Collaborative Research: Land Use and Carbon Sequestration in Eastern Deciduous Forests: Interactions Between Human Activities and Ecosystem Processes

观测到的地球表面变暖引发了人们对二氧化碳增加对全球环境影响的担忧，理解森林作为潜在碳汇的作用正成为国家和全球的优先事项。该项目的目标是调查最近的过去、现在和未来的土地利用变化对北美东部落叶林碳动态的影响。东部落叶林可能在过去的二氧化碳吸收中发挥了重要作用，因为在世纪之交的主要砍伐后重新生长。目前东部落叶林的木材采伐率很高，因此未来土地利用和覆盖的变化可能会再次影响碳循环。这些森林在一套不同的公共和私人管理制度下进行管理，每个群体拥有不同的土地管理动机，并可能对经济激励做出不同的反应。该项目的研究问题涉及西弗吉尼亚州温带落叶森林中人类活动(森林管理)和生态系统过程(碳固存)之间的相互作用：1)不同土地利用方式的森林之间的碳储量有何不同？2)土地管理(1989-2000年)的变化如何影响碳储量，这种土地利用变化的人类驱动因素是什么？3)在未来的条件下，中央阔叶林储存碳的能力如何？为了解决这些研究问题，将在两个空间尺度(流域和国家)对生态系统模型(PNET-CN)进行校准和验证。在流域层面，PNET-CN将针对四种管理处理进行校准：成熟林、幼林和两种类型的直径限制采伐。在州一级，PNET-CN将于1989年和2000年在美国农业部林业局、森林调查和分析(FIA)按管理战略分类的地块位置运行，以与试验流域的地块位置相匹配。这一生产力模型将与一个经济计量模型联系起来，该模型使用FIA地块数据结合关于地块可获得性、管理制度和当地硬木木材价格的信息，调查土地利用/土地管理类别与其潜在驱动因素之间的关系。计量经济学模型将与生态系统模型相结合，以进行情景分析，将土地利用和覆盖变化的驱动因素变化与碳储存的变化联系起来。还将开发保持土地利用和覆盖变化驱动因素固定但气候参数变化的情景。鉴于大气中二氧化碳水平的升高，理解土地利用和覆盖变化的人类原因及其对碳循环的后果至关重要。这项研究通过直接将木材采伐的经济原因与森林生物量和生产力的细节联系起来，解决了土地利用变化驱动因素、陆地生态系统和碳平衡之间的重要相互作用。该项目的成果将帮助州和国家机构在未来经济和气候变化的背景下管理温带落叶林。这项研究还将通过在科学期刊和会议上广泛传播研究成果，在研究生研究助理、本科生实地助理的支持下，以及通过开发研究生和本科教学单元，加强对落叶林在碳循环中作用的科学认识。

ABSTRACTObserved warming at the Earth's surface has raised concerns about the effects of increased carbon dioxide in the global environment, and understanding the role of forests as potential carbon sinks is becoming a national and global priority. The objective of this project is to investigate the role of recent past, current, and future land use change on carbon dynamics in eastern deciduous forests of North America. Eastern deciduous forests may have played a major role in past carbon dioxide uptake due to regrowth following major cutting at the turn of the century. Current rates of timber harvest in eastern deciduous forests are high, so future land use and cover changes may again affect carbon cycling. These forests are managed under a diverse set of public and private management regimes, with each group possessing different motivations for land management and potentially responding differently to economic incentives. The project's research questions address the interactions between human activities (forest management) and an ecosystem process (carbon sequestration) in temperate deciduous forests of West Virginia: 1) How do carbon stocks differ between forests with different land use practices? 2) How have changes in land management (1989-2000) affected carbon stocks, and what were the human drivers of this land use change? 3) How might the ability of central hardwood forests to store carbon change under future conditions? To address these research questions, an ecosystem model (Pnet-CN) will be calibrated and validated at two spatial scales (watershed and state). At the watershed level, PnET-CN will be calibrated for four management treatments: mature forest, young forest, and two types of diameter limit cuts. At the state level, PnET-CN will be run for 1989 and 2000 at USDA Forest Service, Forest Inventory and Analysis (FIA) plot locations classified by management strategy to match those of the experimental watersheds. This model of productivity will be linked to an econometric model that investigates correlations between land-use/land-management categories and their potential drivers, using FIA plot data combined with information on plot accessibility, management regime, and local hardwood timber prices. The econometric model will be coupled with the ecosystem model to conduct scenario analysis linking changes in drivers of land use and cover change to changes in carbon storage. Scenarios holding drivers of land use and cover change fixed, but varying climate parameters, will also be developed. Understanding the human causes of land use and cover change and their consequences for the carbon cycle is critical given elevated levels of carbon dioxide in the atmosphere. This research addresses the important interaction between drivers of land use change, terrestrial ecosystems, and carbon balance by directly linking economic causes of timber harvest to details of forest biomass and productivity. Results from this project will help state and national agencies manage temperate deciduous forests in the context of future economic and climatic changes. This research will also enhance scientific understanding of the role of deciduous forests in the carbon cycle through broad dissemination of results in scientific journals and conferences, through the support of graduate research assistants, undergraduate field assistants, and through the development of graduate and undergraduate teaching modules.