Land use and management activities have a substantial impact on carbon stocks and associated greenhouse gas emissions and removals. However, it is challenging to discriminate between anthropogenic and non-anthropogenic sources and sinks from land. To address this problem, the Intergovernmental Panel on Climate Change developed a managed land proxy to determine which lands are contributing anthropogenic greenhouse gas emissions and removals. Governments report all emissions and removals from managed land to the United Nations Framework Convention on Climate Change based on this proxy, and policy interventions to reduce emissions from land use are expected to focus on managed lands. Our objective was to review the use of the managed land proxy, and summarize the criteria that governments have applied to classify land as managed and unmanaged. We found that the large majority of governments are not reporting on their application of the managed land proxy. Among the governments that do provide information, most have assigned all area in specific land uses as managed, while designating all remaining lands as unmanaged. This designation as managed land is intuitive for croplands and settlements, which would not exist without management interventions, but a portion of forest land, grassland, and wetlands may not be managed in a country. Consequently, Brazil, Canada and the United States have taken the concept further and delineated managed and unmanaged forest land, grassland and wetlands, using additional criteria such as functional use of the land and accessibility of the land to anthropogenic activity. The managed land proxy is imperfect because reported emissions from any area can include non-anthropogenic sources, such as natural disturbances. However, the managed land proxy does make reporting of GHG emissions and removals from land use more tractable and comparable by excluding fluxes from areas that are not directly influenced by anthropogenic activity. Moreover, application of the managed land proxy can be improved by incorporating additional criteria that allow for further discrimination between managed and unmanaged land.

中文翻译：

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划定管理土地，以向联合国气候变化框架公约报告国家温室气体排放量和清除量。

土地使用和管理活动对碳储量以及相关的温室气体排放和清除产生重大影响。但是，区分人为和非人为来源以及土地汇是一项挑战。为了解决这个问题，政府间气候变化专门委员会开发了一个受管理的土地代理，以确定哪些土地造成了人为的温室气体排放和清除。各国政府根据这一代理向《联合国气候变化框架公约》报告受管理土地的所有排放量和清除量，减少土地使用产生的排放的政策干预措施应集中在受管理土地上。我们的目标是审查托管土地代理的使用，并总结政府为将土地分类为托管和非托管而应用的标准。我们发现，绝大多数政府没有报告其管理土地代理的申请。在提供信息的政府中，大多数政府已将特定土地用途中的所有区域都指定为托管区域，而将其余所有土地都指定为非托管区域。这种指定为管理土地的方式对于耕地和居民区而言是直观的，没有管理干预就不会存在，但是在一个国家中可能无法管理一部分林地，草地和湿地。因此，巴西，加拿大和美国采用了其他标准，例如土地的功能性使用和土地的人为活动可及性，对这一概念进行了进一步的划分，并划定了管理和非管理林地，草地和湿地。土地代理管理是不完善的，因为任何地区报告的排放都可能包括非人为来源，例如自然干扰。但是，受管理的土地代理人确实排除了不受人为活动直接影响的区域的通量，从而使报告土地用途的温室气体排放量和清除量更加容易和可比。此外，可以通过纳入允许进一步区分托管土地和非托管土地的其他标准来改善托管土地代理的应用。