Dynamics of Tree Population Structure After Disturbance of Araucaria Forest Remnants

Abstract This study aimed at evaluating and compare the changes from 2012 to 2016 in the structure and floristic composition of a remnant Araucaria Forest. The entry and mortality rates were 2.2% year-1 and 6.9% year-1, respectively. Among the most represented species, those with the greatest yearly increases in their numbers were Sebastiania brasiliensis, Eugenia uniflora, and Allophylus sp. Average mortality density was 498 ind ha-1, and was particularly high for the following species: Casearia decandra (representing 32.3% of total mortality), Eugenia sp. (27.2%), Cinnamodendron dinisii (24.5%), and Lithraea brasiliensis (25.2%). The pioneer species represented 8.33% of income and 29.17% mortality, and secondary species composed 33.33% and 62.50% of income and mortality, respectively. Climax species accounted for 8.33% of income and did not contribute to mortality. The high tree mortality observed in the present study can be attributed, among others factors, to the effects of natural disturbance that occurred in the period.

摘要 本研究旨在评估并比较2012至2016年间一处残存南洋杉林（Araucaria Forest）的群落结构与植物区系组成变化。年迁入率与年死亡率分别为2.2%与6.9%。在优势物种中，种群数量年增幅最大的为巴西赛巴树（Sebastiania brasiliensis）、红果仔（Eugenia uniflora）与异木患属未定种（Allophylus sp.）。平均死亡密度为498株·公顷⁻¹，其中以下物种的死亡占比尤为突出：十蕊脚骨脆（Casearia decandra，占总死亡个体数的32.3%）、番樱桃属未定种（Eugenia sp.，27.2%）、肉药樟（Cinnamodendron dinisii，24.5%）以及巴西乳香（Lithraea brasiliensis，25.2%）。先锋物种占总迁入个体的8.33%，占总死亡个体的29.17%；次生物种分别占总迁入个体的33.33%与总死亡个体的62.50%。顶极物种占总迁入个体的8.33%，未对总死亡个体数产生贡献。本研究中观测到的高树木死亡率，除其他影响因素外，可归因于该时期发生的自然干扰效应。