Interaction of ice storms and management practices on current carbon sequestration in forests with potential mitigation under future CO2 atmosphere
Ice storms are disturbance events with potential impacts on carbon sequestration. Common forest management practices, such as fertilization and thinning, can change wood and stand properties and thus may change vulnerability to ice storm damage. At the same time, increasing atmospheric CO2 levels may also influence ice storm vulnerability. Here we show that a nonintensively managed pine plantation experienced a 250 g C m-22eduction in living biomass during a single storm, equivalent to 30% of the annual net ecosystem carbon exchange of this ecosystem. Drawing on weather and damage survey data from the entire storm cell, the amount of C transferred from the living to the dead biomass pool (26.5 ± 3.3 Tg C), 85% of which will decompose within 25 years, was equivalent to 10% of the estimated annual sequestration in conterminous U.S. forests. Conifer trees were more than twice as likely to be killed as leafless deciduous broadleaf trees. In the Duke Forest case study, nitrogen fertilization had no effect on storm-induced carbon transfer from the living to detrital pool while thinning increased carbon transfer threefold. Elevated CO2 (administered with the free-air CO2 enrichment (FACE) system) reduced the storminduced carbon transfer to a third. Because of the lesser leaf area reduction, plots growing under elevated CO2 also exhibited a smaller reduction in biomass production the following year. These results suggest that forests may suffer less damage during each ice storm event of similar severity in a future with higher atmospheric CO2.