Recherche forestière : libre accès
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Abstrait

Assessing the Effect of Natural Forest Conversion to Coffee Based Forest on Soil Carbon Stock at Anfilo District, West Ethiopia

Yohannes Shifera Daka*

Background: Natural forest degradation for coffee management and intensification in natural forest has been substantially affecting forest Carbon (C) stock potential in western and southwestern Ethiopia which is not studied well. By considering this issue, the current study was conducted with the aim to assess the soil C stock changes as a result of conversion of natural forest to coffee-based forest at Anfilo District, western Ethiopia. The District is 642 km west of Finfinne (The country’s capital city). For the present study, two adjacent land uses, Protected Natural Forest (PNF) (1,576 ha) and Forest with Coffee (FWC) (2,364 ha) were considered. In light of this, soil samples were collected for the analysis of C content and Bulk Density (BD). Soil samples were taken by using ‘‘X’’ design from land size of 1 m × 1 m (four at corners for C content and one in the center for BD analysis) at two levels of soil depths (0 cm-20 cm and 20 cm-40 cm) separately. Accordingly, a total of 120 soil samples (60 for C content and 60 for bulk density) were collected and taken to laboratory for the determination of C content and BD. Walkley-Black method was used to estimate soil C stock. Independent t-test was used to test for differences in soil C stocks at significant level of 0.05.

Results: The findings of the present study revealed that significantly higher soil C stock was recorded for PNF (136.2+8.42 t C ha^-1) than FWC (90.76+4.97 t C ha^-1) (p<0.05). This implies that conversion of natural forest to coffee-based forest leads to a reduction of SOC by 33.4%, which is equivalent to the emission of about 166.613 t CO₂ ha^-1 to the atmosphere.

Conclusion: The study concluded that conversion from original natural forest to coffee-based forest significantly affected SOC of the study area. Thus, maintaining and enhancing the soil carbon sequestration potential of this forest soil should be required through implementation of different conservation mechanisms.