Changes in soil quality after converting iPinus/i to iEucalyptus/i plantations in southern China

摘要

Vegetation plays a key role in maintaining soil quality, but long-termchanges in soil quality due to plant species change and successive plantingare rarely reported. Using the space-for-time substitution method, adjacentplantations of Pinus and first, second, third and fourth generations ofEucalyptus in Guangxi, China were used to study changes in soil quality caused byconverting Pinus to Eucalyptus and successive Eucalyptus planting. Soil chemical and biologicalproperties were measured and a soil quality index was calculated usingprincipal component analysis. Soil organic carbon, total nitrogen, alkalinehydrolytic nitrogen, microbial biomass carbon, microbial biomass nitrogen,cellobiosidase, phenol oxidase, peroxidase and acid phosphatase activitieswere significantly lower in the first and second generations ofEucalyptus plantations compared with Pinus plantation, but they were significantly higherin the third and fourth generations than in the first and secondgenerations and significantly lower than in Pinus plantation. Soil total andavailable potassium were significantly lower in Eucalyptus plantations (1.8–2.5 g kg?1and 26–66 mg kg?1) compared to the Pinus plantation (14.3 g kg?1 and92 mg kg?1), but total phosphorus was significantly higherin Eucalyptus plantations (0.9–1.1 g kg?1) compared to the Pinus plantation (0.4 g kg?1). As an integrated indicator, soil quality index was highest inthe Pinus plantation (0.92) and lowest in the first and second generationsof Eucalyptus plantations (0.24 and 0.13). Soil quality index in the third andfourth generations (0.36 and 0.38) was between that in Pinus plantation and infirst and second generations of Eucalyptus plantations. Changing treespecies, reclamation and fertilization may have contributed to the changeobserved in soil quality during conversion of Pinus to Eucalyptus and successiveEucalyptus planting. Litter retention, keeping understorey coverage, and reducing soildisturbance during logging and subsequent establishment of the next rotationshould be considered to help improving soil quality.