Understanding the drivers of woody plant diversity in urban parks in a snow climate city of China

Urban parks are an important part of urban ecosystems and play an important role in biodiversity conservation. However, it is still unclear how park characteristics affect plant diversity which could hinder the conservation of urban biodiversity due to the ineffective design of urban parks. The diversity of woody plants in 33 parks of Changchun, China, was measured with plot measurements and linked with urban park characteristics (e.g., size and age of the park) to uncover the relationship between them. The results show that urban woody plant species were abundant, with 98 species belonging to 51 genera and 26 families in the snow climate city of Changchun. The variation in woody plant diversity was largely explained by internal patch characteristics (e.g., size, age, shape), and external factors surrounding the park (e.g., land use type and socioeconomic level) accounted for only 16.0% in our study. For internal patch characteristics, older urban parks with larger areas demonstrated a richer level of plant diversity and increased nonlinearly with increasing park area. The threshold size significantly affecting plant diversity variation was approximately 30 ha. Plant diversity had positive linear relationships with the ages of urban parks, supporting the legacy effect. In addition, woody plant diversity nonlinearly decreased with increasing park shape index, which suggested that the plant diversity could also be increased by optimizing the park shape. Regarding the external factors surrounding parks, the spatial distribution of woody plant diversity varied greatly from the urban center to the suburbs. House prices around the park had positive linear relationships with woody plant diversity in parks, supporting the luxury effect. However, building and road proportions, and green space proportion had no relationship with plant diversity in parks. This study can provide a robust reference for enriching plant diversity in urban parks, thus improving the development of urban sustainable cities.