Plant community structure, soil properties and microbial characteristics in revegetated quarries

Quarries are an important type of degraded land in southern China requiring ecological improvement and rehabilitation. In this study, plant community structure, soil properties, and microbial biomass and community function were examined at different rehabilitated phases in three quarries, namely Turret Hill Quarry, Lam Tei Quarry and Shek O Quarry, in Hong Kong. Results show that plant species richness and the percentage of native species increased with rehabilitated ages in the three quarries. The highest coverage of woody species was found at older phases, while the lowest woody coverage occurred at younger phases. Soils were strongly to moderately acidic in reaction, and more acidic soils were found in the older than in the younger sites. Organic C as well as total N and P accumulated in soil along with secondary succession in the three quarries, which were positively correlated with woody species richness. Older phases had higher total microbial biomass C and N which were positively correlated with soil organic C, total N and extractable NO3-N, as well as woody species coverage and native species richness as shown by the biplot of redundancy analysis. Diversity of utilized carbons suggested that metabolic abilities developed gradually with rehabilitation ages in Shek O Quarry, but Turret Hill Quarry and Lam Tei Quarry had similar patterns of carbon source utilization. Principal component analysis further revealed consistent differences in metabolic diversity. Woody coverage and native species richness were significantly correlated with carbon source utilization and functional diversity