Population Structure and Quantitative Dynamics of Degraded Pinus massoniana Forest based on Tree Number and Competition Index
The study on population structure and quantitative dynamics of degraded forest is significance to find out the current situation and development trend of population,and to guide population protection and restoration.Taking the state-owned Langfengguan Forest Farm in Ziyun Miao Buyi Autonomous County of Guizhou Province as the re-search area,this study investigated the typical degraded Pinus massoniana forest in Ziyun Miao Buyi Autonomous County,Guizhou Province.Based on the number of trees combined with competition index,the population structure and quantitative dynamic changes of degraded P.massoniana forest in the study area were comprehensively ana-lyzed by using dynamic index and time series prediction methods.The results showed that:(1)A total of 1 297 Mas-son pine trees were investigated,including 12 age classes.Due to the small number of individuals in age class Ⅰ and the lack of natural regeneration ability of the population,the population showed a declining trend,and the intensity of intraspecific competition decreased with the increase of age class,but the intraspecific competition in Ⅶ age class and Ⅳ age class was too fierce,which led to the instability of population structure.(2)There are more individuals in the small diameter class of the population,and the cauda equina population is a growing population,which is less af-fected by the surrounding environment,but the intraspecific competition is fierce and faces a greater risk of decline.(3)With the passage of time,after the next 6 age classes,the number of aged plants in the population gradually in-creased,the number of young plants decreased seriously,and the intraspecific competition index gradually tended to be stable.To sum up,the lack of juvenile individuals and the fierce competition among trees are the main reasons for the degradation of P.massoniana population in the study area.Although the population structure can be adjusted to achieve stability through self-thinning,it takes a relatively long time.It is suggested that the main forest layer thinning combined with under-forest cutting,irrigation,weeding and replanting should be adopted to adjust the popu-lation structure and achieve stable and sustainable development as soon as possible.