Dynamics of carbon loss from an Arenosol by a forest to vineyard land use change on a centennial scale
Few studies have focused on Arenosols with regard to soil carbon dynamics despite the fact that they represent 7% of the world’s soils and are present in key areas where food security is a major issue (e.g., in Sahelian regions). As for other soil types, land use changes (from forest or grassland to cropland) lead to a loss of substantial soil organic carbon (SOC) stocks and have a lasting impact on the SOC turnover. Here we quantified long-term variations in carbon stocks and their dynamics in a 80 cm deep Mediterranean Arenosol that had undergone a forest-to-vineyard land use change over a 100 years ago. Paired sites of adjacent plots combined with carbon and nitrogen quantification and natural radiocarbon (14C) abundance analyses revealed a C stock of 53 t.ha-1 in the 0–30 cm forest soil horizon, which was reduced to 3 t ha-1 after long-term grape cultivation. Total organic carbon in the vineyard was dramatically low, with around 1 gC.kg-1, and there was no vertical gradient as a function of depth. 14C showed that deep plowing (50 cm) in the vineyard plot redistributed the remaining carbon both vertically and horizontally. This remaining carbon was old (compared to that of the forest), which had a C V N ratio characteristic of microbial organic matter and was probably stabilized within organomineral associations. Despite the drastic degradation of the organic matter (OM) pool in this Arenosol, this soil would have a high carbon storage potential if agricultural practices, such as grassing or organic amendment applications, were to be implemented within the framework of the 4 per 1000 initiative.
Figure 1: Comparison of intra-layer F14C heterogeneity at three depths (5–10, 40–50, and 50–60 cm) in forest and vineyard soils. F14C data were obtained for profiles A (star), B (diamond), C (square), composites ACBCC (triangle), and the average of these data (round) in forest (green) and vineyard (orange) soils. Error bars represent the analytical error for the profiles A, B, and C and the standard deviation for the mean.
Reference : Quéro S., Hatté C., Cornu S., Duvivier A., Cam N., … Basile-Doelsch I., 2022. Dynamics of carbon loss from an Arenosol by a forest to vineyard land use change on a centennial scale. SOIL 8, 517-539 - doi: 10.5194/soil-8-517-2022
Millennial-timescale quantitative estimates of climate dynamics in central Europe from earthworm calcite granules in loess deposits
Ice core and marine archives provide detailed quantitative records of last glacial climate changes, whereas comparable terrestrial records from the mid-latitudes remain scarce. Here we quantify warm season land-surface temperatures and precipitation over millennial timescales for central Europe for the period spanning 45,000–22,000 years before present that derive from two temporally overlapping loess-palaeosol-sequences, dated at high resolution by radiocarbon on earthworm calcite granules. Interstadial temperatures were 1–4°C warmer than stadial climate, a temperature difference which is strongly attenuated compared to Greenland records. We show that climate in the Rhine Valley was significantly cooler during the warm season and overall drier with annual precipitation values reduced by up to 70% compared to the present day. We combine quantitative estimates with mesoscale wind and moisture transport modelling demonstrating that this region was dominated by westerlies and thereby inextricably linked to North Atlantic climate forcing, although ameliorated.
Figure 1: Age-depth model of the Schwalbenberg loess profile RP1. Age-depth model is based on Bayesian modelling using the software Bacon51 with 28 radiocarbon ages calibrated with IntCal20. The chronology of the profile is correlated with the δ18O values of NGRIP3. SU – sediment units. Tundra gley horizons are represented in grey and palaeosols (Cambisols) in brown.
Prud’homme C., Fischer P., Jöris O., Gromov S., Vinnepand M, Hatté C., Vonhof H., Moine O., Vött A., Fitzsimmons K.E., 2022. Millennial-timescale quantitative estimates of climate dynamics in central Europe from earthworm calcite granules in loess deposits. Communications earth & environment 3, 267. doi: 10.1038/s43247-022-00595-3