Lowland bamboo (Oxytenanthera abyssinica) deforestation and subsequent cultivation effects on soil physico-chemical properties in northwestern Ethiopia

Abstract

In Ethiopia, bamboo thickets and woodlands play an important role in soil-water conservation and climate change mitigation in arid and semi-arid regions. However, bamboo mass flowering, rapid demographic changes and expansion of agricultural investments into bamboo dominated areas have led to deforestation and land degradation. This study assessed the effects of deforestation and subsequent cultivation on soil physical and chemical properties along a chronosequence of closely located agricultural lands with different times (1, 3, 5 and 7 years) since conversion from natural lowland bamboo forest. Soil samples (n = 90) were taken from both natural bamboo forests and adjacent agricultural lands at two soil depths (0–20 cm and 20–40 cm). Cation exchange capacity (CEC), K+, Ca2+, Mg2+ and available P varied significantly among cultivation periods and soil depth, while soil pH and Na+ varied with soil depth (P < 0.001). Soil C and total N contents (g/kg) in the 0–20 cm soil layer declined significantly and exponentially with increasing years under cultivation. Conversion of natural bamboo forest to cropland during the past seven-year period significantly increased soil pH with soil depth, while CEC declined throughout the cultivation period and with soil depth. In general, the results revealed that conversion of natural lowland bamboo forest and subsequent cultivation of the soil had negative effects on the measured soil physico-chemical properties.