Feedback: Environmental concerns over habitat fragmentation in Bukit Batok nature corridor and Tengah nature way

[On 18 November 2022, the following feedback has been sent to the representatives of Urban Redevelopment Authority (URA), Housing & Development Board (HDB) and National Parks Board (NParks) as part of our ongoing dialogue.]

Thank you for your reply dated 8 Sep 2022 regarding our email to Dr Amy Khor, in which she advised us to approach Ministry of National Development (MND) for a dialogue. We appreciate the time that you have taken to respond to our email.

As our email to Dr Khor didn’t convey our full feedback on Bukit Batok Hillside Park (BBHP) area, since we were requesting a Meet-the-People session to discuss the details, may we take this opportunity to respond to your email to briefly introduce ourselves and provide some details of our feedback, as part of the dialogue to promote environmental sustainability in the community?

Jimmy Tan’s background

As a resident of Bukit Batok East who is also a nature enthusiast and who works in the vicinity as a part-time food delivery cyclist and freelance writer and editor, Jimmy feels compelled to share his lived experience and observations after moving from his original hometown, Toa Payoh, several years ago, partly to seek refuge in a cooler and quieter environment next to Bukit Batok nature park (which makes him a “microclimate refugee”).

Also, as the creator of the petition to save BBHP area from housing development and one of the co-creators of the petition (with Roxane and Saniroz) to conserve at least 30-50% of Tengah forest, he hopes to be a voice representing almost 15,000 BBHP petition supporters and close to 10,000 Tengah forest petition supporters of nature conservation in some ways, who are concerned about the health, social and environmental impacts of development.

Denise Liu’s background

Denise is a senior researcher working in a social service agency and an associate lecturer with the Singapore University of Social Sciences. She is also an active member of the Bukit Batok community. She chose to purchase a BTO flat in Bukit Batok because she enjoys the greenery in the area. During COVID-19, in particular, taking her dog for long walks around BBHP Hill 2 is essential to her well-being and mental health.

As a member of her neighbourhood’s Resident Network, she has spoken to many residents who also value the greenery and nature of the estate. Many have expressed their concerns about losing these spaces, which provide a much-needed respite from the crowded BTOs they live in. The loss of BBHP Hill 2 will be particularly devastating for the hundreds of residents who cycle, jog or walk around the hill as part of their fitness routines. She spoke to a resident recently who is thinking about selling her flat if/once BBHP Hill 2 is redeveloped, as she cannot imagine living in a neighbourhood surrounded by BTOs, without greenery and the space to bring her dog for walks.

When looking at greenery in a forest, we experience stress relief as we breathe in the immune-boosting phytoncides released by the plants, commune with the flora and fauna, and get a good workout while hiking, jogging or forest bathing. (Map from, photos by Jimmy Tan)

Our response to HDB’s reply to Jimmy’s feedback on EIS report on BBHP area

Firstly, we noted that HDB’s reply dated 9 September 2020 says:

“The land use zoning of this area is gazetted as ‘Residential’ and ‘Park’ in Urban Redevelopment Authority (URA)’s Master Plan since 2003. As reflected in the current Master Plan 2019, the area is safeguarded for housing and park development, which will offer more housing choices and recreational spaces in Bukit Batok town.”

Although URA’s Master Plan 2003 was approved and gazetted after public consultation, we have seen that many things have changed over the past 19 years.

Back then, the urgency of the existential crisis associated with the climate emergency facing us had not received as much attention and concern as it has today.

Early this month, United Nations Secretary-General Antonio Guterres reminded everyone at COP27 that the world was losing the battle against climate change, and it would soon be too late to undo the damage being inflicted on the planet.

Notably, eight of the ten warmest years on record in Singapore have occurred in the 21st century.

Since Singapore is heating up twice as fast as the rest of the world, mainly due to rapid deforestation and urbanisation, especially over the past few decades (as shown in the graphs below), it may be suicidal for us to keep on replacing the naturally cooling dense forests with heat-absorbing concrete and asphalt surfaces.

As the Centre for Climate Research Singapore has projected that Singapore could experience an increase in daily mean temperature of 1.4 to 4.6 degrees Celsius towards the end of this century, more intense and frequent heavy rainfall events, and mean sea level rise of up to 1 metre by 2100, the need to conserve and restore our forests is critical for our survival, as also noted in NParks’ One Million Trees Webinar | Beneath the Canopy: Uncovering the Science of our Forests in December 2020.

According to research studies, sizeable forests (10 ha or above) with dense trees can cool the environment up to 300+ metres, whereas plants on facades of buildings can only cool within 4 metres effectively. (Graphs from Global Forest Watch and, map from NParks webinar, photos by Jimmy Tan)

Secondly, much as we appreciate the efforts and dedication of our urban planners, we note that they have not undergone any mandatory course on basic ecology and the EIA process until the plans were announced in 2020 regarding this requirement.

Hence, it is possible that the Master Plan 2013, as well as the Master Plan 2019, has not taken into consideration the full impacts of continual forest habitat loss and fragmentation on our climate, biodiversity, ecological connectivity and human health and well-being, partly because we did not have the benefit of hindsight.

In the past decade alone, Singapore has witnessed floods, landslides, animal roadkill, human-wildlife conflicts and disease outbreaks – many of which are unprecedented, as mentioned in Jimmy’s blog.

EIS report on BBHP area is likely to have been compromised by certain factors

As regards BBHP area (aka “Zone A” according to your email), while it is commendable that the agencies conducted an EIA in 2018 to better understand the site condition and recommend measures to mitigate environmental impacts of development, we note that the EIA was likely to have been compromised by the ongoing construction of Bukit Batok West Ave 5 in 2018, which divided the two hills (aka BBHP Hill 1 and Hill 2).

(The premature clearing of trees in Kranji woodland by JTC in 2020 before NParks could complete their biodiversity studies serves as a lesson here, since the exact impact on the environment could not be calculated because the offences took place before any studies were undertaken.)

The building of a new road (Bukit Batok West Ave 5) has affected ecological connectivity and might also have compromised the EIA process in BBHP area in 2018. (Sources: BTOHQ, Google Map)

Shouldn’t both BBHP Hill 1 and Hill 2 be studied together before any construction was done in the vicinity, as they were originally part of the same ecological corridor, which was also recognised by a National University of Singapore (NUS)’s paper on vascular plant flora of Bukit Batok in 2013 as having “the highest percentage of native species”?

Moreover, the various feedback from other members of the public, which was compiled by Singapore Youth Voices for Biodiversity (SYVB), also noted that the biodiversity survey was conducted in April over 8 days, which is outside the bird migratory season.

Another feedback noted that there was a lack of reporting being done with regard to the Chiropteran assemblage (bats), who provide an invaluable service as insect predators and seed dispersers.

Over the past couple of years, during recces in/around BBHP area, some native fauna not recorded in the EIS report have also been spotted, such as:

Approximate locations of native fauna sightings in BBHP area in 2021-2022. Note that the list is not meant to be exhaustive. (Source: Google Map, photos by Jimmy Tan)

All these suggest that the EIA done on BBHP area could have been better and more comprehensive in its assessment of the environmental impacts if more time and attention had been given, as it is relatively limited compared to the other EIAs which were done for other ecologically sensitive areas, such as Tengah forest north and south, and Springleaf forest.

This is regrettable because a deeper appreciation and understanding of its relatively rich biodiversity should compel us to focus more on preserving natural features to facilitate ecological connectivity with minimal disruption and harm caused to the well-being of the wildlife and human residents living along and around Bukit Batok nature corridor.

Environmental impacts observed along Bukit Batok Nature Corridor in 2018-2022

As it turns out, we have seen some environmental impacts along Bukit Batok Nature Corridor after the EIA was conducted in BBHP area in 2018, and after about 30% of Tengah forest was cleared since 2018 (as well as 4 ha of the forest in BBHP area was cleared for housing development in early 2021), despite mitigation measures being taken, such as:

Although the colugo, who most likely glided from BBNP and/or Toh Tuck forest (TTF), was not directly impacted by the ongoing deforestation in BBHP area, the fact that it got disoriented illustrates how the loss of ecological connectivity due to the removal of trees during the road widening process between BBNP and TTF has affected safe movements of the wildlife such as the colugos.

The stranded colugo was likely to have been affected by the loss of mature trees between Bukit Batok nature park and Toh Tuck forest due to the roadworks. (Map from LTA, screenshot from Our Singapore Facebook page, photo by Jimmy Tan)

This impact is significant because as noted in the above blog:

“Wouldn’t the ongoing removal of vegetation at BBHP Hill 2, aka Zone B (as well as the planned deforestation for the November 2022 launch of BTO site in BBHP Hill 1, aka Zone A) further disrupt ecological connectivity, which might also further impact the wildlife (such as the uncommon native Sunga colugos, critically endangered pangolins, forest-dependent palm civets, endangered long-tailed macaques, etc) moving between western catchment forests (via Tengah nature way and Bukit Batok nature corridor) and the central nature reserves?”

Why Zone A and Zone B of BBHP area should be protected from further deforestation

While HDB has done well in retaining the natural stream (aka Stream A according to the EIS report) and its catchment area within the planned BBHNP and expanded the original ‘Park’ area from 7.5ha to about 9.2ha, it is regrettable that Stream B and its catchment area in Zone A of BBHP area have not been retained due to their being zoned as a BTO site to be launched in November 2022.

This is because Stream B catchment area has a large fig tree (Ficus vasculosa) with conservation status of Endangered and some seedlings are situated on higher ground immediately next to the stream B (where dragonflies can be found to control the mosquito population), and slender pitcher plants (Nepenthes gracilis), which the rare pitcher blue butterfly is dependent upon, have also been discovered growing on the steep slopes there.

Speaking of which, both the aforementioned areas in Zones A and B have steep slopes along parts of the perimeter of the forest – some of which have gradients of 30 to 40 degrees or more. As noted in an article, “Anything above 20% (incline) is deemed steep. Beyond about 15%, costs begin to increase significantly as the risks become greater and the work becomes more difficult.” (See below image for reference.)

The second BTO site at BBHP area (Zone A) is only about 50 m away from the spot where a previous landslide had occurred on a steep slope, which has since been covered by a protective sheet to prevent further soil erosion. Would it be better to redevelop a previously developed or underutilised land elsewhere than potentially risking lives and further disrupting ecological connectivity by building on the steep slopes in this area? (Source: Google Map,; photo by Jimmy Tan)

Although we appreciate that the agencies seek to provide affordable public housing to Singaporeans, we wonder if it is feasible building BTO flats on such steep slopes, considering that it is more costly and also more risky, since the removal of vegetation that holds the soil together along the slopes may invariably result in soil erosion and even landslides, given the history of landslides occurring in the hilly regions of Bukit Batok and Bukit Gombak as well as the occurrences of more severe storms due to human-induced climate change over the past decades.

Why Tengah forest should also be protected from further deforestation

Speaking of climate change, residents living (and those who work outdoors such as food delivery cyclists and walkers) in Jurong, Bukit Batok West and Choa Chu Kang around Tengah forest risk experiencing heat injuries (such as dehydration, skin rashes, fatigue, irritability, heat strokes and inability to focus on work, affecting safety, creativity and productivity for those who work from home or outdoors) due to the warming microclimate as a result of the deforestation and urbanisation that have been going on since around 2018.

For example, while doing part-time food delivery in this region lately, I (Jimmy) could experience the warming effect on some of the apartment blocks, such as Block 435A, Bukit Batok West Ave 5 (see image below for reference).

Deforestation at Tengah forest increases the urban heat island effect. In their Green SG Policy Paper 2022, Singapore youths have called for Environmental Impact Assessment (EIA) processes to be strengthened, such as “expanding EIAs to include the social impacts of development (i.e. Environment and Social Impact Assessments – ESIAs)”. Would social impacts of development include assessing how residents living near the forests marked for clearance will be affected by the warming microclimate? (Map from Global Forest Watch, photos by Jimmy Tan)

The air outside some units of Block 435A felt stuffy and smelled stale due to lack of ventilation, and since the small units along the narrow corridors seem to be for lower income residents, they may be affected by the urban heat island effect the most due to inadequate or lack of access to air-cooling/conditioning devices and healthcare services, and there is only so much we can do to adapt to the warming climate in our own capacity.

Last year’s SG Climate Rally features Marlina, who shared about the challenges of dealing with the rising heat with no air conditioning in a rental flat, which shows that Muslim women in particular tend to suffer more from heat injuries as they have to wear tudung and full length clothes in the households.

As a Bukit Batok resident working as a food delivery cyclist in the vicinity, Jimmy has also been dealing with symptoms of heat injuries, such as skin rashes, which persisted for months earlier this year and required medical treatment before the symptoms finally subsided. (The receipt of the medical bill is available upon request.)

Last but not least, we learnt that certain fauna in the remaining parts of Tengah forest have been affected by the noise and disturbances caused by the ongoing construction works as well as the habitat loss and fragmentation – they include the native wild boars (Sus scrofa) and the nationally near-threatened (and globally vulnerable) long-tailed parakeets (Psittacula longicauda).

As shown in the above video dated 5 Sep 2022, the wild boar at the forest fringe along (old) Jurong Road somehow got a fright when it saw human beings and ran away even though the hikers stood still. Compared to wild boars in the forests of Pulau Ubin, as well as the nature parks and reserves in mainland Singapore, the wild boars encountered in Tengah forest ever since forest clearance began around 2017 tend to be skittish or nervous, possibly because they have been stressed by construction noise and habitat loss (and it is highly unlikely that the wild boars have been fed by humans since the forest perimeter has been fenced up).

If we are to learn from the encounters with wild boars who have been displaced from their homes and wandered into residential areas in Punggol and Pasir Ris in 2018-2021, in which humans got hurt by the disoriented wild boars, utmost care and attention should be given to minimise habitat loss and improve ecological connectivity in and around Tengah forest, in order to prevent such human-wildlife conflicts in future, such as by conserving at least 30-50% of the original forest.

Tengah Nature Way should be spacious for pangolins, wild boars, etc to travel unharmed, without becoming roadkills or getting into human-wildlife conflicts. (Photo by Jimmy Tan)

As for long-tailed parakeets, even though they might seem to be more commonly seen in residential areas such as Choa Chu Kang, over the past year or so, their conservation status remains vulnerable especially since they are being displaced from their habitats in Tengah forest. Already, some residents find these parakeets too noisy, and it is a sad reality that such beautiful forest-dependent birds are being seen as a nuisance or even pests just because they became homeless and were forced to adapt and co-exist with humans in residential areas as a result of rapid deforestation and urbanisation in Singapore.

Let’s also remember the fate of other native fauna in the diminishing Tengah forest, such as the globally and nationally critically endangered Sunda pangolins (Manis javanica) and the globally endangered long-tailed macaques (Macaca fascicularis).

The current 20 percent of Tengah forest set aside for greenery is unfortunately insufficient to ensure their safety and long-term survival, if we were to go by the artists’ impressions of the manicured, sparsely growing plants in 50-m wide wildlife corridors (which is considered by botanist Dr Shawn Lum as too narrow since at least 50-m buffers are needed on both sides for adequate protection from human disturbances, light pollution, etc) surrounded by buildings and other man-made features, and the absence of eco-links to facilitate their safe movements between Western water catchment and Central catchment nature reserve.

At the very least, the mitigation measures recommended by the Tengah forest EIA reports should incorporate the same considerations for wildlife-friendly environments as those in Springleaf forest EIA report commissioned by URA, which has recommended about 70 percent of the forest to be conserved and specially designed housing and pathways that minimise human-wildlife conflicts to be built.

Why and how ecological connectivity in Tengah nature way and Bukit Batok nature corridor should be improved. (Base map by ST Graphics)

Last but not least, we note that the Straits Times reported on 11 November 2022 that “while Singapore’s forests provide refuge for up to about a third of the world’s straw-headed bulbuls, the globally critically endangered species prized for its singing has increasingly been driven to the brink of extinction.”

If the critically endangered straw-headed bulbuls (Pycnonotus zeylanicus) are becoming more endangered, then their forest habitats should also be even more protected, instead of just having the international songbird trade regulations tightened.

While it is good to show concern and take necessary actions regarding the trade of the endangered songbirds on the international stage, we should also spare no effort to stop the decimation of their forest habitats in our own backyard, such as Bukit Batok hillside park area, Tengah forest and Dover forest, where these songbirds have been seen and heard.

Otherwise, it would be tragic to witness the extinction of the straw-headed bulbuls in the wild happening right under our nose when we already have the knowledge and the means to protect them and their natural habitats, especially since Singapore has only about 200+ individuals left (in mainland Singapore, as of 2021) and is their last stronghold in Southeast Asia, if not the world.

Why we should focus on redeveloping brownfield sites to meet demand for public housing

Finally, we believe that our dialogue to promote environmental sustainability in the community wouldn’t be complete without a brief discussion about HDB’s announcement of strong demand for public housing in Singapore, as it has been cited as a major reason for the need to clear our secondary forests for housing development.

We note that the strong demand for public housing (whether BTO, resale or rental) tends to occur mainly in housing estates close to downtown, such as Bendemeer, Kallang, Queenstown and Redhill, whereas news reports have shown that initial applications for new BTO flats in western parts of Singapore, such as Tengah and Bukit Batok West, tend to be lower than those in Toa Payoh and other central locations in Singapore.

As stated by HDB in June 2022, “There were about 19 BTO projects that had flats with first-timer application rates of 1.7 or lower. The locations for these BTO projects included areas in Bukit Batok, Jurong West and Tengah for non-mature estates, and in Tampines for mature estates.”

Hence, we feel that our focus should be more on redeveloping brownfield sites for SERS, VERS and BTOs (such as in the case of the recent Tanglin Halt and Ang Mo Kio SERS projects as well as redevelopment of Mount Pleasant and Keppel Club golf course for public housing), rather than sacrificing the forests in ecologically sensitive areas and along the nature corridors identified by NParks in their Ecological Profiling Exercise (EPE), which include Bukit Batok nature corridor and Clementi nature corridor.

As also noted in the above blog, the news reported last year that many people buy property just to sell them in 5-10 years upon meeting the Minimum Occupation Period (MOP) to make quick profits, instead of staying long-term.  

Hence, if we keep on building new BTOs and condos in the vicinity to cater to such frivolous housing demands instead of redeveloping brownfield sites elsewhere for genuine buyers who want to stay long-term, we not only may make it more difficult for Singaporeans to find affordable public housing given the space constraints, but also unwittingly sacrifice our precious few forest habitats, such as along Bukit Batok nature corridor, to build housing and widen roads mainly to cater to the rich and privileged who could afford to buy housing for property investment/speculation and drive cars.

There is also a chance that Singapore may eventually experience an oversupply of HDB flats, as noted in a commentary by Stacked Homes dated 20 October 2022, in view of the ageing population (and the global warming fallout).

Our proposals

In view of the climate emergency, biodiversity loss and public health crisis facing us, as well as in the spirit of participating in Forward SG, may we ask URA, HDB, NParks and other relevant agencies to seriously consider the following proposals:

  1. Increase MOP from 5 years to 10 or more years for new BTO flats (especially those that will be built in greenfield sites), so as to discourage people from buying new property purely for short-term investments and profits at the expense of the forests and forest-dependent wildlife.
  2. Make resale/rental flats more affordable/accessible, optimise the allocation of Sale-Of-Balance flats, and make it compulsory for those who own private housing to give up and sell back their public housing flat to HDB because subsidised public housing should not be used for profiteering.
  3. Avoid any further deforestation along Bukit Batok nature corridor (including BBHP Hill 1 and 2 area) and in Tengah forest, so as to maintain ecological connectivity, climate resilience and a liveable environment for humans and wildlife between Western water catchment and Central catchment nature reserve, and focus on redeveloping brownfield sites (such as old industrial sites, underutilised or vacant lands, abandoned schools, golf courses whose leases are expiring soon, etc) elsewhere.
  4. Adopt the Degrowth or Doughnut economic model to ensure that we respect our social foundation and ecological ceiling, so that every Singaporean will lead their life with dignity, opportunity and community within the means of our environment.
No further deforestation along Tengah nature way (at least 30-50% of the original forest with eco-links at both western and eastern ends) and Bukit Batok nature corridor should be carried out, in order to prevent further habitat fragmentation and avoid disrupting the ecological connectivity between the western water catchment and the central nature reserves. (Photo by Jimmy Tan)

Although Bukit Batok Hillside Park area is relatively small and seemingly insignificant compared to other bigger forests in Singapore, it may well be our weakest link because any further disruption along this part of Bukit Batok nature corridor may irreversibly affect the safe movements of fauna (including pollinators and seed dispersers vital for our food security) between Western water catchment and Central catchment nature reserve. The physical and mental well-being of our residents living in the vicinity is also at stake, as shared earlier.

We are only as strong as our weakest link, for we are all members of the same body and citizens of the cosmos, and if the most vulnerable among us suffer as a result of climate emergency, we all suffer together as one. As rightly noted in the vision that Dr Amy Khor has for Hong Kah North (which can be applied for the entire Singapore) - may we build “a place where no one is left behind, but everyone progresses together, each at his own pace”. This can be achieved by adopting the above-mentioned proposals, which include conserving and restoring the forests in Bukit Batok nature corridor and Tengah nature way, to prevent further habitat fragmentation, boost climate resilience, and protect our health, well-being, safety and long-term survival.

Thank you for your attention, and we look forward to continue working with you and Dr Amy Khor on promoting environmental sustainability in the community.

Yours sincerely,

Jimmy Tan San Tek, Bukit Batok East resident

Denise Liu, Bukit Batok West resident


Dr Amy Khor, Adviser to Hong Kah North SMC Grassroots Organisation

Mr Desmond Lee, Minister for National Development of Singapore

[Main text edited slightly to ensure clarity and reflect the latest updates as of 1 January 2023]


The plight of the parakeets in Tengah forest

Although red-breasted parakeets are globally near-threatened, they are considered introduced non-native species in Singapore.

There are concerns that the more urban-adaptative red-breasted parakeets may establish their populations at the expense of the forest-dependent native long-tailed parakeets.

Both parakeet species have been displaced by habitat loss in Tengah forest in recent years, and many are seeking refuge in roadside trees in Choa Chu Kang town nearby.

Alas, their noise has resulted in some residents complaining to the authorities, who have captured many of the parakeets in order to cull the red-breasted parakeets.

Then again, culling appears to be a band-aid solution to a deeper problem of deforestation and loss of habitats.

The native long-tailed parakeets, which are globally vulnerable, continue to face the threat of extinction as long as they lose their forest habitats, not so much because of the so-called competition from the red-breasted parakeets.

Hence, the call to conserve at least 30-50 percent of Tengah forest remains as urgent as ever, for this and many other reasons.

Bukit Gombak Park and other upcoming parks: Have we missed the forests for the trees?

Bukit Gombak Park, which opened on 5 September 2021, used to be a mix of grass and scrubland that remained after the original tropical rainforest was cleared for agriculture two centuries ago.

While it is good to have about 1,500 new trees to improve the ecological connectivity of the region, the eastern part of Tengah forest near the park may soon be cleared as per HDB’s development plan.

The designated wildlife corridor in Tengah is considered too narrow as it does not have sufficient buffer spaces for the safe, quiet and undisturbed habitation of many wildlife. (Source of map: National Parks Board)

If so, it will restrict the effectiveness of Tengah forest corridor to facilitate movement of wildlife, especially amphibians, reptiles and mammals, since NParks seem to focus on birds and butterflies when designating parks and nature ways.

Having only 10% of the original Tengah forest left may result in a loss of half of the species, according to an ecological rule of thumb, as mentioned by Nature Society’s report.

Another section of the western portion of Tengah forest has been cleared, as of September 2021.

This ecological issue begs the question: Have we missed the forests for the trees?

Trees are amazing, no doubt.

They provide ecosystem services, such as purifying the air, providing shade, cooling the urban heat island effect, stabilising the soil, absorbing rainwater and preventing floods, capturing and storing carbon, and so on.

But in the context of tropical rainforests that once graced almost the whole of Singapore 200 years ago, the trees are never meant to exist in isolation or fragmented clusters.

The trees of the forests are meant to live together in close communities, supporting one another as well as providing food and shelter to a huge diversity of fauna species, which range from microorganisms to apex predators.

The bigger and denser a forest, the greater the biodiversity it can support and the more effective it is in providing ecosystem services that can also benefit human residents living nearby.

However, with barely 20% of our land occupied by unmanaged secondary forests that are left standing today (other than the nature reserves occupying less than 5% of Singapore’s land area), we have lost much of the original biodiversity and ecosystem services.

For every new park that opens with fanfare about how many new trees are planted near a residential area, a bigger proportion of the remaining forests elsewhere in Singapore is being sacrificed to build more roads and buildings.

Any potential benefits that are projected to be provided by the new trees in ten years’ time would be outweighed by the immediate costs of losing the mature trees in the forests that are being cut down for development.

These costs may include economic, health and environmental costs, resulting from increasing incidences of roadkills, human-wildlife conflicts, dengue and zoonotic outbreaks, urban heat island effect and flash floods in low-lying areas, as well as declining numbers of forest-dependent species.

P.S. Click here to support the preservation of at least 30-50% of Tengah forest to protect biodiversity and tackle climate emergency.

How important is Tengah forest for dealing with climate emergency and biodiversity loss as well as improving our quality of life?

The much publicised “Tengah Forest Town” development that is planned to clear 90% or more of the original forest has become a controversy. For a start, Tengah forest (aka Bulim forest) has a very impressive record of 262 fauna species, of which 60 are regarded as forest-dependent wildlife species and at least 44 species are nationally threatened, according to HDB’s baseline report dated 2017. The forest also has at least 33 species of plant life with “conservation significance”, as well as 159 significant large trees, of which 90% belong to the fig family (Moraceae). (Photos by Jimmy Tan)

This diagrammatic map illustrates that Tengah forest is a vital conduit and habitat supporting biodiversity and ecological connectivity between Western catchment area and Central catchment area, which are Singapore’s main terrestrial “green lungs”. They provide essential ecosystem services, including removing pollutants, purifying the air, absorbing carbon emissions, cleaning the soil, preventing flash floods, cooling the urban heat island effect, and providing food and shelter for living organisms. Thus, they potentially save billions of dollars’ worth of social, health and environmental costs that would be incurred if the forests were removed or reduced. (Satellite image dated May 2021 by Akihiko Hoshide)

It has been about two years since Housing and Development Board (HDB) has started development works in the 700-ha Tengah forest in early 2019 after fencing up its perimeter. It has resulted in the clearance of about 30% or more (or 210 ha or more) of the forest so far, in a bid to build a “forest town” in Singapore, which would be about the same size of Bishan housing estate.

To date, HDB has launched thousands of new BTO (Build-To-Order) apartment flats in parts of Tengah area in November 2018, May 2019, November 2019, August 2020, November 2020 and February 2021. In May 2021, another 782 HDB BTO flat residential units were launched in Tengah.

However, although an environmental baseline study (EBS) was done in Tengah forest in 2017, we urgently need to reconsider the ramifications of Tengah forest town development because concerns about rapid deforestation and urbanisation in Singapore have been raised by Nature groups and members of the public, especially in recent years.

Since the early 2010s, more and more people in Singapore have been voicing their concerns about the loss of wild green spaces and biodiversity resulting from the destruction of regenerating secondary rainforests, such as Lentor-Tagore forest, Bidadari forest, Tengah forest, Pasir Ris forest, Kranji woodlands, Jurong Eco Garden nature trails, and Bukit Batok Hillside Park area forest. These forests have been sacrificed to varying degrees for development, despite comprehensive descriptions of wildlife sightings having been recorded (and alternative sites for development having been proposed in the cases of Tengah forest and Bukit Batok Hillside Park area).

More recently, three petitions for conserving Bukit Batok Hillside Park area, Clementi forest and Dover-Ulu Pandan forest have been started in Singapore since last year, garnering over 13,000 signatures, 19,000 signatures and 50,000 signatures respectively as of May 2021.

These petitions have highlighted various negative consequences of continual deforestation, such as increased urban heat island effect contributing to climate change, endangerment of forest-dependent species and biodiversity loss, and threat to our physical and mental well-being as well as our very existence.

As the fate of Tengah forest is still hanging in the balance, this blog post serves to provide examples of its rich biodiversity and its indispensable function as an important ecological corridor connecting Western catchment area and Central catchment area. It also aims to highlight the fact that Tengah forest in its current state is crucial for dealing with climate emergency and biodiversity loss as well as improving our quality of life.

In view of the importance of Tengah forest (which we will read about below), we urgently need to preserve the rest of its remaining area as much as possible, or at least 30 to 50 percent of its original 700-ha size (or 210 to 350 ha). In order to do so, we need to:

  1. heed Covid-19 pandemic (and resurgence of community cases) and other warning signs seriously and halt or minimise deforestation in Singapore, including in Tengah forest
  2. treat climate emergency as it really is because we are running against time to deal with its existential threat to our survival, and Tengah forest is big enough to have a significant impact on our microclimate
  3. protect our biodiversity in Tengah forest (and its connecting corridors and core nature areas) from further loss and endangerment of species
  4. establish sizeable wildlife corridors and core habitats areas in Tengah forest in order to maintain a healthy ecosystem that benefits humans, flora and fauna
  5. focus on redeveloping alternative sites or brownfield sites such as underutilised lands and abandoned schools etc in order to achieve a better and more sustainable future for ourselves and our future generations.

1. We need to heed Covid-19 pandemic (and resurgence of community cases) and other warning signs seriously and halt or minimise deforestation in Singapore, including in Tengah forest.

The urgency to protect our forests is compounded not only by worsening climate change but also increasing loss of forest habitats in Singapore. It has resulted in loss of biodiversity, increasing incidences (and recurrences) of flash floods, zoonotic virus pandemic (including COVID-19 virus variants), dengue fever and malaria cases, as well as animal roadkills (resulting in deaths of endangered Sambar deer, Sunda pangolins, palm civets, etc) and human-wildlife conflicts (including the unprovoked wild boar attacks on humans in urban areas that have encroached on their forest habitats).

One of the natural streams running through the verdant landscape of Tengah forest. If the forest is cleared, it may lead to a spike in infectious diseases. According to a study done by Harvard University, “cleared forests lead to ecological changes that increase the risk of disease outbreaks, particularly those carried by mosquitoes — and the mosquito populations that thrive in deforested areas tend to be more dangerous for humans.” Even if we rely on fogging or chemical fumigation, it is not very effective in controlling dengue-carrying mosquitoes’ populations because not only does it cause them to become more resistant but also it harms their natural predators such as frogs, spiders and dragonflies. Thus, it is better to curb deforestation and practise reforestation for dealing with dengue and other such diseases at the root, instead of merely treating the symptoms of the problem. (Photo by Jimmy Tan)

In particular, researchers around the world have been giving warnings about the destruction of tropical rainforests sparking pandemic diseases. Prominent naturalist Jane Goodall has blamed the emergence of Covid-19 on the over-exploitation of the natural world, which has seen forests cut down, species made extinct and natural habitats destroyed.

In view of the possibility that the coronavirus has made the jump from animals to humans in China since late 2019, the Covid-19 resurgence in local community cases in Singapore in late May this year is a cause of concern, especially in the wake of continual deforestation and urbanisation.

On 4 June 2021, scientists behind a new independent taskforce, which is hosted by Harvard University and will report to the coalition on Preventing Pandemics at the Source, said that ending the destruction of nature to stop outbreaks at their source is more effective and cheaper than responding to them.

“Recent research estimated the annual cost of preventing further pandemics over the next decade to be $26bn (£18bn), just 2% of the financial damage caused by Covid-19. The measures would include protecting forests, shutting down risky trade in wildlife, better protecting farm animals from infection and rapid disease detection in wildlife markets.”

World leaders ‘ignoring’ role of destruction of nature in causing pandemics” (4 June 2021)

Incidentally, earlier this year, we have been talking about adopting science-based approach and nature-based solutions in dealing with wildlife management and environmental issues. In the case of Tengah forest, National Development Minister Desmond Lee said:

“we recognised that the forests at the future Bukit Batok Hillside Nature Park and Bukit Batok Central Nature Park are important stepping stones between the Bukit Timah Nature Reserve, and the future Tengah Forest Corridor. That is why we dedicated these nature parks as part of the Bukit Batok Nature Corridor – they will be kept lushly forested, so that they can strengthen not just the area’s green network, but also ecological connectivity between the Nature Reserve and Tengah.”

Speech by Minister Desmond Lee: A City in Nature, a Greener Urban Environment (4 March 2021)

While it is good that we are taking the science-based approach towards wildlife management and forest conservation, we will be ignoring the scientists’ warnings about pandemics and environmental destruction at our peril. In other words, the conservation of Tengah forest (and other secondary forests) is a non-negotiable measure that we must take in order to deal with the urgent public health and environmental crises facing us.

Aerial view of Tengah forest where deforestation has already begun since 2019. Scientists have asserted that forest conservation is a necessary antidote in dealing with the pandemic because natural prevention of zoonotic viruses is better and more cost-effective than vaccination and other measures. (Photo by Jimmy Tan, 10 November 2020)

2. We need to treat climate emergency as it really is because we are running against time to deal with its existential threat to our survival, and Tengah forest is big enough to have a significant impact on our microclimate.

On 1 February 2021, in response to the petitions and the questions raised by various Members of Parliaments (MPs) on behalf of concerned residents and citizens, the Singapore Parliament has rightly declared the issue of climate change a global emergency, recognising it as a “threat to mankind” that requires a concerted effort to “deepen and accelerate efforts to mitigate and adapt to climate change, and to embrace sustainability in the development of Singapore”. 

However, when the SG Green Plan 2030 was launched on 10 February 2021, it did not mention about slowing down or stopping deforestation. This is worrying because land use change or deforestation is a significant cause of carbon emissions and contributor to climate change, resulting in debilitating consequences, such as more extreme weather changes, more frequent flash floods, and so on.

Singapore’s continuous temperature records since 1948 show that the island has warmed, notably in the mid-1970s when rapid urbanisation took place. The upward trend is approximately double the trend in global temperatures. Eight of the ten warmest years on record in Singapore have occurred in the 21st century and all the ten warmest years are since 1997. (Source:

While the Green Plan includes the one-million tree planting programme, which is laudable, botanist Shawn Lum cautioned that “tree planting is beautifully complementary to, and not a substitute for, the care and protection of existing forest habitats.”

In fact, one of the most effective (and cost-effective) nature-based solutions to combat climate change, as also proposed by conservation scientist Professor Koh Lian Pin, is to “protect Singapore’s remaining forests and avoid further emissions from deforestation“.

Moreover, replanting trees, or reforestation, takes decades for the trees to grow and mature under the right conditions, and cannot replace our need for forest conservation, since planting trees does virtually nothing to protect the local biodiversity and ecosystems fully. Also, if we plant trees of similar species for aesthetic landscaping to create manicured parks and gardens, it is like developing monocultures that are incapable of recreating plant diversity as per their existence in the wild.

Although the SG Green Plan may envision Singapore becoming a metropolis like London or New York, we need to bear in mind that unlike these cities in cool temperate countries, Singapore is a small tropical island-state. Since we experience hot, wet and humid tropical climate at the Equator, we cannot keep removing our default natural vegetation, which includes tropical rainforests, freshwater swamp forests and mangrove forests, without facing dire consequences on our health, safety and well-being as well as our flora and fauna.

Being located at the Equator, Singapore receives the maximum intensity of direct sun rays and experiences high temperatures throughout the year. Humans, flora and fauna in this tropical island are much more vulnerable to the effect of climate change, such as heat stress and droughts, than those in cool temperate regions. (Source: National Geographic)

According to the Meteorological Service Singapore’s Centre for Climate Research Singapore, last year’s annual mean temperature of 28 degrees Celsius was half a degree higher than the long-term average, making 2020 the eighth warmest year on record. Singapore’s official meteorological agency also noted a recent sharp rise in temperatures and warned that maximum daily temperatures could reach 40 degrees Celsius by as early as 2045.

The urban heat island effect in Singapore at 2.00 am (April 2016) | Cooling Singapore, 2018. We can see that Tengah forest is cooler than highly built-up urban environments, such as Jurong town and Jurong industrial estate in the southwest. (Base map:

Singaporean climate change scientist and professor Winston Chow attributed the rising temperatures to a phenomenon known as the “Urban Heat Island Effect,” which occurs when cities replace natural land cover with dense concentrations of concrete, pavement, buildings, and other surfaces that absorb and retain massive amounts of heat. He added:

“Singapore has definitely been getting hotter and every degree counts. The hot weather we’ve been experiencing recently is not only a clear indicator of climate change but also the effect of how rapidly urbanization alters local climates.”

Can Singapore Control Its ‘Diabolical’ Hot Weather?” (5 March 2021)

Now that Singapore is heating up twice as fast as the planet due to rapid deforestation and urbanisation, if we continue to remove our few remaining secondary rainforests, such as Tengah Forest, we may soon reach a tipping point at which heat stress affects both human health (through greater risks of dehydration, heat strokes, etc) and carbon dioxide uptake by trees (due to damage to leaf tissue and declining tree health).

For example, according to the US Environmental Protection Agency:

Climate change increases the risk of illness through increasing temperature, more frequent heavy rains and runoff, and the effects of storms. Health impacts may include gastrointestinal illness like diarrhea, effects on the body’s nervous and respiratory systems, or liver and kidney damage.”

In terms of economic and financial implications, it is likely that we will be spending billions of dollars improving healthcare infrastructure and access as well as covering increased medical bills when we see a rise in cases of heat waves affecting the human body and more severe storms and more frequent floods resulting in water-borne illnesses. There are also intangible costs, such as loss of reputation, lost recreation and the psychological impact on people, all of which feed back to the economy, as noted by Nanyang Technological University (NTU)’s head of economics, Euston Quah.

Similar concerns about climate change on the environment have also been raised by scientists around the world. For example, according to Professor Daniel Murdiyarso, principal scientist at the Center for International Forestry Research (CIFOR), based in Bogor, Indonesia:

Deforestation or removal of rainforests has certainly reduced the landscape capacity to absorb atmospheric carbon dioxide. Combined with the effect of climate change, it has caused the ecosystem to be more vulnerable to extensive droughts and wildfires. Rainforests are very fragile. Large-scale disturbance like deforestation or fires will not give them the chance to renew themselves.”

“Forests are needed to absorb carbon, but the overheating planet might soon flip a critical switch” (CNA, updated 4 May 2021)

Already, scientists are concerned that as much as 40% of the Amazon rainforest, which is more than 3,000 times the size of Singapore, may reach a tipping point in 50 years’ time, whereby it may collapse and morph into arid savannahs as a result of climate change.

So we cannot guarantee that we will not be spared from such an ecological catastrophe too, especially since our protected nature reserves occupy less than 5% of our total land area, while we continue to lose our spontaneous vegetation, which includes secondary forests, shrublands and scrublands, and which occupies only about 20% of our total land area.

(In contrast, Mauritius, also a tropical island like Singapore with a high human development index, has 47% of its total area occupied by forests. So, it may very well be a myth that we must keep on sacrificing our forests for economic development in order to enjoy a high standard of living and good quality of life.)

Thus, it is imperative for us to treat climate change as a real emergency and re-emphasise the importance of Tengah forest (as well as other secondary forests) for dealing with climate emergency and biodiversity loss as well as improving our quality of life.

We need dense rainforests, such as Tengah forest, to cool the urban heat island effect through mass transpiration. They function like natural air conditioners of the environment. Imagine how much cost Singapore can save by conserving forests and using less artificial air-conditioning for homes, offices, shopping malls and so on. Studies have shown that mature trees in dense forests have greater cooling power and sequester more carbon than young trees in fragmented parks and gardens too. (Photo taken by Jimmy Tan on 16 June 2021, which shows mist in the morning due to evapotranspiration from the dense trees and natural streams in Tengah forest)

3. We need to protect our biodiversity in Tengah forest (and its connecting corridors and core nature areas) in order to prevent further loss and endangerment of species.

Firstly, an environmental baseline study (EBS) had been initially done for Tengah forest by HDB. Given the findings of this baseline study, the vice-president of the Nature Society (Singapore) (NSS), Dr Ho Hua Chew has pointed out that Tengah forest harbours a rich biodiversity.

An academic paper on updating the classification system for secondary forests in Singapore has noted that rare, threatened or endangered species may be found in regenerating forests. Hence, nature groups and members of the public should be consulted as early as possible on urban planning before any environmental impact assessment (EIA) is carried out and before any developer is awarded a construction project contract tender for any forest patch.

Like Dr Andie Ang from the Wildlife Reserves Singapore Conservation Fund also noted, even if delays were to occur, it is better off to consult green groups and residents at the review stages of the URA Master plan. This is so that we can “ensure a higher quality of urban planning, which can minimise the impact on the environment and improve the overall quality of life for residents. Feedback at an early stage would also help planners to understand what residents want and to build accordingly”.

As it were, the general public were apparently not consulted in advance to gauge if there was a significant demand for housing in Tengah forest before HDB conducted EIA in the forest several years ago. Notably in February 2021, one day after the latest batch of BTO flats were launched in Toa Payoh/Bidadari, Whampoa/Kallang, Tengah and Bukit Batok, the latter two appeared to be not quite popular for home buyers. As the Straits Times noted:

“Those who wish to live in the non-mature estates of Bukit Batok and Tengah may have better luck as application rates were relatively low yesterday evening.”

Thus, in view of the rich biodiversity in Tengah forest and the relatively low initial demand for housing in Tengah, we need to seriously reconsider the need to develop the rest of Tengah forest as originally planned. We should also focus on redeveloping brownfield sites within reasonable distance from existing town amenities and infrastructure, such as vacant lands, underutilised lands, abandoned schools, etc, as well as building taller apartment blocks where possible in order to make up for any shortfall of planned flat units.

Secondly, according to a Straits Times article dated 23 February 2021, National Development Minister Desmond Lee said that “a more comprehensive picture of Singapore’s nature areas and how they connect to one another will be developed. The idea is to map out the islandwide ecosystem and connectivity to better consider how specific sites connect to nature areas, buffers and corridors.”

Indeed, we do need to take into account the big picture of biodiversity on a national scale instead of treating the development of Tengah Forest Town merely as a localised or discrete project. Hence, we need to acknowledge that in view of the rich biodiversity in the regenerating secondary forests between the Western catchment area and Central catchment area (which include Tengah forest, Bukit Batok Hillside Park ridges, Bukit Gombak forest (aka Little Guilin or Bukit Batok Town Park), Bukit Batok Nature Park and Bukit Timah Nature Reserve, etc), it is paramount to preserve the remaining parts of Tengah forest as much as possible (which in fact is one of the largest contiguous patches of green space in Singapore, bigger than even the 163-ha Bukit Timah Nature Reserve).

The big picture: How Tengah forest ecosystem connects with other nature areas, buffers and corridors, such as Green Rail Corridor, Gombak forest, Bukit Batok Hillside Park area, Bukit Timah nature reserve, and so on. According to NParks, these corridors facilitate the movement of native wildlife (including insects, birds, amphibians, reptiles and mammals) and exchange of genetic material between Western catchment area and Central catchment area, leading to healthier populations.

This will ensure that the native wildlife, such as Sunda pangolins, Sunda colugos (or flying lemurs), palm civets, Malayan box turtles, green crested lizards and greater bamboo bats, have sufficient space to live, move, feed, reproduce and carry out pollination and seed dispersal, without ending up as animal roadkills or getting into conflicts with humans in residential areas, which may lead to injuries or even deaths.

During my recces in Tengah forest in 2017-2019, I was fortunate to see a number of resident animals such as a smooth-coated otter, a grey-headed fish eagle, baya weavers and wild boars. It is saddening to see that the forest is losing important habitat niches for these native wildlife species due to forest clearance and human disturbances from the ongoing construction works.

As a testament to the rich biodiversity in Tengah forest, at least a dozen baya weavers’ nests have been found in the northeastern part of Tengah forest. This sighting, together with other wildlife sightings mentioned in this blog, suggests that there is abundant natural food supply and complex food webs of interconnected flora and fauna that already exist in the ecosystem.

From my understanding, HDB is currently doing a new Environmental Impact Study (EIS) in the north of Tengah, including the baya weavers’ nesting area that I have highlighted to them via OneService app. I was told that their EIS consultant will take into consideration my feedback when assessing the potential impacts from the development plans with mitigating measures to be recommended and implemented by the future contractor.

(It must be noted that the new EIS is being done in a smaller area within the original Tengah forest, which is already cleared in some parts. Hence, the results of the EIS may reflect lower biodiversity than before any construction work began in 2019, due to disturbances being caused to the flora and fauna by edge effects, light pollution, noise pollution, etc as a result of the forest clearances. In other words, this new EIS is unlikely to capture the full conservation value of the original Tengah forest, hence our review of the EIS report must take this reality into consideration.)
The baya weaver nests are located at the edge of a scrubland surrounded by the lush forests near the track leading to Jalan Lam Sam. It is about half an hour’s walk from the canal near Brickland Road in the northeast part of Tengah forest. The photos shown in the map were taken in April 2019 when the forest wasn’t fenced up (Source: Google Maps; photos by Jimmy Tan)

As for the beautiful flat yellow butterfly, it is described as rare in the forested plains of Singapore and Malaya, with only a few sightings in parts of Singapore, including Tengah forest. Moreover, according to Delvinder Kaur, junior animal care officer, Zoology, Wildlife Reserves Singapore, “insects are responsible for approximately 80% of the pollination out there. Pollination is needed for our crops, and that gives us food security”. Given Tengah forest’s close proximity to Kranji countryside where farms are plentiful in Lim Chu Kang and Neo Tiew areas, the proliferation of insects, such as bees and butterflies, in Tengah forest is crucial for pollination of crops in the nearby farms to ensure food security for us. This also means that we shouldn’t just focus on protecting rare, endangered and/or endemic species (as crucial as they are), but we should also seek to accommodate common species because they also contribute uniquely to functional diversity, and both rare and common species are all interrelated and interdependent in the ecosystem.

A critically endangered Sunda pangolin was found dead by the roadside along Dunearn Road near Bukit Timah nature reserve in July 2015. It is likely a victim of a road accident. Conservation of rainforest habitats, including a substantial portion of Tengah forest, is necessary for preventing such endangered wildlife from becoming extinct because every individual pangolin’s life matters and counts towards the collective success of their conservation. (Photo by Jimmy Tan)

Both Sunda pangolins and straw-headed bulbuls are globally critically endangered, and their populations are also threatened by poachers for illegal wildlife pet trade. NSS has reported that the confirmed presence of the Sunda pangolin with a young in Tengah forest “reveals that Tengah forest is not just a foraging ground for the species but most notably a breeding ground as well”.

As for the straw-headed bulbuls, they have become extinct in Thailand and parts of Indonesia and are facing a decline in Malaysia. It is estimated that at least 202 individual straw-headed bulbuls are distributed over multiple forest patches, including Tengah forest, in Singapore, which has become a crucial global stronghold for preventing them from becoming extinct in the wild. It would be tragic if such critically endangered species were to disappear altogether in the wild right under our nose due to our neglect to take care of ecological connectivity (just like how the large forest gecko and cream-coloured giant squirrel became extinct after Bukit Timah expressway (BKE) was built in the 1980s) when we have the knowledge and the means to protect them and their natural habitats.

This video has recorded the songs of the critically endangered straw-headed bulbuls in the eastern part of Tengah forest next to Brickland Road. It also shows a baya weavers’ nesting tree next to a trail within the vicinity.

Notably, the presence of eagles (also known as raptors or birds of prey), which are apex predators at the top of a food chain, indicates a healthy, thriving ecosystem in Tengah forest, where there exists a complex food web consisting of plant producers, microorganisms, herbivores, carnivores and omnivores. Also, the endangered changeable hawk-eagles, near-threatened grey-headed fish eagles and near-threatened long-tailed parakeets are forest-dependent native wildlife, hence their populations may be adversely affected if we continue to destroy our secondary rainforests, such as Tengah forest, and replace their natural feeding and breeding grounds with parks, gardens and roadside trees around concrete buildings.

Like Mr Lim Liang Jim, Group Director of National Biodiversity Centre who oversees NParks’ Nature Conservation Masterplan, said:

“We really don’t know at this point in time how species interrelate. So, it could even be a butterfly effect. If you lose one small species, you will never know what it will result in the long term to the health of the forestry.”

(“It’s In Our Nature: Saving Our Wildlife“, Channel News Asia Documentary Episode 2)
(Note: The aforementioned insects, birds and mammals are just some examples of the numerous important native wildlife in Tengah forest. Do refer to Nature Society Singapore (NSS)’s Position Paper on HDB’s Tengah Forest Plan here for more details on its flora and fauna.)

4. We need sizeable wildlife corridors and core habitat areas in Tengah forest in order to maintain a healthy ecosystem that benefits humans, flora and fauna.

As of early May 2021, about 30% or more of Tengah forest (or about 210 ha or more) is estimated to have been cleared so far. It is hoped that at least 30% to 50% of the original forest will be preserved for its indispensable ecosystem services. (Source: Global Forest Watch)

Firstly, while it is somewhat encouraging that the town planners have set aside 50 ha out of 700 ha to create a wildlife corridor of 100 m wide in the Tengah forest town development plan to facilitate animals’ movements as a connector, NSS feels that its effectiveness in helping the wildlife adapt to the change with this corridor is questionable.

According to NSS, the 100 m width will not be enough to mitigate disturbances for wildlife because 50 m is the standard buffer for a forest habitat on all flanks and there will not be any interior space. This will be tragic for the rich wildlife currently inhabiting the area.

Secondly, it is worrying that under the HDB’s plan, only up to 10% of Tengah’s original forest is retained. This means that half of the species there could be wiped out, based on an ecological rule of thumb, the NSS said. Even though HDB said that some 20% of the land in Tengah will be set aside for “green spaces”, the replanted young trees and crops in man-made parks and community gardens and farms cannot substitute the regenerating secondary forest in terms of ecosystem services and biodiversity support.

Based on current estimates, Bukit Batok is rightfully Singapore’s unofficial “forest town”, with the largest percentage of forest cover at 17%. While it is an admirable goal for Tengah to become Singapore’s first smart and sustainable town, it is not appropriate to project Tengah as Singapore’s first “forest town” when only 50 ha out of 700 ha (or a mere 7%) forest cover will be preserved, which is much less than the forest cover in Bukit Batok. (Base map: NParks)

Thirdly, if we were to consider the percentage of forest cover found in housing estates in Singapore, Bukit Batok actually tops the list. It is estimated that Bukit Batok has 17% forest cover, because about 190 ha out of a total area of 1,113 ha is occupied by the forests in Bukit Batok Town Park (77 ha), Bukit Batok Nature Park (36 ha), Bukit Batok Hillside Park area Hill 1 and Hill 2 (30 ha), Bukit Batok East Forest (30 ha) and Bukit Batok Central Nature Park (17 ha).

Thus, it would be incongruous to proclaim Tengah as Singapore’s first “forest town” when its planned forest cover of a paltry 50 ha pales in comparison to that of its neighbouring town Bukit Batok. At this point, credit must be given to the town planners for having set aside 190 ha of the total area of Bukit Batok for the forests. Bukit Batok is a role model for other towns to emulate for its wild green spaces that provide essential ecosystem services and support biodiversity. It is also hoped that no further deforestation should be carried out in Bukit Batok after the unfortunate clearing of part of Bukit Batok Hillside Park area in February 2021 for housing development because the forests there are vital for ecological connectivity.

At the same time, we need to ask ourselves: “Will the word “forest” in the name “Tengah forest town” be merely used as a form of tokenism? Or will it be prioritised to honour the native species whose previous generations have existed and used the forest as a habitat and ecological corridor long before our forefathers arrived on this island?” If it is the latter, then we need to ensure that Tengah “forest town” lives up to its billing by preserving at least 30% to 50% of the original forest cover. May we refer to the map showing the two core areas for wildlife as proposed by NSS below?

Tengah Forest core habitat areas with eco-links for optimal connectivity between Western catchment area and Central catchment area, as proposed by NSS. The approximate locations of some native wildlife sightings from around 2017 onwards are based on various sources such as NParks, NSS, Saniroz and Jimmy. Altogether, the core areas and Tengah Nature Way should take up at least 200 to 300+ ha of the total area of 700 ha, in order for Tengah forest to continue to provide optimal ecosystem services and support biodiversity for ourselves and our future generations. (Base map: Nature Society (Singapore), Photo of pangolin is from Wikimedia, all other photos by Jimmy Tan)

As proposed by NSS’s position paper on Tengah Forest, “the eco-links/bridges that should be created as the essential part of the Tengah Nature Way (TNW) need to be set up first — prior to the further clearing of the forest after Phase 1. This will at least allow the wildlife to disperse to whatever available green refuges outside the Tengah development zone. Otherwise, the problem of wildlife roadkills will be re-enacted as in the tourism development at the Mandai Lake Road recently. Most importantly, some core areas must be designated and left untouched for the future survival of the wildlife within the Tengah Forest itself — so that some, if not all, of the forest-affiliated species recorded there will still have a home for their long-term survival”.

“The Tengah Nature Way is the culmination of the first ever large-scale scheme to promote ecological connectivity, guided with ecological principles, in our town planning processes and we are certainly heartened by this bold plan, but given the rich biodiversity that exists at Tengah Forest, more should be done in terms of biodiversity protection for both resident and migratory species through the setting aside of some parts of the forest as core habitats.”

Nature Society’s Feedback on HDB’s Tengah Baseline Review” (June 2020)

5. We need to focus on redeveloping alternative sites or brownfield sites such as underutilised lands and abandoned schools etc, in order to achieve a better and more sustainable future for ourselves and our future generations

As mentioned earlier, we should also focus on redeveloping brownfield sites within reasonable distance from existing town amenities and infrastructure, such as vacant lands (such as mowed lawns in Bukit Batok, Jurong, Choa Chu Kang, etc), underutilised lands (such as open carparks), abandoned schools (such as the now defunct Jurong Junior College), etc, as well as building taller apartment blocks (within the vicinity and/or elsewhere in Singapore) where possible in order to make up for any shortfall of planned flat units.

Instead of clearing the remaining parts of Tengah forest, we should focus on redeveloping underutilised lands in other parts of Singapore. The graph shows an overview of the utilisation rate of State land in aggregate form. (Source:

Just as the SG Green Plan 2030 advocates that “Reduce, Reuse and Recycle” will become a norm for citizens and businesses, with a national strategy to address e-waste, packaging waste and food waste, we should apply the same 3R principle for recycling our existing built-up lands in order to conserve Tengah forest (and other secondary forests such as Clementi forest, Dover-Ulu Pandan forest, Bukit Brown forest, Pang Sua woodlands, Kranji forest, Sembawang woods, etc) as much as possible. This will ensure that sustainable development will be a living reality for us all. In fact, the following statement released by the Ministry of National Development also supports the move to recycle existing built-up lands.

“In the past, we could build new homes on swathes of undeveloped open land. Now, after 55 years of building and development, there are far fewer of these, and it has become more challenging to balance competing uses for land. In order to continue providing good homes for Singaporeans, we will have to recycle previously developed land.”

Indranee Rajah, Second Minister for National Development, “Striking a balance in building HDB flats in prime locations” (10 June 2021)
Besides abandoned schools and other underutilised lands around the vicinity, alternative sites for development may include the mowed lawns (or vacant cleared lands) along Pan-Island Expressway west of Tengah forest, the mowed lawns along Brickland Road east of Tengah forest, as well as the empty plots of land opposite Bukit Batok Hillside Park area. The empty plot of land between Dulwich College and a cluster of BTO flats along Bukit Batok Road may also be considered as an alternative site. NSS has also suggested in their position paper on Tengah forest to consider the area that will be made available at Paya Lebar Air Base for development in about a decade’s time. Granted that some of these plots of land might have been reserved for other uses such as schools, commercial work spaces and places of worship, the post-Covid era, in which school mergers (amid falling birth rates), home-based learning, online shopping, remote working and live-streaming religious services, classes, prayers and festivals have become the new normal, may render such traditional land uses redundant, or at least, less important. (Map by Global Forest Watch; photos by Jimmy Tan)

Last but not least, it appears that the upcoming Tengah forest town is designed not so much to accommodate genuine home buyers who may be facing prospects of homelessness, but rather to appeal to property investors. The article “Residential hotspots: Districts shaping up to be interesting investment bets” (1 April 2021) reveals such intent with key words like “investors”, “home upgrading”, “property market”, etc. For example, it states “Home-owners in Tengah are likely to look towards the nearest growth centre, JLD (Jurong Lake District), for home upgrading opportunities after serving out their minimum occupation periods (MOPs). While there are no current launches in the JLD, projects such as Parc Clematis and Clavon have seen positive reception from the market as investors buy into the growth potential of the JLD.”

This trend of home upgrading and property investment shows that public housing today is a far cry from what it used to be in the 1960s when many people had lacked safe housing with proper sanitation. Hence, is it justifiable that we continue to sacrifice our few remaining secondary forests to build more BTO flats instead of redeveloping underutilised lands? We are talking about existential threats to our native flora and fauna because it is a matter of life and death for them, whereas for many of us, it is just a matter of material comfort and convenience rather than basic survival or a real housing crisis.

In other words, the proposed development of Tengah forest town seems to be a case of “induced demand” for public housing. There seems to be a growing trend that many people buy BTO flats not because they have no place to live or have a genuine need to move out of existing homes, but rather because more supply of flats invites people to buy property for upgrading and investment.

In the context of climate emergency and biodiversity loss, even if there are people who have a genuine need for new housing or if they want to upgrade and invest in property, it should be better for them to consider resale flats, private property, etc, or at the very least, choose locations where BTO flats are built on existing built-up lands such as mature housing estates, rather than our precious few remaining greenfield sites, such as secondary forests like Tengah forest, Dover forest, etc.


In view of the sheer importance of Tengah forest for dealing with climate emergency and biodiversity loss as well as improving our quality of life, it would be very much appreciated if the authorities could:

  1. preserve the rest of Tengah forest as much as possible, or at least 30 to 50 percent of its original 700-ha size (or 210 to 350 ha) for purifying the air, cleaning the soil, removing pollutants, cooling the urban heat island effect, supporting biodiversity, preventing/mitigating the risk of floods, zoonotic viruses, dengue diseases, saving electricity usage for air-conditioning, enhancing our physical and mental health etc, thereby potentially saving billions of dollars of public funds and personal/household expenses, in terms of healthcare, socioeconomic and environmental costs.
  2. allocate the aforementioned two core habitat areas within Tengah forest to serve as essential resting/feeding/breeding spaces for wildlife, as proposed by NSS
  3. designate eco-links in both the western and eastern parts of Tengah forest to facilitate safer and easier movement of wildlife along the ecological corridors and nature areas between Western catchment areas and Central catchment areas
  4. ensure that the wildlife moving along the long, narrow Tengah Nature Way are protected from traffic noise from the expressway and potential human disturbances from the surrounding new/upcoming residential areas as much as possible
  5. release the latest EIS report on the north of Tengah to Nature groups and members of the public for our feedback and review when it is ready for early engagement in the planning and development process, before any further development work starts and before any developer is awarded the tender for any construction project done in Tengah forest.

The last point is in line with the key changes made to the existing environmental impact assessment (EIA) framework in 2020, which include the following:

“The third change to the framework will see the planning process – and not just the development work itself – become more sensitive to Singapore’s natural environment. This will be done through earlier engagement with nature groups in the planning and development process, and through the introduction of a course on basic ecology and the EIA process for planners from development agencies.”

“Development works in Singapore to be more sensitive to wildlife under changes to EIA framework” (25 October 2020)
It is noteworthy that fig trees make up 90% of the 159 significant large trees recorded in Tengah forest. They are nutritious food sources for humans and animals, and they are also known to restore forests and biodiversity. It is worth reiterating that planting trees in place of a destroyed forest is not the same and will not achieve the same results. The root fungal network that a forest has is ecologically important for natural regeneration, according to researchers such as forest ecologist Suzanne Simard. (Photo by Jimmy Tan)

“We have to look at forests as a whole and not in compartments. You cannot talk about intact forests without talking about the wildlife that lives in the forest. So even if you preserve a green corridor or a strip of greenery, but if it’s an inadequate space for wildlife to really thrive in, that’s not fully protecting our biodiversity.” 

Dr Andie Ang, a Mandai Nature Research Scientist and President of the Jane Goodall Institute (Singapore), “After Dover, Will Clementi Forest Be Next On The Chopping Board?” (5 June 2021)

P.S. May I invite you to click on the petition link here to support the preservation of at least 30 to 50 percent of Tengah forest for protecting our biodiversity and tackling climate emergency?