| Quercus variabilis BI. is widely distributed in 22 provinces of China, which is an important species for cork, tannin, energy, has played a huge role in ecological environmental protection and economic development. Q. variabilis population core of north slope of Qinling and fringe of Huanglong coteau is taken as the object of our study.Through the investigation of typical sample plots, this paper conducts a systematic study about number, origin composition, growth characteristics of Q. variabilis seedings, competition between young individuals of different resources in different disturbed conditions, growth law of stump sprouts and stem basal sprouts. Clarifies the important function of vegetative propagation in population regeneration and proposes promotion measures, which provide a theoretical basis for Q. variabilis population restoration and secondary forest tending. The main results are summarized as follow:There are seedlings, stump sprouts, stem basal sprouts in Q. variabilis population in Huanglong Mountain, north slope of Qinling Mountains and south slope of Qinling, root sptouts have not been found in the area. During 1~8a growth stage, the composition of stump sprouts increases, while that of seedlings reduces. In the same stage,the mean basal diameter, mean height and mean crown diameter of stump sprouts are significantly higher than that of seedlings or stem basal sprouts,while there are no significant difference of that in seeding and stem basal sprouts, which indicates that stump sprouts grow rapidly, but basal sprouts and seedlings grow slowly. The transfer rates from diameter classⅠto diameter classⅡof young total population and seedings population are minimum in the areas (seedlings mortality is highest).Along with aging, the transfer rates gradually add(seedling mortality rate decline),and transfer rates between adjacent diameter classes of sprout population are all higher than that of seeding population, Which shows that sprout population make up for lack of seedling population, expand the number of the total population and play an important role in population recovery.Q. variabilis population A in larger disturbed conditions, with more sprout individuals can be smoothly through "environmental screening", achieve natural regeneration, recover the relative stability of communities rapidly. Q. variabilis population B in small disturbed conditions with a small number of sprouts, shows a clear bottleneck at the sapling stage during population regeneration. Competition of the seedings and the sprouts studied by competition equation. The relative dominance of the seedlings and the sprouts in population A is respectively 35.7% and 88.33% ,when the stand reaches balance,the same as population B is respectively 11.67% and 64.21% . The sprouts is much favored in regeneration layer , and enable recover rapidly the forest. The seedlings dominance increased is good to maintain population genetic diversity and improve the quality.The number, basal diameter and height of Q. variabilis stump sprouts are proportional to whose stump diameter; the mean diameter, mean height and mean crown width of stump sprouts are greater in sunny slope than shady slope; the number of stump sprouts is negatively correlated to mean basal diameter (height) growth of a year; The death rate of 1~4a stump sprouts (stump diameter of 10~20 cm) in the sunny slope is smaller. With the increase of cutting times resprout rate of stump decreases significantly. The same of cutting times, the smaller stump diameter (1~10 cm) is higher resprout rate and the large stumps diameter (10~ 20 cm) lower. The number of 1~2a stem basal sprouts rises with the diameter and height of mother tree raising, the regression equation can be expressed: N=-0.27+0.439D-0.025D~2+ 0.001D3 (R~2=0.910),N=-2.598+0.906H-0.062 H~2+0.002 H~3 (R2=0.901). |
PDF Full Text Request