PROUD of its six million trees three years ago, Johannesburg has even more cause to celebrate as the urban forest has now grown to 10 million trees with active planting taking place in the city and on periphery areas.

One of Joburg's tree-lined streets

Since 2001 when the various municipalities combined to form the Unicity, the City has planted around 1,3 million trees, bringing the tally of trees maintained by the City to 2,5 million, with a further 7,5 million trees in residents' gardens.

The 2,5 million trees are situated within parks, cemeteries, nature reserves, conservation areas, roadsides and on the city's pavements. Johannesburg City Parks, the custodian of the trees, estimates that the trees are worth R13-billion.

On satellite pictures, the city looks like a rain forest, albeit man-made, but because the city does not get the required amount of rainfall to qualify as one, it passes as an urban forest. In the 1860s, when trekkers first settled on the Witwatersrand, there was not a tree in sight, and the area of rocky grassland was dotted with the odd shrub and several streams.

City Parks' Street Tree Management Strategy originally envisaged planting 10 000 trees per year but because of a mayoral request to plant larger trees, which are less vulnerable to vandalism, theft and destruction by goats and horses, the planting quota has had to be cut back to 2 500 trees per year, for budgetary reasons. Larger trees cost R600, compared with R350 for smaller trees. Larger trees are defined as those of over three metres in height, with a girth of more than 50cm.

A priority is to plant trees in the sparse southern suburbs, and despite having planted 17 000 trees in Orange Farm and 4 000 in Soweto in recent years, around 300 000 trees are still required to green these areas.

City Parks estimates that it would need R180-million over a period of 30 years to do the job. While it has budgeted an amount of R1-million for this financial year for the purchase of trees, additional funding of R6-million is still required.

The strategy also includes conservation awareness programmes focusing on the value of trees in the environment, like pollution reduction, oxygen enhancement and cooling qualities. City Parks has formed partnerships with communities, NGOs, national and provincial governments to help develop a green ethos.

To help reduce costs and fast track the planting, City Parks is developing a tree production nursery, to grow their own trees and supply surplus stock to communities for greening projects and planting in their gardens. The nursery produces up to 100 000 tree seedlings a year, which, after five years, will be large enough to plant on pavements and in parks. Younger trees are given to householders to plant in their gardens, particularly where pavements are too narrow to accommodate the trees.

In the past exotics were mostly planted, mainly because they were easier to prune, and their root systems didn't interfere with the underground service pipes. Nowadays, more indigenous trees - stinkwoods, cottons and wild olives - are being planted, and the balance of exotics and indigenous is more or less equal.