**1. Introduction**

Singapore, an island republic, is situated south of the Malay Peninsula, between 1º09´N and 1º29´N and longitudes 103º38´E and 104º06´E. The main island and 60 small islets cover an area of about 710.2 sq km and support a humid tropical type of vegetation. At the time of the founding of modern Singapore in 1819, practically the whole of the main island was forest covered. Land clearance for development was done in massive scale during the colonial times. After the first forest reserves were set up in 1883, efforts to conserve parts of the forested areas have evolved. In 1951 legal protection was given to Bukit Timah, Pandan, Labrador and the water catchment areas. When Singapore became an independent state in1965, there were five nature reserves in all (Wee & Corlett, 1986). Since its independence in 1965, in an effort to develop its economy and infrastructure, Singapore has continued to clear forests to provide land for industries, residential use, military purposes, and infrastructure. With one of the highest population densities in the world, pressure on land is the driving force that has influenced the extents of the forests. But Singapore has managed to provide legal protection to retain some land as reserve forests. Till the 90's nature conservation was a mere governmental task to maintain the forested areas of the island. About 4.5% of the total land area is given to forests and there are a total of four protected nature reserves in Singapore. Of these, Bukit Timah Nature Reserve and Central Water Catchment Reserve are the inland tropical rainforests, with some interior areas of primary rainforest. Protected under the Parks and Trees Act of 2005 for the protection of the native biodiversity, a total area of 3,043 ha is given to these two forests which were contiguous till 1995. Since then a six-lane highway cut through the heart of the forest, segregating Bukit Timah from its much bigger counterpart, into a 164 ha of some secondary and some primary forest. The actual closed forest covers only 75 ha of this. Though small, it is recorded as having 1000 species of flowering plants, 10,000 species of beetles, and many other organisms and does retain an authentic 'feel' of a primeval rainforest in the interiors. The forest is a mixture of lowland and coastal hill dipterocarp forest and some secondary forest, lying on the flanks of the highest (163.6m), mostly granitic hill in Singapore. It is only 12 kms away from the city centre and is surrounded by a fast-growing condominium belt of Singapore. Tagged as the country's flagship nature reserve, Bukit Timah represents the constant struggle and compromise between increasing pressures of urbanization and the commitment towards nature conservation currently faced by all countries.

Sustainability of an Urban Forest: Bukit Timah Nature Reserve, Singapore 145

by measuring the ambient temperature, and relative humidity along the forest boundaries, skirting the urban landuse such as the residential developments and the roads around the forest. Data was then mapped using GIS to ascertain the environmental gradient resulting

To quantify the impact of hiking, jogging on soil properties, a post-impact sampling framework was employed, covering forest, trail, and trail-side segments along the forest paths. Following park-designated hiking trails, measurements were taken along transects through forest, trail and trail-sides, mostly at regular 100m intervals. The results were then compared with adjoining undisturbed forested slopes (used as a control), to ascertain the degree of compaction and other changes trails and trail-side sites have gone

Visitors to the forest are an increasingly important factor in determining the future sustainability of the forest. Hence, apart from getting data on visitors visiting the forest, their profiles, usage preferences, surveys were also conducted to assess the perceptions these people have about the forest, its value as a nature reserve, and its services as a nature reserve. It is thought that such perceptions among the public users of the forest may well

Bukit Timah Nature Reserve (BTNR) is the only primary rainforest in Singapore, housing innumerable species of tropical trees and animals, of which a number are in the endangered list. Originally part of the much larger Central Water Catchment area, this forest was truncated from the bigger part of the forest in 1985 when the six-lane Bukit Timah Expressway (BKE) was constructed to run right through the heart of the forest. In addition to the expressway, currently there are more roads around the forest. As a result BTNR is

Presently the Nature Reserve has a designated size of some 164 ha of land area although the real forest is only about 75 hectares. In spite of the non-urban landscape around the forest, parts of the inner forest still maintain its primeval characteristics (Fig. 1) and offer the urban

A metalled road (not open to vehicular traffic) runs up to the summit, while 10.6 kms of dirt trails, often paved with rocks, concrete steps, or even wooden boardwalks criss-cross the forest, over steep slopes, and rocky surfaces. In addition to these, there are mountain biking trails (6kms) that offer varying degrees of challenge to bikers across steep and rough slopes. The forest interior has small streams and caves that are in the more remote areas and some parts are kept off from visitors by not having trails running through them. These interiors still show characteristics of undisturbed primary rainforest. The forest itself is quite dense with close canopy cover, complete with tall trees, heavy growth of lianas and epiphytes, middle and lower shrub layers with abundant supply of fresh ground litter. Studies on geomorphological processes in the past (Chatterjea, 1989a, b) recorded slow movement of surface sediments and a well-balance sediment budget on the well-drained forest floors of Bukit Timah, providing adequate nutrients to the dense vegetation and support to the forest slopes. Till the 1980s and early 1990s the forest was an unknown natural landscape, visited only by researching scientists, and occasional visitors who came there either for intellectual pursuits or to enjoy the aesthetic appeal of

physically fragmented, permanently severed from the bigger counterpart.

population much respite from the stresses of city life.

an undisturbed forested environment.

from edge effects of the development.

influence the sustainability of the forest.

**3. Background and site details** 

through.

Expanding populations, increased income and leisure time, altered consumer demands, increasing media and commercial propaganda of nature-based attractions, higher awareness of Nature and natural landscapes, increasing interests in non-urban environments and off-the-beaten track places, as well as proliferation of urban lifestyles (Dotzenko et al., 1967; Poon, 1990; Sutherland et al., 2001) in the past decade have seen a rapid rise in the interest in Nature areas. Whether for a piece of Nature or to satisfy the adventurous, nature areas have become common destinations for people during their leisure times. This evolution of tastes has produced growing pressures on natural landscapes, adversely affecting the natural habitat conditions and causing degradation. Visits to remote forests have seen an unprecedented rise as conducted and organized tours to remote areas, sometimes even with comfortable facilities, have allowed otherwise sedate travelers to choose these Nature areas over other choices as their preferred destinations. Large-scale outdoor recreation leads to greater and more widespread ecological impacts on natural ecosystems (Lynn & Brown, 2003) and forests near urban centres have been the worst affected, as these are seen as places of relaxation and physical exercise by increasing number of urban dwellers.

Being close to home, these urban forests also are visited on a regular basis and hence, the impact to such natural sites is more protracted. This paper discusses the case of Bukit Timah Nature Reserve, the 75 ha of partly primary and partly secondary low land Dipterocarp forest, located alongside the popular condominium belt in central Singapore and which is frequented by an unprecedented number of people from the nearby residential areas. The forest has been accorded protection by law as a gazetted Nature Reserve. As for the interiors, the forest in question is crisscrossed by a network of walking trails and the increased popularity of this forest has led to severe degradation of some of the trails. At the outer boundaries, the forest is getting encircled by the ever-encroaching urban residential and infrastructural developments, altering the peripheral environment and steepening the environmental gradients from forest boundaries to the interiors. As for its patrons, the visitor numbers have gone staggeringly high over the decades when the forest came to be more popular. The service demands of this clientele have also seen a distinct transformation and forest management, so far, has focused on keeping up with popular demands by providing various people-friendly facilities and amenities. Bukit Timah Nature Reserve, therefore, exemplifies the aspirations of nature conservation, as well as nature usage and exploitation that many other forested areas near urban developments may go through. Sustainability of such areas depend greatly on the analysis of the issues involved and assessment of the extent of problems brought about by such invasion from urban development.
