In forest environments, the establishment, survival, and recruitment of seedlings of desired species can often be influenced by biotic interactions between the competing understory shrubs and the seedlings, as well as by the understory light environment. Previous studies regarding competing effects were mostly focused on the survival and growth of seedlings, but it is still largely unclear how competition with shrubs impacts the biomass of the seedlings and physiological traits connected to photosynthesis and nitrogen metabolism in various forest ecosystems. Moreover, there is limited knowledge on the influence of light conditions on the biomass of understory seedlings is limited for different species. The main objectives of this study were to examine the effects of understory junipers and light conditions on the above and belowground biomass of black pine seedlings (Pinus nigra Arnold). This study also examined the changes in chemical composition and plant nutrient contents in the organs of black pine seedlings (i.e., root, stem, and needle) with the presence of junipers in the understory. Seedling biomass was significantly affected by understory light conditions, while the presence of junipers negatively affected the root-biomass of black pine seedlings. Moreover, understory junipers influenced some photosynthetic pigments in black pine seedlings.

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 (H 2 O 2 ), 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.