Species diversity and spatial pattern of heritage trees in Taiyuan

Abstract

Heritage trees are key to maintaining biodiversity, supporting ecosystem services, and preserving cultural heritage. This study investigates the species composition, spatial distribution patterns, and conservation needs of heritage trees in ancient Taiyuan city in Northern China, focusing on their cultural-ecological significance and urbanization threats. Using redundancy analysis, we surveyed 4737 heritage trees across ten urban core, suburban and rural districts and nine habitat types and calculated their importance values, species diversity indices, and statistical associations with key socio-demographic and environmental factors. The prized stock comprised 57 species, dominated by Ziziphus jujuba, Styphnolobium japonicum, accompanied by four subdominants such as Platycladus orientalis and Pinus tabuliformis, and 39 uncommon to rare species, contributing considerably to species diversity. Spatial analysis and ecological assessments found distinct distribution patterns, with suburban and rural areas accommodating higher tree abundance and species richness than more urbanized districts. Factors such as altitude, cultivated area, economic activities, and particularly urban development, strongly influenced tree distribution. We analyzed their natural-cum-cultural value and threats from fast urban expansion, habitat fragmentation and loss, and insufficient conservation efforts. The findings underscored the urgent need for targeted and reinforced conservation strategies to safeguard these heritage trees, sustaining their precious legacy for future generations.

Keywords: Conservation strategy; Distribution pattern; Environmental factor; Heritage tree; Species composition; Urbanization threat.

Fig. 1

Images of some typical specimens of heritage trees in Taiyuan. (A) denotes Platycladus orientalis; (B) Ziziphus jujuba; (C) Gleditsia sinensis; (D) Wisteria sinensis; (E) Catalpa ovata; (F) Ginkgo biloba; (G) Styphnolobium japonicum; (H) Syringa reticulata subsp. amurensis; (I) Juniperus chinensis.

Fig. 2

The heritage tree distribution in nine habitat types in Taiyuan’s districts: (a) tree abundance (numbers in brackets); (b) species richness (numbers in brackets). The colors in the pie charts represent tree abundance or species richness in different habitats: A denotes villages and farmland, B parks and gardens, C roadside, D others (not adequately explained or do not fit into any of the other eight groups), E business and commercial premises, F wooded areas and plant nurseries, G government, institutional and community sites, H residential areas, and I religious sites and cemeteries.

Fig. 3

Redundancy analysis (RDA) ordination illustrating the relationship between the species diversity and tree abundance of heritage trees and environmental factors in Taiyuan. Solid arrowheads represent the dependent variables (species diversity and tree abundance), while hollow arrowheads denote the independent variables (environmental factors). The angle between the arrows indicates the nature of the correlation: an acute angle denotes positive correlation, an obtuse angle negative correlation, and a right angle no correlation. The hollow dots represent various districts within Taiyuan and refer to Table 1 for the meaning of district abbreviations.

Fig. 4

Vertical distribution patterns of the heritage trees in Taiyuan in relation to species richness (blue color) and species abundance (orange color). There are ten gradient levels with altitudes ranging from 750 to 1750 m, and each group is separated by 100 m.