Distribution and abundance of invasive alien weed species in Wolayita Zone, Ethiopia.
Invasive alien weed species invasion are observed in areas of Woliata Zone, Southern Nations Nationalities Regional state. However, its distribution and abundance have not been determined. Therefore, the objectives of the study were to assess the distribution of P. hysterophorus, L. camara and A. mexicana in the study area. Data were recorded in a total of 120 quadrants of 5 m x 5 m laid at 10 Km interval on the roadsides. Abundance and distribution of the three selected invasive alien weeds were determined and maps showing these were developed using ArcGIS 9.1 software. A total of 13 invasive weed species that is P. hysterophorus, L. camara, A. Mexicana, Xanthium strumtarium L., Ageratum conyzoides L., Xanthium siponsum L., Cirsium vulgare Savi Ten, Senna didymobotra (Fresen.) Iriwin Bameby, Senna oxdentalis L. link, Casia occidentalis L., Caesalpinia decapetala (Roth) Alston, Datura stramonim L., and Ricinus communis L. representing six families were identified in the study area. The result of the study showed that most of the invasive weed species found were belongs to the family Asteraceae followed by Fabaceae. Invasive alien weed species were differently distributed with the relative frequency of 0.83 (P. hysterophorus), 0.83 (L. camara), 0.5 (A. Mexicana), 0.43 (S. oxdentalis), respectively, while the other IAWs were found less distributed. The result indicated that of the total (120) sampling points P. hysterophorus was found on 100 sampling plots (83.3%). The infestation of L. camara was observed in all districts and Sodo town administration of the zone. A. mexicana was absent on 60 (50.0%) of sampling points which are at Ofa, Humbo, and Sodo zuria districts P. hysterophorus has the highest mean abundance value (22.3%) followed by L. camara (10.0%). Invasive Alien Weed Species were observed in different habitats. Roadside and cultivated lands were the two frequently P. hysterophorus infested habitats. P. hysterophorus, L. camara and A. mexicana were found to a threat to the livelihood of the Wolayita farming households. Thus, there is an urgent need for well organized, coordinated and concerned efforts that must be made to control. Further long-term study is needed to verify the impact of P. hysterophorus L. camara and A. mexicana invasion.