Tallest trees in Africa climbed: Eucalyptus saligna & E. regnans

TREE CLIMBERS MEASURE THE TALLEST TREES IN AFRICA

by Izak van der Merwe (1)

On November 2008 a pair of professional tree climbers scaled the two tallest trees in Africa, also considered to be the tallest planted Eucalyptus trees in the world. Recently dubbed the “Twin Giants of Magoebaskloof”, these Saligna gum trees form part of a magnificent stand of tall trees on the Woodbush State Forest near Haenertsburg planted in 1906. Benefiting from a wet sub-tropical climate and deep soils, they grew to a height not surpassed anywhere in Africa. The tallest tree in this stand was measured by a land surveyor six years ago at a height of 81.5 metres (+265 feet), but the tree toppled over during a storm in September 2006.

Climbing the tallest trees in Africa: Twin Giants of Magoebaskloof, Giant Eucalyptus saligna at Woodbush Forest Reserve & Benvie Giant, Eucalyptus regnans at Benvie Farm Arboretum, South Africa / Escalando el arbol mas alto de Africa: Los Gigantes Gemelos de Magoebaskloof, Eucaliptos saligna gigantes en la Reserva Forestal de Woodbush & Gigante de Benvie, Eucalipto regnans en el Arboreto de Benvie, Sudáfica/ by Izak van der Merwe / Gustavo Iglesias Trabado / GIT Forestry Consulting, Consultoría y Servicios de Ingeniería Agroforestal, Lugo, Galicia, España, Spain / Eucalyptologics, information resources on Eucalyptus cultivation around the world / Eucalyptologics, recursos de informacion sobre el cultivo del eucalipto en el mundo

Fig. 1 - Giant Tree Climbing Expedition members at Benvie Arboretum (New Hanover, South Africa) besides the tallest Eucalyptus regnans in Africa, and possibly the tallest cultivated E. regnans in the world. Photo courtesy Izak van der Merwe. (Click image to enlarge)

A panel of experts assisting the Department of Water Affairs and Forestry (DWAF) to identify and protect trees of national conservation significance as Champion Trees, recently shortlisted the giant eucalypts of Woodbush as a priority for protection. Other three giant eucalypts at Benvie Arboretum seven hundred kilometers from here were also shortlisted. These Mountain ash trees (Eucalyptus regnans) have magnificent trunk circumferences of more than 6.8 m (+22 feet), a trunk size not yet seen among any other trees of this kind in South Africa. They were planted more than a hundred years ago by the Scottish emigrant John Geekie, a cabinet maker by trade, who purchased Benvie Farm in 1882 and imported tree seedlings from around the world. Jenny Robinson, a great granddaughter of John, currently manages the arboretum and keeps the family tradition at Intigo Furniture.

The idea for an expedition to find and measure the tallest tree in Africa originated with Professor Brian Bredenkamp (now retired from the University of Stellenbosch but not from tree matters!). Roy Wilson, of the company Stihl - South Africa was approached for sponsorship, and immediately agreed to cover the travel and accommodation expenses for this expedition. They would be accompanied by the professional tree climbers Leon Visser and Charles Green as well as Izak van der Merwe, coordinator of the Champion Tree Project of the Department of Water Affairs and Forestry.

Fig.2 - Location of the Champion Eucalyptus of South Africa measured during the Giant Tree Climbing Expedition

On the morning of 7 November the expedition left OR Tambo airport for Magoebaskloof. At Woodbush State Forest the search for the potential tallest tree that afternoon ended at a giant eucalypt tree very close to the original champion, which now lies on the forest floor next to its broken stump. The long slender bowl of the tallest tree offered difficult climbing, especially in the prevailing wet weather. The tree climbers then decided to first scale a slightly shorter tree next to it. At 70 metres above the ground they threw ropes around the branches of the targeted tree and bridged the gap through a technique known as “skywalking”. The two trees were measured at 79 metres (259 feet) and 78.5 metres (257 feet) respectively, thus crowning the Twin Giants of Magoebaskloof as the tallest measured trees in Africa.

Fig. 3 - Giant Tree Climbing Expedition members at Woodbush State Forest Arboretum (South Africa) climbing one of the Twin Giants of Magoebasklook, the tallest known trees in Africa, and possibly the tallest cultivated Eucalyptus in the world. Photo courtesy Izak van der Merwe. (Click image to enlarge)

The forester of Woodbush State Forest, Mr Tiennie Nieuwoudt of Komatiland Forests, undertook to reroute the Magoebaskloof hiking trail slightly so that hikers and sightseers will gain access to these trees. DWAF, Komatiland Forests and Stihl - South Africa will work together on appropriate signage and information boards to be placed at these trees.

The Benvie Arboretum eucalypt trees were visited on 9 November, and the height of the tallest of these Eucalyptus regnans was measured at 61 metres by the tree climbers. Two of the three trees standing in line were severely damaged by lightning. The tree climbers discovered that a large part of its top had broken off and was lying on top of the crown, so the tree must have been considerably taller in its prime. Measures are being considered to brace the damaged top of this tree to prevent further damage.

(1) = Izak van der Merwe is Senior Forestry Scientist at the Department of Water Affairs & Forests of the Republic of South Africa. Among other activities, and with the assistance of the Dendrological Society of South Africa he and DWAF have been charting South Africa's Champion Trees in order to help protect and preserve this global monumental natural heritage.

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