The abundance and diversity of large mammals, but also birds, which characterize Hwange National Park and its periphery make this socio-ecosystem a remarkable and important site for the conservation of a large number of species. This territory is part of KAZA, the largest cross-border conservation park in the world, with strong conservation challenges for species with a high ranging capacity, elephants in particular. It is an unfenced site and therefore a privileged site for studying the ecological processes which govern the functioning of this biodiversity without borders, including in the interface zones. This first axis therefore aims to describe and understand the dynamics and functioning of biodiversity, focusing in particular on studying the responses of this biodiversity to environmental changes and anthropogenic impacts to better conserve it. This axis is structured around 5 sub-axes.
(1) Biodiversity observatory
One of the mandates of the Hwange LTSER is to monitor biodiversity through the building of long-term databases on the abundance and distribution of biodiversity on a gradient of anthropization in the socio-ecosystem. In addition to continuing the monitoring carried out for many years (counts of large mammals, camera trap monitoring, permanent vegetation plots, biodiversity in waterholes), new approaches are planned in the coming years: (i) a more precise approach than simple counts and developed from a detailed assessment of the age structure of groups to estimate and predict the dynamics of the elephant population; (ii) expanding the long-term monitoring to other components of biodiversity (e.g. birds, plankton, insects, plant communities); (iii) implementation of new biodiversity monitoring methods (acoustics, AI); (iv) participatory science approaches by involving people living at the periphery of the protected area in order to integrate local knowledge; and (v) training to expose local stakeholders and young people to biodiversity monitoring methods. Ultimately, all of these approaches will make it possible to describe the responses of this biodiversity to surface water management, the presence of an abundant elephant population, various anthropogenic impacts and climate change.
(2) Study of animal movements
Animal mobility is at the heart of many research carried out in the Hwange LTSER at several scales: inside the protected area, between the protected area and its periphery, and between protected areas at the scale of KAZA (e.g. regional migration of elephants, movements of large carnivores outside the protected area, network of contacts as part of the study of the transmission of pathogens). The CNRS Ecology & Environment, through the SEE-Life labeling of the long-term monitoring of the Hwange elephant population, makes it possible to consolidate the monitoring of the distribution of elephants, at the individual scale by GPS monitoring and at the population scale mainly by observations by camera traps. This will allow us to question the effect of climate change on this population. This work strongly contributes to the KAZA Elephant Sub-Working Group’s region-wide discussions focused on elephant conservation. In particular, we seek to confirm or refute the hypothetical existence of certain migration routes. Subject to funding, studies of the movements of wildebeest and hippos will be carried out in the coming years because these species are expected to be strongly affected by climate change. Indeed, it is expected that wildebeest, ruminants grazing on short grass, are very sensitive to episodes of drought and that this species responds through mobility. However, although it is a priori migratory, its movements within the park and possibly outside are unknown. Hippos are completely dependent on waterholes, but their dynamics are likely to change in the context of aridification in southern Africa. The recent rise of animal-borne bio-logging sensors and the use of artificial intelligence for the processing of large data sets make it possible to carry out monitoring on an unprecedented scale and to ask new scientific questions about animal mobility.
(3) Understanding interspecific interaction networks
The description of these networks and the study of their functioning (on the gradients of anthropization and influence of surface water) is important to both this research axis and the research axis “Eco-health in the socio-ecosystem”. To describe these networks, we work with classic ecological tools, such as telemetry or camera traps. Training activities to understand these tools and the analysis of the data generated by them are regularly organized by the LTSER team. A research project funded by the ANR (PULSATION project) aims at understanding how episodes of elephant mortality, expected to become more and more frequent and serious in a context of worsening droughts, affect the functioning of the community of large mammals. These peaks of mega-carcasses, which occur episodically for a short period with an abundance much higher than that of other resources, can be considered as a pulsed resource and are likely to modify the dynamics of the populations consuming them, with indirect effects on other populations. We study (1) the impact of these carcasses on the spatial distribution and feeding behavior of lions and spotted hyenas, the most common large African carnivores, both facultative scavengers that use elephant carcasses when they are available – which will make it possible to study the interactions between active hunting and scavenging processes; (2) the consequences on prey populations through the alteration of the lethal (i.e., consumption of prey) and non-lethal (i.e., fear) effects of these predators; (3) implications for the food web. This work will feed into the reflection carried out with ZimParks on the role of water management, determining the dynamics of the elephant population, in the functioning of the socio-ecosystem.
(4) Interaction of biodiversity and biogeochemical cycles
As part of a thesis and the WetArid project, funded by the EC2CO INSU-INEE program, research is being developed to study climate forcing on the dynamics of water filling (fundamental information for all research axes) and drying of the wetlands, associated plant communities, as well as the carbon and nitrogen cycles in these environments. More precisely, the surfaces of wetlands, whether vegetated or not, are being studied by remote sensing between 1985 and 2022, taking into account rainfall and temperatures. The monitoring of plant communities in wetlands as well as soil parameters (humidity, compaction for example) will help calibrate data collected by remote sensing. Due to significant inputs of organic matter from megafauna excreta, carbon and nitrogen cycles can be modified in wetlands. These changes are likely to be amplified by the increased use of wetlands by megafauna in response to the reduction of water resources, itself linked to climate change. Initially, in order to understand these cycles in the wetlands of the park, monitoring of organic matter inputs as well as microbial activities for degradation of organic matter is implemented in Hwange. As part of the SPACE project (2024-2026) financed as part of the TOSCA (CNES) call, this work will be extended to the landscape structure of the savanna, its temporal dynamics and the consequences on the exploitation of water and plant resources by wildlife.
(5) Elephant engineering and ecosystem services provided by elephants
With over 30000 elephants, Hwange National Park is home to one of the continent’s largest elephant populations. The elephant is central to the functioning of the socio-ecosystem of Hwange, with, among other things, strong effects on the woody and the structure of the dry forest-type savannahs which dominate Hwange, and which constitute the most widespread savannah of the southern hemisphere. We hope to better understand the functions and services associated with elephant ecological engineering in the years to come. We further seek to understand the effect of elephants on carbon sequestration in landscapes shared and not shared with humans within the Hwange socio-ecosystem (MITI thesis in progress). This work is carried out in close partnership with the Forestry Commission and the villages.