干旱区生态环境知识资源中心

The use of enclosures has globally gained popularity as an effective strategy to enhance soil carbon sequestration, but empirical evidence is lacking particularly in arid and semi-arid rangelands of Africa. This study addressed the effectiveness of long-term (15-37 years old) enclosures in enhancing soil carbon sequestration in a semi-arid rangeland of Southern Ethiopia. We tested for differences in soil properties and vegetation characteristics between enclosures and adjacent open-grazed areas, while accounting for effects of age of enclosures and soil depths. Three enclosures age categories ( < 20, 20-30 and > 30 years) each paired with adjacent open grazed areas were selected. We collected soil samples at three soil depths (0-5 cm, 5-15 cm and 15-30 cm), and vegetation attributes from 90 plots within 9 enclosures and adjacent open grazing sites. The results showed that soil properties did not differ significantly (P > 0.05) between the two management systems across the three soil depths. However, relatively higher soil organic carbon content and stock was recorded in the enclosures than open-grazed lands. We recorded an overall mean of soil organic carbon stock of 39.6 +/- 3.5 Mg ha(-1) in enclosures of < 20 years old, 40.8 +/- 3.4 Mg ha(-2) in enclosures of 20-30 years old and 51.0 +/- 4.4 Mg ha(-1) in enclosures of > 30 years old. The soil organic carbon stock for the adjacent open-grazed areas ranged from 34.4 +/- 2.5 to 47.9 +/- 5.1 Mg ha(-1). The age of enclosures did not show any significant effect on soil organic carbon stocks. However, enclosure management had a significant (P <= 0.05) effect on vegetation attributes. We concluded that enclosure had a significant role in terms of soil carbon sequestration and adaptation to climate change.