Regeneration Of The Natural Mongolian Pine Forest In Hulun Buir Sandland

Mongol Scotch Pine distributes in the fixed sandyland at the east of Hulunbeier plateau and watershed which formed by Hailar River,Yimin River and Halakhah Rivernatively. It has good adaptability to cold, drought and barren environment, and a prominent advantage to wind control and shifting sand fixed with the notable regeneration ability. The natural regeneration process of Mongol Scotch Pine in the sandyland is important to vegetation rehabilitation and reconstruction of degraded ecosystems, sandy ecosystem benefit sustaining development, as well as the establishment of green ecological barriers in north of China. Since the 21st century, under the context of global change, the natural regeneration of Mongol Scotch Pine has been disturbed seriously. The expansion scale and speed has been slow down, and the trend in some areas has been adverse. Therefore, exploring the impact factors of natural regeneration, taking effective measures to ensure and promote the natural regeneration and making sure the long-term stable development to play a greater ecological benefit, which have been concerned by the forestry staffs.The natural regeneration process and character of Mongol Scotch Pine have been studied from the age pattern and spatial structural changes based on the multi-disciplinary theories and methodologies, including silviculture, population ecology, geo-statistics and multi-statistics in this study. By all kinds of observation means, the main impact factors in natural regeneration process, the regeneration model in forest edge and gap, the role of different artificially vegetation rehabilitation means were discussed and summarized to provide the scientific basises and technological supports to ecosystem protection and desertification combating. The main findings were as the following:Mature trees of Mongol Scotch Pine seed in twenty years old nearly, and the abundant year will be iterated in every 3 to 4 years. Mature trees of 150 ~ 200 years old still seed frequently. In the forest stands of canopy density is 0.5 ~ 0.6, the average amount of seeding-tree will be 230 per hm2, the cones collected will be 358 kg, the seeds produced will be 3.6 kg which 30% of the pest and empty seeds have been removed. Seeds of spread nearby the mature tree in the distance of 0 ~ 8m, and the density of seeds will decrease with the distance increase from the mature trees. The seeds density in east and north is significantly higher than that of in the west and south. Vertical distribution of soil seed banks is very distinct, and most of seeds lie in the surface litter layer more than soil. The seed density of level distribution in soil seed banks is highest in less than 3m from the observed tree. The seeding clusters near the observed tree in a fan-shaped region composed in the north east direction.The seedling population is stable growth type, which the proportion of young growth stocks is larger than the others, and the stand age structure shows as the steady growth trend. In research area, there are 2.30×104 seedlings in per hm2 natural forest and the density decrease with the forest canopy density increase, seedling density is largest in sparse stand.The relationship between the gap area and seeding density is quadratic curve function which means the seeding density increase with the area and then decrease. The natural regeneration status in west margin of gap is better than the eastern margin and it significantly better in the southern than the northern, which formed the south-west gap significantly better than in the northeast, eventually leading to south-west gap extension faster than the northeast. Generally speaking, the largest seeding spread distance from south to north is close to 100 ~ 125m, from north to south is 25 ~ 50 m, and the largest seeding spread distance from west to east is close to 150m, from east to west is nearly 75 m.The forest edge region is conducive to the growth of seedlings, which show as a greater seedlings density and better natural regeneration status. The seeding near the forest edge was the cluster distribution pattern, and with away from the edge, the seeding is in random distribution pattern. The seeding density in forest edge of north-east and north were significantly higher than that in the west and south, and the expansion distance in north forest edge was significantly higher than other directions. Compared with convex and linear forest edge, the concave edge has a greater natural regeneration status and more favorable conditions, which showed with a long spread distance, and a faster expand invasion to pasture.