Western Cape
Plant species threatened
10:57 (GMT+2), Mon , 15 September 2014
Western Cape
Key species in the Cape Floral Kingdom (CFK) may be threatened if huge changes occur in weather patterns. With global climate change imminent to some degree, it is difficult to predict what the future holds for some of these species, in particular the proteas in Agulhas National Park. The concern is that the plants may not be able to adapt quickly enough. Now a group of researchers is about to find out. It is investigating ecological differences between the protea species and whether some are more sensitive to change than others. People often think only temperature will alter when climate change occurs, but this is not true. “The indirect impact in temperature rise could change rainfall, frost, drought and ground water. Even the fire regimen is included here,” says Martina Treurnicht, PhD candidate at the universities of Stellenbosch and Hohenheim (Germany). For the study, 26 sprouting and non-sprouting species of protea and leucadendron were targeted, flagship species of the CFK. “Although we focus on the Proteaceae, our work will have profound implications for the botanical diversity of the entire region, a global biodiversity hot spot of conservation priority,” says Treurnicht. Changes which will include hotter and drier weather are a grave concern as they correlate indirectly with the frequency of fires. Fynbos needs fire for survival, but it can have devastating effects. The interaction of changing climate and fires in the CFR is something that cannot be decoupled in predicting the future of our proteas, she explains. Another aspect of their research entails noting the tolerance levels of different species. The Cape sugarbush (Protea repens) for example, has a large distribution throughout the CFR. Not only does it occur on the Agulhas plains, but also in the Cederberg range, Stellenbosch, the Langeberg and Swartberg ranges and as far east as Port Elizabeth. “From determining the amount of seed a population produces and seedlings after a fire, we can quantify its performance throughout the range. Linking the adult and seedling phases of the plant’s life cycle provides detailed insight into a species’ performance throughout its range. This can identify areas where a species might do better than elsewhere,” says Treurnicht. Interrupted rainfall patterns during this time will cause fewer plants to mature. “It is important that we identify which species are ecologically more resilient, or vulnerable to changes in both climatic 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 conditions that drive species occurrence and they would struggle to persist if any major changes occurred, for instance, if rainfall was less than their required minimum precipitation.” While research is ongoing, Treurnicht believes that changes could be so small as not to have an immediate short-term effect. However, it will be important to know what change will mean for the CFR. At this point, specialist species such as the limestone-adapted Protea obtusifolia and Leucadendron muirii might currently face a far greater threat from invasive alien vegetation alone, she says. The project is a collaborative effort between the universities of Stellenbosch and Hohenheim, and is funded by the German Research Foundation.

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