The tropical rainforest that was observed along the trail was a secondary forest. The following characteristics are present in a secondary forest.
The trees observed along the trail all have thin tree trunks. This shows that they are all grown quite recently and are quite young, not like those in the primary forest, which have thick tree trunks (Fig 1).
There is also thick undergrowth present. Thick undergrowth will be present when there is a break in the canopy. Sunlight will be able to reach the forest floor, allowing plants to thrive, thus creating dense undergrowth. In Fig 2, it can be seen that there is a clearing on the forest floor, and as a result, there is thick undergrowth. In Fig 3, there is also a clearing and thick undergrowth. However, the plants present are different from those in Fig 2. There are plants such as sugarcane planted. These do not belong to the forest, and people planted them there. It can be seen that the piece of land was used for agricultural purposes in the past and men cleared the area of any trees. As there is disturbance and changes made to the forest, it can be considered as a secondary forest.
The trees in the forest also had comparatively thinner bark (Fig 4). This suggests that they are quite young, not like primary forest, where the trees there (that are older) have a thicker bark. As the trees grow older, they will comparatively have a thicker bark and thicker trunks.
There are remains of wells and bases of houses present in the forest (Fig 5 and 6). This shows that there is human interference to the forest, so the forest seen is a secondary forest, as there are already changes made to the forest, so it is not a primary forest.
(i) The Eco-Link is like an overhead bridge, linking between the Bukit Timah Nature Reserve and the Central Catchment Nature Reserve, crossing over the Bukit Timah Expressway. Linking the two high points on the opposite slopes, the overhead ecological bridge will be shaped hike an hourglass...