City parks and gardens are the basic landscape that provide recreative services to humankind, and play essential roles in promoting our mental and physical health under the ongoing urbanization and global change processes. These urban greenspaces have a tremendous and diverse community of soil organisms including bacteria, fungi, protists and invertebrates, which are far less noticeable compared with plants and animals. However, the roles of plant diversity and belowground soil biodiversity in maintaning ecosystem functions and services remains virtually unknown in urban greenspaces.

To address this knowledge gap, we conducted a global study from 56 municipalities across six continents, and collected data of 18 surrogates of ecosystem functions and thousands of species of soil microbes and fauna, to decipher the importance of plant diversity and soil biodiversity for the maintenance of city parks and gardens.

Our work contributes to our knowledge on the important role of soil organisms in supporting multiple functions such as microbial-driven C pools, organic matter decomposition, plant productivity, nutrient cycling, water regulation, plant–soil mutualism, plant pathogen control, and antibiotic resistance regulation in parks across the globe, and further suggests that considering different aspects of soil biodiversity in urban planning is essential to ensure the sustainability of urban greenspaces ecosystems.

Our findings showed that soil taxonomic and genetic diversity are positively correlated with multiple dimensions of ecosystem functions in urban greenspaces, which goes from organic matter decomposition and water regulation to plant pathogen control, and antibiotic resistance regulation. The diversity of different types of organisms has important roles to play in urban soils. For example, we tend to regard invertebrates as a key engineer of terrestrial ecosystems, because of their relatively larger body size, higher capacity to move and prey. We indeed detected the biodiversity of soil invertebrates is especially important for supporting all kinds of functioning in urban greenspaces, while that of microbes helps to support the basal levels of functioning. We also highlighted the more important roles of most common species in supporting multiple functions when compared with the rare species in urban greenspaces soils.

Unlike in natural ecosystem, plant diversity had a limited capacity to influence soil ecosystem functioning of city parks. Plants in the city parks are often non-indigenous species, city gardeners select plants mainly for their horticultural value rather than their capacity to improve surface soils. Even so, we highlighted that plant diversity might still play vital roles in affecting ecosystem functioning, such as, by forming symbiotic systems, benefiting soil biodiversity, or altering soil conditions. However, plant diversity is likely to be indispensable for other non-measured ecosystem services such as air purification, cooling, relaxation, and beautification, other than the basic ecosystem functions in natural ecosystems. Therefore, both plant diversity and soil biodiversity should be the fundamental components of urban greenspaces, biodiversity conservation is the eternal theme in deriving sustainable benefits for present and future generations.

Reference:

Kunkun Fan, Haiyan Chu, David J. Eldridge, Juan J. Gaitan, Yu-Rong Liu, Blessing Sokoya, Jun-Tao Wang, Hang-Wei Hu, Ji-Zheng He, Wei Sun, Haiying Cui, Fernando D. Alfaro, Sebastian Abades, Felipe Bastida, Marta Díaz-López, Adebola R. Bamigboye, Miguel Berdugo, José L. Blanco-Pastor, Tine Grebenc, Jorge Duran, Javier G. Illán, Thulani P. Makhalanyane, Arpan Mukherjee, Tina U. Nahberger, Gabriel F. Peñaloza-Bojacá, César Plaza, Jay Prakash Verma, Ana Rey, Alexandra Rodríguez, Christina Siebe, Alberto L. Teixido, Pankaj Trivedi, Ling Wang, Jianyong Wang, Tianxue Yang, Xin-Quan Zhou, Xiaobing Zhou, Eli Zaady, Leho Tedersoo, Manuel Delgado-Baquerizo. Soil biodiversity supports the delivery of multiple ecosystem functions in urban greenspaces. Nature Ecology & Evolution 7, 113-126 (2023). DOI: 10.1038/s41559-022-01935-4.