Ozone vegetation damage effects on gross primary productivity in the United States

摘要

We apply an off-line process-based vegetation model (the Yale InteractiveTerrestrial Biosphere model) to assess the impacts of ozone (O₃)vegetation damage on gross primary productivity (GPP) in the United Statesduring the past decade (1998–2007). The model's GPP simulation is evaluatedat 40 sites of the North American Carbon Program (NACP) synthesis. Theecosystem-scale model version reproduces interannual variability andseasonality of GPP at most sites, especially in croplands. Inclusion of theO₃ damage impact decreases biases of simulated GPP at most of the NACPsites. The simulation with the O₃ damage effect reproduces 64% ofthe observed variance in summer GPP and 42% on the annual average. Basedon a regional gridded simulation over the US, summertime averageO₃-free GPP is 6.1 g C m?2 day?1 (9.5 g C m?2 day?1in the east of 95° W and 3.9 g C m?2 day?1 in the west).O₃ damage decreases GPP by 4–8% on average in the eastern US andleads to significant decreases of 11–17% in east coast hot spots.Sensitivity simulations show that a 25% decrease in surface O₃concentration halves the average GPP damage to only 2–4%, suggesting thesubstantial co-benefits to ecosystem health that may be achieved via O₃air pollution control.