Impact of Parthenium on species diversity in Gamo Gofa, Ethiopia

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1 Scholarly Journal of Agricultural Science Vol. 5(7), pp August, 2015 Available online at ISSN Scholarly-Journals Full Length Research Paper Impact of Parthenium on species diversity in Gamo Gofa, Ethiopia Gebrehiwot, N. 1* and Berhanu, L. 2 1,2 Arba Minch University Department of Plant Science P. O. Box 21 Arba Minch, Ethiopia Accepted 20 August, 2015 A study was conducted at Gamo Gofa, Ethiopia, to assess the impact of parthenium on plant diversity. Species diversity was computed using Importance value index, Shannon-diversity index, Simpson`s index and evenness index. A total of 21 plant species distributed under 13 families were identified with the most frequent families being Amaranthaceae (19.05), Poaceae (14.28), Asteraceae (9.5) and Cyperaceae (9.5) accounted 52.37% of the total flora. Mean Importance Value Index (IVI%) of Parthenium hysterphorus, Althernathra pungens and Cynodon dactylon were 76.15, and respectively. Eighteen species manifested low to moderate IVI levels. The diversity indices such as Shannon`s index and evenness index of plant species were reduced rapidly as dominance of parthenium increased in the study area. This indicated that the lowest Shannon Diversity Index value was due to the fact that plant species diversity was highly affected by parthenium. Thus, there is an urgent need to take appropriate measures in the study area, especially, in Arba Minch, to stop its further spread to Nesh Sar Park, known in species richness. Key words: Impact, IVI, Parthenium, Diversity, Index. INTRODUCTION Parthenium hysterophorus L. (Asteraceae) is one of the worst and noxious weeds in the world (Rao, 1956; Timsina et al., 2011) and originated either in the Gulf of Mexico or in Central South America (Haseler, 1976; Dale, 1981; McClay, 1984; Navie et al., 1996), but later Parthenium hysterophorus found its way accidentally to tropical and subtropical parts of Africa, Asia and Oceania with cereal and grass seed shipment from America during 1950s (Bhoumik and Sakkara, 2005). It has been reported from United States, Central America, South America, India, Nepal, Africa, China, Vietnam and Australia (Towers et al., 1977; Aneja et al., 1991). Parthenium was first noticed in 1980s near food-aid distribution centres in Ethiopia, around Dire-Dawa (Medehin, 1992; Frew et al., 1996; Tamado, 2001). This weed entered the country during the Ethio-Somali war in *Corresponding author ggebre2009@gmail.com. 1976/77 through military vehicles (Frew et al., 1996). It has also been distributed to almost all areas of the country (Seta et al., 2013; Tamado and Milberg, 2000; Seifu, 1990; Ayele et al., 2014; Mcconnachie et al., 2010). Parthenium has been rapidly invaded grazing land, wastelands and cultivated areas, roadsides, recreation areas, railway tracks as well as river banks and floodplains (Singh, 1997; Huy and Seghal, 2004). The spread of seeds plus their ability to remain viable in the soil for many years pose one of the most complex problems for control and this fact makes eradication difficult for many seed producing weeds (Monaco et al., 2001). Weed seeds may also move with surface water, runoff, in natural streams and rivers, in the irrigation and drainage channels, and in irrigation water from pods (Monaco et al., 2001). The weed grows fast and confortable on alkaline to neutral clay soils (Dale, 1981). However, its growth is slow and less prolific on a wide range of other types.

2 Gebrehiwot and Berhanu 227 Gamo Gofa, a home of Nech Sar Park, possessed highly diversified indigenous plant species. However, these plant species are already under risk of parthenium because of its prolific seed production and fast spreading ability (Haseler, 1976) and allopathic effect on other plants (Adkins and Sowerby, 1996). Very little or sometimes no other plant species are seen in Parthenium hysterophorus-dominant areas that result in suppression of the natural vegetation, pose a strong threat to biodiversity. It has the capacity to rapidly replace the natural flora (Oudhia, 2000). This weed is also known to badly affect crop production, biodiversity, animal husbandry, human health and even ecosystem integrity (Adkins and Sowerby, 1996; Navie et al., 1996; Kumari et al., 2014). Therefore, it is increasingly seen as a threat not only to biodiversity and ecosystem services, but also to economic development and human well-being. Previous studies on parthenium weed and its effect on plant biodiversity have reported a total habitat alteration and rapid replacement of native grasses (Evans, 1997), a reduction in the diversity of other plant species (Navie et al., 2004). Although a number of studies on the impact of parthenium weed have been done in different countries, yet there is no documented scientific study and little effort made to quantify the plant diversity associated with parthenium in Southern Ethiopia. Thus, this work was designed to determine the impact of parthenium on plant diversity in Gamo Gofa, Ethiopia. measuring 1m x 1m (1 m 2 ) sample quadrate was laid around roadsides, farmlands, flood plains and wastelands to assess the impact of parthenium on species diversity in the study area. The majority of weed species collected from the quadrats was identified in the field. For species difficult to identify in the field, voucher specimen were collected, pressed and dried properly and transported to Arba Minch University for identification and proper naming. The nomenclature of the plant species followed the flora of Ethiopia and Eritrea (Hedberg and Edwards, 1995). Data Analysis The data on individual plant species were counted and then, importance value index (IVI%) for each species was determined as the sum of relative frequency (%) and relative density (%) (Curtis and McIntosh, 1950). IVI % =Relative Density (%) + Relative Frequency (%) Species diversity was computed using Shannon-diversity index (H) (Shannon & Wiener, 1963) and is used to assess the impact of parthenium on diversity of plant species. MATERIALS AND METHODS Study area The present study was conducted in Gamo Gofa (6 0 2' N latitude and ' E longitudes), south of Addis Ababa, is located in the beautiful rift valley at an altitude range from meter above sea level. Arba Minch, Mole and Shelle and BrBr were randomly selected study areas. The climate of the study site is semi-arid, having two seasons: summer (November-December) and spring (March-June). Annual mean temperature was 31 0 C. The monthly mean temperature ranged from 18 to 34. Annual mean rainfall ranged from mm, of which about 87% occurred in rainy season. Sampling of weed species The study was conducted by applying Quadrat Method and road transect survey methods (Wittenberg et al., 2004) in 50 m distance. A total of 64 quadrats in each four sample sites (BrBr, Mole, Arba Minch and Shelle), sixteen sample quadrates were randomly laid from every study site in different season over two years. GPS reader was used to locate each quadrat and study site. Each Where, H = Shannon diversity index; pi is the importance value of the i th species (pi = ni/n); ni is the number of individual species, N is the total number of individuals). Species dominance (C) by Simpson`s index (Simpson, 1949), C = (pi) 2 The evenness (E) of species calculated as suggested by Hill (1973) and Pielou (1966). E = H`/lnS, where S is the number of species. This index explains how equally abundant each species would be in the plant community and high evenness is a sign of ecosystem health. RESULTS AND DISCUSSION Weed flora Composition A total of 21 weed species composition associated with

3 Scholarly J. Agric. Sci. 228 Table 1. Importance value index (IVI) of P. hysterophorus and associated weed species in study area Plant/Weed species Importance Value Index (IVI%) Family Arba Minch BrBr Mole Shelle Mean Parthenium hysterophorus Asteraceae Althernathera pungens Amaranthaceae Cynodon dactylon Poaceae Cyperus rotandus Cyperaceae Althernathera repens Amaranthaceae Amaranthus graecizans Amaranthaceae Cyprus esculentus Cyperaceae Amaranthus spinosum Amaranthaceae Lantana camara Verbenaceae Tribulus terrestis Zygophyllaceae Alectra vogeli Orobanchaceae Solanum incanum Solanaceae Convolulus arvenesis Convolvulaceae Chrysopogon ancheri Poaceae Xanthium strumarium Asteraceae Argemone Mexicana Papaveraceae Balanites aegyptica Zygophyllaceae Eleusine indica Poaceae Euphorbia hirta Euphorbiaceae Portulaca oleracea Portulacaceae Polygonum nepalensis Polygonaceae Table 2. Number and percentage of plant species within the four top diverse families in four locations Family Number of species Percent flora Amaranthaceae Poaceae Asteraceae Cyperaceae Total Parthenium hysterophorus were reported from the study area and classified under 13 families (Table 1 and 2). Of the 13 plant families, based on the number of taxa, Amaranthaceae accounts the highest %, followed by Poaceae 14.28%, Asteraceae and Cyperaceae accounts 9.52% each holding the third place among the plant species recorded in the study area (Table 2). These four families contributed 52.37% of species to the total flora in the study site. These families were also reported to be economically important and common in different parts of Ethiopia (Taye et al., 1998; Firehun and Tamado, 2006). Poaceae and Asteraceae were the most important family in the highland Peru, central Mexico and northern Zambia (Afos, 1994; Becker et al., 1998; Vibrans, 1998). These families are very rich in species composiotion so it is not surprising that they contain many weeds (Tamado, 2000). Asteraceae, Poaceae and Amaranthaceae were also found to be most important in other studies in the tropics (Tamado and Milberg, 2000; Ayele et al., 2014; Seta et al., 2013; Belachew and Tessema, 2015). Importance value index of weed flora Among all weeds species, Parthenium hysterophorus was highly dominant species with very high IVI (100.95) in BrBr followed by at Mole and in Arba Minch. It was the most important weed at all locations with higher mean value (76.15) (Table 1). Much less IVI was noted for Parthenium hysterophorus in Shelle. However, the weed was still found to be dominant among 21 weed species in its invaded areas with maximum IVI of Similar result was found from Huy and Seghal (2004) showed as parthenium was highly dominant species with

4 Gebrehiwot and Berhanu 229 Table 3. Diversity indices of P. hysterophorus and other weed species in the study area. Indices Arba Minch BrBr Mole Shelle Shannon Diversity Index (H) Species evenness index (E) Species dominance index(c) very high IVI in the area studied. Khan et al. (2014) also confirmed that importance value data (IVI) showed the superiority of Parthenium hysterophorus at all the locations studied. In addition, the weed was also confirmed as dominant and most competitive species in east shewa, northern and eastern regions of Ethiopia (Belachew and Tessema, 2015; Taye, 2002). This dominance may be happened due to its aggressiveness and allelopathic effect on neighbouring plants (Adkins and Sowerby, 1996). Kohli and Rani (1994) said that the high IVI of the weed in general is attributed to its competitive ability, allelopathy and strong adaptive and reproductive potential. Other workers like, Krishnamurthy et al., (1997), Evans (1997) and Dayama (1986) reported that the allelopathic nature of parthenium weed and its impact on plant diversity. Kohli et al. (2004) also reported that three exotic weeds including parthenium adversely affect the structural composition and dynamics of the diversity of the native flora. In addition, due to its high growth rate, the weed becomes competitive and develops the ability to exclude the growth of other species. In similar ways, studies in Australia and India have also demonstrated that parthenium adversely affects the composition and diversity of species thereby resulting imbalance in natural and agricultural system (McFadyen, 1992; Grice, 2006). The co-dominant species were Althernathera pungens (43.78) at Mole and Cynodon dactylon (35.55) in Shelle as well as their mean value for all four sites were and respectively. This result was in agreement with the finding of Shabbir and Bajwa (2006) who reported Cynodon dactylon as co-dominant species in Pakistan. In this study three weed species: Parthenium hysterophorus, Athernathera pungens and Cynodon dactylon showed the highest IVI in BrBr, Arba Minch, Mole and Shelle with mean value of 76.15, and IVI respectively. However, Cyperus rotandus, Althernathera repens, Amaranthus graecizans, Cyprus esculentus, Amaranthus spinusom, Lantana camara, Tribulus terrestis, Alectra vogeli, Solanum incanum, Convolulus arvenesis, Chrysopogon ancheri, known as white grass, Xanthium strumarium, Balanites aegyptica and Eleusine indica were also found in the study sites with 3.44 to IVI. From these weeds, even if the IVI of Lantana camara was far less than Parthenium, it was noted that, the location, Arba Minch, was highly occupied by Lantana camara which used as a fence for banana plantation and grown around the water canals. This was supported by Huy and Seghal (2004) in Japla. Similarly, Shabbir and Bajwa (2006) revealed that P. hysterophorus had an appreciable degree of sociability with Lantana camara. Minimum IVI was belonged to Argemone mexicana (1.87), Euphorbia hirta (1.47), Polygonum nepalensis (1.73) and Portulaca oleraceae (2.07). From the above table, some weeds species found in specific area while others were frequently occurred in all study sites. For example, Chrysopogon ancheri, Argemone Mexicana and Balanites aegyptica commonly occurred in Arba Minch while Eleusine indica and Euphorbia hirta in Shelle. Whereas Polygonum nepalensis and Portulaca oleraceae found in Mole. However, regarding this, no found in a specific site/area, it is not mean that it would not happen, but it might be due to the unavailability of its seed and invading factors. From the present study, the total weed species occurred in BrBr was less than other studied sites (Table 1). This is due to the impact of parthenium weed on plant species diversity. Shabbir and Bajwa (2006) indicated that parthenium showed a tremendous decline in herbs population in Islamabad. Chippendale and Panetta (1994) revealed that this weed had the potential to disrupt the natural ecosystems of Australia. The weed has also replaced the precious native flora and poses a strong threat to biodiversity (Khan et al., 2014). Species Diversity and Evenness Result from the diversity indices of P. hysterophorus and other weed species showed that the highest Shannon`s diversity (1.73) index were noted for all weed species in Shelle, suggesting high degree of weed diversity. However, the minimum Shannon diversity index (1.15) was obtained at BrBr, where the lowest Shannon Diversity Index value was due to the fact that their species diversity was highly affected by parthenium (Table 3).The maximum species evenness (0.65) index was recorded for all weed species in Shelle (Table 3). This indicated that the species are evenly distributed and the ecosystem is healthy. In contrast, the least mean value of (0.45) evenness was obtained at BrBr. The fact that it was lesser in the weed-infested area indicated patchiness in distribution.the highest species dominance index (0.50) was observed in BrBr than Arba Minch (0.31), Mole (0.33), and Shelle (0.24) (Table 3 & Fig 1).

5 Scholarly J. Agric. Sci. 230 Figure 1. Showing the species diversity This showed high level of parthenium and low plant diversity in BrBr as compared to Shelle where low dominance of parthenium and high plant diversity observed. The present study (Tabel 3 and Figure 1) revealed that there was a sharp reduction of diversity index as dominance of parthenium increased. This finding was consistent with Kumari et al (2014) who reported that there was a sharp decline of diversity index as the density of parthenium increased. Our result validates Kohli et al. (2004) findings that the Shannon index showed great plant diversity in uninfested area where as the index was reduced by 36 to 51% in the weed infested areas. Navie et al. (2004) also pointed out that the diversity values depend on the dominance of the parthenium weed in the community and it may reduce the diversity of weed species. Similarly, Huy and Seghal (2004) showed that high concentration of dominance of parthenium in a site would result less species diversity of its ground vegetation. Belachew and Tessema (2015) supported that the diversity and evenness of species declined with increasing spread of parthenium which suggests negative influence that parthenium had on the status of species diversity in the studied area. They also reported that it is possible that the persistence infestation of parthenium in the study area might have contributed to low plant species diversity and evenness values. CONCLUSION AND RECOMMENDATION The innovation of this work is that Parthenium hysterophorus identified as the dominant weed species that reduced the composition, diversity and evenness of various plant species. Thus, there is an urgent need for a concerted management effort directed at parthenium weed in the study area, especially in Arba Minch, before it further spread to Nech Sar Park, a home of many plant species. ACKNOWLEDGEMENTS We are highly thankful to Arba Minch University for financial support. REFERENCES Adkins, S.W. and Sowerby M.S. (1996). Allelopathic potential of the weed Parthenium hysterophorus L. in Australia. Plant Protection Quarterly, 11: Ȧfons, m. (1994). Weeds and weed management in small- scale cropping systems in northern Zambia. Crop Production Science 21, Uppsala, Sweden. Aneja, K.R., Dhawa, S.R. and Sharma, A.B. (1991). Deadly weed- Parthenium hysterophorus Linn and its distribution. IJWS, 23: Ayele, S., Nigatu, L., Tana, T. and Adkins, S.W. (2014). Impact of parthenium weed (Parthenium hysterophorus L.) on the aboveground and soil seed bank communities of rangelands in Southeast Ethiopia. Glob. J. Pest Dis. Crop Prot. Vol. 2(1). pp Becker, B, Terrones, F. and Horchler, P. (1998). Weed communities in Andean cropping systems of northern Peru. Angewandte Botanik. 72, Belachew, K., and Tessema, T. (2015). Assessment of Weed Flora Composition in Parthenium Infested Area of East Shewa, Ethiopia. Malaysian Journal of medical and Biological Research, 2, Bhowmilk, P.C. and Sarkar, D. (2005). Parthenium hysterophorus: Its world Status and Potential management. Proceeding of the Second International Conference on Parthenium Management, Bangalore, 5-7 Dec. 2005, 1-6. Chippendale, J.F. and Panetta, F.D. (1994). The cost of parthenium weed to the Queensland cattle industry. Plant Prot. Quart., 9: Curtis, J.T. and McIntosh, R.P. (1950). The Interrelations of Certain Analytic and Synthetic Phyto-Sociological Characters. Ecology, 31, Dale, I.J. (1981). Parthnium weed in America. Report on the ecology of Parthnium hysterophorus in south central and North America. Australian weeds, 1:8-14.

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