Abstract
Questions
Bush encroachment, (i.e. disproportionate woody vegetation increase at the cost of grassland) has negative impacts for biodiversity conservation and tourism by homogenising habitat structure and decreasing grazing and game-viewing. While herbivory, rainfall, and CO2 all influence changes in woody vegetation cover, fire has the best potential for vegetation management. 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. Therefore, this study 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; and (c) what are the management implications?
Location
Bwabwata National Park (BNP), Namibia.
Methods
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
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 englerianum, 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.
Conclusions
Both early- and late-season fires are of value in management of 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.
Bush encroachment, (i.e. disproportionate woody vegetation increase at the cost of grassland) has negative impacts for biodiversity conservation and tourism by homogenising habitat structure and decreasing grazing and game-viewing. While herbivory, rainfall, and CO2 all influence changes in woody vegetation cover, fire has the best potential for vegetation management. 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. Therefore, this study 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; and (c) what are the management implications?
Location
Bwabwata National Park (BNP), Namibia.
Methods
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
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 englerianum, 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.
Conclusions
Both early- and late-season fires are of value in management of 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.
| Original language | English |
|---|---|
| Article number | e13123 |
| Number of pages | 12 |
| Journal | Journal of Vegetation Science |
| Volume | 33 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 1 Mar 2022 |
| Externally published | Yes |
Bibliographical note
Funding Information:This study was funded by the African Origins Platform Grant number 117666, National Research Foundation, and the Southern African Science Centre for Climate Change and Adaptive Land Management (SASSCAL) Grant number 118589, South Africa.
Funding Information:
This study was funded by the African Origins Platform Grant number 117666, National Research Foundation, and the Southern African Science Centre for Climate Change and Adaptive Land Management (SASSCAL) Grant number 118589, South Africa. This study was funded by the National Research Foundation (NRF) of South Africa, African Origins Platform Grant number 117666 and the Southern African Science Centre for Climate Change and Adaptive Land Management (SASSCAL) Grant number 118589, South Africa. Lyn Halstead and the late Garth Owen-Smith of the Integrated Rural Development and Nature Conservation (IRDNC), Namibia, initiated the monitoring effort by taking photos in 1999. Great appreciation is extended to Dave Ward of World Wildlife Fund (WWF) Namibia for making the repeat photos available for research purposes. We thank the Ministry of Environment, Forestry and Tourism (MEFT) and National Council for Science Research and Technology in Namibia (NCRST) for granting the research permit. Dr. Adele Julier provided invaluable botanical expertise during the fieldwork component of the study. Dr. Zander Venter and Dr. Wesley Bell guided the use of Google Earth Engine to extract vegetation productivity and rainfall data. Nick Lindenburg from the University of Cape Town?s GIS laboratory aided the spatial analysis of fire. This work would not have been possible without the commitment of Namibian stakeholders. We are indebted to the park rangers, game guards and members of the Kyamaracan Association for their continuing work.
Funding Information:
This study was funded by the National Research Foundation (NRF) of South Africa, African Origins Platform Grant number 117666 and the Southern African Science Centre for Climate Change and Adaptive Land Management (SASSCAL) Grant number 118589, South Africa. Lyn Halstead and the late Garth Owen‐Smith of the Integrated Rural Development and Nature Conservation (IRDNC), Namibia, initiated the monitoring effort by taking photos in 1999. Great appreciation is extended to Dave Ward of World Wildlife Fund (WWF) Namibia for making the repeat photos available for research purposes. We thank the Ministry of Environment, Forestry and Tourism (MEFT) and National Council for Science Research and Technology in Namibia (NCRST) for granting the research permit. Dr. Adele Julier provided invaluable botanical expertise during the fieldwork component of the study. Dr. Zander Venter and Dr. Wesley Bell guided the use of Google Earth Engine to extract vegetation productivity and rainfall data. Nick Lindenburg from the University of Cape Town’s GIS laboratory aided the spatial analysis of fire. This work would not have been possible without the commitment of Namibian stakeholders. We are indebted to the park rangers, game guards and members of the Kyamaracan Association for their continuing work.
Publisher Copyright:
© 2022 International Association for Vegetation Science.
Keywords
- EVI
- MODIS
- bush encroachment
- fire management
- remote sensing
- repeat photography
- savannas
- vegetation change
- woody vegetation
