第1茬林分密度对2茬2年生杉木林生长影响

通过建立固定标准地,研究福建南平峡阳林场一片29年生第1茬杉木人工林的林分密度对第2茬杉木林的造林成活率和2年生林分生长的影响,结果表明,第1茬杉木林分密度与第1茬林分蓄积量呈显著正相关关系;最高密度等级(1500株·hm-2以上)的第1茬杉木林在采伐后营造的第2茬杉木林,其造林成活率和2年生的生长量最低.第1茬杉木林较高的林分密度不利于对土壤性质具有改良作用的林下植被的发育,导致林地土壤容重显著增大,引起第2茬杉木造林成活率和生长量降低,对长期生产力的维持不利,其对地力的影响程度甚至超过立地管理措施.前茬林分密度过大(密度超过1500株·hm-2)可能是杉木连栽地力衰退的重要原因之一.

Impacts of Stand Density of First-rotation Chinese fir on Growth of 2-year-old,Second-rotation Chinese fir Plantations

The effects of the stand density of a 29 year old,first rotation Chinese fir plantation on survival rate of planted seedlings and growth of 2 year old,second rotation Chinese fir plantation in Xiayang Forest Farm,Nanping,Fujian,China,were investigated by permanent plot samplingAnalysis of the results showed that stand volume was positively correlated with the stand densitySurvival rate of planted seedlings and growth rate of 2 year old,second rotation Chinese fir plantation were significantly lower in the plots with highest level of stand density (over 1 500 stem·hm-2) of the first rotation Chinese fir than those in the plots with lower levels of stand densityHigh stand density of the first rotation Chinese fir was not favorable to the development of understorey vegetation which may improved soil properties, and it caused an increase in soil bulk density leading to lower survival rate of planted seedlings and growth rate of the second rotation Chinese fir plantation,and was a disadvantage to maintain the long term productivity of forest plantationsThe degree of impact on the long term productivity of stand density factor was greater than that of site management factorHigher stand density (over 1 500 stem·hm-2) of former rotation may be one of the important factors responsible for the soil deterioration and yield decline