By Amresh Gunasingham
- A SPECIAL soil mix to grow rain trees in spaces
typically not favourable to them, such as footpaths and road
carriageways, may be a step closer to reality here.
A team of 13 researchers is experimenting with four variations
of soil mixture to plant 20 rain trees - a common roadside tree in
Singapore - on a vacant plot opposite the IMM shopping complex in
Jurong.
The trial is being carried out under a $130,000 project jointly
funded by the National Parks Board (NParks) and Nanyang
Technological University (NTU).
Rain trees were chosen because they have relatively faster
growth rates and hence, can provide 'fast solutions,' said Dr Tan
Puay Yok, Assistant Director of the Centre for Urban Greenery and
Ecology at NParks, who led the four year research effort which will
be completed in May.
Rain trees can grow up to 25 metres tall.
The team's findings so far have shown that rain trees planted on
structured soil - which consists of a mix of coarse gravel and
topsoil - show a comparable growth rate to trees grown on normal
topsoil.
'If we are able to put structural soil under under foot paths,
road crossings and carraigeways, for example, it offers a solution
to plant trees in areas previously not suitable for growing trees,'
said Dr Tan.
The soil mix also has the added advantage of enhancing tree
stability, as it allows for deeper root penetration and access to
water and nutrients required for growth.
'Trees grown on structural soil have a reduced chance of being
uprooted in the event of heavy thunderstorms, which are common in
the region,' added Dr Tan.
Last year, the incidence of tree uprooting dropped by 62 per
cent, from over 3,000 cases in 2000, said Mr Simon Longman,
Director of Streetscape at NParks.
Over the last two decades, the amount of green cover over
Singapore has jumped from 36 per cent in 1986, to 47 per cent in
2007, said an NParks spokesman.