Abstract: This paper studied the fine-root character and its action mechanism of forest reestablished by different models for 10 years on a seriously degraded red soil,and analyzed their correlation with soil property.The results showed that fine-roots mostly distributed in 0～20 cm soil layer,accounted for 73.39%～87.41% of those in 0～40 cm soil layer.There were notable differences in nutrient storage of fine-roots under different reestablishment models.The fine- roots of medium density pure Pinus serotina forest had a much higher storage of total nitrogen,phosphorus and potassium,with the content of total nitrogen,phosphorus,potassium,calcium and magnesium being 84.47,5.55,38.42,17.00 and 10.76 kg·hm^-2,respectively.Soil organic matter,total nitrogen,available nitrogen,available potassium and pH had significant correlations with fine-root biomass (P<0.05).The effects of fine-roots on soil physical properties mainly reflected on soil capillary porosity and total porosity.Fine-roots obviously increased the contents of >0.25 mm and >5 mm soil waterstable aggregates,and improved soil structure-stability.The correlations between fine-roots and soil bacteria and microbial quantities were significant.

Key words: Degraded red soil, Forest reestablishment, Fine-root, Action mechanism