Browsing by Subject "soil carbon"

Promoting carbon sequestration and storage is an important part of climate change mitigation. Soils play a prominent role in this, as they contain the largest terrestrial carbon pools. Urban soils have been shown to contain significant amounts of carbon, and thus, urban green spaces have the potential to contribute to climate regulation through soil carbon sequestration and storage. Many green spaces in cities consist of managed lawns containing significant amounts of soil organic carbon, although management activities such as mowing can also be a source of carbon emissions. A low-maintenance alternative to lawns is urban meadows. The benefits in terms of soil carbon sequestration in urban meadows, however, are still poorly documented. This study aims to contribute to an increased understanding of the ecosystem services urban meadows provide, which is valuable in the planning of urban green infrastructure. I quantified soil organic carbon content in 140 urban meadows of different land use types in the Helsinki Metropolitan Area to determine their value in terms of carbon storage and to compare this with the soil carbon storage in highly managed urban lawns. The meadow types explored included valuable grasslands, which have special nature or cultural values, landscape meadows, road verge grasslands, and rocky outcrops. Soil samples were taken from a depth of 0–10 cm using a soil corer. The soil organic matter content and bulk density were measured. Existing data from the soils of city park lawns in Helsinki were used for comparison in the analysis. The soil organic carbon content in the different meadows, as well as in the lawns, was then analysed using land use type and site productivity as explanatory variables. Results show that park lawn soils have a significantly higher carbon density (kg C per square meter) than any of the meadow types. Out of the meadow sites, valuable grasslands had the highest carbon density. The higher carbon content in park lawn soils may be due to increased productivity due to frequent mowing, as well as the fact that these lawns were likely established on nutrient-rich soil. Interestingly, the highest %C was detected in rocky sites. However, the total carbon stocks of rocky sites are lower due to the soil cover being shallow and large portions of the sites not having soil cover at all. To answer the question of whether a lawn should be converted into a meadow in hopes of increasing carbon sequestration and storage, future studies should focus on meadows that were formerly lawns, and that had the same or similar initial conditions as a typical lawn.