Impacts of different exotic tree plantation forests on soil physico-chemical properties in the Central Highlands of Ethiopia

Abstract

This study aims to assess the impacts of plantations of different exotic tree species (Eucalyptus globulus, Cupressus lusitanica, Grevillea robusta, and Pinus patula) on soil physicochemical properties in the central highland of Ethiopia. Soil data were collected using a systematic sampling design over five different forest land-use systems. A total of 15 transect lines and 25 quadrats were used to collect soil data, with 3 transects and 5 quadrats per forest land-use system. The analysis of variance (ANOVA) for the majority of soil physico-chemical variables, including texture, moisture content (MC); bulk density (BD), particle density (PD); soil porosity (SP); organic carbon (OC);  total nitrogen (TN), available P, soil pH, EC, CEC, and exchangeable bases (Ca, Mg, K, Na) showed a significant variation among forest land-use systems at (P<0.0001). The study findings confirmed that different exotic trees species have different effects on soil physico-chemical properties. In comparing the soil physicochemical properties among five forest land-use systems, the highest mean values of MC, OC, TN, available P, CEC, and Exch. Ca, Exch. Mg, and Exch. K was observed in natural forests. On the other hand, soil BD, PD, and EC properties in natural forests were significantly the least. In contrast, the lowest mean values of soil MC, SP, O, TN, available P, BS%, and the highest mean values of BD, PD, EC, and Exch. Na were observed under the Eucalyptus globulus plantation forest. The physico-chemical properties of soil are subject to significant changes in land use systems when different exotic tree species are grown under similar climatic conditions.