EFFECTS OF ENVIRONMENTAL VARIABLES ON THE PATTERNS OF PLANT COMMUNITY DISTRIBUTION IN THE AFRO- ALPINE VEGETATION OF SIMIEN MOUNTAINS NATIONAL PARK, ETHIOPIA

Abstract

Effect of environmental factors on the patterns of plant community formation and species distribution in the afro-alpine vegetation was conducted at Simien Mountains National Park, Northwest Ethiopia. Data were collected from stratified mountains by using systematic sampling in each stratum from October to November 2015. Vegetation and soil were sampled from 30 plots with the size of 20m X 20m and five 1m X 1m subplots, one at each corner and one at the center. Specimens were collected and identified at field and also confirmed at National Herbarium, Addis Ababa University. The analysis of soil samples were done at the Amhara Design and Supervision Work Enterprise soil test laboratory. Cluster and canonical correspondence analysis (R program version 3.1.3) were employed to identify plant community types and effects of environmental variable s that shaped the patterns of community formation. Three plant community types were recognized in the study area. In the study area, altitude was the most important environmental variable followed by pH that influenced plant community formation and species distribution. Elevation was positively correlated with pH in the higher elevation and negatively correlated in the lower areas. Keywords: Canonical correspondence analysis, environmental factors, vegetation relationship, ordination, plant community, soil analysis.