ASSESSING TREE SPECIES DIVERSITY AND STRUCTURE EFFECTS ON SOIL PROPERTIES IN SMALLHOLDER FARMERS LAND IN ARBA MINCH ZURIA DISTRICT, GAMO ZONE, SOUTHERN ETHIOPIA.

Abstract

Woody plants in farmlands have been shown to provide numerous benefits such as soil fertility enhancement to farmers in many parts of Ethiopia through their effects on plant-soil interactions. Yet, existing evidences are mainly based on individual tree species effect undermining the true effects of multiple trees in farmlands. This study was conducted to investigate woody plant species and their structure in the farm land on soil properties in smallholder farmers land in Kola-Shele Kebele Gamo Zone Southern Ethiopia. A randomized complete block design was used to collect vegetation data and soil samples from systematically placed plots along transect across six purposively selected farmlands. In each plot, vegetation composition and structure were surveyed while a total of 24 composite soil samples were drawn from a fixed depth of plow layer (0-20 cm) to determine soil organic carbon, total nitrogen, available phosphorus, electrical conductivity, and cation exchange capacity contents. Results showed that tree species diversity positively and significantly affected on soil organic content, total nitrogen, available phosphorous, electrical conductivity, cation exchange capacity and soil texture. The results also revealed that community weighted mean basal area positively and signincatly affected soil properties such as pH, soil organic carbon, total nitrogen, cation exchange capacity and electrical conductivity. In conclusion, the results showed that more diverse and older trees contribute better to the soil fertility compared to less diverse and younger woody plants. Yet, to optimize agricultural crops production, we recommend future studies to focus on revealing the optimal level of tree species combinations and density per a unit of farmland