The study looked at how different forms of phosphorus are distributed in the soil around the roots of Populus deltoides cv. 'lux' trees grown in marine soil. They found that available phosphorus accumulated more in the soil near the roots of older trees compared to younger ones. The levels of Ca 2-P were higher in the root zone than in other areas, and this effect increased with tree age. In older trees, Ca 8-P increased while Ca 10-P decreased, suggesting a shift towards more available phosphorus. There was no significant difference in Al-P, Fe-P, and O-P between the root zone and other soil areas.