Terrestrial carbon stocks following 15 years of integrated watershed management intervention in semi-arid Ethiopia

Tigist Araya Gessesse, Asia Khamzina, Girmay Gebresamuel, Wulf Amelung

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Our study investigated the total terrestrial stock of organic carbon and its controlling factors in prevalent land‐use systems in semi-arid Ethiopia (610 mm of annual rainfall), as part of the impact assessment of the national Integrated Watershed Management (IWM) program. Above- and below-ground biomass and soil organic carbon (SOC) stocks of major land-use systems (i.e., exclosure, cropland, rangeland, and bare land) were quantified after field sampling along a topographic gradient. We found that aboveground carbon stocks peaked in the 15-year-old exclosures (9.08 ± 1.44 Mg ha−1) owing to intact woody and grass vegetation as well as substantial litter cover (>20% of the total biomass). Croplands cultivated with wheat and rangelands vegetated with perennial grasses showed average aboveground carbon stocks of 3.16 ± 0.24 and 1.45 ± 0.19 Mg ha−1, respectively. The belowground biomass carbon stock was particularly low in croplands (0.76 ± 0.09 Mg ha−1), exceeded by that in both exclosures and rangelands, where values averaged 3.67 ± 0.06 and 3.04 ± 0.42 Mg ha−1, respectively. The topsoil (0–30 cm) SOC stocks also varied with land-use systems but showed a different order, peaking in rangelands (53.9 ± 10.1 Mg ha−1) and exclosures (41.4 ± 8.1 Mg ha−1), followed by bare lands (29.0 ± 11.5 Mg ha−1) and croplands (26.4 ± 4.6 Mg ha−1). The sub-soils (30–100 cm) added 40% to this SOC storage. The greatest total SOC stock identified in exclosures that had been established primarily on degraded hillslopes may signify a successful restoration effort under the IWM program. However, croplands exhibited the lowest SOC stock, which implies the need for urgent interventions to improve the soil fertility.

Original languageEnglish
Article number104543
JournalCatena
Volume190
DOIs
Publication statusPublished - 2020 Jul

Keywords

  • Biomass carbon
  • Carbon sequestration
  • Land-use system
  • Soil organic carbon stock
  • Tigray

ASJC Scopus subject areas

  • Earth-Surface Processes

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