Vol.:(0123456789) Environmental Sustainability https://doi.org/10.1007/s42398-023-00300-w ORIGINAL ARTICLE Soil nitrogen availability determines the CO 2 fertilization efect on tree species (Neolamarckia cadamba): growth and physiological evidence Manish Singh 1  · Hukum Singh 2  · Amit Kumar 3  · Narendra Kumar 2  · Manoj Kumar 4  · Santan Barthwal 2  · Ajay Thakur 5 Received: 27 November 2022 / Revised: 5 December 2023 / Accepted: 6 December 2023 © The Author(s) under exclusive licence to Society for Environmental Sustainability 2024 Abstract Urban plantation species experience multiple stresses. Among these, the two signifcant challenges are increasing atmospheric CO 2 concentration and nutrient-depleted soils, which signifcantly impede growth, development, as well as the adaptation and mitigation capacity of plant species. This study hypothesized whether nitrogen availability improves CO 2 fertilization efects and the growth of urban plantation tree species (Neolamarckia cadamba) under rising atmospheric CO 2 concentra- tion.The plants were grown in nitrogen regimes (low-N 200 Kg N ha −1 , medium-N 300 Kg N ha −1 , and high-N 500 Kg N ha −1 ) under elevated CO 2 concentration (eCO 2 ; 800 ± 20 µmolCO 2 mol −1 ) and ambient conditions (aCO 2; 400 ± 14 µmolCO 2 mol −1 ). We reported that growth and physiological traits were signifcantly improved under elevated CO 2 concentration and applied nitrogen compared to low nitrogen and ambient CO 2 concentration. The height, stem diameter, leaves, leaf area, and branches were increased by 25%, 13%, 12%, 6%, and 21%, respectively, under N 300 and eCO 2 than counterparts. The leaf CO 2 assimilation, transpiration, and stomatal conductance were enhanced by 17%, 39%, and 57%, respectively, whereas water use efciency declined under N 300 and eCO 2 but slightly increased in eCO 2 and N 500 . We inferred that nitrogen man- agement practices would improve the benefts of rising atmospheric CO 2 concentration, resulting in improved plant growth and development and better adaptive physiological response and mitigation potential of plantation species. Keywords Carbon sequestration · Elevated CO 2 concentration · Neolamarckia cadamba · Soil nitrogen · Tree growth · Urban tree physiology · Urban resilience * Hukum Singh hukumsingh97@yahoo.com Manish Singh manish.s92@gmail.com Amit Kumar amitudu@gmail.com Narendra Kumar narendra.physiol@gmail.com Manoj Kumar manojfri@gmail.com Santan Barthwal barthwal.santan@gmail.com Ajay Thakur mithoojorhat@yahoo.co.in 1 Forest Ecology and Climate Change Division, Forest Research Institute, P.O. New Forest, Dehradun 248006, Uttarakhand, India 2 Plant Physiology Discipline, Forest Research Institute (FRI), P.O. New Forest, Dehradun 248006, Uttarakhand, India 3 Department of Forestry, North Eastern Hill University, Tura Campus, Tura 794002, Meghalaya, India 4 GIS Centre, Forest Research Institute, P.O. New Forest, Dehradun 248006, Uttarakhand, India 5 Biotechnology Discipline, Forest Research Institute, P.O. New Forest, Dehradun 248006, Uttarakhand, India