Biogeographic and anthropogenic factors shaping the distribution and species assemblage of heritage trees in China

Abstract

Heritage trees are recognized as elements of cultural landscapes and as keystone ecological entities in human-dominated landscapes, often bestowing high socio-cultural and ecological values. Current understanding of species distribution patterns and broad-scale species assemblages of heritage trees is limited. This study analyzed the diversity, distribution patterns, and origins of heritage trees and assessed the underlying factors contributing to their occurrence at the national scale in China. Data were drawn from published and online sources representing 561 regions across China. There were 1140 species including 105 endangered ones preserved as heritage trees. Heritage trees originated from four sources of species provenance: natural forest species 73.51 % of total species), native ruderal species (10.53 %), domesticated species (6.75 %) and exotic species (9.21 %). The origin of heritage trees differed across climatic zones. At the national and climatic zone scale, species similarity (Jaccard Index) among regions was low, constrained by geographic distance, climate (e.g., mean annual precipitation) and anthropogenic factors (e.g., population density). Mean annual precipitation, mean annual temperature, population density and GDP per capita were the main determinants of species provenance. Most heritage tree species serve tangible uses, especially domesticated and exotic species. Species assemblages of heritage trees were mainly associated with the local plant species pool, climate, socio-economic development status and human preference. As living heritage, the trees need dedicated protection measures based on their main tangible and cultural values for human, primary threats, and statutory protection degree at the species level. Regional culture, belief, and customary laws should be considered in formulating policies for protection and conservation of these trees.