and PMPs did not differ significantly in N, P or K content, but PMPs had significantly lower SOC and boron in the A horizon than EPs. Low pH and poor capacity to buffer acidification generally occurred in all cover types. Both EPs and PMPs showed a decline in soil properties relative to NBFs, but EPs and PMPs exhibited no significant difference. These results indicate that actions are needed to ameliorate the potential negative effects on soil quality in forestry plantations.