Effects of Different Regeneration Patterns on the Growth and Biomass Allocation Characteristics of Eucalyptus urophylla × E. tereticornis in Leizhou Peninsula,China
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.
Eucalyptus urophylla × E. tereticornisregeneration patterngrowth characteristicbiomass