The growth and overall health of a tree can be negatively impacted by various contaminants, and the specific concentration at which these effects occur can differ from one tree species to another, as well as between different contaminants. This study aimed to explore the phytoremediation potential of Tectona grandis, Gmelina arborea, Shorea roxburghii, Terminalia ivorensis, and Terminalia superba in soils contaminated with heavy metals from the Forestry Research Institute of Nigeria (FRIN) in Ibadan, Oyo State, and Ijebu-Igbese in Ogun State. The heavy metals analyzed included copper, zinc, manganese, lead, and cadmium. The soil was contaminated at three different levels: double the permissible level (twice the tolerable limit in soil) with cadmium at 0.006 g/kg, copper at 0.2 g/kg, lead at 0.4 g/kg, zinc at 0.6 g/kg, and manganese at 6 g/kg, triple the permissible level (three times the tolerable limit) with cadmium at 0.009 g/kg, copper at 0.3 g/kg, lead at 0.6 g/kg, zinc at 0.9 g/kg, and manganese at 9 g/kg, and a control group with no contamination. Particle size analysis revealed that the soil was loamy sand with a pH range of 5.69 to 6.44. Gmelina arborea exhibited significantly greater height (176.00 cm) and collar diameter (29.78 mm) compared to the other species, while Terminalia ivorensis produced a higher number of leaves. In conclusion, Gmelina arborea seems to demonstrate a greater tolerance to higher levels of contamination than the other species studied, indicating that it may have a natural ability to adapt to adverse conditions.
Olayiwola Victor (Sun,) studied this question.