New research highlights how unique group of South African species relies on wildfires for seed dispersal and germination

In a new paper, published today in the journal Oecologia, scientists from the Royal Botanic Gardens, Kew, together with partners in Australia and South Africa, reveal the unique germination requirements of 40 species in the genus Leucadendron, an ecologically important group of plants in the protea family that grows in the fire-prone South African fynbos, a small belt of heathland in the Western and Eastern Cape.

These new data highlight how 40 Leucadendron plants are dependent on wildfires to either release seeds from their cones or to enable seeds to germinate. The authors hope this new information will support the future conservation of these species in their unique native habitats in the Cape, an area of great importance for biodiversity supporting thousands of endemic species.

Dr Rosemary Newton, Conservation Scientist at the Royal Botanic Gardens, Kew and lead author of the paper says: “Leucadendron plants play a major role in the ecology of the fynbos, and in addition, 51 species are threatened with extinction, so understanding their germination requirements is imperative to help inform restoration initiatives.”

Carrying out germination tests in labs at Kew’s Millennium Seed Bank, Dr Newton along with researchers from Curtin University, the University of New South Wales, and the Nelson Mandela Metropolitan University, found some surprising germination responses from the plants.

“Being able to predict germination requirements of a plant is extremely helpful, and we would usually expect seed morphology and seed storage location – either on the plant or in the soil – to provide a reliable guide, but during this research we found some surprising exceptions which suggest that every species should be tested for its specific requirements”, says Newton.

The scientists found that some plants release seeds from cones once incinerated which can then germinate without further help, while others also need to receive smoke from that fire to germinate. Other species release their seeds as soon as they are ripe and they may be stored in the soil for many years until a fire occurs when they in turn respond to smoke from the fire. Some even germinate in response to both heat from the fire as well as smoke. The authors were then able to officially define the 40 species for the first time as either ‘fire-independent’, ‘fire-enhanced’ or ‘fire-dependent’ based on their germination responses.

Professor Byron Lamont, co-author of the paper, remarks “This is the first study to look specifically at a wide range of Leucadendron species and the diversity of germination requirements found is extraordinary and unknown in any other group of plants”.

Newton continues, “Our research highlights the importance of determining the germination needs of indigenous species, especially for those that are threatened with extinction, endemic to a particular country or geographical area, or economically or ecologically important in some way. To effectively propagate seeds from seed banks such as Kew’s MSB in the future, it is imperative to understand the conditions they need to germinate.”

The research was undertaken as part of a long-standing partnership between Kew’s MSB (Millennium Seed Bank) and SANBI (South African National Biodiversity Institute) using seeds from fynbos plants in the MSB’s collections as well as seeds collected from South Africa specifically for the project.