Giant Araucaria trees in Brazilian Atlantic forests today are rare but remain critically important for structuring these ecosystems, providing unique and rare habitat elements that can serve as points of reference for their management. Old-growth Araucaria trees, with their complex crowns and big trunk cavities, supply more important ecological services than smaller trees with simple crowns. Forest ecology managers lack information on the old-growth structures of Brazilian Araucaria forest, their ecological importance and their potential societal values and uses. In this study, we investigated old-growth attributes of Araucaria angustifolia and relate their wide structural variability to ecological management goals. In this study, we used currently available data on the last large old Araucaria trees, as well as our own new records, from large trees of 1.6–3.2 m diameter in the Araucaria forests in southern Brazil. In order to quantify the structural attributes of these remnant trees, their main trunks, any reiterated canopy trunks and trunk cavities were measured for diameters, heights and volumes. These old-growth trees had an average height of 38.4 m, and total tree volumes ranged from 21.5 to 106.6 m³. The biggest reiterated trunk was 1.1 m in diameter and 17 m long, which is larger than most adult Araucaria trees. Number of cavities and number of reiterated trunks were all significantly related to the diameters of these large remnant Araucaria trees; both features are absent in Araucaria <50 cm in diameter. The maximum diameter and average length of reiterated trunks were correlated with the number and size of trunk cavities. Commercial wood values and uses are limited for all trees with main trunk diameters exceeding 1.5 m due to large internal cavities—however, these rare, relictual old-growth structures are of high ecological value for the local fauna and flora.

中文翻译：

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与南美洲最后的巨型亚热带针叶树相关的古老结构属性

今天，巴西大西洋森林中的巨型南洋杉树很稀有，但对于构​​建这些生态系统仍然至关重要，它提供了独特而稀有的栖息地元素，可以作为其管理的参考点。古老的南洋杉树具有复杂的树冠和大的树干空腔，比具有简单树冠的小树提供更重要的生态服务。森林生态管理者缺乏关于巴西南洋杉森林古老生长结构、其生态重要性及其潜在社会价值和用途的信息。在这项研究中，我们调查了南洋杉的老生长属性并将其广泛的结构变异性与生态管理目标联系起来。在这项研究中，我们使用了巴西南部南洋杉林中直径为 1.6-3.2 m 的大树的最后一棵大型古南洋杉树的现有数据，以及我们自己的新记录。为了量化这些残余树木的结构属性，它们的主要树干、任何重复的树冠树干和树干腔都测量了直径、高度和体积。这些古树平均高度为38.4 m，总树量为21.5～106.6 m ³。最大的重复树干直径1.1 m，长17 m，比大多数成年南洋杉都大树木。腔数和重复树干的数量都与这些大型残存南洋杉树的直径显着相关；在直径 <50 cm 的南洋杉中没有这两个特征。重复树干的最大直径和平均长度与树干腔的数量和大小相关。由于较大的内部空洞，主干直径超过 1.5 m 的所有树木的商业木材价值和用途都受到限制——然而，这些稀有的、残存的古老结构对当地动植物群具有很高的生态价值。