Growth Dynamics of Araucaria after Management Interventions in Natural Forest

ABSTRACT The objective of this study was to evaluate the effect of selective logging on the growth dynamics of Araucaria angustifolia in a natural forest of Rio Grande do Sul state, Brazil. Treatments were based on percentage reduction of the basal area per DBH class, namely, T0 (control) = 0%; T1 (light selective logging) = reduction of 20-30%; T2 (moderate selective logging) = reduction of 40-50%. Data were obtained prior to the management interventions and four, eight and 13 years after selective logging. Changes between treatments were assessed using the following parameters: absolute density, absolute dominance, importance value index, and growth rates. Results show that population reduction and canopy opening provided greater recruitment and higher growth rates for araucaria in the management treatments (T1 and T2) compared with those of the control treatment (T0). These results reinforce that management practices are necessary for the continuous development of araucaria in this forest formation.

摘要 本研究旨在评估选择性采伐对巴西南里奥格兰德州天然林内窄叶南洋杉（Araucaria angustifolia）生长动态的影响。试验处理以各胸径（DBH，Diameter at Breast Height）径级的断面积缩减百分比为划分依据，具体设置如下：T0（对照组）=0%；T1（轻度选择性采伐）=20%~30%断面积缩减；T2（中度选择性采伐）=40%~50%断面积缩减。数据采集于经营干预实施前，以及选择性采伐后的第4、8和13年。本研究采用绝对密度、绝对优势度、重要值指数及生长速率四项参数，评估不同处理间的变化差异。结果显示，与对照组（T0）相比，经营处理组（T1与T2）通过种群缩减与林冠开放，为窄叶南洋杉带来了更充足的更新苗补充与更高的生长速率。上述研究结果证实，针对该林分类型开展经营措施，对窄叶南洋杉的可持续发展具有必要性。