Abstract

To determine the resilience of soil organic C and N pools during land degradation processes in a semi-arid landscape of West Africa, we compared the magnitude of soil organic C and N differences in bulk soil and aggregate fractions between contrasting types of land cover (degraded land and native land cover) and soil (Luvisols and Cambisols). We analyzed the following soil key indicators: CEC, soil respiration, C and N contents, and δ13C and δ15N signatures of soil organic C. The average CO2respired from native land cover was at least 82% higher than its value from degraded land cover and was significantly higher in Luvisols than in Cambisols. Likewise, the soil organic C and N contents in bulk soil were significantly affected by land cover and soil contrasts. The average C loss in bulk soil from degraded land cover was equivalent to 49% in Cambisols and 54% in Luvisols. In both soil types, all aggregate fractions were sensitive to land degradation processes and the C loss decreased from macroaggregates to the clay+silt fraction. Compared to the native land cover, organic C loss from the macroaggregates in degraded land cover was 92% and 84%, respectively, in Cambisols and Luvisols. The soil type affected significantly the C content only in the clay+silt fraction. The C/N ratio of finer fractions (microaggregates and clay+silt) was significantly higher in degraded land cover than in native land cover, indicating greater losses of N than C during land degradation processes. The differences of δ13C signatures throughout C pools between the two types of land cover suggest a relative dominance of C3derived C in macroaggregates and C4derived C in the clay+silt fraction in the degraded lands. The reduction of soil respiration and the rapid N loss in degraded land cover slowed down the humification processes of C3plant derived materials which were effectively dominant in macroaggregates.

Keywords

C/N ratio; Land degradation; Soil fractions; Soil respiration; Stable isotopes

Published in

Geoderma
2015, Volume: 241-242, pages: 330-338

SLU Authors

• Ilstedt, Ulrik

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Malmer, Anders

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Nyberg, Gert

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss


UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1016/j.geoderma.2014.11.027

Permanent link to this page (URI)

https://res.slu.se/id/publ/63384