Hydrologic controls on carbon sequestration in different age afforested pine forests under changing climate

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A significant portion of Eastern forests in both Canada and United States are plantation (afforested) or regenerated stands of different ages. These forests have been a large carbon (C) sink over the last many decades to offset some of the fossil fuel emissions. However, recent studies indicate that their C sequestration capabilities are being affected by changes in regional climate. Apart from increasing winter/summer temperatures and heat events, climate warming has accelerated the hydrologic cycle, resulting in increased evaporation and more frequent drought and flooding events. Changes to the forest hydrologic cycle alters soil and plant nutrient cycling, which feeds-back on both C and water cycles and hence, can induce further climate change. There is an urgent need to explore the interaction between hydrologic, nutrient and C cycles in forests--in particular in afforested and managed stands to fully understand their functioning and response to future climate change. This proposal will investigate the impact of changes in hydrologic and nutrient cycling on the C sequestration potential of three Eastern Canadian age-sequenced (70-, 35-, 7-year-old) afforested temperate pine stands, to sequester atmospheric CO2 and their response to future climate change (e.g. warming, drought, etc.). It would also focus on further developing and testing a C and nitrogen coupled terrestrial ecosystem model (CLASS-CTEM+N) used in Canadian Global Climate Model as well as a hydrologic model (MIKE-SHE). Few researchers have investigated the integration between hydrologic, nutrient and carbon cycling and particularly in afforested stands. This knowledge would help to develop adaptation strategies for the growth and survival of forests, which provide numerous ecological and recreation services and clean water to society, under changing future climates. Implementation of CLASS-CTEM+N model in Canadian Global Climate Model would provide an assessment tool to generate scenarios of future climate for policy development and help Canada meet its international obligations.