Essay: African Savannah Ecosystem And Current Threats.

Describe African savanna ecosystems and examine the current threats facing these systems.

African Savannah Ecosystem

Introduction- like the several other biomes in the world, the same way the savannah grasslands also sustain through a balance between the various species, humans and environmental factors. Drought can severely jeopardise the sustainability of the grasslands, while the indigenous people and poachers which threaten to misbalance the food web by killing the animals for survival and sports (Perrings and Halkos 2015). The usage of the savannah biome by humans is increasing and it has led to the increase in imbalances in nutrient availability, water balance, nutrient loses, no cultivation of the cash crops with overemphasis on the subsistence cultivation, degradation of the soil resources and vegetation resources. in addition to the wood production, fibre and food, the savannahs are also used for urban developments, tourism developments, national parks and mining (Osborne et al. 2018). This study will be based on the description of the African savannah ecosystem and the current threats faced by these systems.

African Savannah ecosystem- the African Savannah can be described as a tropical grassland and it includes is located between the latitudes of 15^o N and 30^o S and longitude 15^o W and 40^o W. The annual rainfall in Savannah grasslands is similar to the rainfall in Wisconsin. During the months of rainy the rainfall gets to about 15 to 25 inches in a single month. The span of the dry season is seven months a year. The wet season has a high sun period and the dry season has a low sun period (Ogutu et al. 2012). Savannah has a combination of wet-dry climate. The African Savannah can be characterized by dispersed or small trees, grasses and the trees do not form closed canopy and it provides ample space for the sunlight to reach the ground. The African Savannah has a community of diverse organisms and they interact to form a complex food web. The Ngorongoro and Serengeti are the two major conservation areas which has also been marked as a World Heritage Site. The half of the African continent is savannah and it takes up about 5 million square miles (Hoffmann et al. 2012).

Threats faced by the African Savannah ecosystem- Beale et al. (2013), highlighted the need for the conservation of the savannah ecosystem and ten major issues were found through workshops. The ten major problems or the issues identified are the inadequate science and practitioner interaction; allowing the loss of the functional heterogeneity; inappropriate planning of the roads; late response to the invasive species; insufficient law enforcement; insufficient protection of the river catchments; degradation of the migratory corridors; lack of the buffer zones; inferior quality of the public relations, wrong boundaries.

Wildlife- It has been highlighted by Waldram, Bond and Stock (2008), that herbivores can change the spatial heterogeneity and the structure of a vegetation. An experiment was carried out the authors on the effect of white Rhino on the grass sward. It has been found that the white Rhinos were capable of maintaining the patches of short grass and when the white Rhinos were removed, the height of the sward grass increased. Also, it is seen when the white rhinos were removed, the other grazing communities were unable to maintain the short grass communities. While in the semi-arid regions, the small grazers are being able to maintain the height of the communities of short grasses. The vital part is that the removal of the white Rhino increased the rates of fire by indirectly increasing he fuel continuity and fuel load. Thus, according to the authors White Rhino in the Savannah ecosystem is ecosystem engineer in both maintaining and creating short grass swards. The Savannah ecosystem is an amalgamation of the different type of the flora and fauna. According to Bennett (2015), there are several types of the poaching activities of the African wild animals and specially they are done for trade of animal parts. One such poaching activity is the illegal hunting of the African elephants for the trade of ivory and this is causing major decline in the population of the African elephants. Since the year 2007, the ivory trade doubled and it has led to the crisis in the conservation of the African elephants. However, one solution to end this problem was put forward and it was to legalise and control the trade of the ivory. The implementation of this solution has not been fructified due to the corrupt officials operating in the area. It is important to highlight that the poaching related threats are also faced by animals like saiga, tigers, pangolins, Asiatic black bears, freshwater turtles and tortoise.

Threats Faced by the African Savannah Ecosystem

Trees and vegetation- According to Bond (2008), the plenty of the areas in savannahs are under the climate types that support forests. There are several factors that contribute to be detrimental for the formation of vegetation and it includes the soil, fire and climate. It is important to highlight that the grass population differs from the woody ecosystems in terms of the regeneration niche. The grasses are unable to grow within the tree population due to the varying degrees of competition, herbivores, and fire. In several grasslands the population of the tress are increasing and it has led to the shifting in the grass-forest boundaries. This has affected the functioning of the ecosystem and it has cascading effects on the ecosystem. In order to analyse the changes in the C4 grass biomes, it is necessary to integrate the aspects like the demography, herbivore ecology, fire, ecosystem physiology. It has been highlighted by Sankaran et al. (2005), disturbance regimes like herbivore, fire and availability of the resources like nutrients and water plays a major role in the regulation of the woody cover in the savannah ecosystems. Authors have mentioned that the across the African Savannah, approximately 854 sites receives a rainfall of less than 650 mm. This plays a role in controlling the coexistence of the grass and woody cover. Smit et al. (2010), has mentioned that the fire plays a role in shaping the savannahs. Both the fire season and the fire frequency plays a cascading effect on the biodiversity. According to Wigley, Bond and Hoffman (2010), the woody plants move into the grassy biomes and this is contributed by the factors like the atmospheric carbon dioxide, fire suppression, heavy grazing and changes in the land use. Studies by the author have indicated that tree cover has increased in the areas like commercial sites, communal sites and the conservation sites and this is contributed majorly by the land use practices.

Building of roads- Dobson et al. (2010), has mentioned that building of roads within the Serengeti National Park will ruin the ecosystem and it will hamper the environment within the National park. The construction of the roads will act to disrupt the environment and will hinder the migration of the wildebeest. Studies have shown that the construction of the roads will plays a major role in reducing the population of the migrator species and it will result into the collapse of the Serengeti national park. The region from being sink of carbon dioxide will turn into a source of carbon dioxide.

Conclusion- from the above discussion it can be concluded that the African Savannah can be characterized by dispersed or small trees, grasses and the trees do not form closed canopy and it provides ample space for the sunlight to reach the ground. The African Savannah has a community of diverse organisms and they interact to form a complex food web. The usage of the savannah biome by humans is increasing and it has led to the increase in imbalances in nutrient availability, water balance, nutrient loses, no cultivation of the cash crops with overemphasis on the subsistence cultivation, degradation of the soil resources and vegetation resources. in addition to the wood production, fibre and food, the savannahs are also used for urban developments, tourism developments, national parks and mining.

References

Beale, C.M., van Rensberg, S., Bond, W.J., Coughenour, M., Fynn, R., Gaylard, A., Grant, R., Harris, B., Jones, T., Mduma, S. and Owen-Smith, N., 2013. Ten lessons for the conservation of African savannah ecosystems. Biological conservation, 167, pp.224-232.

Bennett, E.L., 2015. Legal ivory trade in a corrupt world and its impact on African elephant populations. Conservation Biology, 29(1), pp.54-60.

Bond, W.J., 2008. What limits trees in C4 grasslands and savannas?. Annual review of ecology, evolution, and systematics, 39, pp.641-659.

Dobson, A.P., Borner, M., Sinclair, A.R., Hudson, P.J., Anderson, T.M., Bigurube, G., Davenport, T.B., Deutsch, J., Durant, S.M., Estes, R.D. and Estes, A.B., 2010. Road will ruin Serengeti. Nature, 467(7313), p.272.

Hoffmann, W.A., Geiger, E.L., Gotsch, S.G., Rossatto, D.R., Silva, L.C., Lau, O.L., Haridasan, M. and Franco, A.C., 2012. Ecological thresholds at the savanna?forest boundary: how plant traits, resources and fire govern the distribution of tropical biomes. Ecology letters, 15(7), pp.759-768.

Ogutu, J.O., Owen-Smith, N., Piepho, H.P., Kuloba, B. and Edebe, J., 2012. Dynamics of ungulates in relation to climatic and land use changes in an insularized African savanna ecosystem. Biodiversity and Conservation, 21(4), pp.1033-1053.

Osborne, C.P., Charles?Dominique, T., Stevens, N., Bond, W.J., Midgley, G. and Lehmann, C.E., 2018. Human impacts in African savannas are mediated by plant functional traits. New Phytologist.

Perrings, C. and Halkos, G., 2015. Agriculture and the threat to biodiversity in sub-saharan Africa. Environmental Research Letters, 10(9), p.095015.

Sankaran, M., Hanan, N.P., Scholes, R.J., Ratnam, J., Augustine, D.J., Cade, B.S., Gignoux, J., Higgins, S.I., Le Roux, X., Ludwig, F. and Ardo, J., 2005. Determinants of woody cover in African savannas. Nature, 438(7069), p.846.

Smit, I.P., Asner, G.P., Govender, N., Kennedy-Bowdoin, T., Knapp, D.E. and Jacobson, J., 2010. Effects of fire on woody vegetation structure in African savanna. Ecological Applications, 20(7), pp.1865-1875.

Waldram, M.S., Bond, W.J. and Stock, W.D., 2008. Ecological engineering by a mega-grazer: white rhino impacts on a South African savanna. Ecosystems, 11(1), pp.101-112.

Wigley, B.J., Bond, W.J. and Hoffman, M.T., 2010. Thicket expansion in a South African savanna under divergent land use: local vs. global drivers?. Global Change Biology, 16(3), pp.964-976.