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.