The influence of contrasting fire management practice on bush encroachment: lessons from Bwabwata National Park, Namibia.

Bush encroachment has negative impacts for biodiversity conservation and tourism as it homogenises habitat structure and decreases grazing and game-viewing. While fire, herbivory, rainfall, and CO2 can all influence changes in woody vegetation cover, fire management has the best potential for intervention. Changes in fire management can either encourage or suppress bush encroachment and a better understanding of how changes in fire regime affect vegetation structure is needed.

To explore fire management and woody cover change in Bwabwata National Park (BNP), Namibia, we addressed three questions: (a) how has woody cover changed over two decades (1999 – 2019)? (b) what is the role of land use, rainfall, and fire in influencing woody cover change? (c) what are the management implications?

The study used a novel combination of repeat ground photography and satellite-based remote sensing products to explore the change in woody vegetation in relation to rainfall, land use, and fire seasonality.

Results showed that woody vegetation has increased by 13% since 1999 in BNP. Change in vegetation structure differed in the east and west of the park. Early season burns in the east of the park were associated with an increase in trees over 3 m tall consisting primarily of Dialium engleranum, Terminalia sericea and Burkea africana. Repetitive late dry season fires in the west of the park were associated with an increase in shrubs under 3 m dominated by Baphia massaiensis and Terminalia sericea.

Our conclusions state the value of the use of both early and late season fires to manage bush encroachment. Early dry season fires appear to reduce the rate of bush encroachment and contribute to maintaining a heterogeneous vegetation structure. This fire management strategy reduces wildfire risk, conserves biodiversity, and promotes tourism and is, therefore, recommended for the park.