Help deepen the green

South Africans love to plant trees, writes Tim Con­radie

Business Day - Home Front - - HOMEFRONT -

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.

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