NEWS
Range of variation in wetland vegetation on a subcontinental scale in Southern Africa
Erwin Sieben
During the 2000s , it was clear that the South African Government started to place more value on aquatic ecosystems as they understood that South Africa is a water-scarce country . Various decision-making tools were developed to evaluate wetland ecosystems and the services they deliver . These were ‘ quick ’ assessments based on a single field visit that helped managers to make decisions about wetland restoration measures , prioritization of how important a wetland was within the wider catchment and what the causes of degradation in a wetland were . Most of these types of decision-making tools were designed to use very little data as there was very little information on biodiversity in wetlands on a national level . As a group of wetland scientists , we started worrying that for many politicians and decision-makers , these tools would be the final story . We thought that while these decision-making tools were being used to protect and restore wetlands , at the same time , we should also develop a database that would go into greater detail to provide actual data on wetlands and wetland vegetation so that better decisions for reference conditions and environmental monitoring could be developed in the future . It all started at a workshop organized in August 2009 . Here we looked at what vegetation data already existed across the country and how we should bring it all together , based on what was considered the minimum data requirements . they collected soils for every single plot ( in the case of the Free State plots , even for every diagnostic horizon within the soil profile ).
We settled on a set of minimum data requirements and started to get to work on compiling a database on South African wetland vegetation , based on historical studies . Wetland plots had been sampled in the past , but in South Africa , the focus had always been on terrestrial vegetation with a few wetland plots in each study included as ‘ azonal vegetation ’. Only a few areas where wetlands were very abundant or where there were very large wetlands of special significance , had studies that focused in their entirety on wetland vegetation , such as on the coastal flats of Northern KwaZulu-Natal , near Lake St . Lucia . In those studies , special focus was directed towards the measurements of soil factors that were important to understand the context and the ecology of the wetland in itself . Most importantly , the hydroperiod , which is the time period that an area is saturated with water , could be assessed by looking at soil hydromorphic features ( which worked in most cases but proved tricky in some situations , for example , on coastal sands ). For this reason , a soil auger was used to dig a hole up to 1 m deep in most wetlands . It became clear that the studies done by Fynn Corry and Nacelle Collins , who extended these methods over much larger regions , were really the first of their kind , but we wanted to do this type of work to cover the entire country , so a proposal was submitted to the Water Research Commission for funding to do that work .
Two exemplary studies that were carried out at that time were Fynn Corry ’ s work on the use of vascular plants as bio-indicators on the Cape coastal forelands and Nacelle Collins ’ work on the wetlands of the Free State Province , where he also sampled soils in great detail . Both studies involved the sampling of soils in the same place where vegetation samples were collected from , and
Figure 1 . Sampling a wetland near Port St . Johns along the Eastern Cape coastline , South Africa ( Photo credit : Erwin Sieben )
33 Grassroots Vol 22 No 1 March 2022