Abstract: Professor Liu Shene was a celebrated Chinese botanist, ecologist, and forester, who proposed the theory of dynamic geo-botany in the early 1960s. Under the theory framework of dynamic geo-botany, we studied several key scientific questions in vegetation in Northeast China: (1) The zonal climax is the core issue of dynamic geobotany. In a particular area, there is only one zonal climax, which is controlled by the macroclimate. The other communities are formed as nonzonal climaxes in the area, driven by local environmental conditions. In Northeast China, humid, semi-humid and semi-arid areas exist along with the moisture gradient from southeast to northwest, and the zonal climax appears correspondingly as forest, foreststeppe and typical steppe. From south to north along the temperature gradient, zonal climax vegetation types exist as warmtemperate Pinus densiflora-Quercus spp. mixed forest, warmtemperate Pinus tabuliformis-Quercus spp. mixed forest, temperate Abies holophylla - Pinus koraiensis broad-leaved mixed forest, temperate Pinus koraiensis broad-leaved mixed forest and cold-temperate bright coniferous forest. In addition to the horizontal zonal climax, we also studied the vertical zonal climax or climate layer climax, preclimax, postclimax, and their conversion relationships. (2) Following the polar tundra migration route in dynamic geo-botany, Xu Wenduo discovered the second tundra vegetation in China, i.e., the subalpine tundra in Daxing Anling, and clarified the basic concepts and essential differences between mountain tundra and mountain crymic in the fields of ecology and physical geography in China. Xu claimed that the Northeast China mountain tundra originated only in the Arctic tundra of Eurasia, being part of the Eurasian polar tundra flora. (3) The importance of evolutionary ecological process of plant species and the correct identification of species is emphasized in dynamic geo-botany. A new species of sandy spruce (Picea mongolica) was recorded in the Hunshandake sandy land, a fragile ecological landscape. The Picea mongolicadominated super-zonal climax is a very special type of forest ecosystem. We systematically investigated the composition, structure and function of sandy spruce forest ecosystem from aspects of ecological environment, species origin, molecular ecology, individual ecology, population ecology, community ecology, ecosystem ecology, and protection ecology. (4) According to dynamic geo-botany theory, climate is constantly changing, and vegetation is sensitive to global climate change. The relationship between vegetation and climatic conditions is dialectically unified: climate determines the climax vegetation, with only one type of climax vegetation under a particular climatic zone. Global warming has added new content to dynamic geobotany research and opened up new research areas. The zonal climax vegetation is controlled by the macroclimate and is the most sensitive and representative type. If temperature increases by 2 ℃ in the future, the zonal climax forest in Northeast China will change significantly in distribution pattern, in addition to changes in vegetation composition, structure and function, and will migrate 443-708 km northward. The grassland zonal climax will migrate 926 km eastward. (5) Vegetation zoning is an application of dynamic geo-botany in ecological construction. Vegetation zoning should base on zoning and reflect historical circumstances and climate relations in the past. High-level areas should be mainly maintained in the zonal climax, while low-level areas can consider non-zonal climax vegetation types. Vegetation zoning is the most scientific basis for dynamic geo-botany in combination with production practice and sustainable use of natural resources. Based on the principles, bases, indicators and systems of vegetation zoning in dynamic geo-botany, we studied the vegetation zoning in Heilongjiang Province and Northeast China, and the ecological zoning of vegetation in Northeast China.

Key words: red soil region, engineering accumulation, rainfall intensity, gravel content, runoff and sediment yielding.