Ozone Susceptibility of Tropical Tree Species
Mst Nahid Farha, Flossie Brown, Lucas A. Cernusak, Stephen Sitch, Alexander W. CheesmanABSTRACT
Tropical forests account for approximately 60% of global terrestrial photosynthesis, yet their function into the future may be compromised by rising ground‐level ozone (O 3 ) pollution. Although O 3 is known to impair plant productivity, the physiological mechanisms underlying interspecific variation in O 3 susceptibility—especially among tropical trees—remain poorly resolved. Here we exposed 11 tropical tree species to a gradient of O 3 concentrations using open‐top chambers and quantified whole‐plant biomass responses alongside key plant functional traits. Species varied markedly in O 3 susceptibility, with relative growth reductions best explained by differences in plant mass per unit leaf area (PMA). Contrary to expectations, antioxidant capacity and leaf mass per area were not predictive of O 3 susceptibility of tropical tree species. These findings indicate that fundamental structural traits may mediate tropical tree responses to O 3 , and that species with higher PMA exhibit greater resilience—within the experimental framework employed here. Our results help inform trait‐based risk assessments and support the need for improved representation of O 3 impacts in models of carbon cycling in tropical forests.