The Singapore Botanic Gardens is about to get greener, even as it awaits the results of its Unesco World Heritage Site bid.

The National Parks Board (NParks) yesterday announced that a nature area within the Gardens will be more than tripled in size to 20ha, about the size of 30 football fields.

Nature areas are green spaces with ecological significance and will be preserved as long as development is not needed. There are 24 such areas across Singapore, including the nature reserves.

The Gardens' existing 6ha nature area is one of Singapore's few remaining patches of primary rainforest and has been preserved since 1859. The expansion includes a 10ha fragment of secondary forest next to the Gardens known as the Learning Forest, and surrounding forest areas.

NParks said the ecology in these areas complements the primary rainforest. More trees, including exceptionally tall and rare ones, will be planted in them, and an existing freshwater swamp will be restored and enhanced as part of the nature area expansion.

"The additional 14ha will enhance the forest habitat in the Gardens as it forms a contiguous swathe of forest through the heart of the Gardens," NParks said.

It added that this will create more opportunities for pollination and seed dispersal of native forest trees, help the rainforest regenerate, aid in the conservation of plants native to the region and create additional habitats for native wildlife such as the Red-legged Crake bird.

The new nature area could also take some pressure off the rainforest, by spreading visitors more evenly across the larger space.

The expansion is in line with the Gardens' site management plan for its Unesco bid.

The new trees to be planted include the Tualang and Kempas species, which have some of the tallest trees in South-east Asia.

These forest giants can grow up to 60m or even taller. Many rare species like the Damar Hitam Gajar and the Giam will also be planted to safeguard them from extinction here, and for research.

The freshwater swamp, which will be completed next year, willhave boardwalks and viewing decks to bring visitors closer to the flora and fauna.

Minister of State for National Development Desmond Lee launched the new nature area yesterday at the Gardens.

He helped to plant 100 trees, together with MPs for Holland-Bukit Timah GRC Dr Vivian Balakrishnan, Minister for the Environment and Water Resources, Ms Sim Ann, Minister of State for Education, and Communications and Information, and Mr Christopher De Souza, as well as about 130 residents and community gardeners.

Mr Lee said: "The rainforest has been largely untouched for hundreds of years... and holds some rare and unique species that can only be found here and nowhere else.

"All these upcoming developments will truly enhance our Botanic Gardens."

zengkun@sph.com.sg