Differences in fine root traits between early and late-successional tree species in a Chinese subtropical forest

The aim of this study was to compare fine root (≤2 mm diameter) traits (i.e. biomass distribution and architecture) of three tree species (Alniphyllum fortunei, Liquidambar formosana and Cyclobalanopsis glauca) growing in a mixed-species stand in a subtropical forest. Fine root samples were collected using soil cores. The collected samples were scanned with the Win-RHIZO system to analyse architectural parameters and were then oven-dried to determine dry mass. Fine roots of the three species were mainly distributed in the top 15 cm of soil and decreased with soil depth across all horizontal distances. C. glauca had the highest fine root biomass at 15–30 cm depth at 1.0 m from the tree trunk. The specific fine root area (SRA) and the length (SRL) were the highest for C. glauca, followed by L. formosana and A. fortunei. These species use different soil exploitation strategies. The early-successional species (A. fortunei and L. formosana) increase their fine root biomass and length through high carbon investment, whereas late-successional species (C. glauca) increase nutrient uptake efficiency via changes in fine root morphology and higher SRA and SRL values. In secondary broadleaved forest management and mixed plantation establishment, root trait differences among tree species and their effects on belowground competition and species coexistence should be considered.