The Effect of Mixed Plantation on the Stand Yield and Soil Attributes of Eucalyptus globulus and Acacia decurrens in North Shewa Zone, Ethiopia

Abstract

Eucalyptus plantation has been playing a vital role in narrowing the gap between the supply and demand for wood and wood products in the region. Though eucalyptus is fast-growing and has a better survival rate compared to other exotic species, there is a claim that Eucalyptus species over exploiting the nutrients and water. This consequently led to land degradation and soil fertility decline. Hence, it is important to develop mixed plantations to minimize the gap of monocultures. This study aimed to select Acacia decurrens-Eucalyptus Camaldulensis mixed plantation to obtain better woody yield and improve site productivity than sole plantation. A. decurrens and E.camladulensis seedlings were planted with the proportions of: 0%:100%, 100%:0%, 25%:75%, 75%:25% and 50%:50%. The experiment was arranged in a randomized complete block design with three replications. Results showed that the tree height and total volume not varied significantly between the mixed and pure stand plantations. Soil nitrogen varies significantly between the treatments. The plantation with 50% E.camaldulensis and 50% A.decurrens proportion had higher total nitrogen, organic carbon and organic matter in the soil. In line with the experiment, the farmers confirmed that the 50% E. camaldulensis with 50% A.decurrens plantations had relatively a better economic benefits and soil improvements. Further investigation is required to know the contribution of each species in soil nutrient addition. Investigation of the mixed plantation of exotic and indigenous is required to optimize economic and environmental benefits.