Vegetation and land cover dynamics play a crucial role in shaping ecosystem processes and services making them essential aspects of environmental management and conservation efforts (Dzawanda & Ncube, 2020). However, the effects of climate change and anthropogenic activities have profoundly impacted land cover patterns in recent decades, altering the stability and resilience of ecosystems globally. Understanding these dynamics and their causes is critical for developing successful conservation policies and practices for long-term land management.
Chizarira National Park (CNP) in Zimbabwe is characterized by Miombo woodlands. CNP's Miombo woodlands are predominantly deciduous, with dominant tree species experiencing brief leaf loss during the dry season, including Brachystegia spiciformis (Musasa), Julbernardia globiflora (Munhondo), Brachystegia boehmii (Mupfuti), Combretum collinum, Combretum molle (Mugodo), Terminalia sericea (Mususu), Combretum zeyheri, and Combretum apiculatum. While human-induced tree felling is more prevalent near the park boundaries, natural factors such as climatic events like droughts, floods, herbivory (Hanspach & Ha, 2021), frost, and fire (Dawson et al., 2016), along with overlapping anthropogenic activities, drive vegetation changes in CNP. Miombo woodlands are particularly susceptible to changes in rainfall and temperature, making CNP an interesting case study to examine the relationship between spatiotemporal land cover dynamics and climatic variables.
In recent years, there has been growing evidence of woody encroachment in African protected areas (Eastment, 2020). The drivers of woody encroachment in African protected areas remain a topic of ongoing debate (Devine et al., 2017). Climate fluctuations are thought to significantly influence the dynamics of vegetation because of its effect on the biophysical processes of plants such as respiration and photosynthesis (Garai et al., 2022). In CNP, woody vegetation has considerable impacts on tourism by reducing primary and secondary production in the ecosystem by shading and competing with other plants for light, water and food. The dense woody cover in Chizarira National Park (CNP) is negatively impacting game viewing experiences for tourists and hindering research efforts, particularly concerning elusive animals such as lions. Despite CNP's status as a national park, historical trends in vegetation cover in CNP have yet to be thoroughly explored. There has been a lack of initiatives to monitor and detect changes in vegetation since the production of the 1975 map. As a result, there is currently a lack of information regarding the dynamics, composition and structure of the park's vegetation. Given these circumstances, this study aims to assess vegetation dynamics in CNP, focusing on the period from 1992 to the present, in order to obtain a comprehensive understanding of the park's current vegetation status. This assessment will enable informed decisions regarding woodland management strategies for CNP.
The objectives of this study were (a) to determine the variations in mean annual Normalised Difference Vegetation Index (NDVI) in relation to mean annual precipitation (MAP) from 1992 to 2022 in CNP, (b) to assess the changes in mean annual Normalized Difference Vegetation Index (NDVI) in association with mean annual temperature (MAT) from 2000 to 2022 in CNP and (c) to map and determine decadal variations in land cover classes in CNP (1992, 2002, 2012, 2022).
The Normalized Difference Vegetation Index (NDVI) is a widely accepted and credible indicator of ground vegetation cover, derived from satellite data. It is commonly used for detecting vegetation cover dynamics due to its high sensitivity to changes in vegetation. In this study, NDVI will be utilized to represent vegetation cover as it serves as a sensitive indicator of climate influences on vegetation, altering energy balance, hydrological and biological cycles (Islam & Mamun, 2015). NDVI quantifies the quantity of vegetation using satellite data bands, providing an approximation of the vitality and density of vegetation at a pixel based on reflected sunlight from the visible (VIS) (0.4–0.7 m) and near infrared (NIR) (0.7–1.1 m) spectrums detected by the satellite sensors. This metric proves to be a vital tool for acquiring vegetation data and assessing the direct and indirect impacts of environmental change on vegetation at a large temporal and spatial scale.
This study holds substantial significance as it provides a historical context for understanding the current state of the ecosystem's vegetation in Chizarira National Park. By examining vegetation trends over time, this research offers valuable baseline data that can be utilized to establish monitoring and evaluation programs for assessing ecosystem dynamics. Identifying areas that have undergone degradation through historical vegetation analysis enables the prioritization of targeted restoration efforts (Brink et al., 2013). Moreover, by investigating the underlying causes of vegetation changes, this study will assist park managers in developing sustainable and effective management practices. Understanding the drivers behind these changes allows for the implementation of appropriate interventions to mitigate negative impacts and promote ecosystem health and resilience. In addition, this study's findings will provide policymakers with essential baseline information and empower them to make learned decisions and develop evidence-based policies. By incorporating scientific evidence on vegetation dynamics, policymakers can develop strategies that balance conservation objectives with socio-economic considerations, ensuring the long-term sustainability of Chizarira National Park and its surrounding communities.