This study aimed to conduct an ecophysiological investigation of monumental plane trees (Platanus orientalis L.) located in the Abana district of Kastamonu province. To this end, we measured the amounts of some bioactive chemicals in the leaves of the trees and young plane trees in the immediate vicinity, in addition to enzyme activities and nutrient contents. The data show that the oldest trees have the highest contents of chlorophyll and carotenoid pigment, proline, and protein, in addition to APX activity, and that the contents of glucose and pyruvic acid, in addition to the chlorophyll a to chlorophyll b ratio and CAT and SOD activities are higher in young trees. K, P, S, Cl, Zn, Ni, and Cu ions show the highest value in monumental trees, but Mg, Ca, Na, Si, and Fe show the highest value in young trees. The results show that photosynthetic pigments, proline, protein, hydrogen peroxide (H₂O₂), sucrose, and K, P, S, Cl, Zn, and Cu have had a positive effect on the growth physiology of monumental plane trees. The findings indicate that understanding the ecophysiology of plane trees may help in ensuring the long-term and damage-free survival of these trees.