In total, six plantations with ca. 2.2 ha per plantation were selected representing three Eucalyptus species (E.urophylla×E.grandis (EUG), E. camaldulensis (EC) and E. pellita (EP)) with different ages (1-year-old, 5-year-old or 11-year-old). Each of the three species had 1-year-old (EUG1y, EC1y and EP1y) and 5-year-old (EUG5y and EC5y) plantations, except for EP with 11-year-old (EP11y) plantation. The symbol of 5+-year-old plot thereafter was used to refer to 5-year (EUG5y and EC5y) and 11-year (EP11y) plantations. In each plantation, three subplots (15 m × 15 m) were selected randomly, in which three trees were chosen randomly per subplot for sampling. After the litter removal, three soil cores (100 cm3) around each tree were collected at a depth of 0–10 cm from three directions with 120°and then mixed as one sample, resulting 9 samples per plantation and 54 samples in total. The samples were put into carry-on ice box immediately and delivered to the laboratory. All the soil samples were taken on the same day in rain season on May 18th 2017.
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