How to create a tropical rain forest

This is my response to a recent email: "We intend to create a multi-tier tropical rainforest along the riverbank of our (residential and commercial) scheme. We would like to know what trees and palms you would suggest for the first (uppermost) tier. If possible the tree specifications (diameter, overall height etc,) and the planting pattern and distances. What shrubs and plants would be suitable for the lower tiers including ground covers."

The property is located in Malaysia, where the climate supports tropical rain forest. To recreate such forest would be easy given time, say 20 years. But of course in a commercial property they would want it done within 20 weeks.

At the 'One Utama' shopping mall in Kuala Lumper, we were promised 18 months to create an indoor rain forest, but in the end we were able to plant our first trees only after the builders had finished and moved out. Nevertheless, our rainforest was presentable within 3 months. We had an advantage that the big trees we needed were growing close by on the same property and could be transported on a private road, and with their spreading crowns sticking out of the back of the transporter. We did not lop off any of the branches. On public roads this would not be possible.

So the size and shape of the largest trees will depend on what can be transported and the crowns may have to be trimmed. The species that can be transplanted as big trees are not many, and most are species of seasonally dry tropical forests, not of true rainforests. They include Tabebuia rosea, Pachira aquatica, Hura crepitans, Khaya senegalensis, Pterocarpus indicus and Shorea roxburghii.

Before moving big trees, I would advise removing the leaves by hand, leaving only the growing tips and youngest leaves intact. This will slow down water loss while the roots are recovering from transplanting. Wrapping the trunks in plastic sheets may also help keep the trees from drying out. The presence of growing tips will speed up recovery. Tree with big leaves are easier to deleaf than trees with lots of small leaves.

Trees should be spaced with 1m gaps between crowns. It will take a couple of years for the crowns to close up. Under the gaps, put in the smaller trees and shrubs. Fill up the gaps and plant close to get faster effect. Ground covers are sensitive to shade and moisture and each species has its own requirements. Try out different species and replace those that fade out. Palms have difficulty recovering from leaf loss, so keep as many leaves as possible while transplanting.