Bukit Timah Nature Reserve has well over 400 species of trees growing in it, an "incredible number" for an area so small, says Dr Stuart Davies, director of the Smithsonian's forest monitoring programme ForestGEO.
The Forest Global Earth Observatories (ForestGEO) programme is a network of 61 tropical and temperate forest plots in 24 countries, where scientists examine function and diversity.
A 4ha patch of primary rainforest in the 1.64 sq km Bukit Timah forest is one of the sites being studied, along with others in countries such as China, Malaysia and Thailand.
In Singapore, researchers have found that a 1ha plot within Bukit Timah Nature Reserve, possibly the world's most ancient small rainforest reserve, contains more tree species than the whole of North America.
Scientists from the Smithsonian and NTU's National Institute of Education, who have been studying the Bukit Timah plot for the past 23 years, have also found that the trees there are dying faster.
Dr Shawn Lum, a lecturer at the National Institute of Education who has been working with Dr Davies on the Bukit Timah plot, said that in general, the trees in Singapore's forests have a mortality rate about 3 per cent higher than a forest plot in Malaysia, but the trees which do not survive are young specimens.
"Even though the small trees may be dying, they are being replaced by faster-growing smaller trees.
It is interesting that the higher mortality is being offset by higher recruitment," said Dr Lum, who is also president of the Nature Society (Singapore).
The next step is to find out why - a question that researchers will hopefully answer with help from their counterparts in NTU's Asian School of the Environment.
Dr Davies also hopes to tap NTU's expertise at genetic sequencing to study forest ecology. For instance, the seraya tree native to Singapore has a symbiotic relationship with a fungus called ectomycorrhiza, which helps the tree absorb nutrients from the ground.
In return, the tree provides the fungus with food it makes during photosynthesis. But as this fungus does not produce mushrooms often, it is hard to detect its presence - which makes it difficult for researchers to learn more about it.
"With DNA technology, however, we can find this fungus very quickly in the roots or in the soil," said Dr Davies.
Under the new partnership, he is also hoping to study more forest plots, including those in the Central Catchment Nature Reserve.
By doing so, more data can be collected about the mortality of forests here, and how this affects the animals.
This article was first published on May 3, 2015.
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