The future of proteas

Key species in the Cape Floral Kingdom (CFK) may be threatened if remarkable changes in weather patterns occur. It is difficult to predict what the future holds for some of these species, in particular the proteas in the Agulhas National Park. The concern is that the plants may not be able to adapt fast enough, writes SANParks Times reporter René de Klerk

Protea cynaroides Photo: Martina Treurnicht

Protea obtusifolia Photo: Martina Treurnicht

A group of researchers are investigating ecological differences between the protea species and whether some are very sensitive to change. “The indirect impact in temperature rise could change rainfall, frost, drought and ground water. Even the fire regime is included here,” says Martina Treurnicht, PhD candidate at the universities of Stellenbosch and Hohenheim in Germany.

For the study, 26 sprouting and non-sprouting species of Protea and Leucadendron are targeted, flagship species of the CFK. “Although we focus on Proteaceae species, our work will have profound implications for the botanical diversity of the entire region, a global biodiversity hotspot of conservation priority,” says Treurnicht.

Hotter and drier weather is a big concern as it correlates indirectly with the frequency of fires. Fynbos need fire for survival, but it can have devastating effects. “The interaction of changing climate and fires in the CFK is something that cannot be ignored in predicting the future of our proteas”, she explains.

Another aspect of their research entails looking at different tolerance levels of the species. The Cape Sugarbush (Protea repens) for example has a large distribution throughout the CFK. Not only do they occur on the Agulhas plains, but also in the Cederberg mountains, Stellenbosch, the Langeberg and Swartberg mountains and as far east as Port Elizabeth.

“From determining the amount of seeds a population produces and seedlings after a fire, we can quantify their performance throughout the range. Linking the adult and seedling phases of the plant’s life cycle provides detailed insight in a species’ performance throughout their range. This can identify areas where a species may do better than elsewhere,” says Treurnicht. Interrupted rainfall patterns during this time will cause fewer to reach adulthood. “It is important that we identify which species are ecologically more resilient, or vulnerable to both changes in climate and fire conditions.”

The more resilient species could survive, but there are already a number of endangered Proteaceae that face the risk of extinction, such as the Skilpadbossie (Leucadendron modestum). In the event of major environmental changes, they may be the first to disappear.

“If we consider climate alone, there are certainly specific climatic conditions that drive species occurrence and they would struggle to persist if any major climatic changes would occur, like if they need a certain minimum rainfall.”

While research is ongoing, Treurnicht believes that changes could be so small that it will not have an immediate short term effect. At this point, specialist species such as the limestone-adapted Protea obtusifolia and Leucadendron muirii may currently face bigger threats from invasive alien vegetation alone.

The project is a collaborative effort between the universities of Stellenbosch and Hohenheim, and is funded by the German Research Foundation.