Evergreen-deciduous broad-leaved forest ecotone in eastern china: retrospect and new perspectives

As a transition, the evergreen-deciduous broad-leaved forest ecotone (EDF ecotone) in eastern China occurs between the Yellow River (Huang He) and Yangtze River (Chang Jiang). Due to its wide extent, the EDF ecotone was usually treated as an independent vegetation zone in China. In this chapter, we summarize historical debates about its zonal vegetation and boundaries, and present new perspectives based on a case study that considers effects of topography on the vegetation transition pattern across the EDF ecotone. The case study showed that topographic differentiation in the forest transition pattern from evergreen to deciduous forest occurred in both latitudinal and altitudinal gradients, causing a hierarchical transition process in three dimensions. Based on these results, a mosaic transition pattern across the EDF ecotone is proposed, with more and larger evergreen patches toward the south and more and larger deciduous patches toward the north. This could result in stable mixed evergreen-deciduous broad-leaved forests in the transition areas between evergreen and deciduous patches. Finally, by comparing climate-vegetation relationships in China and Japan, we discuss the formation mechanism of the EDF ecotone and offer a new proposal for its boundary determination, based on these new perspectives.