Help deepen the green
South Africans love to plant trees, writes Tim Conradie
ALOOK at our cities shows enormous urban forests where once there was rolling grasslands or fynbos, and it’s often stated that Johannesburg is the largest planted urban forest in the world. We have collectively created forests of enormous size and diversity — and each homeowner who has a garden is effectively the creator and manager of their own patch of the greater forest.
Unfortunately most of the trees in our urban areas are exotic. This is hardly surprising, as until comparatively recently few indigenous trees were available from nurseries, and the average South African homeowner thought of indigenous trees almost exclusively as “thorn trees”.
But times have changed. The exotic forest — beautiful as it is — can be quite sterile and it usually doesn’t support the diversity that it could. Because indigenous trees have coexisted with the local fauna for millennia, they obviously have a much higher carrying capacity in terms of diversity. While the ideal scenario might be to replace the entire exotic forest with an indigenous one, it’s impractical. We should rather look to slowly manage and enhance our “own” patch of forest.
Identifying which are the “beneficial” or “benign” exotics versus the “bad” or “invasive” ones is a good start. If a garden is supporting trees or plants that are environmentally unsound or invasive, then perhaps these can and should be replaced. Rather than employing the instant and dramatic approach of felling all offensive trees and planting new ones, replacement is a much gentler way. Replacement entails the growing of a more desirable tree in the shadow of the less desirable one. It may require more patience and longterm commitment, but it’s worth it. Most tree felling companies are able to “prune up” or “crown lift” big trees to allow more light in underneath.
Once this has been done, one then plants the new tree under and alongside the one being replaced, allowing your new tree (or trees) time to establish themselves while continuously “pruning up” the offending giant. Once the young tree starts to come into its own (mostly in three to five years) you can then fell the exotic. In the long term you have re- placed a foreign giant with one of more appropriate African temperament and complexion.
It is deeply satisfying to be helping to add to health of our urban forest and to see the corresponding increase in bird, bat and insect species — and it’s not too farfetched to look forward to a time when our local forest will be comprised mostly of local trees. Aside from environmental benefits, the need to constantly police invasive aliens would evaporate. We live in an ever changing ecosystem. The time is right for us to help deepen the green.
A Celtis africana tree at right, with an acacia tree, below.