Impact of invasive alien plant species, Lantana camara, on the species composition, richness and evenness of invaded plant communities in Sidama, Gamogofa and Gedio Zones, Ethiopia


 Invasive alien species represent one of the major threats to biodiversity and all economic sectors. Lantana camara has been ranked as the highest impacting invasive plant species in the study areas. However, its impact on diversity and composition of invaded plant communities has not been well studied. Therefore, the objective of this study was to investigate the impact of Lantana camara on species diversity and composition of invaded plant communities in the study areas. A total of 120, 10m X 10m plots were sampled so as to examine its effects of invasions on the species diversity and composition of invaded communities. A total of 109 species were found in the non-invaded areas as compared to 56 in the invaded areas. The number of species decreased by 48.6% in Lantana camara invaded areas as compared to the control. The mean evenness values of the entire invaded sampled study site and that of the control were 0.24 and 0.81 respectively. Thus, the heterogeneity of the invaded study sites was reduced by 57%. The number of plant families was 44 in the control areas in contrast to only 30 in the invaded areas. The number of plant families decreased by 31.8% in the invaded areas as compared to the control. Therefore, it was noted that Lantana camara has a serious impact on plant diversity hence the finding calls for an urgent management and control strategy against the spread of Lantana camara so as to save the ongoing threat to biodiversity.


Introduction
Invasive alien species (IASs) represent one of the primary dangers to biodiversity, human health and all economic sectors, especially in developing countries (Hejda et al., 2009).It has become one of the main causes of economic and ecological damage in most of the countries across the world (Paini et al., 2016).
Almost, all ecosystem types on the planet are affected by IASs and they pose one of the biggest threats to biodiversity next to habitat destruction (GEF, 2003, Genovesi andShine, 2004). Globally, the cost of damage caused by IASs has been estimated to be £1.5 trillion per year -close to 5% of global Gross Domestic Product (GDP). In developing countries, where agriculture accounts for a higher proportion of GDP, the negative impact of IASs on food security as well as on economic performance can be even greater which affect human well-being, contributing to lower food security, harsher living conditions, reduced wealth, social instability and poverty alleviation (IUCN, 2009, BIOCEM-RD, 2016and Shaheen, 2019. Globalization through increased trade, transport, travel and tourism will inevitably increase the intentional introduction of organisms to new environments. Various IASs have been introduced to Ethiopia, like other countries in the tropics. Recently, in Ethiopia there are more than 35 Invasive Alien Plant species(IAPSs) spreading at alarming rate, threatening agricultural lands, power dams, rangelands, national parks, lakes, rivers and roadsides. IASs have been identi ed by the Environmental Policy of Ethiopia (EPE) and the National Biodiversity Strategy and Action Plan (NBSAP) as posing a major threat to biodiversity and economic well-being of the country. Parthenium weed (Parthenium hysterophorus), Prosopis juli ora, Water hyacinth (Eichhornia crassipes) and Lantana weed (Lantana camara) are the most known IAPSs in Ethiopia (Rezene Fessehaie and Taye Tessema ,2014).
Lantana camara L. is one of the worst IAPS worldwide. It is erect and a hardy evergreen perennial shrub up to 5 m tall. It is a species of owering plant within the verbenaceae family. It is native to tropical and subtropical America and the West Indies. It is common as an ornamental plant in all parts of the Flora of Ethiopia within an altitudinal range of 500 to 2500 meter above sea level (Sebsebe Demissew and Hedberg, 2006). The distribution of Lantana camara in Ethiopia is great and many ecosystems are affected by this species are cultivated and non-cultivated land, road side, grazing area, rural villages, river side, wetlands, forest and urban areas .It causes the loss of maximum amount biodiversity (Aravind et al.,2010, Habtamu Kefelegn, 2015, Kumar et al.,2016. Lantana camara has usually been deliberately introduced into various localities in Ethiopia (particularly urban settings) as an ornamental shrub and has been quickly spread by birds and animals that eat its fruits but cannot digest the woody seeds (Abiyu Enyew and Raja, 2015). In Ethiopia, it is one of the four major IAPSs those posing negative impacts on country's biodiversity. However, no adequate latest evidence exists about the impact of Lantana camara on species diversity (evenness and richness) and composition. Therefore, this study aims to assess the impact of Lantana camara on the species diversity and composition of invaded plant communities in Sidama, Gamogofa and Gedio Zones, SNNPR, Ethiopia.

Description of the study areas
The study was conducted in the three Zones (Gedio, Sidama and Gamogofa ) of SNNPR. Gedio zone is located in North eastern part of the region, It roughly lies between 60 0 59-60'62"N, latitude and 38 0 40-380'.43" E, longitude. The altitude ranges from 1500 to 3000 meter above sea level. Sidama is also located in the north eastern part of the region. Its geographic location lies between 6 0 14' and 7 0 18' N, latitude and 37 0 92' and 39 0 14' E, longitude with an elevation ranges from 1500 and 2500 m above sea level (Zebene Asfaw and Agren, 2007). Gamo-Gofa zone is named for the Gamo and Gofa peoples, whose homelands lie in this Zone. The administrative center of this zone is Arba Minch (Vaughan, 2003).

Materials
The common equipment and tools used in voucher specimen collection during the study were clippers, eld press, newspapers, pencils, camera, measuring tape, diggers, GPS, study location and documentation data form.

Method of data collection
This study was conducted between January 2020 and August 2020 in Sidama, Gedio and Gamogofa Zones, South Nation Nationality People Regional government (SNNPR), Ethiopia. The study zones and districts were selected purposively on the basis of the level of Lantana camara invasion with the help of information obtained from Agricultural o ce of Sidama, Gedio and Gamo-Gofa Zones. Based on the above selection criteria, from the three zones, three districts were selected. In each Zone one district was selected. Mirab Abaya, Dilla Zuria and Dara districts were selected from Gamo-Gofa, Gedio and Sidama respectively. From each district one kebele( the smallest administrative zone in Ethiopia) was selected.
From Mirab Abaya, Woze Kebele was selected while from Dara and Dilla zuria Mechisho and Waleme kebele were selected respectively. In Each Kebele Community forest areas were selected. Accordingly, Woze,Mechisho and Waleme kebele community forests were selected. The impact of Lantana camara on the species diversity and composition of invaded plant communities was studied by applying Quadrat Method following (Hejda et al.,. 2009, Dogra et al., 2009, Lisanework Nigatu,2010.

Sampling Techniques
To examine the effects of Lantana camara invasions on the species diversity and composition of invaded communities, a total of 120, 10mX10 m quadrats were sampled (60 quadrats for invaded and 60 quadrats for un-invaded or control).In each selected district 40 quadrats were laid (20 quadrats for invaded and 20 for non-invaded). In each selected study Kebele, a single quadrat of the set was placed in severely annexed plant communities ("invaded quadrat") where the aggressor was dominant and had a high concealment, and the next quadrat was located in adjacent plant community where Lantana camara had no cover (control) purposively. As much as possible, the control was selected to have analogous site conditions (< 10 m) to the invaded quadrat following (Hejda et al., 2009 andDogra et al., 2009). The location of each quadrat and study sites were recorded with GPS.
A control was selected in order to compare the species richness, evenness and composition of plant communities in the invaded and non-invaded areas. All the plant species appeared in the invaded and control areas were sampled and identi ed. Most of the plant species discovered in the quadrats was identi ed in the eld. For species di cult to identify in the eld, voucher specimens were collected, pressed and dried properly and transported to Ethiopian Biodiversity Institute for identi cation and proper naming. The nomenclature of the plant species followed the Flora of Ethiopia and Eritrea.

Method of data analysis
The collected data was analyzed by using SPSS (version 21) and R-package (version 3.6.2). A descriptive statistical method was employed to analyze and summarize the data. Inferential statistical method was also employed. Linear Regression Analysis was used to predict the value of a variable based on the value of another variable. The percentage and number of Lantana camara per study site and per quadrat was taken as the independent variables while diversity of plant species, Species richness, Simpson_1-D dominance index, Shannon-H diversity index and Evenness were taken as the dependent variable or outcome variable. Results were also statistically analyzed by PCA to extract the signi cant correlations from species data set or the correlation between a row (site/plots) and a column (the plant species/variable).
Plant species diversity analysis (Shannon1949, H') and richness and evenness of each study sites were analyzed. Evenness was calculated as H′/lnS, where S is the species richness expressed as the number of species (Hejda et al., 2009). Simpson index of dominance is calculated using the formula, D = N (N-1)/Σni (ni-1) Where ni is the number of individuals in the i th plant species; N is the total number of individuals (Barrantes and Sandoval, 2009). Changes in species richness S, Simpson 1-D index of dominance, Shannon index of diversity H′ and evenness between invaded and control quadrats were used to quantity the in uence of invasion on these plant communities' characteristics. These changes in plant communities' characteristics between invaded and control sites were used as a measure of the impact of invasion on species richness, evenness, index of dominance, and calculated and compared to nd out the loss of plant diversity due to invasion of Lantana camara.

Tests of association
Various inferential statistical tests were performed on the different types of data collected. The signi cance impacts of the number of Lantana camara on diversity of plant species had been also tested with one way ANOVA, while the differences in Margalef's index of species richness, evenness, Simpson and Shannon-H index of diversity between invaded and un-invaded areas were checked with the help of t test following Wambua(2010).

Impact of Lantana camara on species evenness and richness in the study areas
In the present study there were found a total of 109 species in the control or un-invaded areas as compared to 56 in Lantana camara invaded areas. Hence, the number of species lessened by 48.6% in the Lantana camara invaded localities as compared to the control. Simpson_1-D index of dominance, Shannon_ H index diversity, Margalef's index of species richness, and evenness index were also reduced via 66.04%, 74.48%, 51.95% and 57% respectively in the Lantana camara invaded areas (Table 1). The mean Evenness value or Equitability_J of the entire invaded sampled study sites was 0.24 indicated that 24% of the plant communities had uniform distribution while the mean Evenness value of the controls (the entire un-invaded) samples was 0.81 indicated that 81% of the plant communities had uniform distribution. Thus, the heterogeneity of the invaded study sites was reduced by 57%.  (Table 3). Concerning to Woze kebele community forest, the number of species decreased by 52.94% in the Lantana camara invaded area as compared to control. In addition, Simpson_1-D index of dominance, Shannon_H index diversity, Margalef's index of species richness, and evenness index were reduced by 65%, 68.55%, 54.49% and 60% respectively in the Lantana camara invaded areas as compared to control (Table 4).  Generally, the reduction over control on the plant diversity, Simpson_1-D index of dominance, Shannon_H index diversity, Margalef's index of species richness and evenness index were highest in Mechisho kebele followed by Woze and Waleme kebeles respectively (Table 6). This could be due to the substantial impact of Lantana camara invasion in the stated study areas. equation and the value of R 2 indicated there was a strong negative relationship between the percentage of Lantana camara and Simpson_1-D index of diversity. As the percentage of Lantana camara increase Simpson_1-D index of diversity decease (Fig. 2).Similarly, there was strong negative relationship between the percentage of Lantana camara and Simpson_1-D index of diversity per study kebele (Y= -0.013X + 1.406 with R 2 = 0.998) (Fig. 3).
There was also a strong negative linear relationship between Shannon_H index diversity and the  (Fig. 8).
Relationship between diversity of plant species and number of individuals Lantana camara per quadrat The study proved that there were considerable variations in the numbers of Lantana camara and diversity of plant species per plot which could be able to make a model to show the severity of the invasion. Both the numbers of Lantana camara and diversity of plant species contribute to the model. As the number of Lantana camara increased, the varieties of plant species decreased. R 2 value indicates how much of the dependent variable (diversity of plant species) can be explained by the independent variables (number of Lantana camara).To determine the degree of impact of Lantana camara on diversity plant species linear regression analysis was conducted. The regression equation that describes a simple linear regression relationship in a population is expressed as: Yi = α + β Xi + εi Where α is the intercept and β is the slope of the relationship, εi is referred as residual or error term and it is the departure of an actual (measured) Y from the estimated Y using the above regression equation ( ) ( Barrantes andSandoval,2009, Pallant,2011).In this study, Yi is the dependent variable (diversity of plant species) and Xi is the independent variable (number of individual Lantana camara).
Hence, the regression equation can be presented as: Y= -0.0386X + 9.1994, where Y is diversity of plant species and X is number of Lantana camara. In this case, R 2 = 0.6168, or 61.68% of the dependent variable (diversity of plant species) can be explained by the independent variable (number of Lantana camara) .The regression equation and Pearson correlation (-0.785) indicated the existence of strong negative linear relationship between diversity of plant species and number of Lantana camara (Fig. 9).
The number of Lantana camara per plot (sig.0.000) had signi cant in uence on the diversity of plant species. Furthermore, there was an inverse relationship between the diversity of plant species and number of Lantana camara per each selected study kebele. For instance, the regression equation can be presented as: Y= -0.091X + 10.591, R 2 = 0.614 for Waleme kebele (Fig. 10) and Y= -0.03X + 7.064, R 2 = 0.611, Woze kebele (Fig. 11) community forest where Y is diversity of plant species and X is number of Lantana camara. Therefore, the regression equation and R 2 values indicated the existence of strong negative linear relationship between diversity of plant species and number of Lantana camara.
Generally this study indicated that plant species diversity in Lantana camara invaded areas was low.
There was signi cant variation in plant species diversity between the invaded and non-invaded plant community in the study areas (t = -4.2839, df = 59, p-value = 6.868e-05 which is < 0.05). The signi cance impacts of the number of Lantana camara on diversity of plant species had been also conducted with the help of One way ANOVA which revealed that number of Lantana camara had signi cant impact on the diversity of plant species (F = 126.62, d.f = 1,P value = 3.267e-16 which is P < 0.05. Principal Component Analysis (PCA) was also conducted for invaded and non-invaded oral communities of the study areas. As to the non-invaded oral communities, the rst two principal components (PC1 and PC2) together accounted for 31.6% of the total variance in data set or 19.9% and 11.7% variance were accounted by the rst and second principal components, respectively following by the third principle components. Majority of the species were at the origin or at their average values especially in non-invaded study sites. Moreover, the PCA biplot axis, indicated the separation of the common plant species including Solanum incanum, Datura stramonium, Amaranthus caudatus, Ageratum conyzoides, Ziziphus abyssinica,Osyris quadripartita, Acacia abyssinica, Achyranthes spp., Stephania abyssinica and Acacia saligna (Fig. 12).
Concerning to the invaded oral communities, majority of the plots were close together. Moreover, the invaded study areas the rst, second and third principle components accounted by 16.7%, 12.3% and 10.9% of the total variance in data set respectively. Therefore, the rst three principal components together accounted for 39.9% of the total variance in data set (Fig. 13). On the other hand, plots 52, 53 and 55 were far apart to each other's and from the other plots.

Impact of Lantana camara on the composition of plant species in the study areas
Lantana camara invasion heavily damaged the composition and structure of invaded oral communities in the study areas. In this study a comparison in oristic composition was made between Lantana camara invaded and non-invaded areas. An entire of 125 plant species(56 plant species in invaded,109 in control and 38 common to both) belonging to 49 families of plants were identi ed in this study. From the total plant families 44 of them were recorded in the control area in contrast to only 30 in the Lantana camara invaded areas. The number of family decreased via 31.82% in the Lantana camara invaded area as compared to control.
In invaded areas, of the 30 plant families, Fabaceae was the highest (14.29%), followed by Euphorbiaceae (8.93 %), and Malvaceae and Myrsinaceae accounted 7.14% each allotting the third place amongst the plant species recorded in the Lantana camara invaded study areas (Table 7). In the invaded areas 37.5% of the plant species placed within these four common families. In non-invaded areas, of the 44 plant families, Fabaceae was the highest (15.74%), followed by Asteraceae (10.18%), Malvaceae (5.71%) apportioning the third place, and Euphorbiaceae and Celastraceae (4.63%) each allocating the fourth place amongst the plant species recorded in the noninvaded study areas (Table 8). These ve families shared 40.89% of species to the over-all ora in noninvaded (controlled) study sites. From 125 plant species identi ed during the study, 38 plant species were found common in control and invaded areas (Table 9). Lantana camara was found to be the most dominant plant species in invaded study sites followed by Solanum incanum, Achyranthes aspera and Parthenium hysterophorus respectively. Trees and shrubs (78.4%) were the major plant species identi ed during this study. In invaded and control (non-invaded) areas 44% and 34.4% were shrubs and trees respectively.

Discussion
Lantana camara affected severely the diversity and composition of invaded ora in the study area. The result of this study indicated that the number plant species, Simpson_1-D index of dominance, Shannon_H index diversity, Margalef's index of species richness, and evenness index were reduced signi cantly in the Lantana camara invaded areas as compared to control. The report of the study by Ghisalberti, (2000), Sharma et al.(2005), French et al. (2009) and Nel (2015 indicated that the impacts of Lantna camara on native biodiversity is highly marked because of the species' invasive characteristics, such as rapid vegetative growth, aggressive competitive ability, high seed production, and proliferation throughout the year in ideal environmental conditions. In addition, there are allelochemicals present almost in all parts of the plant ( Choyal and Sharma,2011).
Besides, the higher value of index of dominance in the invaded areas would be predicted that the communities were homogenous in nature and dominated by a single whereas the lower value of index of dominance for non-invaded oral communities would be indicated that the heterogeneous nature of these communities and the communities were not dominated by a single or few species. Moreover, a low value of the Simpson diversity index in invaded study sites also suggests an area was dominated by a few species, homogenous nature of these communities. For instance, in Mechisho community forest On the other hand, if there are more successful species with no species completely dominating the area, the value of the Simpson diversity index is high (the control) (Barrantes and Sandoval, 2009). The communities were showing more heterogeneity in the un-invaded study areas. A high diversity index of Waleme community forest suggests that the area was not dominated by one or two species rather by large number of species which result a more stable ecosystem as reported by Chatterjee (2015) on the impact of Lantana camara on the diversity of plant species. Waleme area community forest was the least affected by the invasion of Lantana camara. This might be due to the soil or other environmental factor limited the expansion of Lantana camara when compared to other study areas.
The result of the study by Dobhal et al. (2010) also indicated that Lantana camara is a serious threat to all major native shrubs growing along Nayar river of Pauri Garhwal, in Uttarakhand State, Himalaya, Northern India which were affected by speedy blowout and distinctive capacity to seize empty niche. In addition the study by Lwando (2009) also indicated that Lantana camara has predominant impact on Plant Diversity in Zambia. Generally, Shannon_H index diversity decreased with the corresponding increase in the Percentage of Lantana camara. The result of study by Hejda et al. (2009) also con rmed the impact of IAPSs on the species richness, diversity and composition of invaded communities.
As the coverage of Lantana camara increased, Species Evenness per study site decreased. Evenness (E) has values between 0 and 1.0, where 1.0 represents a situation in which all species are equally abundant (Nagendra, 2002). The result of this study also con rmed that regression equation Furthermore, in this investigation PCA (Ordination) was conducted in order to place the points such that points that are nearby together match to sites that are comparable in species composition and points that are distant apart relate to sites that are unrelated in species composition (Chahouki,2012). The plots for both invaded and non-invaded sites, the region from the origin for a row (site/plots) implies how much the point differs from the average and the area from the origin for a column (species, variable) implies how much the point increases to that direction. Accordingly, PCA was performed in invaded and noninvaded oral communities in three selected Kebeles to know the correlation between plots and the plant species. If two plots close to each other in ordination they have similar plant species and if two plots have analogous plant species, they have related environment. Two sites extreme away from each other in ordination have unrelated plant species, and perhaps have different environment (Paliy andShankar, 2016, Oulu, 2016).
The scores acquired from a PCA for species and sites can be used to prepare a bi-plot. Consequently, PCA displayed that the species distribution scheme in association with the speci c sites in the invaded and non-invaded study areas. Regarding to the non-invaded oral communities, the rst two principal components together accounted for 31.6% of the total variance in data set following by the third principle component. This means that the rst principal component is superior for demonstrating the distinction of the diversity of plant communities in the three study Kebeles following by the second and third principal components. Moreover, the PCA biplot axis, indicated the isolation of the common plant species including Solanum incanum, Datura stramonium, Amaranthus caudatus, Ageratum conyzoides, Ziziphus abyssinica, Osyris quadripartita, Acacia abyssinica, Achyranthes spp., Stephania abyssinica and Acacia saligna indicating the existence of various plant species which might be due to the suitable environmental condition in non-invaded study sites.
Concerning to the invaded oral communities, majority of the plots were close together which might be revealed that those sites/plots were similar in species diversity and composition. This might be resulted that the reducing diversity levels with increasing cover of the Lantana camara (Wekhanya, 2016, Shaheen et al., 2019. On the other hand, plots 52, 53 and 55 were far apart to each other's and from the other plots which might be indicated that those plots were unrelated in species diversity and composition. The diversity and number of family declined considerably in the Lantana camara invaded area (Vardien et al., 2012, Gantayet et al., 2014. Fabaceae, Asteraceae, Malvaceae, Euphorbiaceae and Celastraceae contributed most of species (40.89%) to the total ora in non-invaded study sites. Fabaceae was the dominant family in both invaded and non-invaded study areas. This might be due to the suitable environmental condition to the species in the family and large number of species in this family.

Conclusion
Lantana camara categorized as the dominant IAPS in selected study Kebeles of the study areas that reduced species diversity and composition of various plant species in invaded communities. Information on impact of IAPSs on diversity and composition of any plant community is very important for their management. This invasive species has negative impacts on the indigenous plant and its impacts are projected to increase with time. The problem is however aggravated in the majority of terrestrial habitat.
Therefore, a management and control strategy for Lantana camara and other IAPSs needs to be instituted. Finally, Lantana camara has already been established in the study areas and other parts of the country; therefore, further research is required to ascertain the best control and management strategy. Figure 1 Administrative Map of the study area  The relationship between Percentage of Lantana camara and Shannon_H index diversity per invaded quadrat (R2 = 0.847, p < 0.01).  The relationship between Percentage (coverage) of Lantana camara and Evenness of Plants per invaded quadrat (R2 = 0.8662, p < 0.01). Diversity of Plant species (Y) and Number of Lantana camara per invaded plots (X) (Woze kebele community forest (R2 = 0.611, p < 0.01).

Figure 12
Principal Components Analysis (PCA) ordination diagram of the plots and plant species for non-invaded Floral Communities Photo showing Level of Invasion by Lantana camara from Mirab Abaya district (Woze kebele Community forest: -photo taken in April, 2020).