Characteristics of seedlings regeneration in Quercus aliena var. acuteserrata secondary forests in Qinling Mountains
秦岭山地锐齿栎次生林幼苗更新特征

We analyzed important value of tree and woody seedlings species, regeneration niche breath, tree regeneration dynamics under different factors, including stand densities, slop direction, altitude in Quercus valiena var. acuteserrata secondary forests in Qinling Mountains. The results showed there were 25 species in tree layer. Quercus valiena var. acuteserrata occupied dominant status in community,its important value was 149.18%. The subdominant species was Pinus armandii, Carpinus cordata,ect. There were 25 tree species among 41 woody species in regenerational layer, occupying 68% of total amount. The dominant species was Acer grosseri , Litsea pungens,ect.The seedlings bank was abundent ,the height class and age class were lower. The main regeneration type was seedling. We analyzed 10 kinds of dominant regeneration tree population . The regenerational niche breath of saplings population was higher than that of seedlings population for same tree species .The niche breath sequences from high to low of seedlings population was Corylus heterophylla, Quercus valiena var. acuteserrata,Acer grosseri,ect.while that of saplings population being Corylus heterophylla, Acer grosseri , Quercus valiena var. acuteserrata,ect. The effect of stand density on saplings or seedlings density was different ,the saplings and seedlings density was increased with the stand density from 720 trees?hm-2 up to 1460 trees?hm-2 ,then decreasing with the stand density increasing. The saplings density decreased continuously with the stand density increasing. There were various effects of slop direct on the seedlings or saplings. The sunny slop (SW 3)direct was benificial to saplings or seedlings.The seedlings density decreased sharply. As changing direction to shady slop, the seedlings density increased. The saplings density decreased nevertheless. The saplings density increased as altitude from 1083 m up to 1547 m, then decreasing with altitude up to 1882 m. The seedlings density increased from lower altitude to higher altitude.