[Non-monetary accounting on forest ecosystem services value: Case study of forests in Beijing-Tianjin-Hebei Region]

Forest ecosystem has significant functions and services. The accounting on forest ecosystem services valuation (ESV) is one of the key prerequisites to forest ESV pricing, ecosystems protection, and the implementation of that "Lucid waters and lush mountains are invaluable assets". We first reviewed the advantages and limitations of current forest ESV counting methods, and then established the non-monetary accounting method on forest ESV based on emergy method. Further, we used forests in Beijing-Tianjin-Hebei area to test this accounting method. In addition, we modified the ESV accounting results based on normalized differential vegetation index (NDVI). Meanwhile, considering the uncertainty of data source, we conducted the uncertainty analysis on the accounting results. The results showed that the order of forest ESV in the different areas of Beijing-Tianjin-Hebei was Chengde > Beijing > Baoding > Zhangjiakou > Shijiazhuang > Qinhuangdao > Tianjin > Tangshan > Xingtai > Langfang > Hengshui >Cangzhou. The ESV order of different forest types was deciduous broad-leaved forest > evergreen coniferous forest > deciduous coniferous forest. In terms of different ecosystem services subtypes, the largest type of the ESV per unit area in Beijing-Tianjin-Hebei was climate regulation, accounting for around 60% of the total ESV per unit area, following by net primary productivity (NPP) increase and carbon sequestration, accounting for around 23%, and the proportion of other subtypes were small. The forest ESV in Hebei Province contributed most to local GDP, followed by Beijing and Tianjin. The non-monetary forest ESV accounting method established here could overcome the limitations of previous methods, including double counting, failure to establish ESV from donor side and the improper use or replacement of emergy transformities. We systematically assessed the forest ESV and could provide more effective optimization and decision-making basis on forest ecosystem services pricing, eco-compensation establishment and ecological civilization promotion.