Urban tree effects on soil organic carbon

Area of Science:

• Urban ecology
• Soil science
• Forestry

Background:

• Urban trees provide aboveground ecosystem services, driving global tree planting initiatives.
• Soils store a significant portion (approximately 75%) of ecosystem organic carbon.
• Understanding urban trees' impact on soil organic carbon (SOC) and related properties is crucial for belowground ecosystem services.

Purpose of the Study:

• To investigate the effects of different urban tree genera and mixed woodlands on soil properties compared to urban grasslands.
• To determine if aboveground biomass and belowground ecosystem services are coupled.
• To assess the genus-specific influence on soil organic carbon enhancement.

Main Methods:

• An observational study was conducted comparing soil properties (to 1m depth) under three tree genera and mixed woodlands against adjacent urban grasslands.
• Soil bulk density and C:N ratio were analyzed as indicators of regulating ecosystem services.

Main Results:

• Soil organic carbon (SOC) enhancement varied by tree genus; it was highest under Fraxinus excelsior and Acer spp. but similar to grasslands under Quercus robur and mixed woodland.
• Aboveground biomass and belowground ecosystem service provision by urban trees were not directly coupled.
• Soil bulk density and C:N ratio were not influenced by tree cover type.

Conclusions:

• Genus selection is critical for maximizing long-term SOC storage in urban environments.
• Emerging threats from genus-specific pathogens necessitate careful consideration in urban tree management.
• The study highlights the importance of belowground impacts of urban trees, which are often overlooked.