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Point Journal of Agriculture and Biotechnology Research, 1(1): 001-012 June, 2015. Available online at http://www.pjournals.org/PJABR ISSN 2467-8805 @ 2015 Point Journals International Received 07 May, 2015 Accepted 04 June, 2015, Published 24 June, 2015 Review Environmental degradation and its effect on terrestrial and aquatic diversity in the Abijata-Shala Lakes National Park, Ethiopia Getaneh Gebeyehu, Temesgen Gashaw* and Damena Edae Center for Environmental Science, Addis Ababa University, Ethiopia. *Corresponding author. Email: [email protected] Abijata-Shalla Lakes National Park has immense natural resources which comprises two types of 2 2 2 ecosystems: aquatic (482 km ) and terrestrial (405 km ) ecosystems covering a surface area of 887 km . These ecosystem types favor more of diverse species of birds, mammals and plants. Diversity of birds accounted 52.5% of the country of which one endemic, five near endemic and one threatened species are found in the park. The park is also home to 76 mammal species including six endemic species. However, reptiles, fish, amphibians and invertebrates species are not well recorded in the area. In case of plants, 97 plant species are identified in the Acacia-Commiphora woodland ecosystem type comprising of the acacia woodland, acacia bush land, scrubland and grassland vegetation. However, there was an expansion of cultivated and grazing land by 4.1% and 8.6% respectively between 1973 and 2000 at the expense of protected/dense woodland, water bodies and wetlands, grazed woodland and shrub land, barren land and broad-leaved forest. As a result, the park is highly affected by environmental degradation. The main activities those adversely affecting the park ecosystem and its biodiversity includes: expansion of settlement and cultivated land, overgrazing, deforestation, increased irrigation, overfishing and soda ash mining. The decline of water capacity in the aquatic habitat has affected the abundance of bird species as result of its impact on the edge of lakes which has diversity of phytoplankton. The degradation of terrestrial habitat affected the diversity and abundance of birds and mammalian in the park due to its change to vegetation community structure and composition. Therefore, this paper aims to assess environmental degradation and its effect on terrestrial and aquatic diversity in Abijata-Shala Lakes National Park, and propose technologies and practices for ecosystem restoration. Key words: Aquatic ecosystem, Environmental degradation, Species diversity, Species interaction, Terrestrial ecosystem Citation: Getaneh, G., Temesgen, G. and Damena, E. (2015). Environmental degradation and its effect on Terrestrial and Aquatic diversity in the Abijata-Shala Lakes National Park, Ethiopia. Point J. Agric. Biotechnol. Res. 1( 1): 001-012 INTRODUCTION Background Ethiopia has a long history of conservation. The first recorded indigenous conservation-oriented activity took place during the reign of Emperor Zerea Yacob (14341468). The country has a very diverse set of ecosystems ranging from humid forest and extensive wetlands to the desert (Melaku, 2011). Representative examples of Ethiopia's remaining ecosystems are conserved through a network of effectively managed protected areas. Protected area of the country covers approximately 16.4% of the land including 20 national parks, 3 wildlife sanctuaries, 2 wildlife reserves and 17 controlled and 7 open hunting area and 3 community conserved area (EWCA, 2014). Abijata-Shalla Lakes National Park (ASLNP) is one of protected area found in the country which was established in 1963. Its primary objective of establishment was to conserve bird species (EWCA, 2014). The park comprises two ecosystems which cover aquatic Getaneh et al. 2 2 (482 km ) and terrestrial (405 km ) ecosystems. These ecosystems dominated and characterized by presence of large diversity of migratory and resident birds of which 52.5% of bird species of the country are founded in the area. Comparatively, the park host less number of mammalian species because of disturbance, habitat loss and interactions with domestic livestock. According to Ethiopian ecosystems types, the terrestrial part of park is characterized by Acacia-commiphora type. However, Ethiopia’s protected areas are increasingly degraded (Young, 2012). Land is being converted for subsistence and commercial agriculture, timber used for fuel wood and construction, protected grasslands used for livestock grazing. The loss of forests and other protected land is underpinned by a growing population, unsustainable natural resource management, poor enforcement of existing legislation, uncertain land tenure and very low public awareness of the impact of climate change and the importance of biodiversity and ecosystems. ASLNP is under serious treats due to water abstraction for Soda Ash enterprise, increased irrigation, expansion of settlement, cultivated land and grazing land, deforestation and over grazing (Flower, 2011, Temesgen et al., 2013). As a result, the aquatic habitat has confronted problem of water resource exploitation and decline of lake water capacity. The source of these problems is both internal that is, limited into the park boundary and also some others are external in their origin. Similarly, the terrestrial habitats faced degradation and fragmentation due to major agricultural activities which compete with wildlife for food, cover and space. Subsequently, the biodiversity of both terrestrial and aquatic habitats are under great challenge (Tafesse, 2008). Objectives The overall objective of this review is to assess environmental degradation and its effect on terrestrial and aquatic diversity in the Abijata-Shala Lakes National Park. Specific objectives include: i. To characterize the park ecosystem in terms of species diversity and species interactions ii. To assess the type and extent of environmental degradation including land use/ land cover changes and loss of habitat iii. To assess the impact of degradation on the aquatic and terrestrial biodiversity resources iv. To propose technologies and practices for ecosystem restoration MATERIALS AND METHODS Study area ASLNP is located within the central portion of the Great 002 Rift Valley, in Oromia Region, 207Km south of the capital (Addis Ababa) between 7°15’–7°45´N and 38°30´– 38∘45´E at elevation of between 1,540 and 2075m a.s.l. The entire park falls within the ecological-climate zone III semi-arid. The main rainy season generally occurs between late June and September. The annual rainfall is on average between 500-600mm. Temperature normally range between 16°C and 24°C with the highest temperature occurring in March and the lowest in 2 December. The ASLNP encompass an area of 887 km , 2 of which 482 km is aquatic ecosystem (it include lake Abijata, Shalla and Chitu and their shorelines) and 405 2 km is land or terrestrial ecosystem, which comprise the acacia woodland, acacia bush land, scrubland and grassland vegetation and the rocky outcrops (Rezenom, 2012; Fekadu and Fekadu, 2014). Data collection and analysis The data was collected from published journals, proceedings, thesis and workshops. Species diversity and interaction, type and extent of environmental degradation with its causes, and effects of environmental degradation on terrestrial and aquatic ecosystem was assessed in detail. The data were analyzed using excel spread sheet and the results were displayed by graphs. After an in-depth analysis, technologies and practices for ecosystem restoration was proposed. RESULTS AND DISCUSSION Species diversity and their interaction Species diversity ASLNP comprises two types of ecosystems: aquatic (482 2 2 km ) and terrestrial (405 km ) ecosystems covering a 2 surface area of 887 km (Fekadu and Fekadu, 2014). According to WWF eco-regions division, ASLNP vegetation is Acacia-Commiphora woodland ecosystem type within Somali Masai biome (Tafese, 2008). Terrestrial ecosystem favors savanna vegetation zone and small diversity of species compared to others. While, aquatic ecosystem favors more on bird species. Species diversity in ASLNP is well documented in the taxonomic groups of mammals, birds and plant species (Figure 1). The park also provides protection to six endemic mammal species (EWCA, 2014), five near endemic and one endemic bird species (Rezenom, 2012). The park also accommodates four vulnerable and four threatened of which the Lesser Flamingo is considered to be a globally threatened species, finds a home in the waters of Abijatta. The Great White Pelican has a breeding colony on the islands of Shalla and this colony is considered to be one of the most important aggregations on the 003 Point J. Agric. Biotechnol. Res. Taxonomic groups Vascular plants Butterflies Endemic and near endemic spp.at ASLNP Amphibinas Endemic and near endemic spp.at Country level Fish Reptiles No. of species at ASLNP Birds Mammals No. of species at country level 0 2000 4000 6000 8000 Number of species Figure 1. Comparative Statistics for major groups of species recorded to date in Ethiopia and ASLNP. Source: Authors’ compilation. continent. One reason that the park plays an important role in protecting such a unique assemblage of species can be related to its vulnerable but equally life maintaining waters. The waters are full of productivity and this has in turn enhanced the life forms that depend upon it. However, fish, reptiles, amphibians and other invertebrate species are not recorded and further investigation need for justification. The most notable taxonomic groups are discussed as: Mammals Large animal diversity found in the national park of the world comprises five major classes of vertebrates. According to Vreugdenhil et al. (2011), about 320 species of mammals recorded in Ethiopia. This is one of Africa's most diverse countries for mammals, most of the medium and large sized species are severely depleted and difficult to see, as they suffer from habitat loss and hunting pressure almost everywhere, even in many protected areas. Similarly, ASLNP hosts less diverse number of mammals due to the disturbance, habitat loss and competition with domestic animals for forage. Thus, the acacia woodland favors few mammals which have decreased in number (Tafese, 2008). According to the Park document cited in Tafess (2008), a total of 76 mammal species have been recorded so far, of which the most commonly potted are Grant’s gazelle, Oribi, Warthog and the Golden Jackal. About 31 species from large mammals are endemic in the country level (Melaku, 2011). Out of these, ASLNP hosts six endemic mammal species such as Scott’s Hairy Bat (Myotis scotti), White toothed shrew (Crocidura sp.), Mahomet’s mouse (Mus Mahomet), White toothed rat (Berylmys sp.), Ethiopian grass Rat (Arvicanthis sp.) and Harrington’s Scrub rat. Birds The Ethiopian avifauna represents an interesting mixture of African, Palearctic and some strikingly unusual endemic components, that in recent years has caught the interest of the international birding community, making Ethiopia one of Africa’s fastest growing destinations for bird watching (Vreugdenhil et al., 2012). The ASLNP contains diverse avifauna compared to mammals’ diversity including six endemic bird species. ASLNP in Ethiopia is established primarily to conserve the diverse bird life of the area (EWNSH, 2010). The scientific investigation of bird species diversity recorded shows different numbers of bird species in different time. For example, a total of 436 bird species were recorded of which, 114 species are wetland birds while 282 species are terrestrial (Melaku and Rezenom, 2002). More study on bird species in the ASLNP is also indicated, their presence include 453 bird species (representing 52.5% of the country total) representing 73 Families and 22 Orders (Rezenom, 2012). Thus, the values of Abijatta-Shalla from a conservation point of view are one of the sites of highest wetland bird diversity in Ethiopia. Legesse et al. (2005) stated that Park provides wintering and maintenance station for such a large number of terrestrial and aquatic birds, which include Southern African, Sub-Saharan and Palaearctic species. According to Rezenom (2012) studies, the park accommodates interims of geographical occurrence 305 (67%) species are resident and (including one endemic and five near endemic). The endemic bird species in the park include Yellow-fronted Parrot (Pocicphalus flavifrns) and five Near-endemic bird species of Wattled Ibis (Bostrychia carunculata), Black-winged Love Bird (Agapornis taranta), Banded Barbet (Lybius undatus), White-winged Cliff Chat (Mytmecocichala semirufas), Getaneh et al. 004 Abyssinian Black-headed Oriole (Onychognathus albirosris) and Thick-billed Raven (Corvus crassirosris). A total of 148 (33%) species are migratory of which (99) Northern migrants; (7) African migrant; (20) Intra African migrant; (8) Intra African –northern migrant and (14) Northern migrants with resident sub species. Besides, 18 and 25 species were found Afro tropical Highland Biome Species and Sommali-massi Biome Species respectively. Based on habitat classification 317 (70%) species are terrestrial and 136 (30%) are wetland (of which106 species are wetland specialist and 30 species are generalist). The park is also home of four nearly threatened bird species such as Lesser Flamingo (Phoeniconaios minor), Pallied Harrier (Circus macrourus), Basra Reed Warbler (Acrocephalus griseldis), Black-winged Pranticole (Glareole nordmanni) and four vulnerable bird species such as Imperial Eagle (Aquila heliaca), Lesser Kestrel (Faco naumanni), Wattled Crane (Grus carunculatus) and Ferruginous Duck (Aythya nyroca) (Rezenom Almaw, 2012). species of legumes and 179 species of browse trees are known (http://etflora.net/). In terrestrial ecosystems, plants form the basis of all communities, in terms of both structure and function. The abiotic environment sets the particular form of structure, with cold and dry climates often having slow and intermittent growth. Thus, plants determine the niche possibilities for animals. Vegetation zone is identified to be savannah and the habitats surrounding the lakes are largely Acacia and Euphorbia woodlands with few Ficus trees. Small areas of riverine forest and open scrub on the rocky slopes are also important habitats. Lakeshores around Lake Abijata have short grasslands comprising of Cynodon and Sporobolus spp. that are important for stabilizing the fragile soils. Other key Gramminae species include various spp. of Hyparrhenia. The dominant tree species in the park are Acacia tortilis, A. senegal, A seyal, Agerrardi, Balanites aegptiaca, Ficus sycomorus and Mytenus senegalensis. Other species include Acacia ethbaica, Grewia sp., Ziziphus macronata, Calpurnia subdecandara and Croton macrostachys from the park. Herptofuana Species interaction Of the approximately 240 reptile species recorded from Ethiopia, 15 are endemic. Most of the endemic species have been recorded in protected areas. With a total of 71 amphibians for the country, the amphibian herpetofauna of Ethiopia is rather poor and probably insufficiently studied. Nevertheless, with 30 endemic species, it has a high degree of endemism (Vreugdenhil et al., 2012). Most species are probably protected in the existing protected areas. However, reptiles species of the ASLNP has not been documented and they will be further studied on the occurrence of species. The park was created for many species of aquatic birds, particularly great white pelicans and greater and lesser Flamingoes. Lake’s islands are used as breeding sites by many birds including pelicans; and Lake Abijata is their feeding sanctuary. Other birds in the area include white necked cormorant, African fish eagle, Egyptian geeze, various plover species and herons (EWCA, 2014). The dependence of species habitat relationship on factors ranging from local vegetation structural features suggests that several processes operate simultaneously at different scales of influence. For example, strong interaction between the habitat type and helmeted guinea fowls indicates that certain habitat is very important for the survival of birds (Tewodros Kumssa and Afework Bekele, 2013). Due to these biological characteristics the lake is the major feeding site for aquatic and terrestrial bird including both migratory and resident ones. Flamingos and White Pelicans are among the water birds that depend on the Lake. In the past, the lake was fished by the local population but now it is rarely reported. The ecosystem destruction affects the different ecological processes and components of ASLNP (Tafese, 2008). Mammal species in the area include Grants Gazelle, Jackals, Oribi, Warthog, and others. But the majority of the mammal species have been reduced or eliminated because of habitat disturbance and severe competition with livestock for forage. The mammalian herbivores are important components of terrestrial ecosystem in maintaining the diversity and composition of mammalian carnivore populations. However, insensitive domestic animal grazing is causing major changes in composition diversity and abundance of Ichthyofauna With 150 species generated from Fish base (http://www.fishbase.com), the ichthyofauna of Ethiopia does not seem all that numerous, considering the size of the country, but with about 40 endemic species, endemism is proportionately high. The fish fauna of the Abijata and Shala lakes has not been studied well and it is recommended that they will be surveyed on the occurrence of new species. Plant diversity A total of 97 plant species were recorded distributing in 28 families of which Poaceae (40 species (41.2%) and Fabaceae (19.6%) were largest diversity (Tolcha Regassa et al., 2005). A large number species is adapted to grazing and browsing: 736 species of grasses, 358 005 Point J. Agric. Biotechnol. Res. Table 1. Distribution of land use/land cover in 1973, 1986 and 2000. Land use/land cover type Broad-leaved forest Protected/dense woodland Grazed woodland and shrubland Cultivated land Grazing land Barren land Water bodies and wetlands 1973 Area (ha) 379 7696 16 906 2023 12 713 4293 19 855 (%) 0.6 12 26 3 20 7 31 1986 Area (ha) 755 10 962 19 488 2538 11 210 2560 16 232 (%) 1.2 17 31 4 18 4 25 2000 Area (ha) 302 4183 15 822 4602 18 156 4180 16 506 LUCC(%) (%) 19731986 19862000 19732000 0.5 7 25 7 28 7 a 26 +0.6 +5.2 +4.1 +0.8 -2.3 -2.7 -5.6 -0.7 -10.6 -5.8 +3.2 +10.9 +2.5 +0.4 -0.1 -5.5 -1.7 +4.1 +8.6 -0.2 -5.2 a Including three small reservoirs existing at Alage Source: Temesgen et al. (2013) herbivore wildlife assemblages. An increase in complexity of vegetation structure, floristic composition and heterogeneity can increase niche diversity of birds and vice versa (Leito et al., 2006). Both natural and human induced disturbances such as floods, drought, deforestation change in land use, natural resources and seasonal climatic changes affect vegetation and bird community structures (Rahayuninagsih et al., 2007). The change in vegetation community structure alters the availability of nest, cover and food for birds. Change in structural and compositional diversity of native vegetation would alter composition of bird community (Leito et al., 2006; Acevedo and Aide, 2008). This could be the case in the disturbed habitat that was prone to loss of its native vegetation. Lake Abijata is known to be productive in phytoplankton. A dominant population of Spirulina species was reported from Lake Abijata and nitrogenfixing cyanobacterium Anabaenopsis abijatae (Kebede and Willén, 1998) as the dominant phytoplankton species. The lake currently recognized as a diatoms lake. Lake Chitu still maintains an abundant Spirulina which is the main food source for huge flocks of the lesser flamingo. Two major phytoplankton classes namely, Bacillariophyceae (Diatoms) and Cyanophyceae (blue green algae) were identified from Lake Abijata (Tewodros and Afework, 2014). Land use/land cover changes A study by Temesgen et al. (2013) in main Ethiopian rift valley, in which about 80% of it is within ASLNP, indicated that there was an expansion of cultivated and grazing land between 1973 and 2000 at the expense of protected/dense woodland, water bodies and wetlands, grazed woodland and shrub land, barren land and broadleaved forest (Table 1). Similarly, a study conducted by Molla (2014) in Arsi Negele district, which is part of the park, showed that the increased of cultivated land and grassland from 1973 to 2010 at the expense of acacia woodland, shrub/bush land and bare/open land. These were mainly caused by the current population pressure in the district. Hence, the expansion of cultivated land and grassland into marginal land lead to more sever land degradation. Similarly, a study by Hurni and Ludi (2000) revealed that human land use around the Simen Mountains National Park has accelerated the degradation of vegetation and soils, and land use has also intensified basically through shortening of fallow periods and through expansion of cultivated land. Due to the human use in the highlands and lowlands puts pressure through crop cultivation and livestock rearing for subsistence agriculture, those natural forests and grasslands which still occur in all altitudinal belts are thus increasingly coming under pressure. Type and extent of environmental degradation Diminishing of lake size Since the mid 1980s, Lake Abijata water levels have been in almost constant decline, which is not explainable through the rainfall record, indicating that water abstractions are the main cause of the decline. Lake Abijata is sensitive to any reduction of flow in the Bulbula River, either through lake levels in Lake Ziway dropping or through direct pumping of water along the course of the Bulbula River to supply Ziway and Bulbula town water supplies, or diverted for small irrigation plots. The direct pumping of water from Lake Abijata for commercial exploitation of soda ash by evaporation of brine also impacts on lake levels. In addition, over-exploitation of wood for fuel-wood and building materials in the park led to a decline in woody vegetation which could induce changes in the local climate, a more erratic rainfall and severe soil erosion caused siltation that resulted in decline in the size of the lake (Fekadu and Fekadu, Getaneh et al. 006 Figure 2. Area of Lake Abijata (Temesgen et al., 2013). 2014). Research finding indicated that Lake Abijata’s area decreased by 5.2% between 1973 and 2000. It is also known that the lake lost 46% of its area between 2000 and 2006 (Figure 2) (Temesgen et al., 2013). In addition, the water level of the lake is dropping because of increased irrigation for agriculture in/around Lake Ziway (Flower, 2011). If current trends in natural and socio economic conditions continue, Lake Abijata is likely to disappear by 2021 (Figure 3) (Meshesha et al., 2010). There are contrasting ideas about Lake Shalla. According to Flower (2011), Lake Shalla is not currently decreasing. This is due to the alkaline nature of the lake which makes water abstraction for irrigation not possible (HGL and GRID, 2009). But, water extraction for soda ash production is a future threat (Flower, 2011). However, Meshesha et al. (2010) indicates that the area of the lake deceased over 1973–2006, and projected to decrease over the coming years (Figure 3). Thus, further study is required on Lake Shalla. Deterioration of vegetation According to WWF eco-regions division, ASLNP vegetation is Acacia-Commiphora woodland ecosystem type within Somali Masai biome. It has dominant acacia trees with bush land and shrubs. The dominant acacia trees are: Acacia tortilis, Acacia Senegal, Acacia seyal, and Balanties aegipticus (Tafese Kefyalew, 2008). However, charcoal making and farming has depleted the vegetation cover (Fekadu and Fekadu, 2014). Grazing of Acacia woodland inside the Park is additional cause of vegetation degradation (Tafese, 2008). As a result, the park is one of the country’s most fragile area as a result of habitat loss, mainly that of Acacia (BirdLife International, 2012). Grazing land degradation Grazing land in the area was heavily degraded as a result of local communities over dependence on diminishing natural resources. The drivers were overgrazing and poor rangeland management systems (BirdLife International, 2012). Because the Park area supports thousands of population and their huge number of livestock which increases overtime (Table 2), the area is deforested and overgrazed leaving the area bare. Over grazing as a result of overstocking of the wetlands and the savannah grass of the acacia woodland leads to soil erosion and 007 Point J. Agric. Biotechnol. Res. Figure 3. Areas of Central rift valley lakes 1973-2006 and projected areas in 2016 and 2021 (Meshesha et al., 2010). Table 2. Livestock population in the park in different years. Types of livestock Cattle Shoat Equinesa Total 1971 21,485 6476 2449 30,410 Livestock population 1978 1996 27,670 48,890 11,000 19,100 5380 6716 44,050 74,706 2007 132,629 40,490 10,153 183,272 2010 134,260 54,574 11,200 202,644 Note: a Horse, mule, and donkey. Source: Debele (2007); Districts’ Agricultural Office (2010) in Fekadu Teferra and Fekadu Beyene (2014) degradation (Tafese, 2008). Causes of environmental degradation Contested land tenure and overlapping claims Ethiopia has implemented several changes in its land ownership system since 1975, and these changes are a source of uncertainty among farmers and rural communities (Meshesha et al., 2010). In the study area, local people have legitimate claims from a historical and socio cultural perspectives with regard to property rights to the park resources. As a result, conflicts related to the park lasted over nearly 40 years (Table 3). The recurrence of the conflict and unstable property rights structure has weakened park management, which was partly attributed to the grievance inherent in the loss of the rights to benefit from resources inside the park (Fekadu and Fekadu, 2014). This resulted lack of sense of ownership and aggravated degradation of resources. There are a variety of factors that contribute to tenure insecurity. Gizachew (1994) stated that factors that cause land tenure insecurity are: growing population pressure which in turn causes scarcity and fragmentation of farm lands; lack of a proper and accessible juridical body responsible for land disputes; lack of knowledge on the part of rights holders of their rights and their inability to defend their rights; and increasing rural poverty and the fact that farm life is becoming unviable. This implies tenure insecurity is one factor for degradation of resources in the park. Tenure security is considered to be ensured through rural land registration and certification program. This in turn enables farmers to conserve their lands (Ayele and Tahir, 2015). Demographic pressures There has been a rapid growth of human population experienced recently between 2000 and 2010 from 24,785 to 43,673 with a rate of 6% owing to high birth rate, declining mortality rate and migration from the surrounding highlands for cultivation. This has resulted in the decline of average holdings and further competition among farmers to expand land for cultivation which has caused encroaching on land available for grazing and wildlife conservation (Fekadu and Fekadu, 2014). Similarly, a study by Tesfahun and Temesgen (2014) in Bantneka watershed, Southern Ethiopia verified that due to high population growth, average landholding size per households has decreased from 0.68ha in 1994 to 0.48ha in 2007. As a result, agricultural practices have expanded into upland and marginal areas, and clearing of Getaneh et al. 008 Table 3. Historical overview of property rights and conflict in ASLNP. No. 1 Time line Pre-Italian Period (before 1939) Chronological events Land was used for communal grazing 2 1942–74 (resource depletion) Land distributed to individuals where state granted use rights; Small scale modern farms introduced; Environmental damage incurred by the introduction of tractors; ASLNP established without the consent of local community 3 1974–91 (Revolution and post revolution) Communities entered the race of resource exploitation, exploiting the abandoned acacia trees(1974–78); Soda Ash plant established in the northern shore of Lake Abijata ; Strict government control of the forest and the park in place 4 Park condition since 1991 (transition to nearly open–access condition) ASLNP fell victim of despairing communities; There was extensive damage to the property of ASLNP and wildlife; Illegal harvesting of trees, farm land expansion, and charcoal making was no longer a risky venture; ASLNP was divided into 11kebeles 5 1996–2009 (contested decentralization) ASLNP management relegated under Oromia Agriculture Bureau; There was lack of coordination and overlapping claims between different Bureaus of Oromia Regional Government regarding ASLNP; The park was divided into 18 kebeles resulting in boundary disputes; The park fell victim to land grabbing in the name of investment promotion 6 From 2009 (recentralization) ASLNP recentralized under Ethiopian Wildlife Conservation Authority Source: Fekadu and Fekadu (2014) indigenous trees has become prevalent. Impacts of environmental degradation ASLNP is endowed with mosaic array of micro habitats and niches which serves for various resident wetland and terrestrial bird species. Since the park is geographically located along the Great Rift Valley, the entire ecosystem serves as wintering and feeding for several migratory bird species from Europe, Asia and other African country (EWCA, 2012). Establishment of this park is to endorse environmental and socio- economic services of this area. The international effort of its establishment is to protect wetlands of international importance for resident and migratory bird species. The other purpose of ASLNP establishment is to maximize the tourism potential of the area that enables to meet the socio- economic and environmental benefit that can sustain the park ecosystem. The economic, ecological and cultural significance of wildlife resource continuation depend on the health and integrity of its ecosystem. ASLNP has immense natural resources including wetland, aquatic and terrestrial birds. However, due to different socio-economic activities the biodiversity of this park has under gone dramatic environmental changes (Tewodros Kumssa and Afework Bekele, 2014a). Impact on aquatic biodiversity resources Unsustainable resources used for several years of this fragile park ecosystem have lead to its present degraded state. The main activities adversely affecting the park ecosystem and its biodiversity includes: settlement, overgrazing, deforestation, sand mining, overfishing and soda ash mining. As result of these economic based activities the park area is overpopulated and the trend of ecosystem change growing. The productivity of the water habitat can no longer support the once rich bird and fish life as major ecological systems has been broken. The area is located in water deficit spot of the country which is the result of the natural environmental problems. On the other hand up stream water abstraction especially from Bulbula River, increased human settlements on the periphery of the park and deforestation of water catchments on all sides of the basin are among external 009 Point J. Agric. Biotechnol. Res. Figure 4. Drying Lake Abijata (UNEP, 2009). problems (Tafesse, 2008). According to Legesse et al. (2005) the surrounding lakes including Lake Ziway and Lake Langano through Bulbula River and Hora Qelo River respectively are main feeders of Lake Abijata. The main inflow of water from these two lakes is from highland on either sides of the rift. Lake Abijata may receive, during exceptionally prolonged high rainfall periods an overflow from Jido River. This indicates the threats to the lake habitat were not confined only into the park boundary; in addition the degradation of the rift watershed is the significant external problem. Among one of the economic impact of degradation on the aquatic habitat is Abijata Soda ash enterprise expansion for which its first phase of production operated by 1987 following the feasibility conducted during 1985/86. The production capacity of the enterprise was also intended to eventually expand up to 200,000 and 1000,000 tons of soda ash per year in the second and the final phase of production operation, respectively ; where lake Shalla will be used as a main source of water and lake Abijata as evaporation ponds (Tigist, 2009). These economic activities, drought and high evaporation rate retreated the water capacity of Lake Abijata affecting the bird abundance and diversity since it is the feeding habitat for many birds due to its algal growth. As it was showed (Figure 4) the retreated water capacity along the edge of Lake Abijata is declining the size of significant feeding area for birds. Abijata–Shalla aquatic habitat is primarily created to serve its aquatic birds life, particularly those feed and bread on lake in large number. There are about 400 bird species recorded in ASLNP, almost proximate half the number recorded for the whole county. The islands in Lake Shalla are real bird’s paradise however, birds fly to Lake Abijata to feed. Although, it has high alkaline nature Lake Abijata is preferred habitat by these birds for its shallow depth along its edge where algal food source concentrate (Tafesse, 2008). Due to these biological characteristics the lake is the major feeding site for aquatic and terrestrial bird birds including both migratory and resident ones. Flamingos and White Pelicans are among the water birds that depend on the Lake. In the past, the lake was fished by the local population but now it is rarely reported. The study result of Tewodros and Afework (2014b) reported that Flamingos typically are the most prominent and important consumers in the lakes. The largest concentration of flamingo was 24,417 in Lake Abijata. However, drastic and sudden fluctuations in number can occur and there is a very marked exchange between the lakes. There were more flamingos during the dry season than the wet season in Lake Abijata and contrary to Lakes Shalla and Chitu during the wet season. Despite the observed fluctuations, the total flamingo population of the area remained relatively stable, suggesting that the flamingos responded to the effect of seasonal variation by moving between lakes. This aspect of behavior makes flamingos nonresident in any saline lake, moving and exploiting various nearby lakes as their home range. Impact on terrestrial biodiversity resources An increase in complexity of vegetation structure, floristic composition and heterogeneity can increase niche diversity of bird species and vice versa. The study of Girma et al. (2011) detailed that, both natural and human induced disturbances to habitat including flood, drought, deforestation change in land use, natural resource and seasonal climatic changes affected vegetation and birds Getaneh et al. community structure. The change in vegetation community structure alters the availability of nest, cover and food for birds. Additionally, the change in vegetation community could affect the quantity and quality of food, water and cover which in turn alters the diversity, abundance and distribution of birds. The study focused on comparative analysis of the bird community structure in the disturbed and undisturbed habitat of ASLNP the undisturbed habitat comprises different life forms such as woody, Shrubs, herbaceous and grasses. These different life forms will contribute to the species abundance, richness and diversity in the undisturbed habitat. While in the disturbed habitat different life form is not observed except open woody is the only dominant stratum. The result of this comparative analysis also describes the significant effect of environmental degradation on ASLNP terrestrial biodiversity (Girma et al., 2011). Girma et al. (2011) data was gathered in dry and wet seasons since season affects the abundance and richness of bird due to its migratory behavior. The result from this comparative analysis shows that, bird species richness was high in the disturbed habitat but species diversity was high in the undisturbed habitat of the ASLNP. This confirms that environmental degradation which is natural or anthropogenic in it origin will adversely affect the biodiversity of terrestrial habitat in ASLNP. The analysis of mean cover abundance of vegetation communities was computed with mean abundance of birds, the correlation coefficient is negatively correlated with undisturbed habitat but it is positive for disturbed habitat. According to the study of Mesele and Afework (2012) the average number of Giant’s gazelle population decreased from dry season to wet season in Abijata Shalla Lake National Park. This is related to the increase in number of cattle population in the park during the wet season. The mammalian herbivores are important components of terrestrial ecosystem in maintaining the diversity and abundance of mammalian carnivore populations. However, insensitive domestic animal grazing is causing major changes in composition diversity and abundance of herbivore wildlife assemblages. Tewodros and Afework (2013) studied on Warthogs population in this park and described that the Warthogs population shows tendency of decline in ASLNP of terrestrial habitat due to decrease in the quality and quantity of their habitat range. The consequence is migration of this population to other locality in search of food and cover. Conclusion ASLNP has diverse species in terms of birds, mammal and plant species. The park is also home to endemic mammals and bird species that show to climatic 010 response restricted to certain area. Comparatively in vertebrate species, the park is home to diverse bird species. Thus, the park is still recognized and has potentials for conservation sites of bird species. However, reptiles, fish, amphibians and invertebrate species did not well documented in the area. The park is also characterized by Acacia-Commiphora woodland ecosystem type which favors savanna vegetation zone. The most oblivious species interaction is seen in bird species, mammals and plants. The mammalian herbivores are important components of terrestrial ecosystem that stabilize ecosystem of savanna grass lands. However, the park has adversely affected by environmental degradation, which has resulted from expansion of settlement and cultivated land, overgrazing, deforestation, increased irrigation, overfishing and soda ash mining. In the aquatic habitat the disturbance to diversity of phytoplankton along the edge of lakes is affecting the abundance of birds during dry season. In addition the terrestrial vegetation is under serious threat which in reverse affecting the richness and diversity of birds and mammalian wildlife. Recommendations i. Further investigation and justification is mandatory in the taxonomic groups of fish, reptiles, amphibians and other invertebrates in the park since these groups of species in the ASLNP has not been documented. ii. Reduce disturbance, habitat loss and competition with domestic animals for forage to maintain the unique features of the park. iii. Land use changes towards cultivated land and grazing land is a serious problem which has causing environmental degradation mainly due to rapid population growth. Therefore, creating off farm activities, family planning measures, controlling immigration from the surrounding highlands and maintaining soil fertility will reduce the problem. iv. Lake Abijata is seriously treated due to water abstractions for Soda ash enterprise, increased irrigation for agriculture and over-exploitation of vegetation (it could induce severe soil erosion and causing siltation of the lake). Thus, efficient water utilization and effective watershed approach to water and soil management is recommended. v. Land tenure insecurity is causing degradation of resources in the park. Thus, land registration and certification might reduce the problem. vi. The restoration and management approach of Lake Abijata – Shalla cannot be isolated from other rift valley lakes (Lake ziway and Lake Langano) due to their hydrological connection. Afforestation of the ASLNP and its surrounding areas can improve the biophysical and socio –economic condition of this park area and enhance ecosystem function. 011 Point J. Agric. Biotechnol. Res. vii. It is currently the contesting issues of socio-economic development and natural resource conservation that degrading the biodiversity of ASLNP. Therefore it is important to find the platform that help to meet the winwin strategy to simultaneously meet both human welfare and conservation of natural system in ASLNP. Ecotourism is one of the development strategy to reconcile the economic development, socio- cultural development and nature conservation. REFERENCES Acevedo, M.A. and Aide, T.M. (2008). 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