Woodland Conversion by Elephants in Africa: The Search for Causal Factors, Processes, Mechanisms and Management Strategies

Abstract

The impacts of elephants on woodlands have triggered concerns that elephants were converting woodlands to grasslands in African savannas leading to the loss of biodiversity. Therefore, the objectives of the study are to identify the causes, processes and impacts of woodland conversion by elephants and thereby propose a guideline for formulating management strategies. The study is conducted through reviewing published documents on elephant-woodland interaction, factors, mechanisms and processes of woodland conversion to grasslands and impacts on biodiversity have been identified. The study reveals that: 1) the large nutritional and energetic requirements by elephants and high elephant population densities are two driving forces that may cause elephants to convert woodlands to grasslands; 2) the process of woodland conversion is not just elephant-tree interaction, but usually included other agents such as fires, droughts or other herbivores. Woodlands are converted to grasslands or scrublands because elephants, fires, droughts and other herbivores prevent recruitment of tree to larger class sizes and regeneration of seedlings of woody plants; 3) whereas there are few studies that support biodiversity decline due to impacts of elephants on woodlands, there are studies that indicate woodland disturbance by elephants have benefited and increased diversity of other species. It is concluded that woodland disturbance by elephant is not always detrimental to biodiversity, but may create heterogeneity and suitable habitats for other species. In formulating management strategies, considerations must be made to elephant densities, other agents that interact or work with elephants in woodland conversion and the benefits of woodland changes to biodiversity due to elephants.

Niche partitioning on Sumatran Elephant (Elephas maximus sumatranus) and human in space and resources in Riau, Indonesia

“…Location of open land is like a savanna with a relatively large number and spread. This location is also suitable for several types of mammals (Young et al 2009;Alikodra 2010;Sitompul 2011;Zyambo 2016). In accessing resources (analysis with the Pianka index (Mouillot et al 2005), Desma with Balai Raja community and Angelina and Butet with the Tesso Nilo community have a similarity in the use of resources.…”

Conservation with elevated elephant densities sequesters carbon in soils despite losses of woody biomass

“…Further increases are envisioned for the future. In the core areas of the conservancies, wildlife numbers are highly variable, but still low (Mashi-Report, 2019;Wuparo-Report, 2018).…”

“…At the dry climate of KAZA, the C loss from the dung will largely occur as CO 2 , or it is taken away by small animals such as beetle and termites (Andriuzzi & Wall, 2018). Yet, there are also continued dung-C reimports, constantly replenishing the pool and compensating the losses (Zhu et al, 2020), that is, under steadystate conditions the amount of C in the dung is withdrawn from the atmosphere irrespectively of the dung turnover time. Future studies should thus include the amount of dung C into climate change mitigation calculations, because even this labile dung C may add to climate change mitigation if the decomposing dung is continuously replaced by fresh one.…”

“…As elephants prefer nutrient‐rich trees over nutrient‐poor ones (Skarpe et al, 2014), they modulate both biodiversity and spatial structure of savanna ecosystems (Teren et al, 2018; Thornley et al, 2020) toward tree species with higher disturbance tolerance and resprouting ability (Neke et al, 2006; Ouédraogo et al, 2015). Related changes in fire frequency (Pellegrini et al, 2017), droughts, and other herbivore populations accompany this process (Zyambo, 2016).…”

Land Use and Land Cover Change Within and Around the Greater Serengeti Ecosystem, Tanzania

“…Fire partly drives woodland conversion to savannah and grassland not only in the Serengeti [117] but also in Kagoma Forest Reserve [118] in Tanzania and in South Africa [117,119,120], and to shrubland in South Africa [121]. Herbivory and its interaction with rainfall can also transform woodland to grassland and other cover types [121,119,122]. For example, browsing-rainfall interactions transformed shrubland to grassland in the Maasai Mara in Kenya [98,115].…”