Soil biodiversity supports progress in the study of ecosystem functions in urban green spaces

Urban green spaces, including urban forests and lawns, are in many cases the only point of contact between city dwellers and nature, and healthy, sustainable urban green space ecosystems are fundamental to
maintaining people's health and vitality.
In addition to providing people with entertainment and leisure places, reducing noise and pollution, regulating hydrology, mitigating climate change and other functions, urban green space also includes a variety of ecosystem functions
such as soil nutrient cycling, plant-soil reciprocal relationship, and plant productivity.
The contribution of biodiversity to ecosystem versatility has been widely demonstrated in natural ecosystems, but the relationship between aboveground-subsurface biodiversity and ecosystem versatility in urban green ecosystems with frequent anthropogenic disturbances is unknown
.
With the increase of global urban population and people's increasing concern about climate change, it is particularly important
to analyze the ecological mechanism of aboveground-underground biodiversity to maintain the ecosystem functions and services of urban green spaces, and explore the environmental factors and management practices closely related to ecosystem functions and services.

Therefore, the team of Chu Haiyan, a researcher at the Nanjing Institute of Soil Science, Chinese Academy of Sciences, together with the Institute of Natural Resources and Agrobiology of Seville, Spain, and the University of Pablo de Olavid in Spain, conducted a standardized survey of green spaces in 56 cities in 17 countries on six continents to study aboveground plant diversity and subsurface soil biodiversity (including soil bacteria, fungi, protists and invertebrates, as well as the diversity of functional characteristics of microflora based on metagenomics) Relationships
with 9 key ecosystem services covering 18 ecosystem functions (microbiome-driven carbon pool, organic matter decomposition, plant productivity, nutrient cycling, water regulation, plant-soil reciprocal symbiosis, plant pathogen control, and antibiotic resistance gene regulation).
The study found that soil biodiversity (taxonomic diversity and functional property diversity) was significantly positively correlated with ecosystem functioning, including ecosystem versatility, multiple thresholds of ecosystem function, multiple dimensions of ecosystem function, and key ecosystem services
.
Compared with rare soil biodiversity, soil dominant biodiversity has a more significant role
in supporting the multi-functionality of urban green space ecosystems.
Compared with bacteria, fungi and protists, relatively large soil invertebrates at high trophic levels are closely associated
with more urban green space ecosystem functions.
There is still a stable correlation
between soil biodiversity and the multi-functionality of urban green space ecosystems under the conditions of spatial scale, climatic factors, environmental variables and management measures.

Conversely, it is found that the contribution of aboveground plant diversity to the ecosystem functions and services of urban green spaces is weak, and plant diversity only indirectly affects the multi-functionality of urban green space ecosystems by regulating soil biodiversity and soil traits
.
Since plants in urban green spaces tend to be non-native species, people choose these plants mostly because of their horticultural value, not their ability to improve the topsoil, and these plants cannot form a co-evolution effect with the local climate, environment, soil organisms, etc.
in the short term, thereby weakening their positive response
to ecosystem functions.
However, plant diversity remains an important component of
urban green spaces as it is essential for other unmeasurable ecosystem services such as air purification, cooling, recreation and urban beautification.
This research work provides an important reference for the conservation of soil biodiversity and ecosystem functions in urban green space ecosystems, and is essential
for maintaining the sustainable development of urban environments and human well-being in the context of global change and urbanization.

The research results were published in Nature Ecology and Evolution, with Fan Kunkun, Special Research Assistant at Nanjing Institute of Soil Science, as the first author of the paper, and Researcher Chu Haiyan and Professor Manuel Delgado-Baquerizo as corresponding authors
.
The research was supported
by the National Key Research and Development Program of China, the National Natural Science Foundation of China and other projects.

Paper link

Figure 1: Geographical locations of 56 surveyed cities in 17 countries on six continents and their urban green landscapes

Figure 2.
Contribution
of soil biodiversity in urban green spaces to ecosystem functioning.
(A) The rate
of interpretation of ecosystem functions by soil biodiversity, plant diversity, spatial scale, environmental factors, etc.
(b) Direct and indirect impacts
of spatial scale, environmental factors, plant diversity and soil biodiversity on ecosystem multifunctionality.