Field Weed Vegetation in Relation to site Characteristics in Bale Highlands, Southern Ethiopia )

Abstract

The species composition and the habitat of the field weeds is described on the Dinkiti vertisols in the southeast of the Ethiopian highlands, bassed on 113 vegetation samples from grain fields (according to the Braun-Blanquet method), distributed across the farm estate. In addition, vegetation samples were also taken from surrounding peasants’ fields. As a whole, we distringuished 83 different species, with 54 species (65 %) as annual weeds. The average number of species found per investigated area is 17.6. The field weed coverage within the area under investigation averages 45 %. This accounts for the high degree of weed infestation of the fields. The most important and persistent field weeds with a wide locational amplitude and an often high covering degree are Guizotia scabra, Galium spurium, Galinsoga parviflora, Amaranthus graecizans, Polygonum nepalense, and Digitaria abyssinica. Indicator plants for relatively dry soils well suited for wheat production (pellic vertisols) are various Chenopodium species, Commelina benghalensis, Solanum nigrum, Crambe abyssinica, and Caucalis melanantha. The sites suffering from soil wetness (attached soil water, waterponding), mostly gleyic chromic vertisols posing great problems in wheat cultivation, are characterized by a great group of species, which include mainly Gnaphalium species, Echinochloa colona, Rumex bequaertii, Cyperus rigidifolius, Commelina africana and Commelina subulata, Cotula abyssinica, Senecio coronopifolius, Spilanthes mauritiana, Limosella africana, and Crassula granvikii. The study differentiates 8 sociological groups of species which are interpreted ecologically. Including the peasants“ fields, there are 8 weed types well distinguishable as to flora and ecology.