Topsoil Carbon Stocks in Urban Greenspaces of The Hague, the Netherlands

Abstract

Urbanization influences soil carbon (C) stocks and flows, which, in turn, affect soil-derived ecosystem services. This paper explores soil C storage in urban greenspaces in the Dutch city of The Hague along a transect from the suburban seaside towards the city centre, reflecting a toposequence from dune to peaty inland soils. C storage and C mineralisation potential were evaluated in relation to soil type and greenspace categories. Several soil-quality characteristics were measured, including dissolved organic C, pH, electrical conductivity, nitrogen, phosphorus, sulphur, calcium carbonate, and the water-holding capacity of the soil to evaluate what drives soil C storage in the urban context. The total SOC storage of the upper 30 cm of the greenspaces in The Hague (20.8 km2 with 37% greenspace) was estimated at 78.4 kt, which was significantly higher than assumed given their soil types. Degradability of soil organic matter in laboratory batch tests varied between 0.2 and 3 mg C gSOC−1 day−1. Degradability was highest in the seaside dune soils; however, extrapolated to the topsoil using the bulk density, topsoil C mineralization was higher in the urban forest. Soils beneath shrubs appeared to be hotspots for C storage, accounting for only 13% of the aerial cover but reflecting 24% of the total C storage. Land ownership, land use, greenspaces size, litter management and soil type did not result in significantly different C stocks, suggesting that processes driving urban soil C storage are controlled by different factors, namely land cover and the urbanization extent.

Methodological Approaches and Literature Analysis in the Study of Soil Carbon in Urban Green Spaces: A Systematic Review

“…The included studies examined soil carbon using both direct and indirect approaches. Direct studies explicitly focused on carbon stock analysis in urban green areas [4,17,18,21,25,28,[48][49][50][51][52][53][54][55][56][57][58][59][60][61]. The indirect studies deviated from a specific focus on soil carbon as a central theme.…”

“…As mentioned in the introduction, a predominant focus on soil carbon has been studied in the form of SOC [1,2,4,[16][17][18][19]21,22,[26][27][28][29]43,45,[48][49][50][51][52][54][55][56][57][58][59][60][61][62]65,67,[69][70][71][72]74,76,[80][81][82][83] and in the form of Total Carbon [25,50,51,63,65,66,68,73,75,[77]…”

BIS-4D: Mapping soil properties and their uncertainties at 25 m resolution in the Netherlands

“…Finally, prediction uncertainty of most soil properties was also higher in urban areas, which can be attributed to limited soil samples and heavily disturbed soils in urban areas. With increasing population growth in an already densely populated country, this highlights the need to map urban soils (Römkens and Oenema, 2004;Vasenev et al, 2014Vasenev et al, , 2021Kortleve et al, 2023). The PICP90 (Table 7) and the PICP (SI) indicated that prediction uncertainty was estimated relatively accurate using QRF, but small differences were found among the predicted soil properties.…”

BIS-4D: mapping soil properties and their uncertainties at 25 m resolution in the Netherlands

“…Prediction uncertainty in most soil properties was also higher in urban areas, which can be attributed to limited soil samples and heavily disturbed soils in urban areas. With increasing population growth in an already densely populated country, this highlights the need to map urban soils (Römkens and Oenema, 2004;Vasenev et al, 2014Vasenev et al, , 2021Kortleve et al, 2023). The PICP90 (Table 7) and the PICP (the Supplement) indicated that prediction uncertainty was estimated relatively accurately using QRF, but small differences were found among the predicted soil properties.…”