不同林龄杉木檫树混交林内檫树的生长规律

Growth rhythm of Sassafras tzumu in Cunninghamia lanceolata and S.tzumu mixed forest at different ages

[目的]分析不同林龄杉木檫树混交林内檫树的生长规律,为杉木檫树混交林科学经营提供依据。[方法]以12、24年生杉木檫树混交林为研究对象,采用树干解析法测定檫树胸径、树高、单株材积和胸高形数等生长指标,并对檫树生长特性与土壤物理性质进行相关性分析。[结果](1)随着林龄的增长,12、24年生檫树胸径、树高及单株材积均呈逐渐上升的趋势。其中胸径、树高均在0~5 a生长速度最快,而单株材积在5 a后增长速度加快。12年生檫树树高在5~12 a高于24年生檫树。(2)随着林龄的增长,12、24年生檫树胸径平均生长量均呈先升高后下降的趋势,单株材积平均生长量则逐渐升高;12年生树高平均生长量呈平稳降低趋势,24年生则逐渐下降;12、24年生檫树胸径连年生长量分别在第4年与第9年急剧下降,树高与单株材积连年生长量波动性较大。(3)12、24年生檫树胸高形数变化范围分别为0.42~0.78、0.44~0.59,其中12年生檫树胸高形数随着林龄的增长呈先下降后上升趋势,24年生则呈“W”型变化趋势。(4)相关分析表明,檫树胸径、树高连年生长量与土壤容重呈显著正相关,树高连年生长量与土壤非毛管孔隙度呈显著负相关。[结论]不同林龄杉木檫树混交林内檫树的生长表现不同,应依据檫树生长规律制定合理的林分密度控制技术。

[Purpose]The aim of the study was to analyze the growth of Sassafras tzumu in Cunninghamia lanceolata and S.tzumu mixed forests at different ages,so as to provide theoretical basis for scientific management of C.lanceolata and S.tzumu mixed forests.[Method]The study was conducted in 12-and 24-year-old C.lanceolata and S.tzumu mixed forests.The trunk analytical method was used to determine the DBH,height,volume growth and stem form factor at breast height of S.tzumu,and correlation analysis was carried out to explore the relation between growth characteristics of S.tzumu and soil physical properties.[Result](1)With the increase of forest age,the DBH,height and individual volume of both 12-and 24-year-old S.tzumu increased gradually.The DBH and height of 12-and 24-year-old S.tzumu grew the fastest in 0-5 years,and the growth rate of single tree volume accelerated after 5 years.The height of 12-year-old S.tzumu was higher than that of 24-year-old S.tzumu at 5-12 years.(2)The average DBH growth of 12-and 24-year-old S.tzumu showed the tendency of increasing and then decreasing,while the average individual volume gradually increased with stand age.The average height growth of 12-year-old S.tzumu decreased mildly while that of 24-year-old S.tzumu decreased gradually with age.The current annual DBH increment of 12-and 24-year-old S.tzumu decreased sharply in the 4th and 9th years respectively,and the current annual increment of tree height and individual volume fluctuated greatly.(3)With the increase of forest age,the number of breast height of S.tzumu of different forest ages decreased at first and then increased.The variation range of stem form factor at breast height of 12-and 24-year-old S.tzumu was 0.42-0.78 and 0.44-0.59,the stem form factor of 12-year-old S.tzumu decreased at first and then increased with forest age,while that of 24-year-old S.tzumu showed a W-shaped trend.(4)Correlation analysis showed that the current annual increment of DBH and height of S.tzumu were significantly positively correlated with soil bulk density,while the current annual increment of tree height was negatively correlated with soil non-capillary porosity.[Conclusion]The growth performance of S.tzumu was different in the mixed forest of C.lanceolata and S.tzumu at different ages.Reasonable stand density control techniques should be established according to the growth of S.tzumu.