生态系统碳收支研究大部分停留在自然生态系统过程的角度，对生产经营等人类活动的碳收支贡献尚无清楚认知，更未建立社会碳收支的定量评估理论和方法。本项目选择人类活动频繁、经营景观多样的温性草甸草原为对象，基于全生命周期分析（LCA）建立生产经营活动碳收支贡献分析方法，研究各种类型的草甸草原经营景观（放牧、刈割、开垦、城市化等）在年尺度上的碳收支变化，探讨不同经营景观下碳收支的影响机理。重点关注3个科学问题：①地表覆盖、气候变化和生态系统经营管理对草甸草原景观的社会经营碳收支当量（SocCO2eq）和自然碳收支当量（PhyCO2eq）的贡献大小如何？②不同经营管理方式下草甸草原景观SocCO2eq和PhyCO2eq时空变化如何？③未来土地利用变化和经营管理情景对草甸草原碳收支的影响如何？本研究有助于我们更全面理解草地生态系统碳收支及其机制，为草地畜牧业有效经营管理提供理论依据。

Our current knowledge on ecosystem carbon gains and losses relies mostly on conventional biophysical ecosystem principles and methods, with no consideration of the contribution of the carbon input/out from management practices that maintain the ecosystems and landscapes. We have almost no knowledge, methods, and models to quantify the amount and the magnitude of carbon fluxes resulted from human activities during ecosystem/landscape management (e.g., land conversion, harvesting). This proposal is endeavored with an innovative approach and new school of thought for understanding and forecasting carbon budget at ecosystem and landscape levels by focusing on the contribution of relevant management activities to the actual carbon fluxes and budget using temperature meadow steppe in Inner Mongolia as a case landscape. After defining and introducing a suit of new concepts and terminologies, we propose to quantify the carbon fluxes from management activities (e.g., grazing, mowing, reclamation, urbanization, etc.) at multiple temporal and special scales. Life cycle assessment (LCA) and Bayesian hierarchical structural equation modeling (SEM) will be applied as the primary tools to achieve our study objectives. The three fundamental questions are: (1) What are the quantitative contributions of land cover change, climate changes, and specific ecosystem management practices to the social and physical carbon fluxes of managed meadow steppe ecosystems and landscapes? (2) What are the spatial and temporal changes of their contributions in managed meadow steppe landscapes? and (3) How will future land use changes and alternative management practices impact carbon budget at meadow steppe? Lessons learned by answering these questions will provide us with a new way of thinking real-world carbon cycle – with potential breakthrough of new theory -- that can be transformative to other landscapes and regions.