论文部分内容阅读
In Hebei Province of North China,forest was recovered with natural recruitment in plantations with large area of clear-cutting Chinese pine (Pinus tabuliformis).This study was aimed to demonstrate the dynamic characteristics of recruits during the natural recruitment.Both plot survey and the spatial point-patt analysis were performed.Five developmental stages of natural recruitment were selected and studied,including 1 year before and 2,5,8,and 11 years after clear-cutting.Different slope aspects were also included.Natural recruitment was always dominated by Chinese pine with a proportion of higher than 90％.For plots of 1 year before clear-cutting on east-and north-facing slopes,recruit densities were 7886 and 5036 stems/hm2,the average heights were 0.78 (±0.85) and 1.06 (±1.15) m,and the average diameters at breast height (DBH) were 3.21 (±1.38) and 2.91 (±1.38) cm,respectively.After clear-cutting,recruit density was initially increased,then it was gradually declined with dme;however,the variation of average DBH was contrary to that of recruit density.Both of them were no longer varied between 8 and 11 years after clear-cutting.The average height of recruits continued to increase after clear-cutting.For the plots of 11 years after clear-cutting on east-and north-facing slopes,average heights of recruits reached 2.00 (±1.14) and 2.24 (±1.20) m,respectively.The statuses of recruits on north-facing slopes were better than those on east-facing slopes after clear-cutting.Meanwhile,recruits on east-facing slopes were always aggregated at small scales,while spatial patt of recruits varied with time on north-facing slopes.Moreover,forest was recovered more quickly by natural recruitment than by artificial afforestation after clear-cutting.The structural diversity was higher in naturally regenerated forests than in plantations of the same age.Our results demonstrated that clear-cutting of Chinese pine plantations recovered by natural recruitment has the potential to be an effective approach for establishing multifunctional forest.