The world is becoming increasingly urbanized, an example of global environmental change. Urban parks are designed and managed in a similar way across the globe. They often consist of expanses of lawns with individually planted trees of varying appearances and functional traits. These parks can provide various ecosystem services, including those related to soil properties. Our goal was to investigate whether soil properties in urban parks differed under vegetation producing labile or recalcitrant litter, and whether climatic zones (from boreal to temperate to tropical city) had an impact. We also compared these properties to those of (semi)natural forests outside the cities to assess the influence of urbanization on plant-trait effects. Our findings showed that vegetation type affected soil organic matter (OM), total carbon (C), and total nitrogen (N) percentages, but inconsistently across climatic zones. Plant-trait effects were particularly weak in old parks in the boreal and temperate zones. However, in young parks in these zones, soils underneath the two tree types accumulated significantly more OM, C, and N in comparison to lawns. Across climatic zones, human-made drivers dominated natural ones, and organic-matter-related soil properties under trees producing labile or recalcitrant litter were consistently lower in parks compared to forests. The impact of urbanization is also reflected in its ability to homogenize soil properties in parks across the three cities, particularly in lawn soils and soils under trees irrespective of functional trait. Our study shows that soil functions related to carbon and nitrogen dynamics in urban green spaces have diverged from those in natural ecosystems. This implies that anthropogenic drivers have had a long-lasting influence on soil ecosystem services, even in old urban green spaces where plant-soil interactions have a long history.
 

urbanization,plant traits,soil organic matter