DIVERSITY OF FARM FORESTRY TREE AND SHRUB SPECIES, AND THEIR SOCIO-ECONOMIC AND SOIL FERTILITY IMPROVING ROLES IN THE CENTRAL HIGHLANDS OF ETHIOPIA

Abstract

ABSTRACT Research work was carried out in Galessa-Jeldu areas from 2004 to 2006 to; • identify traditional farm forestry practices in different farm niches; • rank the tree and shrub species found in some farm forest practices in terms of their fodder value and soil improvement potential; • evaluate the nutrient content and fodder nutritional value of the foliage of selected tree and shrub species, and • assess the socio-economic importance of the species in some of the farm forest practices Traditional farm forest practices and the tree composition of some of the practices were identified through participatory rural appraisal techniques (PRA). Fodder lots, woodlots, contour hedges, scattered trees on croplands, live fences and home garden were the traditional farm forest practices in the study areas. Local farmers also helped to rank the fodder and soil improving tree and shrub species. Soil samples were collected under the farmers' top ranked indigenous species and analyzed for various soil attributes, and plant samples were collected to determine their macronutrient contents, fodder nutritional parameters and other green biomass quality indicators. Hagenia abyssinica, followed by Dombeya torrida and Buddleja polystachya were the three top ranked tree species for animal fodder. Farmers selected Senecio gigas followed by H. abyssinica and D. torrida for soil fertility improvement. The green biomass of S. gigas was rich in important plant nutrients. Chamaecytisus palmensis, D. tórrida and B. polystachya had a significantly higher N content than H. abyssinica. The foliage from H. abyssinica and D. torrida had a relatively low content of chemicals that lower palatability and dry matter digestibility. All these species can play an important role in soil management in high altitude areas where soil erosion and nutrient depletion are critical problems.