基于碳收支的中国土地覆被分类系统

Classification system of China land cover for carbon budget

生态系统的碳收支是影响全球变化的重要环节,而土地覆被变化改变了生态系统碳收支的现状、速率。提出了面向碳收支的中国土地覆被分类系统,服务于生态系统碳收支估算和国家生态环境监测。分类系统由一、二级土地覆被类型、三级土地覆被辅助特征构成。通过物质组成、结构、排列、季节特征等19个指标,将土地覆被划分38个二级类型,反映生态系统的碳储量现状。三级土地覆被辅助特征利用9个指标补充了二级土地覆被类型的属性。其中5个环境指标主要反映生态系统碳储备的潜力和强度,土地利用方式指标反映植被演替过程植被碳收支中的人为扰动影响,植被覆盖度、植被生育期、物种特征指标用于进一步细化植被类型。二级类型与三级特征为分层组织的土地覆被产品,有利于产品管理和应用。分类系统已应用到面向全国生态系统碳收支的30m格网的中国土地覆被制图中。

The carbon cycle greatly influences global change,and the land cover changes contribute to the status and rate of the carbon budget in ecosystems. This paper proposes a land cover classification system for land cover mapping for the estimation of carbon storage in ecosystems and the national environmental assessments. The classification system consists of basic land cover classes at level Ⅰ and Ⅱ,and auxiliary features at level Ⅲ. The basic 38 classes at level Ⅱ characterizing land cover features are derived from 19 criteria referring to aspects of composition,structure,pattern,phenology,etc. The basic classes reflect the status of carbon storage in ecosystems. The system defines more detail in vegetation,the criteria includes life form,vegetation height,leaf type,vegetation phenology,vegetation cover,soil disturbance under vegetation,harvest disturbance,spatial relationships between vegetation and artificial surfaces. Meanwhile,non- vegetation criteria is considered in non- vegetation types definition for large scale ecological monitoring and assessment,such as the water conditions,the artificial surface features,soil structure,land granular,soil salinity,soil moisture,surface state,the water flowing. The auxiliary classes at level Ⅲ complement the attributes of level Ⅰ and Ⅱ by 9 criteria. The 5 environmental criteria of temperature,moisture,landform,aspect and slope mainly reflect the potential and intensity of carbon storage in ecosystems. The disturbance of vegetation succession caused by land use type influences the vegetation carbon budget. The other 4 criteria of vegetation cover,vegetation growing period,land use and species characteristics further refine the vegetation types,and land use typically impact the carbon storage. The structure of the land cover map of the classes of levels Ⅰ and Ⅱ is independent of the products of level Ⅲ,which is helpful for land cover product management and applications. The classification system has been adopted in the Chinese national land cover database（ China Cover2010） forthe carbon budget in ecosystems at a 30 m scale. The classification system is characterized by the factors of intrinsic attributes and extrinsic property of land cover. It is able to effectively reflect the status of ecosystem carbon stocks,rate of change,the potential and mechanism. Classification system uses a flexible definition of vegetation cover,and it is able to re-organize vegetation classes by different vegetation coverage,this approach allows analysis and comparison on different classification system among countries or organizations. Class definition is performed by using FAO LCCS tools through dichotomy which is defined in quantified approach of land cover. LCCS method provides relatively accurate and comprehensive type definition,a priori design to make it much fair,balanced,but also makes the system extensive application. With the increasing attention to global environmental issues,land cover data used in the international exchange and comparison become more frequent,standardized LCCS will be the future application trends.