Dr. Ute Schmiedel

In 2001, a team of African and German scientists established a network of xx standardised long-term biodiversity observatories along the major rainfall gradient in southern Africa, stretching from the South African Cape to the Kavango in northern Namibia and later extended into Angola and Zambia (www.sasscalobservationnet.org). The aim of the project is to initiate a timeseries of annual data on the vegetation dynamics in response to climate and land use. Each biodiversity observatory is 1 km² in size (representing the respective landscape) and subdivided into 100 one-hectare plots. Twenty hectares were randomly selected for the botanical monitoring and nested plots of 100 m² and 1000 m² were laid out in the centre of these plots. The plots in South Africa have been monitored annually since 2001. The timeseries of annual vegetation data, which can be related to hourly recorded weather data (www.sasscalweathernet.org), provide insight into the effect of inter- and intra-annual variation of weather conditions. A drought period, which started in 2015 and was only partly lifted by above-average rainfalls in March 2022, had severe negative impacts not only on the richness, diversity and cover of the herbaceous plants but also on the perennial shrubs. The survival of shrubs showed to be particularly dependent on rainfall and moderate temperature conditions at the end of the dry season. Long-term biodiversity monitoring provides invaluable data to inform future projections of the changes of the vegetation and plant populations in arid areas–where climate change will likely have the strongest effect.