MILESTONE FOREST

BALGOWAN TREE WALK
Milestone Forest, a National Heritage Site, owned by Col. and Mrs. Peter Francis. Each species of tree will be labelled with its botanical and common names. Visitors will experience a huge variety of indigenous trees and become aware of protected species such as Podocarpus Henkelii, Podocarpus latifolius, among others. Funding has been provided by Wildlands Conservation Trust. The trees have been identified by Dr David Johnson and labelled by Walter Addison. Once parking and directions signs have been erected the walk will be open to visitors.

Milestone is an example of Afro-Montane Forest, an interesting living monument to our tumultuous climatic history. Afro-Montane Forest has its ancestral home in the highlands of east Africa. From there it colonised southwards during the wetter episodes of the Pleistocene. At the height of wet periods this forest would have been continuous all the way to the Cape. The direction of colonisation is easily demonstrated by the fact that tree diversity falls moving south-west. The species that best withstood cold, temporary drought, and the genetic problems associated with being a tiny population at the frontier were those that spread furthest. Dry interludes would see the forest shrinking back to the north-east, but leaving behind remnant outliers, sufficiently established in gulleys and on south-facing slopes to survive a climate now marginally dry. Isolating populations of species in this way is also the perfect formula for speciation, and this is how endemic species - those confined to one or a few forests - arose.

Milestone is one of these outliers, and is relatively young by geological standards, its whole story falling within the past four million years. It contains a number of southern African endemics - species not found in the present east African forests, although having their origins there. Burchellia bubalina , Cassinopsis ilicifolia , Combretum kraussii , Cryptocarya woodii, Dais cotinifolia, Grewia occidentalis, Hippobromus pauciflorus, Leucosidea sericea, Podocarpus henkelii, Rhoicissus digitata, Rhus dentata, R. pyroides, Vepris lanceolata and Zanthoxylum davyi are examples. Podocarpus henkelii is exceptionally interesting because it has a very narrow range centred upon south-western KZN, and it is the dominant tree in much of Milestone.

Podocarpus has an ancient lineage. Remarkably, we also find it in South America and Australasia, but not in any northern continent. Podocarpus could not now cross such distances across the sea, and its presence in the southern continents is best explained by continental drift. When Podocarpus was young the southern continents were much closer together than they are now. Other evidence confirms that they were indeed once joined, so Milestone is our own piece of the Gondwana super-continent. A lesser light is Selaginella kraussiana which forms a fern-like mat over much of the forest floor. This too is a Gondwana relic.