The main associated trees of Parrotia subaequalis in eastern China

Parrotia subaequalis (H. T. Chang) R. M. Hao et H. T. Wei is a rare and endangered Tertiary relict tree that is endemic to subtropical China. However, little is known about its growth condition and relationship with associated tree species. Here, we for the first time measured the structural diversity of P. subaequalis communities at three representative sites in eastern China using four structural indices including mingling, tree-tree distance, diameter and tree height differences. This dataset is about the main associated trees of Parrotia subaequalis in eastern China. It includes the species names, individuals, distributing sites of main associated trees in the three sample areas. The results showed that: 1) Collectively, most P. subaequalis and associated tree species were small and mid-sized classes in tree height, and small-sized class in diameter; 2) There were two or more other tree species around most of P. subaequalis individuals across the three sites; 3) Overall, the mean distance between reference trees and their neighbors was mainly 1–2 m. Our results indicated that a strong interspecific competition existed between P. subaequalis and its associated tree species. Meanwhile, although the reference tree P. subaequalis had slight advantages in both horizontal and vertical planes, we think that it is necessary to take some effective measures to reduce the interspecific competition and thereby keep it at a proper successive stage. In addition, we also discuss the protection level of P. subaequalis in China, and propose to keep this species at the First-Grade State Protection.

银缕梅（Parrotia subaequalis (H. T. Chang) R. M. Hao et H. T. Wei）是中国亚热带特有的珍稀濒危第三纪孑遗树种。目前对其生长状况以及与伴生树种的关系尚缺乏深入了解。本研究首次在中国东部3个代表性样地，采用混交度、树间距离、径级差和树高差4种结构指数，对银缕梅群落的结构多样性进行了测定。本数据集涵盖中国东部地区银缕梅的主要伴生树种信息，包含3个样区内主要伴生树种的物种名称、个体数量及分布位点。研究结果显示：1） 多数银缕梅及伴生树种的树高均属于中小径级，径级则以小径级为主；2） 3个样地的多数银缕梅个体周围均存在2种及以上其他乔木树种；3） 总体而言，参照树与邻体间的平均距离主要集中在1~2米。本研究结果表明，银缕梅与其伴生树种间存在强烈的种间竞争。同时，尽管作为参照树的银缕梅在水平和垂直空间上均具备微弱优势，但仍需采取有效措施缓解种间竞争，以维持其处于适宜的演替阶段。此外，本研究还探讨了我国银缕梅的保护等级，并建议将其列为国家一级保护植物。