Natural Forest Conversion and its Impact on Populations Of Key Livelihood Tree Species in Omo Biosphere Reserve, Nigeria

Abstract

Natural forest conversion and unsustainable use of forest resources are on the increase without adequate consideration of their implications for sustainable livelihoods. This study examined the impact of natural forest conversion on key livelihood tree species in Omo Biosphere Reserve, by examining their populations in the Strict Nature Reserve (SNR), Nauclea diderrichii Plantation (NDP), Tectona grandis Plantation (TGP), Pinus caribaea Plantation, Gmelina arborea Plantation, Theobroma cacao Plantation (CP), and three age-sequences of arable farmland – AF1, AF2, and AF3. The SNR was the most species rich (n = 17) and diverse (H = 2.6210; Simpson 1- D = 0.9127) of all the land use types. Key livelihood tree species diversity was higher in the arable farmlands (H = 0.7608 to 1.3810; Simpson 1- D = 0.3765 to 0.7111) than in the monoculture plantations (H = 0.0313 to 1.311; Simpson 1- D = 0.0099 to 0.6701) with GAP being the least diverse. The NDP was more similar to the SNR (SI = 21.74) than any other land use type. The NDP showed a closer association with AF1 and AF₂ in its key livelihood tree species than with other  monoculture plantations. The CP was ecologically the farthest from the other land use types with respect to key livelihood tree species  composition. The study showed that natural forest conversion to monoculture plantations and arable farm reduce key livelihood tree species richness and diversity, and that higher degree of disturbance as a result of high impact logging and longer period of cultivation, beyond thirty years, exacerbates the problem.

Key words: Land use, deforestation, livelihood, tree diversity, monoculture, farming