Abstract
Background: Welwitschia mirabilis is highly specialised to survive the harsh climate of the Namib Desert. Changes in land use, such as the expansion of mining activities, may endanger their survival.Objectives: The purpose of this study was to understand the photosynthetic potential of W. mirabilis plants to provide a baseline for future long-term monitoring, and for future comparison to determine plant health status after the onset of mining operations.Methods: The study was conducted in a population of W. mirabilis on the Welwitschia Plains. Chlorophyll a fluorescence data were used to measure plant photochemical potential and analysed using the JIP-test.Results: Significant differences in the photosynthetic potential was observed for W. mirabilis plants located in different catchments. The partial parameters of the PIABS values were also significantly lower, which indicated that all aspects of photosynthesis were influenced.Conclusion: PIABS values can serve as a baseline for future long-term monitoring studies to detect any changes in the health status of W. mirabilis that might result from land use change.
Highlights
Predicted increasing drought intensity and frequency, combined with higher average temperatures due to global climate change, are threatening biodiversity, and the stability, functioning and sustainability of terrestrial ecosystems (Barros et al 2018)
Drought is a common phenomenon in semi-arid rangelands (Vetter 2009) and has been shown to cause rapid and lasting effects on vegetation dynamics and ecosystem function and services (Barros et al 2018; Ploughe et al 2019)
Forb communities were studied in the semi-arid savanna of the greater Kruger National Park (KNP)
Summary
Predicted increasing drought intensity and frequency, combined with higher average temperatures due to global climate change, are threatening biodiversity, and the stability, functioning and sustainability of terrestrial ecosystems (Barros et al 2018). Drought is a common phenomenon in semi-arid rangelands (Vetter 2009) and has been shown to cause rapid and lasting effects on vegetation dynamics and ecosystem function and services (Barros et al 2018; Ploughe et al 2019). In herbaceous layers of semi-arid savannas, these communities are composed mainly of annual grasses and both annual and perennial forbs (O’Connor 1998; Buitenwerf et al 2011). Increased frequency and intensity of droughts related to climate change are predicted to induce pressure on herbaceous communities. Considering that forbs contribute significantly to savanna ecosystem resilience, we investigated forb communities of a protected semi-arid savanna during an extensive drought
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