Response of phosphorus distribution to burn frequency and seasonality in the Sanjiang Plain wetlands (Northeast China)

•The replicated experimental annual burns in freshwater wetlands in three-year period.•Thrice burns increase the soil P content but decrease the stem and leaf P content.•Autumn burns facilitate the transfer of P in plants to soil compared to spring.•The increase in time after burning causes a decrease in litter necromass P density.•The once-a-year autumn burn will be an important tool to promote wetland P cycling.