Kent Ridge Park, opened in 1954 as a public park, is designed to adapt to the natural vegetation and topography of the site (“Kent Ridge Park Visitor Info, 2013). As such, it is largely undisturbed and is habitat to a large variety of flora and fauna. Such abundance allows for the study of the many different types of vegetation found in the walk, both native and exotic, and the inter-dependent interactions between the flora and fauna that are required for the continuity of the web of life. Besides being an important natural site in Singapore, what makes it even more unique is that it holds a significant position in Singapore’s natural heritage as the location where the battle for Pasir Panjang took place. (H.T.W. Tan et al.). The walk also enlightened me about how human actions affect the vegetation of a forest, as I realised the changes Kent Ridge forest had undergone due to man’s actions. Kent Ridge was originally a lowland evergreen rainforest, specifically a coastal hill dipterocarp forest. (H.T.W. Tan et al.). Such forests were the most common in areas with year-long moisture and well-drained soils, as found in Singapore. (R.J Morley). Such forests are dense, and lack ground plant growth. They also have a higher diversity of flora and fauna as compared to other forest types. Due to clearance of the forest by man for the cultivation of rubber, pepper and pineapple crops in the past, the forest had lost its original vegetation. Other kinds of vegetation then grew in the ground that had been previously disturbed, forming the secondary forest. The secondary forest vegetation differs from the primary forest vegetation due to the different conditions that are present. Some of the changes in conditions include higher light intensity, higher temperatures and lower humidity. These changes are mostly brought about due to the lower plant density. As such, the vegetation that is growing adapts to the different conditions through various mechanisms. One such adaptation is the ability to grow quickly such that it is able to take ground of deforested areas before other plants do. As such, the biodiversity in secondary forests is much lower due to such more stringent adaptation conditions. This is further worsened by nutrient poor and acidic soil. Furthermore, the steep slopes of the Kent ridge forest combined with rains throughout the year, results in soil erosion and leaching of nutrients from soil as the top-soil is stripped. This also contributes to the lower variety in flora and fauna in secondary forests as compared to primary forests. There are many plants that have adapted to the drier secondary forest conditions and we would discuss some of them now. One such plant is the Dillenia suffruticosa (Simpoh Air). It is a keystone species of the forest. Keystone species play an important and significant role in the ecosystem (Mills et al., 1993).They are able to provide food throughout the year, meaning they are able to bear fruits and flowers throughout the year. This firstly ensures their widespread dispersal and thus survival of the species throughout the year. Importantly, it also ensures that it is able to provide energy to the fauna such as the bees and birds. This ensures

that the ecosystem remains healthy, and that all the flora and fauna continue to survive and flourish. The removal of keystone species could have very dire consequences in the ecosystem of the forest (Mills et al., 1993). The removal of the keystone species results in the possible death of animals that are dependent on it as food source. These animals might be seed dispersers or pollinators of other plants, which then results in other plants not being able to propagate. This would decrease the diversity of plants and animals in the ecosystem. As such, the Simpoh Air plant is very important to the survival of the Kent Ridge forest ecosystem. It provides pollen for the pollinating bees and fruit for the birds, and has some very special adaptive features to ensure its survival. The flowers it bears are large and bright yellow in colour. This attracts the carpenter bees (Xylocopa species), which carry out pollination. The figure below also shows green unripe fruits. The fruits which ripe after 5 weeks , would then open one day around 3AM , forming a star-shaped capsule in which the seeds are stored. The bright pink flesh, as seen in Fig.1 attract and reward the birds who swallow the seeds along with the flesh. The seeds are then dispersed by the birds in their waste (“Simpoh air Dillenia suffruticosa”-Ref 6). Furthermore, it has deep roots that allow for the tapping of ground water and its water sources are higher, ensuring attainment of nutrients. Also, it has long twining stems that “strangle” other plants to death , allowing for it to obtain maximum sunlight possible.

Figure 1: Showing the attractive pink flesh and red seeds that would be dispersed by birds. Due to such adaptations, the Simpoh Air is one of the most prevalently seen plants in Kent Ridge Forest. Its ability to attract birds that disperse the seeds allowed it to regenerate the previously disturbed areas of the forest, and thus is found in large numbers. Other keystone species include Adinandra dumosa ( Tiup Tiup), Melastoma Malabathricum and the Ficus. These plants bear fruits throughout the year to provide food for the fauna. The Ficus plant has tiny holes in their syconia to allow the small fig wasps to pollinate. The fruits of the plant are also not brightly coloured – dull green or yellow in colour. This shows that it is not eaten by birds as they are not brightly coloured enough to attract birds. Furthermore, the fruits grow on the stems. These indicate that the fruits are eaten by bats which are colour blind and have greater access to the hanging fruits. This indicates the mutually benefitting relationship between the characteristics of a species and its interaction with the different type of fauna in the forest (Seah,2001).

Such adaptations are also seen in the exotic species of the forest. One such species is the Acacia auriculiformis. It is the most prevelant exotic species in the forest due to its ability to adapt very well to the conditions. The phyllodes are oriented in a vertical fashion such that it is protected from the higher light intensities. As such, it is able to grow quickly and even outcompetes native species by competing for required space and nutrients. (Seah, 2001) .Such competition endangering the native keystone species is dangerous for the ecosystem as explained earlier. The field-trip through Kent Ridge forest opened my eyes to the different categories of plants in the forests; mainly native and exotic. I learnt about the different adaptive mechanisms and features the plants have in order to maximise their survival, be it a native or exotic species. I also learnt how the survivals of the different species, particularly the keystone species, are important to the balance of the existing ecosystem in the forest. Other interesting information were the medicinal properties of some of the plants seen, such as Fagraea fragrans which could be used to treat wounds. Though we were able to spot just a few species out of the many species of plants growing in the forest, I now understand biodiversity in a way I did not before the trip. I understand the connections between the flora and fauna better and it has made me appreciate the complex beauty of nature a little more.

Literature Cited 1. “Kent Ridge Park , Visitor Info” Retrieved 20 Jan 13 from : http://www.nparks.gov.sg/cms/index.php?option=com_visitorsguide&task=parks&id =20&Itemid=73 (accessed on 21st Jan 13) 2. “THE HISTORY AND BIOLOGY OF KENT RIDGE PARK”, H.T.W. Tan, T. Morgany and Tan Kai-Xin, Hosted on : http://www.nus.edu.sg/oes/pdf/natural_krp_history.pdf. 3. Brandon Seah, Dec 2001. “A Guide To The Plants Of Kent Ridge” , Hosted on : http://habitatnews.nus.edu.sg/heritage/pasirpanjang/ridgeplants/index.htm 4. Earth System : History and Natural Variability – Vol.3-Tropical Rain Forests-R.J Morley , Hosted on: http://www.eolss.net/Sample-Chapters/C12/E1-01-06-01.pdf 5. Mills, L. S. et al. The keystone-species concept in ecology and conservation. BioScience 43, 219–224 (1993). 6. Simpoh air Dillenia suffruticosa Family Dilleniaceae ,updated Jan 13. Hosted on : http://www.wildsingapore.com/wildfacts/plants/others/dillenia/suffruticosa.htm

Images 1. Figure One : http://1.bp.blogspot.com/zf86uCtJZIQ/TbZG5Hh8U8I/AAAAAAAADQo/Wu9Rwd3zr0A/s400/flower_dilleni a2.jpg