Structural diversity and conservation implications of Parrotia subaequalis (Hamamelidaceae), a rare and endangered tree species in China

Jie Liu,Guang-Fu Zhang,Xue Li

doi:10.3897/natureconservation.44.69404

Abstract

Parrotia subaequalis (H. T. Chang) R.M. Hao &amp; 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, for the first time we measured the structural diversity of P. subaequalis communities at three representative sites in eastern China using four structural indices, including mingling, tree-tree distance, and diameter and tree height differences. 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.

Highlights

Analyzing species composition, structure and function of endangered plant communities is essential for understanding the growth of a target species, its relationship with surrounding tree species and predicting its population dynamics (Hui et al 2019; Alavi et al 2020)
Zhang et al (2018a) used this approach to measure the structural diversity of Chinese yew (Taxus wallichiana var. mairei) population in an ex situ conservation established in Nanjing of eastern China, and considered that these yews faced strong interspecific competition from their neighbors and that most yews were found beneath a single tall neighboring tree
The first four top species at each site took obvious advantages in abundance, and these dominant species were very similar (Appendix 1). They were in order as follows: P. subaequalis, Pistacia chinensis, Celtis sinensis, Cyclobalanopsis glauca in Wanfo Mountain (WF), Cyclobalanopsis glauca, P. subaequalis, Pistacia chinensis, Dalbergia hupeana in DL, and Celtis sinensis, P. subaequalis, Dalbergia hupeana, Platycarya strobilacea in Longwang Mountain (LW)

Summary

Introduction

Structure and function of endangered plant communities is essential for understanding the growth of a target (endangered) species, its relationship with surrounding tree species and predicting its population dynamics (Hui et al 2019; Alavi et al 2020). On a small scale, the horizontal and vertical structure of a forest community is largely influenced by the arrangement, position, and mixture degree of the surrounding tree species and their competition for light, water, minerals, space and other environmental resources (Pommerening 2002; Ruprecht et al 2010). For those endangered species which have a limited distribution within a certain area, their populations usually share similar climate, soil, human disturbance and other environmental factors. This result provides a theoretical basis for the protection of Chinese yew. Sefidi et al (2015) studied the structural diversity of Persian ironwood (Parrotia persica) in northern Iran, and found that Persian ironwood almost grew in fairly pure forests in three sampled plots and the interspecific competition was weak

Methods

Results

Discussion

Conclusion