Re-discussion about the forest vegetation zonation in eastern China

There is a long_standing controversy about division of forest vegetation zonation in eastern China. Recently, Prof. SONG Yong_Chang has summarized the viewpoints of different authors on the division of vegetation zone, discussed the principles of the division, and proposed a new divisional system. In the present paper, based on a historical review on the division of vegetation zonation, the author reconsidered the principles of the division, and proposed a climate_vegetation relation_based divisional scheme involving the following viewpoints: (1) in reality, vegetation zonation division in eastern China is likely a kind of potential vegetation regionalization because little primary vegetation types occur in this region resulted from a long_historical human activities; (2) both characteristic of vegetation types, especially zonal vegetation types, and the climatic factor that delimits the distribution of the vegetation are coequally important in the division of vegetation zonation; and (3) as a reference information, species distribution is important in the division, but not a critical element in some cases. Based on these views, the relationships between distribution of primary vegetation types and climate conditions were analyzed, and then the vegetation_climate relation_based division for vegetation zones of eastern China was made. In the divisional scheme, warmth index ( WI ) and coldness index ( CI ) were used as thermal parameters, and moisture index ( Im ) as indicator of arid/humid climate. As a result, the vegetation zones in the eastern China arranged from north to south as cold_temperate conifer forest zone ( WI 50 ℃·month), temperate conifer and broadleaf mixed forest zone (50 ℃·month WI 90 ℃·month), warm_temperate deciduous broadleaf woodland zone (90 ℃·month WI 120 ℃·month, -20 Im 0), warm_temperate deciduous and evergreen mixed broadleaf forest zone (120 ℃·month WI 135 ℃·month, 0 Im 60), subtropical evergreen broadleaf forest zone (135 ℃·month WI 240 ℃·month, Im 60), and tropical rain and monsoon forest zone ( WI 240 ℃·month), respectively. In the subtropical zone, three subzones, northern, southern and western parts, were further divided on the basis of an isotherm of WI =175 ℃·month. The present divisional scheme is not only based on the principles mentioned above, but also incorporated with the term usage in vegetation science in China and the convenience for international scientific communications. In addition, it was emphasized that a division of dynamic vegetation zones was an increasing interest because of the changing climate and renewed vegetation information in this region.