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

加拿大和美国东部森林的很大一部分是不同年龄的人工林（造林）或再生林。在过去的几十年里，这些森林一直是一个巨大的碳汇，以抵消一些化石燃料的排放。然而，最近的研究表明，它们的碳固存能力正受到区域气候变化的影响。除了冬/夏气温和高温事件增加外，气候变暖还加速了水文循环，导致蒸发增加，干旱和洪水事件更加频繁。森林水文循环的变化改变了土壤和植物养分循环，这对碳循环和水循环都有反馈作用，因此可以诱发进一步的气候变化。迫切需要探索森林中水文、养分和碳循环之间的相互作用，特别是在造林和管理林分中，以充分了解它们的功能和对未来气候变化的响应。本研究将研究水文和养分循环变化对加拿大东部3个按年龄排序（70年、35年、7年）的温带松林固碳潜力的影响，以固碳大气CO2及其对未来气候变化（如变暖、干旱等）的响应。它还将重点进一步开发和测试用于加拿大全球气候模型的C和氮耦合陆地生态系统模型（CLASS-CTEM+N）以及水文模型（MIKE-SHE）。很少有人研究水文、营养和碳循环之间的整合，特别是在造林林分。这些知识将有助于在未来气候变化的情况下，为森林的生长和生存制定适应战略，森林为社会提供大量的生态和娱乐服务以及清洁的水。在加拿大全球气候模式中实施CLASS-CTEM+N模式将提供一个评估工具，为政策制定提供未来气候情景，并帮助加拿大履行其国际义务。

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.