不同更新方式对雷州半岛尾细桉生长及生物量分配特征的影响

Effects of Different Regeneration Patternson the Growth and BiomassAllocationCharacteristics of Eucalyptus urophylla×E.tereticornisinLeizhou Peninsula,China

为准确认识更新方式对桉树人工林生长及生物量的影响,进而为不同培育目标桉树更新方式的筛选提供理论依据和数据支持,文章以相同林龄梯度的尾细桉植苗林和萌芽林为研究对象,探讨两种更新方式对生长和生物量分配特征的影响。结果表明:萌芽林前期胸径和树高显著大于植苗林,但增长速率的下降幅度大于植苗林,胸径在5年生时以及树高在7年生时两种更新方式之间已无显著差异。两种更新方式之间尾细桉各器官的生物量分配随林龄变化存在显著差异,但这种差异主要体现在树干和树根上。两种更新方式下的尾细桉各器官生物量均随着林龄的增大呈极显著的线性增加,但增长速率表现为萌芽林小于植苗林。萌芽林各器官的生物量显著大于植苗林的优势平均可维持到5年生,之后两种更新方式之间各器官生物量基本无差异,但从增长速率的趋势来看,植苗更新在生长后期的生长潜力要高于萌芽更新。因此,在桉树栽培实践中,可根据不同的培育目标选择不同的更新方式以获得最大的效益,以培育短轮伐期为主的尾细桉人工林利用萌芽更新的方式造林;而以培育大径材为目标的尾细桉人工林可利用植苗更新的方式造林。

In order to understand the effects of regeneration patterns on growth and biomass of eucalypt plantations,and to provide a theoretical basis and data for evaluation of eucalypt regeneration patterns for different cultivation objectives,the present study took planted and coppiced plantations of Eucalyptus urophylla×E.tereticornis with the same age gradient as the objects of study.These were used to investigate the effects of these two types of regeneration on the characteristics of their growth and biomass allocation.The results showed that the diameter at breast height(DBH)and tree height(H)in the early stage of coppice regenerated plantations were significantly larger than those in planted(seedling)plantations,but then at later ages the coppiced plantations showed a decrease in growth rate to below that of the planted plantations,with no significant differences between the two regeneration patterns for DBH at age 5-years or H at age 7-years.There were significant differences in biomass allocation of various organs of E.urophylla×E.tereticornis across stand ages between the two regeneration patterns,but this difference was mainly in trunk and roots.The biomass of all organs of E.urophylla×E.tereticornis under the two regeneration patterns showed a highly significant linear increase with stand age,but the growth rate showed a lower increase in the coppiced plantations than in the planted plantations.The advantage of significantly greater biomass of each organ in the coppiced plantations than in planted plantations was maintained on average up to age 5-years,after which there was essentially no difference in biomass of each organ between the two regeneration patterns.However,growth rate trends showed that the planted plantations had a higher growth potential than coppiced plantations at later ages.Therefore,in eucalypt cultivation practice,different regeneration patterns can be selected according to different cultivation objectives to achieve the greatest benefits.For short rotation plantations,use of coppice regeneration gives the highest yields whilst planted plantations will provide better yields for longer rotation plantations aiming at larger diameter timber production.