Based on data from 210 meteorological stations in Northeast China and survey on zonal climax vegetation, the Kira's warmth index (W l), coldness index (C l), and Xu Wenduo's humidity index (H l) were adopted to simulate and predict the dynamics of the vegetation eco-boundary under climate warming in Northeast China. The future vegetation eco-boundary alteration types of zonal climax vegetation could be divided into three types, such as extended vegetation eco-boundary species (W l value range for 45–95°C · month) which would move northwards under climate warming, retreated vegetation eco-boundary species (W l value range for 25–65°C · month) which would retreat from the present localities, and extinct population species (W l value range for 5–35°C · month) which would be extinguished because the ecosystems they depend on disappeared. In Northeast China, there were differences for 15° latitudinal and 2600 m altitudinal. Based on our research results, the edificators would move northwards about 400–700 km, steppe vegetation would move eastwords 900 km, and the populations would move upwards about 260–360 m in mountains if the global temperature increases 2°C in the future. However, the moving distance would become shorter and shorter as the latitude and altitude increased. Therefore, the populations in alpine tundra zone at Daxing'an Mountains and Changbai Mountain might disappear. The results were expected to supply reference to local government when they set down strategies to respond to climate change in the future.
In sandy forest with a forest canopy gap for a period of over 30 years, the spruce（Picea mongolica） seedlings were monitored on two 5-m- wide transects from the center of a large gap into the surrounding forest. The farther they were to the far center, the taller grew the seedling and the more is the number of seedling. There were many seedlings under the canopy but almost all seedlings died before they grow up. Along the forest edge, growth of seedlings was temporarily enhanced by lateral penetration of light from the gap. The implications for natural forest regeneration dynamics are discussed. Our results prove that in P mongolica forest a gap disturbance creates a non-uniform environment for regeneration of the species, and determines that the forest was a non-even aged forest.
The research was carried out on sandy natural forest ecosystems in sandy forest-steppe ecotone in the northern area of China from 1980’s. In this paper, we introduced the concept and origin, distribution and actu- ality,types and succession of sandy natural forests in the northern area of China. The conservation value and strategy for sandy natural forests were also discussed. We hope to supply some scientific basis for performing "the Natural Forest Protection Program" reasonably in China.
