陈山红心杉人工林最佳轮伐期的确定

Determination of the optimal rotation period of Chenshan red-heart Chinese fir plantation

轮伐期的确定是实现人工林永续利用、科学经营和管理森林生态系统的重要手段,本研究以江西陈山红心杉人工林为研究对象,选取29年生的红心杉人工林,设置20 m×30 m的标准地5块,在每块标准地内按3级林木分级办法选择标准木,进行树干解析,分析分级木生长及红心杉心材形成过程;计算红心杉的数量成熟年龄、工艺成熟年龄和经济成熟年龄,从而确定红心杉的最佳轮伐期。研究结果表明:(1)红心杉3个分级木的胸径、树高、材积的生长过程均表现为初期均缓慢生长,之后开始快速生长的特点,最大生长速率出现的时间不同,优势木的材积生产力在第11年时最大,达到0.0216 m^(3)·a^(-1);(2)红心杉3个分级木的材积连年生长量与平均生长量曲线,均相交于20年左右,红心杉材积数量成熟期为20年左右。(3)红心杉心材开始形成时间在第7年,Logistic模型能很好地模拟红心率与年龄的关系,40年时,红心率达到了峰值60%左右。且木材基本密度随着林木年龄的增大而增大,红心杉的工艺成熟年龄大于数量成熟年龄。(4)森林年均纯收益和年均净现值的最大值均在29年,内部收益率最大值在25年。综上,陈山红心杉的数量成熟龄在20年,工艺成熟龄在40年,经济成熟龄在29年。因此,最佳轮伐期按照“以工艺成熟为基础,重点考虑经济成熟,适当兼顾数量成熟”的原则确定:陈山红心杉的最佳轮伐期在40年,此时,胸径、树高和材积已经达到成熟,可获得最大木材产量,红心率也达到了极值,木材品质最佳,且经济收益最高。

Optimal rotation period determination was to achieve the sustainable use and scientific management of the forest ecosystem.In this study,we selected 29 years red-heart Chinese fir plantation in Chenshan,set 20 m×30 m standard 3 blocks,for each sample sampling of the tree trunk,analyzed the growth process of classified wood and calculated the quantitative mature age,technologically mature age,economic mature age and to comprehensive analysis the optimal rotation age of red-heart Chinese fir.The results showed that:(1)The growth process of the DBH,tree height and timber volume of the three graded trees of red-heart Chinese fir were all shown as the characteristics of slow growth in the initial stage and rapid growth later.The maximum growth rate was different.The timber accumulation productivity of superior wood was the largest in the 11th year,reaching 0.0216 m^(3)·a^(-1);(2)The annual growth and average growth curves of the three graded trees of red fir were all in about 20 years,and the maturity period of red fir wood was about 20 years.(3)In the seventh year,the Logistic model could well simulate the relationship between the red heart rate and age.By 40 years,the red heart rate had peaked by about 60%.And through the determination of the wood basic density,it was found that the basic density of wood increases with the increase of forest age.(4)Forest net and annual returns peaked at 29 years,and annual NPV also peaked in 29 years;the IRR peaked in 25 years.To sum up,the number of Chenshan red-heart Chinese fir mature age is 20 years,the process mature age is 40 years,and the economic mature age is 29 years.Therefore,the best rotation period according to the"based on technology mature,key economic consideration,the mature proper quantity mature"principle to determine:the best rotation in 40 years,at this time,the DBH,tree height and timber volume had reached mature,could obtain the maximum wood yield,the red heart rate also had reached the extreme value,the best wood quality was the best,and the highest economic income.