2016/07/12 Dresden, Germany
Mount Kilimanjaro’s shrinking glaciers have drawn much attention to Africa’s highest mountain among scientists. Global change, both natural and driven by human activity (anthropogenic), has various impacts on nature. At times some of these impacts have the potential to further aggravate other related impacts. At the 13th and final Nexus Seminar of the summer semester jointly organised by UNU-FLORES and Technische Universität Dresden yesterday, PD Dr. Andreas Hemp from University of Bayreuth delivered a breathtaking presentation on the impact of global change on Mount Kilimanjaro in Tanzania.
Dr. Hemp began presenting the main findings from his study of over 20 years by first discussing Mount Kilimanjaro’s vegetation zones, diversity patterns, biogeography, and vegetation history, before elaborating on the global change impacts. Rising approximately 5,895 metres above sea level, this world heritage site has strong climatic gradients. This translates into different vegetation zones – ranging from semiarid to perhumid with warm tropical lowland to cold afro-alpine temperature regimes. The mean annual temperature ranges from 0.5 to 21.5 degrees Celsius.
Within the context of the KiLi project funded by the German Science Foundation (DFG), Dr. Hemp’s research focuses on the biodiversity and ecosystem processes on Mount Kilimanjaro. In particular, he and his team seek inter alia to assess the influence of climate and anthropogenic disturbance on biogeochemical processes and genetic, species, and interaction diversity, and to quantify biodiversity-ecosystem functioning relationships along elevational gradients.
Walking the audience through the natural habitats of Kilimanjaro from the savanna through the montane forest and then the alpine zone, Dr. Hemp presented the rich diversity of East African vegetation. The Obstgartentreppe (fruit garden stairway in German) is testimony to the wide variety of plants growing, with vertical vegetation structure peaking at intermediate elevations and being higher in natural habitat areas.
Natural savanna vegetation, however, is increasingly converted into cultivated fields. As a result Kilimanjaro is becoming an island surrounded nearly entirely by cultivation. Direct global change impacts, such as land-use intensification and land cover changes, in turn increase climate change impacts. Altogether this leads to the destruction of natural habitats, ecosystems, and biodiversity, and at the climatic level it explains the vanishing icecap, trends of decreasing precipitation, and marginal increase in temperatures.
The fast growing population (grown by a factor of 12 over 20 years) means that the submontane cultivation zone becomes densely populated and calls for the multiple use of land. Savanna grasshoppers are migrating upslope due to the anthropogenic opening of the forest. The land cover changes also contribute in part to the disappearing Meru-Kilimanjaro forest corridor and pose a major impact on forest organisms.
Another dynamic that is disturbed due to human activity is the water balance of the whole mountain. Fires, in combination with illegal logging, affect fog water collecting capacity and with this the water balance when Kilimanjaro is supposed to be the “watertower” of South-eastern Kenya and North-eastern Tanzania. The demand for freshwater is rapidly increasing. Additionally, the logging of indigenous trees is another threat. Selective logging changes the forest composition.
As the occurrence of large herbivores depends on topography and human cultivation, we see the changing migration behaviour of megaherbivores (elephants) due to global changes. Changes in the Amboseli Park caused an increasing migration of elephants into the forests of Kilimanjaro with negative consequences for forest cover.
While Dr. Hemp suggested that tree planting would help alleviate the problem through the protection of forests, there appears a lacuna that is yet to be addressed on a different level: the socioeconomic dimension of the issue. Members of the audience raised the need to consider the political dimension of the results of his study in order to influence policy. One way is to quantify the trade-offs involved as considered in the Nexus Approach. In response, Dr. Hemp clarified that the team works in close cooperation with Tanzanian authorities and civil society through its NGO outreach activities.