The Effects of Altitudinal Gradients in Botanical Composition and Dry Matter Yield of Herbaceous Species of Natural Grazing Lands of West Shoa, Ethiopia

Abstract

The study was conducted at Meta Robi district, west Shoa zone of Oromia Regional State in October 2015 with the objectives to assess the effects of altitudinal gradients on grazing lands vegetation patterns with the objectives of assessing the vegetation pattern quantify the biomass yield of the grazing land along with different altitudinal gradients of meta-robi district. The Vegetation assessment was conducted with transect walk with in 4-5kms of in 270 quadrat 90 from each three altitudes having 1mx1m (for herbs layer) quadrant size. The botanical composition was determined by harvesting the herbaceous randomly selected samples (1m × 1m quadrat) within each transect at height of 0–5cm above the ground. Each botanical components were weighed separately to determine the contribution of each component in the total DM yield of the pasture (ILCA 1990). The DM yield of each botanical component in each plot was determined by drying a representative sample in an oven at 70 °C for 48h until constant weight followed by weighing (ILCA, 1990). A total of twenty-four herbaceous species are identified, at the study area. Among them 62.5% were different grasses species, 8.3% were legume species, 25% were forbs or weeds species and 4.2% were sedges. In life form 75% were annuals, while 25% were perennials in life forms. Higher botanical composition of grass species were recorded at lower altitude while higher legumes botanical composition was recorded at upper altitude. The highest dry matter yield of herbaceous species was recorded at lower altitude.

Keywords: Botanical composition , dry matter yield, altitudes, Herbaceous species , Grasses and legumes