Articles | Volume 2, issue 2
Original research article
25 Apr 2016
Original research article |  | 25 Apr 2016

Effect of grassland cutting frequency on soil carbon storage – a case study on public lawns in three Swedish cities

C. Poeplau, H. Marstorp, K. Thored, and T. Kätterer

Abstract. Soils contain the largest terrestrial carbon pool and thus play a crucial role in the global carbon cycle. Grassland soils have particularly high soil organic carbon (SOC) stocks. In Europe (EU 25), grasslands cover 22 % of the land area. It is therefore important to understand the effects of grassland management and management intensity on SOC storage. City lawns constitute a unique study system in this context, since they provide a high functional diversity and thus a wide range of different management intensities per unit area. In this study we investigated frequently mown (on average eight times per season) utility lawns and rarely mown (once per season) meadow-like lawns at three multi-family housing areas in each of three Swedish cities: Uppsala, Malmö, and Gothenburg. The two different lawn types were compared regarding their aboveground net primary production (NPP) and SOC storage. In addition, root biomass was determined in Uppsala. We found significantly higher aboveground NPP and SOC concentrations and significantly lower soil C : N ratio for the utility lawns compared with the meadow-like lawns. On average, aboveground NPP was 24 % or 0.7 Mg C ha−1 yr−1 higher and SOC was 12 % or 7.8 Mg ha−1 higher. Differences in SOC were well explained by differences in aboveground NPP (R2 = 0.39), which indicates that the increase in productivity due to more optimum CO2-assimilating leaf area, leading to higher carbon input to the soil, was the major driver for soil carbon sequestration. Differences in soil C : N ratio indicated a more closed N cycle in utility lawns, which might have additionally affected SOC dynamics. We did not find any difference in root biomass between the two management regimes, and concluded that cutting frequency most likely only exerts an effect on SOC when cuttings are left on the surface.

Short summary
We compared two long-term contrasting systems of urban lawn management (frequently cut utility lawn vs. seldomly cut meadow-like lawn) regarding their effect on soil carbon in three Swedish cities. Biomass production was also measured during 1 year. The utility lawns had a significantly higher biomass production, which resulted in a higher soil carbon storage, since clippings were not removed. Soil carbon sequestration outweighed the higher management-related CO2 emissions of the utility lawns.