University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Frederik Nygaard Philipsen
(2022):
A Hedgerow chronosequence: SOC sequestration potentials and persistence in cultivated soils of Lower Austria.
Master / Diploma Thesis - Institut für Bodenforschung (IBF),
BOKU-Universität für Bodenkultur,
pp 72.
UB BOKU
obvsg
FullText
- Abstract:
- Changes in soil organic carbon (SOC) stocks can affect atmospheric CO2 concentrations, soil nutrient cycling, and water-holding capacity. To increase SOC, reforestation, integration of agroforestry elements in SOC-depleted cropland soils may serve as potential means for SOC sequestration. However, SOC varies in persistence, and it is recognized that the fine SOC fraction (f<20 µm) associated with mineral particles and microaggregates are more persistent than large, free fractions (f>20 µm). Since the proportion of f<20 µm can become saturated, knowledge of its saturation level and developments over time is important to evaluate the feasibility of increasing persistent SOC storage. In this master thesis, a space-for-time substitution approach was employed based on a hedgerow chronosequence (1950-2019) and adjacent agricultural fields in Lower Austria. By selecting 13 proximate sites in the Pannonian region, the aim was to simulate decadal-scale changes in SOC-fractions in cultivated soil after hedgerow planting. Particle size fractionation via ultrasonic aggregate dispersion and sequential wet sieving was performed to analyze the temporal dynamics of hedgerow induced SOC sequestration, and its partitioning into size fractions. The results showed that hedgerows significantly sequestered SOC in 0-20 cm – equal to a sequestration rate of 0.48 t C ha-1 in bulk soil, while no effects were observed in 20-40 cm. SOC was mainly stored in f<20 µm for both land uses, however SOC f>20 µm constituted a larger proportion of hedgerow topsoil. While SOC enrichment under hedgerows took place in all size fractions, SOC in f>20 µm showed a stronger relationship with hedgerow age than in f<20 µm. Modelling carbon saturation potentials revealed that soils were generally far from saturation, indicating a large unused storage potential, though hedgerows slightly increased saturation levels. Overall, hedgerows can contribute to SOC sequestration in the study area, however more data is needed to verify the trends observed.
- Beurteilende*r: Wenzel Walter