The Changing Landscape of South Africa: How the History and Future of Oak Trees are Shaping Urban Spaces

Thursday - March 21 2024, 07:45 UTC - 8 months ago

The iconic oak trees that have been a part of South Africa's landscape for nearly 400 years are now facing multiple challenges. Invasive species and diseases, such as the polyphagous shot hole borer, are threatening the survival of oak trees in cities and towns. The emotional attachment to oak-lined streets and parks may hinder efforts to replace infected trees, which could lead to conflicts between management and stakeholders. Additionally, the disposal of thousands of diseased trees could also have a significant impact on carbon emissions.

Oaks have been a familiar and iconic part of the South African landscape for nearly 400 years. But with recent developments, their presence in the country might be coming to an end, changing the streets and parks of cities and towns such as Cape Town, George, Paarl, Stellenbosch, and Swellendam.

In a research paper published in the South African Journal of Botany, ecologists from the Centre for Invasion Biology (CIB) at Stellenbosch University traced the history of oak trees in South Africa, as well as their current status and the factors shaping their distribution in the country today. The study, led by postgraduate student Christiaan Gildenhuys, sheds light on the significant role oak trees have played in shaping the urban landscape and the factors that may lead to their decline.

Gildenhuys found that three oak species - English oak, Pin oak, and Cork oak - have become invasive along riverbanks and in the urban-wildland interface in Stellenbosch and Cape Town. Although they are not causing major problems as invaders yet, they have the potential to become a significant threat in the future. Additionally, many oak species, including the widely recognized English oak, are highly susceptible to diseases and invasive beetles such as the polyphagous shot hole borer (PSHB). As a result, century-old oak trees are at risk, and infected trees must be removed to prevent further spread of the infestation.

According to Prof. Dave Richardson, co-author of the study and an ecologist at CIB, the story of oaks in South Africa is a prime example of how global changes are transforming the roles and perspectives of species in urban areas. He notes that the emergence of the polyphagous shot hole borer has been a game changer, significantly impacting the treescapes of many towns in South Africa. Replacing infected trees with less susceptible species may seem like a viable solution, but it also brings up conflicts between management and stakeholders who have become attached to the iconic oak-lined streets in their cities and towns.

Replacing diseased trees with indigenous species may be the ideal solution, but Prof. Richardson warns that the emotional attachment to oak trees may hinder replacement efforts and lead to conflicts between management and stakeholders. However, he also highlights the crucial role that trees play in mitigating the effects of climate change, such as reducing heat stress in urban areas. This dual role of trees in South Africa will have significant implications for the management of urban green spaces.

One of the challenges that come with the decline of oak trees in South Africa is the issue of disposal. Thousands of diseased trees will need to be removed, potentially leading to a significant impact on carbon emissions and contributing to the ongoing debate on the role of trees in mitigating climate change.

The research paper by Gildenhuys et al. provides valuable insights into the history and future of oak trees in South Africa and highlights the need for careful management and replacement of infected trees. As the landscape of South Africa continues to change, it is essential to consider the impact and implications of these changes on our cities and towns.