摘要
【目的】探讨初植密度对不同产区杉木人工林优势高生长全过程的影响规律和发生程度,揭示杉木人工林优势高生长的初植密度效应及其对立地质量指示性的有效范围,为杉木人工林优势高生长评价及密度有效调控提供科学依据。【方法】以杉木中带东区(江西分宜)和中带中区(四川纳溪)共30块长期定位观测的杉木密度试验林样地(林龄范围为2~30年生)为研究对象,分析杉木人工林在不同产区和不同林分生长发育阶段下优势高对初植密度的响应规律。【结果】林分优势高与初植密度呈负相关关系,即初植密度越小,优势高越大。在林分生长发育前期,不同初植密度林分优势高生长轨迹几乎重合,初植密度影响较小,随林龄增长,不同初植密度间林分优势高生长差异呈增大趋势,至成熟龄期,林分优势高受初植密度的影响因产区而异,在中带东区影响仍很明显,在中带中区影响逐渐减弱。优势高年均生长量和连年生长量与初植密度呈负相关关系,且初植密度越大,其峰值越小,峰值出现时间越早。同一林龄下,与中带中区相比,立地条件整体更优的中带东区林分优势高生长受初植密度作用产生的分化程度相对更大。中带东区试点在5年生以后,中带中区试点在10~19年生期间,在低、中初植密度范围(1667~3333株·hm^(-2))或高初植密度范围(6667~10000株·hm^(-2))内,林分优势高生长不受初植密度显著影响,当初植密度达到或超过5000株·hm^(-2)后,其与相对低的初植密度(1667~3333株·hm^(-2))林分相比,林分优势高生长则受初植密度的显著制约。【结论】初植密度不同,林分优势高生长过程明显不同。在一定初植密度级差范围内,初植密度对林分优势高生长没有显著影响,超过一定级差时则高、低初植密度间林分优势高生长具有显著差异。标准年龄20年生时,中带东区试点差异显著的密度组合中,优势高差值最大达2.46 m,超过一个立地指数级,此时用优势高指示立地质量缺乏一定准确性。预估立地指数时,对初植密度高于5000株·hm^(-2)的林分需要修正密度的影响。
【Objective】To determine the effect of initial planting density on the dominant height growth of Chinese fir plantations and its effective range for indicating site quality,as well as to provide a scientific basis for the evaluation of dominant height growth and effective density regulation of Chinese fir plantations,the impact of initial planting density on the entire growth process of dominant height of Chinese fir plantations in various production areas was explored.【Method】The eastern region in the middle subtropics(Fenyi,Jiangxi)and the central region in the middle subtropics of Chinese fir(Naxi,Sichuan)were used as the research objects to analyze the response dynamics of dominant height to initial planting density of Chinese fir plantations in different production areas and different stand growth stages.A total of 30 long-term positioning observation plots of Chinese fir density test forests(ranging from 2 to 30 years old)were used.【Result】Dominant height was negatively correlated with the initial planting density,the lower the initial planting density was,the higher the dominant height became.In the early stage of stand,the growth trajectory of dominant height with different initial planting densities almost overlapped,and the difference among the densities was small.With the increase of stand age,the difference of dominant height growth among initial planting densities increased.At the mature stage,the effects of initial planting densities on dominant height varied with distribution areas,which was still obvious in eastern region in the middle subtropics,but gradually weakened in central region in the middle subtropics.The mean annual increment and current annual increment of dominant height were negatively correlated with the initial planting density,and the higher the initial planting density was,the smaller the peak reached and the earlier the peak appeared.Under the same stand age,compared with the central region in the middle subtropics,the eastern region in the middle subtropics with the overall better site condition had a higher differentiation degree of dominant height by the effect of initial planting density.Initial planting density had no significant effect on the dominant height growth in the range of low and middle initial planting densities(1667-3333 trees·hm^(−2))or high initial planting densities(6667-10000 trees·hm^(−2))after 5 years in eastern region in the middle subtropics and during 10-19 years in central region in the middle subtropics.When the initial planting density reached or exceeded 5000 trees·hm^(−2),the initial planting density had a significant restriction effect on the dominant height growth,compared with the relatively low initial planting densities(1667-3333 trees·hm^(−2)).【Conclusion】With various initial planting densities,the growth process of dominant height in stands varies dramatically.The initial planting density has no significant impact on the dominant height growth of the forest within a specific range of initial planting density variations.When the initial planting density exceeds a certain range,there is a significant difference between high density and low density.At the standard age of 20 years,the maximum difference value of dominant height is 2.46 m among the density combinations with significant differences in eastern region in the middle subtropics,which exceeds one site index class.At this time,it is not accurate to use dominant height to indicate site quality.The influence of density should be corrected for the site index prediction of the stand with initial planting density higher than 5000 trees·hm^(−2).
作者
李晓燕
段爱国
张建国
Li Xiaoyan;Duan Aiguo;Zhang Jianguo(State Key Laboratory of Efficient Production of Forest Resources Key Laboratory of Tree Breeding and Cultivation of National Forestry and Grassland Administration Research Institute of Forestry,Chinese Academy of Forestry,Beijing 100091;Collaborative Innovation Center of Sustainable Forestry in Southern China Nanjing Forestry University,Nanjing 210037)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2023年第8期22-29,共8页
Scientia Silvae Sinicae
基金
“十四五”国家重点研发计划项目“杉木用材林定向培育技术研究(2021YFD2201301)”。
关键词
杉木
优势高
初植密度
年均生长量
连年生长量
Chinese fir
dominant height
initial planting density
mean annual increment
current annual increment
