Quercus robur was initially introduced into South Africa in 1656. Today it is one of the most widespread and acknowledged trees in the South African landscape, such as the centuries-old oak trees lining the streets of Stellenbosch (likewise called Eikestad or Oak City). These centuries-old trees are also the most susceptible to insects and infections such as the polyphagous shot hole borer. Credit: Christiaan GildenhuysThe almost 400-year-old history of oaks in South Africa might be coming to an end, forever changing the treescape of towns and cities such as Cape Town, George, Paarl, Stellenbosch, and Swellendam.In a term paper released in the South African Journal of Botany, ecologists from the Centre for Invasion Biology (CIB) at Stellenbosch Universitys School for Climate Studies, traced the history of the intro of the genus Quercus into South Africa, in addition to its current status and the aspects that are altering its circulation throughout our landscapes.Christiaan Gildenhuys, a postgraduate student in SUs Department of Botany and Zoology and very first author on the article, says the first composed record of English oak (Quercus robur), dates to 1656, reportedly introduced under the authority of Jan van Riebeek himself: “Dozens of other oak types were presented to the Cape of Good Hope by early Dutch settlers and the British colonial government. Many oaks were subsequently extensively cultivated throughout the nation and have actually given that turned into one of the most prevalent and acknowledged tree genera in South Africa today,” he explains.But now the types may have come to a crossroads.The Threat of Disease and Invasive SpeciesGildenhuys found that three oak species– English oak, Pin oak, and Cork oak– have actually ended up being intrusive along riverbanks and the urban-wildland interface in Stellenbosch and Cape Town. These oaks do not trigger major issues as intruders now but may do so in the future.At the same time, lots of species (consisting of the most prevalent species, Q. robur or English oak) are extremely susceptible to illness and invasive beetles such as the polyphagous shot hole borer: “Not only does this mean that lots of century-old oaks are at risk, but it likewise means that contaminated trees should be removed before the problem spreads further,” states Gildenhuys.The oak-lined streets of historical towns such as Stellenbosch in South Africa (the second oldest town in South Africa after Cape Town) are set to change over the next decade. These centuries-old oak trees are particularly vulnerable to the assault of the Polyphagous shot hole borer. Credit: Christiaan GildenhuysProf. Dave Richardson, an ecologist at CIB and co-author, says the story of oaks in South Africa is a timeless example of how worldwide change is rapidly changing the roles and perspectives of types in metropolitan locations.”We must accept that the prospective effect of the polyphagous shot hole borer is a video game changer. As an outcome of this invasion, the treescapes of many towns in South Africa are going to change rather radically. Landowners and authorities who may decide to replace infected Q. robur trees with less susceptible tree species need to also think about the potential unfavorable impacts of these types,” he explainsThe suitable would be to change the infected trees with indigenous types which are less prone to insects and illness such as the PSHB. Individualss accessories to their oak-lined streets may prevent replacement efforts and cause conflicts between management and stakeholders, he warns.Prof. Guy Midgley, interim director of the School for Climate Studies, says trees make an essential contribution to minimizing the impact of climate change by reducing heat tension in metropolitan locations. On the other hand, the way thousands of infected trees are disposed of might considerably impact carbon emissions.Adding fuel to the fire is the debate about the cultural worth of oaks in general. In one sector of South African society, these centuries-old trees are commemorated as part of our cultural heritage. In another sector, they are considered undesirable relics from a colonial past.Reference: “The genus Quercus (Fagaceae) in South Africa: Introduction history, present status, and intrusion ecology” by Christiaan P. Gildenhuys, Luke J. Potgieter and David M. Richardson, 17 February 2024, South African Journal of Botany.DOI: 10.1016/ j.sajb.2024.01.066 The research study was moneyed by the Universiteit Stellenbosch and the Natural Sciences and Engineering Research Council of Canada.
Credit: Christiaan GildenhuysThe nearly 400-year-old history of oaks in South Africa may be coming to an end, permanently changing the treescape of cities and towns such as Cape Town, George, Paarl, Stellenbosch, and Swellendam.In a research study paper released in the South African Journal of Botany, ecologists from the Centre for Invasion Biology (CIB) at Stellenbosch Universitys School for Climate Studies, traced the history of the intro of the genus Quercus into South Africa, as well as its present status and the factors that are changing its circulation across our landscapes.Christiaan Gildenhuys, a postgraduate trainee in SUs Department of Botany and Zoology and very first author on the post, states the very first written record of English oak (Quercus robur), dates to 1656, reportedly introduced under the authority of Jan van Riebeek himself: “Dozens of other oak types were introduced to the Cape of Good Hope by early Dutch inhabitants and the British colonial federal government. Many oaks were subsequently extensively cultivated throughout the country and have considering that ended up being one of the most prevalent and recognized tree genera in South Africa today,” he explains.But now the species might have shown up at a crossroads.The Threat of Disease and Invasive SpeciesGildenhuys found that 3 oak species– English oak, Pin oak, and Cork oak– have become invasive along riverbanks and the urban-wildland user interface in Stellenbosch and Cape Town. These oaks do not cause significant problems as intruders now however might do so in the future.At the very same time, many species (including the most prevalent species, Q. robur or English oak) are highly susceptible to illness and invasive beetles such as the polyphagous shot hole borer: “Not only does this mean that lots of century-old oaks are at risk, however it also implies that infected trees should be eliminated before the problem spreads out further,” says Gildenhuys.The oak-lined streets of historic towns such as Stellenbosch in South Africa (the 2nd oldest town in South Africa after Cape Town) are set to alter over the next decade.