Impact of Parthenium hysterophorus L . ( Asteraceae ) on Herbaceous Plant Biodiversity of Awash National Park ( ANP )

This study was conducted in Awash National Park (ANP), East Shewa Zone of Oromia National Regional Sate, Ethiopia, aimed at determining the impact of parthenium weed (Parthenium hysterophorus L.) on herbaceous diversity. A transect belt of 13.5 km * 0.10 km of parthenium weed infested land was identified for the determination of the impact. Four quadrats were purposively laid every 250 m interval two for infested and two for non-infested each from both sides of the road and a total of 216 quadrats of 2 m x 2 m (4 m 2 ) were considered. A total of 91 species were identified from which five of them were out of the quadrats. All species were categorized into 21 families, from which Poaceae and Fabaceae shared about 40%. The species in the non-infested quadrats were found to be more diverse and even when compared to those of the infested quadrats. Infested quadrats were found to be more abundant and dominant. Tetrapogon tenellus was found the dominant specie in the noninfested quadrats while Parthenium hysterophorus was found dominant in the infested followed by T. tenellus. There was no statistically significant difference between the total stand crop biomass of the infested and noninfested. Parthenium weed have been found creating great challenge on herbaceous plant diversity of ANP.

Invasive Alien Species yet identified in Ethiopia.Since its introduction in 1976 into Ethiopia (Tefera 2002) parthenium weed has been reported as relentlessly spreading throughout the agricultural lands, forests, orchards, poorly managed arable crop lands and rangelands, almost throughout the country.EARO (2002)

Study area
The

Impact of Parthenium Weed on Herbaceous Diversity
A total of 91 species were identified

Herbaceous Stand Crop Biomass
Valuable species in the infested area which were essential for grazing reported as, Awash National Park, one of the prominent national parks in Ethiopia and where a number of wild animals and various woody and herbaceous species inhabit has been at risk due to the aggressive spread of the weed to the park.Herbaceous vegetations are the dominant component of most wildlife reserve areas.It was reported as parthenium weed has the potential to decline adversely the herbaceous components of the vegetation upto lantana weed (Lantana camara) and witch weeds (Striga species) are among the major Abstract two for infested and two for non-infested each from both sides of the road and a total of 216 quadrats of 2 m x 2 m (4 m 2 ) were considered.A total of 91 species were identified from which five of them were out of the quadrats.All species were categorized into 21 families, from which Poaceae and Fabaceae shared about 40%.The species in the non-infested quadrats were found to be more diverse and even when compared to those of the infested quadrats.Infested quadrats were found to be more abundant and dominant.Tetrapogon tenellus was found the dominant specie in the noninfested quadrats while Parthenium hysterophorus was found dominant in the infested followed by T. tenellus.There was no statistically significant difference between the total stand crop biomass of the infested and noninfested.Parthenium weed have been found creating great challenge on herbaceous plant diversity of ANP.Resumen Este estudio se realizó en el Parque Nacional de Awash (ANP), Oriente de Shewa, zona de Oromia del Estado Regional Nacional, Etiopía, con el fin de determinar el impacto de la mala hierba parthenium (Parthenium hysterophorus L.) sobre la diversidad herbácea.Se realizó un transecto de 13,5 km * 0,10 kilometros en la tierra infectada por la mala hierba parthenium para determinar su impacto.Se colocaron cuatro cuadrantes en intervalos de 250 m, dos para infectados y dos para no infectados a cada uno de los lados de la carretera, considerando un total de 216 cuadrantes de 2 m x 2 m (4 m2).Se identificaron un total de 91 especies, cinco de ellas ubicadas fuera de los cuadrantes.Todas las especies fueron clasificadas en 21 familias, de las que Poaceae y Fabaceae compartían alrededor del 40%.Se encontró mayor diversidad de especies en los cuadrantes no infectados, e incluso en comparación con los cuadrantes infectados.Los cuadrantes infectados resultaron ser más abundantes y dominantes.Tetrapogon tenellus se encontró como especie dominante en los cuadrantes no infectados, mientras que Parthenium hysterophorus se encontró dominante en el infectado seguido de T. tenellus.No hubo diferencias estadísticamente significativas entre la biomasa total de la cosecha de pie de los infectados y no infectados.La mala hierba Parthenium se presenta como un gran reto en la creación de diversidad de plantas herbáceas en el ANP.Palabras claveEste de Shewa, infectación, invasión de especies alóctonas, Oromia, turismo.
Figure 1.Map of study area (Awash National Park) (Source: Ethiopia Institute of Agricultural Research, GIS unit)

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Apendix1) and grouped into 21 families, of which, Poaceae is Shannon and Yi = the abundance of species I = the sum of the lesser scores of species i where it occurs in both quadrats m = number of species highway run east-west a total length of 50 m x 13.5 km was considered in both sides of the road.A preferential sampling method was used.The sampling plots were arranged on the transect line laid on both side of the road.A quadrat of 2mx2m was laid in an interval of 250.At each point two quadrats, one from infested (IN) and one from non-infested (NI) and a total of 216 quadrats were considered.Each species available in the quadrat was counted and recorded.Visual cover estimation of each specie was taken.

The
because of its direct threat to the habitat of species that are key to the tourism industry(Raghubanshi et al. 2005;   www.unep.org).ANP has been providing tourism and conservation services for the country but currently because of parthenium weed it has been losing its previous value.Parthenium weed caused a decline in stand density of herbaceous species by an average 69% within a few years from its introduction into ANP.This is in agreement with whatEvans (1997) stated that parthenium weed has the potential to replace dominant the same line a decline in biomass of up to 41% was recorded in ANP.This was recorded from the middle of the Park where interference of livestock was said minimum.Although, not thoroughly seen in this study, areas around the border of the Park where regularly visited by livestock of the more abundant than the noninfested quadrats (Table3).This could be because of that parthenium weed is an addition on the prevailing vegetation and it is moreover denser than any of the others vegetation where infestation did not take place.Although most of the associated species were found susceptible to the competition and allelopathic effect, the over all stand density of the infested was found greater.Despite the increment in total stand density and canopy cover, the species diversity (H') and evenness (J) value declined in infested quadrats.This could be due to the fact that some species

Table 1 .
Comparison in absolute frequency (AF), absolute stand density (AD) and mean absolute stand density (MAD)

Table 2 .
The Czekanowski similarity coefficient (Sc) among the IN, NI and

Table 4 .
Stand crop biomass ANOVA summary

Table 5 .
Stand crop biomass mean separation *Means with the same letter are not significantly different at α= 0.05.

Table 2
Herbaceous species index of Awash National Park (ANP)