Biodiversity

        Flora

The vegetation along the TRANSCO CLSG transmission line shows a high variety of different habitats ranging from mixture of primary forest, shrubs, wetlands and patches of cultivated areas including plantations (cocoa, coffee, kola-nut and oil palm), vegetables and rice farms by locals. The transmission line cuts across contiguous parcel of land with patches of areas that are of locally High Conservation Value (HCV) areas. The locally HCV areas within the corridor include patches of secondary and riverine forests, swamp edges and watersheds. Around the Moa and the east is Gola West, the Lowland Rainforest dominates the north of Pujehun District which is interspersed with some moist semi-deciduous forests. Towards the north, protruding into Kenema District around Kambui South, are forest reserves (Dodo and the Nimini Hills) and further north is the Outamba Kilimi National Park (OKNP) in Bombali District. The areas of designated reserves (276,800 ha) indicate that they constitute only about 5% of the total land area of the country Sadly enough, even these reserves are subjected to deforestation and resource degradation just like off-reserve areas, for satisfying man’s insatiable demand for forest products. A total of 175 species belonging to 60 vascular plant families have been recorded by various studies. This includes six species of trees that are listed by IUCN (2015) – Afzelia africana, Copaifera salikunda, Hallea stipulosa, Lophira alata, Nauclea diderrichii and Terminalia ivorensis, all of which are categorized as vulnerable (VU). The diversity of plant species also includes 21 species of fruits, and 19 species used as medicinal plants.

        Fauna

The transmission line bypasses numerous forest reserves, most prominently the Gola forest, Kambui Hills, Nimini Hills, and Outamba Kilimbi, which houses many animals, including large mammals both vulnerable and endangered, reptiles, amphibians, birds, and fish (fresh water fishes). A total of 18 mammal species are known to be popular within the project area. Of the 18 species, two (Cercocebus atys and Hydrictis maculicollis are species of IUCN conservation concern). The Cercocebus atys is Vulnerable while the Hydrictis maculicollis is near threatened. About seven primates’ species were recorded within the boundary area between the Nimini Hills, leakage belt and the Gola forest. Previous studies have identified three of the primates species, including Diana Monkey, Sooty Mangabey and Chimpanzee around the pocket of forest located to the north east (Tama &Tonkoli) along the Mano river to the south east.

Amphibians and reptiles are found in almost all the habitat types within the Project area, from forests to grasslands. Amphibians often require both aquatic and terrestrial habitats because of their unique life cycles. The project area generally constitutes some appropriate habitats for reptiles and amphibians owing to the fact that all required habitat types for the species’ survival are present in these areas. The habitats include secondary forests, farm bush, wetlands (swamps and streams) and grasslands.

Previous studies conducted within the Project area found that a range of 140-146 species distributed into 36 avian families are common within the project area. Four species of global conservation concern were recorded: the endangered Hooded Vulture (Necrosyrtes monachus), the vulnerable Yellow-casqued Hornbill (Ceratogymna elata) and African Grey Parrots (Psittacus erithacus), and the near threatened Rufous-winged Illadopsis (Illadopsis rufescens). Two species restricted to the Upper Guinea forest were encountered: Sharpe’s Apalis (Apalis sharpie) and Rufous-winged Illadopsis Illadopsis rufescens. Sixty-seven species restricted to the Guinea-Congo forest biome and two species restricted to the Sudan-Guinea savanna were recorded. Of the total number of species recorded 91% (134 species) are residents with proof of breeding, whilst 9% (2 species) are migratory, four of which are Palaearctic migrants and six are intra-African migrants.

A total number of 16 families of fish comprising 100 species have so far been documented from the freshwater ecosystem. However, record from www.fishbase.org for Sierra Leone freshwater fish species is 167 (Eagbayani, 2007; Dsantos, 2014). Most of the fish species that occur within the rivers of Sierra Leone include Brycinus longipinnis, Epiplatys fasciolatus, Hepsetus odoe, Ctenopoma kingsleyi kingsleyae, Hemichromis fasciatus, Tilapia sp., Clarias gariepinus, Clarias laeviceps and Mormyrus macrophaalus. Important families, as in most African rivers, include Cichlidae, Cyprinidae, Mormyridae, Characidae and Clariidae (Payne et al, 2006 cited in BHEP, 2006). Several species of catfish including Bagrus bayad, Synodontis nigrita, Clarias platycephalas, Clarias lazera and Chysichthys furcatus also occur in the rivers, lakes and lagoons (Payne, 1986, NBSAP, 2013).

        Project Activities that May Cause Impacts

The main project activities with the greatest potential to impact ecosystems, flora and fauna include construction of transmission line right-of-way, access roads, and substations; installation of conductor wires; and maintenance activities along the transmission corridors.

       Potential Physical Impacts to Fauna

Potential physical impacts to fauna that could arise as a result of the CLSG Project in Sierra Leone include:

• Avian and bat collisions and electrocutions
• Den and nest destruction
• Destruction of habitats of herpetofauna
• Temporary obstruction of movement of wild-herbivores
• Exposure of wild herbivore to electric and magnetic fields
• Other physical impacts, including crushing of eggs, suffocation etc.

        Potential Impacts on Terrestrial Habitat

The construction, operation and maintenance of substations and transmission line right-of-way, especially for sections that pass through or very close forested areas, will result in alteration and disruption to terrestrial habitat. Excavation, grading, and earthmoving activities physically disturb and remove topsoil which contains plant seeds and invertebrates which are critical for a healthy ecosystem. Erosion and associated loss of topsoil become a concern in terrestrial habitats due to construction activities. In some locations, including that portion of the route that passes very close to the Nimini Forest Reserve, access may be made by helicopter. Maintenance activities for the project to control vegetation will be conducted mechanically with cutting activities occurring every six to eight years. Herbicides will not be used for vegetation control, which reduces the potential impacts to plants and to terrestrial habitat.

Adequate terrestrial habitat is critical for the survival of plant species, and must provide suitable food resources, territory, loafing areas, nesting sites, and reproduction dens for birds and animals which depend on the ecosystem. Major impacts of the project are expected to be loss of wildlife habitat including fragmentation of forest, potential for forest fires, and establishment of non-native invasive species due to site development and the presence of construction workers, vehicles and machinery, disturbance of soil and vegetation, and trimming and removal of trees. These are described in more detail below.

       Potential Impacts on Aquatic Habitat

Construction and maintenance activities may negatively impact water quality of streams, water bodies and groundwater, resulting in potential impacts on local aquatic habitat and downstream river biota, communities, and fisheries. Impacts to water quality may result from erosion and accumulation of sediment and organic debris in water bodies (for example, at river crossings of the transmission line right-of-way and access roads.
Chemical contamination may occur from use and spills of pesticides, liquid fuels or lubricants, equipment coolants, and transformer lubricants. Increased nutrient loads may result from erosion and use of fertilizers. Changes in stream flows may affect fish and aquatic biota populations.

Cutting and filling activities can result in accelerated surface erosion, channel scouring, and sediment transport, which can lead in turn to increased turbidity and sediment deposition in receiving water bodies. The same thing can occur when vehicles cross small streams or tributaries of rivers, or when vehicles traffic reduces vegetation cover near streams. Such impacts can adversely affect water quality and, in turn, the health of fish and aquatic invertebrates by interfering with respiration, feeding, and other activities. Depositions of large amounts of silt and sediment can also cover critical habitat and spawning grounds, making them unavailable for use, and can smother incubating eggs.

Impacts to water quality are not expected to be significant; therefore, the impacts to the wildlife that use these habitats will also be insignificant. However, impacts on a specific small stream or wetland could be significant. For that reason, project activities should avoid activities near and in water as much as is possible, and any damage to streambanks or streambeds should be repaired when work is concluded.

Power lines and associated roads and facilities may require heavy machinery working in, or construction of crossings over, aquatic habitats. Such activities may disrupt affected watercourses and wetlands, physically uproot aquatic vegetation, and interrupt fish migration/spawning patterns. Slash and debris from construction and maintenance clearing can accumulate in ditches and other drainage structures, enter lakes, streams and wetlands, and block natural hydrologic flow and migratory pathways. Cutting and filling activities may disrupt surface and subsurface hydrologic flows and bring water to the surface in new areas, including existing streams and rivers. Hydrologic changes (i.e., changes in flow rates; flow velocities; etc.) can result in conditions that are unsuitable for certain species or life stages.

Overall impacts to water flow are not significant; therefore, the impacts to the wildlife that use these habitats will also be insignificant. However, impacts on a specific small stream or wetland could be significant. For that reason, project activities should avoid activities near and in water as much as is possible, and any damage to streambanks or streambeds should be repaired when work is concluded.

Intentional or accidental introduction of alien or non-native species of flora and fauna into aquatic areas where they are not normally found can be a significant threat to biodiversity, since some alien species can become invasive, spreading rapidly and out-competing native species. Invasive, exotic species may force resident species out of the area, introduce diseases which existing species have no resistance to, compete with indigenous species, or lead to increased predation of resident plants and animals. There are no activities that will occur close to aquatic habitats that could introduce invasive exotic species into these habitats.

       Sensitive Areas (Ecosystem Hotspots) that Could be Affected

In addition to the general impacts discussed above, the project was assessed with respect to the potential for impacting ecosystems (flora and fauna) in specific areas (protected areas, fauna and flora) in the vicinity and along the transmission line where the most significant impacts can be expected. The transmission line route bypasses legally constituted National Forest Protected Area in the Southeast of the country (Gola Forest National Park), in the North (Outamba-Kilimi National Park), in the South East both (Tiwai Island Sanctuary and Kambui Hills) and one designated Protected Forest in the North East of the Country (Nimini Hills).