Ferraz Filho Antonio C, Mola-Yudego Blas, González-Olabarria José R, Scolforo José Roberto S
Departamento de Ciências Florestais, Universidade Federal do Piauí/UFPI, Campus Professora Cinobelina Elvas, Avenida Manoel Gracindo, Km 01, 64900-000 Bom Jesus, PI, Brazil.
School of Forest Sciences, University of Eastern Finland/UEF, P.O. Box 111, FI-80101 Joensuu, Finland.
An Acad Bras Cienc. 2018 Jan-Mar;90(1):255-265. Epub 2018 Feb 5.
This study focuses on the effects of different thinning regimes on clonal Eucalyptus plantations growth. Four different trials, planted in 1999 and located in Bahia and Espírito Santo States, were used. Aside from thinning, initial planting density, and post thinning fertilization application were also evaluated. Before canopy closure, and therefore before excessive competition between trees took place, it was found that stands planted under low densities (667 trees per hectare) presented a lower mortality proportion when compared to stand planted under higher densities (1111 trees per hectare). However, diameter growth prior to thinning operations was not statistically different between these two densities, presenting an overall mean of 4.9 cm/year. After canopy closure and the application of the thinning treatments, it was found that thinning regimes beginning early in the life of the stand and leaving a low number of residual trees presented the highest diameter and height growth. Unthinned treatments and thinning regimes late in the life of the stand (after 5.5 years), leaving a large number of residual trees presented the highest values of basal area production. The choice of the best thinning regime for Eucalyptus clonal material will vary according to the plantation objective.
本研究聚焦于不同间伐方式对桉树无性系人工林生长的影响。采用了1999年种植于巴伊亚州和圣埃斯皮里图州的四项不同试验。除间伐外，还评估了初始种植密度和间伐后施肥情况。在林冠郁闭之前，也就是树木之间尚未发生过度竞争之前，发现低密度种植（每公顷667株）的林分与高密度种植（每公顷1111株）的林分相比，死亡率较低。然而，在间伐操作之前，这两种密度下的直径生长在统计学上并无差异，总体平均直径生长为每年4.9厘米。在林冠郁闭并进行间伐处理后，发现林分生命早期开始且保留少量残留树木的间伐方式，直径和树高生长最高。未间伐处理以及林分生命后期（5.5年后）进行的间伐方式，保留大量残留树木的，其断面积生长值最高。对于桉树无性系材料，最佳间伐方式的选择将因种植目标而异。
