Objective The aim was to investigate the short-term effect of piled burning nematode-infected harvest residues of Pinus massoniana on soil nutrient availability, in order to provide insightful information for maintaining soil fertility and enhancing vegetation restoration in the burnt plantation.

Method Soils were collected at 0 ~ 5 and 5 ~ 10 cm depth from the unburnt area and different positions (center and edge) of the post-fire piles one day after burning in a recently harvested P. massoniana in mid-subtropical China. Soil pH, moisture content, organic matter, total carbon (C), the total and available contents of (N, P, K, Ca, Mg, Na, Fe, Mn, and Al) were measured, and Fe/Mn, Ca/Al, Ca/Mg, and SPAR were also calculated.

Result ① Soil pH, available K and Ca concentrations, and Ca/Mg in the burnt area were significantly increased by 3.19%, 50.83%, 56.13%, and 28.01% compared to the unburnt control. ② Soil moisture, organic matter, total C and total N concentrations in the center of the piles were significantly reduced by 14.66%, 15.90%, 19.97%, and 17.25%, respectively. However, the burning increased soil Ca/Al ratio by 107.01%. There was no significant difference in soil moisture, organic matter, and total C concentrations as well as the Ca/Al ratio between the edge of the burnt pile and the control. ③ Soil available P concentration at 0 ~ 5 cm depth in the center of the pile was significantly increased by 67.88% than that of the unburnt control, while no significant change was observed in the 5 ~ 10 cm soil. ④Pile burning had no significant effect on soil total P, K, Ca, Mg, Na, Fe, Mn, and Al concentrations, and Fe/Mn and SPAR. ⑤The principal component analysis showed that pile burning changed soil properties at the 0 - 5 cm but not the 5 - 10 cm soil layer, and soil total C was the key factor driving the change in soil properties.

Conclusion Pile burning improved the availabilities of P, K and Ca in recently harvested P. massoniana plantations in the short term, and the center of piles should be taken into account in maintaining forest fertility and restoring vegetation.