Singapore's Green Paradox: A Million New Trees as Secondary Forests Make Way for Development

More Trees, Less Forest?

Singapore plans to plant one million additional trees by 2030, yet secondary forests that have grown over decades are being cleared for public housing, industrial parks and infrastructure. Up to 7,331 hectares, roughly 10 percent of the country's land area, could be developed under current urban planning masterplans over the coming decade. Much of that land is covered by secondary forest.

The contrast sits at the heart of Singapore's ambition to become a City in Nature. New trees, small urban forests and greenery on buildings can cool streets and provide space for wildlife. Existing forests already perform those jobs across larger areas, with ecosystems that have developed through years of natural recovery.

Singapore has greened approximately 47 percent of its spaces since the 1960s. Its parks, gardens and nature reserves support surprising biodiversity on an island of just 728 square kilometers. Secondary forests account for 18 to 20 percent of its total area, but have limited protection against development needs driven by a growing population.

Environmentalists call this tension a green paradox. The city-state is expanding greenery while losing established wooded habitats. Its reputation as a lush urban oasis, with trees around skyscrapers and vertical gardens climbing walls, exists alongside the clearance of forests for new neighborhoods and economic activity.

The choices involve more than the number of trees planted. They also concern where trees grow, which species are chosen, how much land remains connected as habitat, and whether newly planted greenery can supply the cooling, water management and wildlife support of an established forest.

How Abandoned Land Became Forest Again

Singapore lost most of its original primary forest cover during the early 1800s, when colonial agriculture, particularly rubber and gambier plantations, spread across the landscape. By independence in 1965, much of the island consisted of degraded agricultural land and urban sprawl.

Founding Prime Minister Lee Kuan Yew promoted the Garden City concept as a way to improve quality of life and strengthen economic competitiveness. Singapore's subsequent transformation combined deliberate planting with natural regeneration on land that people stopped farming or occupying.

Anuj Jain, director at the biomimicry consultancy bioSEA, explained how quickly vegetation can return when abandoned land is allowed to recover:

So, if you leave the land right, very quickly, it becomes secondary forest.

Secondary forest is woodland that grows back after earlier vegetation has been cleared or disturbed. In Singapore, much of it developed over abandoned agricultural land and villages. Over decades, these areas became complex ecosystems supporting wildlife ranging from endangered birds to rare millipedes.

Primary forest is the original forest that survived clearance. Singapore retains a small percentage of it within its four gazetted nature reserves, meaning reserves formally designated for protection. Secondary forests occupy nearly a fifth of the island, while other green spaces include managed parks, gardens, vertical gardens and rooftop planting.

The shift from Garden City to City in Nature reflects an ambition to make greenery function as habitat and environmental infrastructure, rather than mainly decoration. Critics argue that the change remains incomplete while established forests continue to face development.

The main milestones show how Singapore's landscape and greening priorities have changed:

• Early 1800s: Colonial agriculture cleared most original primary forest cover.
• 1965: At independence, Singapore was largely deforested, with degraded agricultural land and urban sprawl.
• March 2025: City Developments Limited established a 260 square meter microforest at City Square Mall.
• Within a year of its establishment: The City Square Mall microforest doubled in size.
• 2030: Singapore's target year for planting one million additional trees.

A Small Forest in Little India

City Developments Limited (CDL) has become a pioneer in Singapore's use of microforests, small areas planted densely to imitate the structure of a natural forest. Its project at City Square Mall in Little India began in March 2025 with an area of 260 square meters, then doubled in size within a year.

The planting uses the Miyawaki method, which brings trees and other vegetation together in a compact space. The aim is to create a small forest environment within an urban setting, supporting wildlife and providing cooling where extensive woodland cannot fit.

Researchers from the National University of Singapore (NUS) collected data showing that temperatures inside the microforest were up to 5 degrees Celsius lower than in surrounding roadside areas at midday. Cooling extended 1 to 2 meters beyond the forest edge.

Acoustic monitoring, which uses recordings to detect wildlife through its sounds, identified 31 bird species. They included oriental pied hornbills, which were once extinct in Singapore. The findings show that even a small patch of densely planted vegetation can attract a range of birds within a busy urban neighborhood.

Environmental DNA sampling suggested approximately 70 percent greater species richness than in nearby grass patches. This technique looks for genetic traces left by living things. Species richness means the number of different species detected, giving researchers a way to compare the variety of life in the forest planting and the grass nearby.

CDL's project therefore provides a concrete example of the gains possible when a small urban plot becomes more ecologically varied. Its measurements also show the importance of scale: the strongest temperature reduction was inside the planting, with a limited cooling reach outside it.

Why Forest Size Matters for Cooling

Professor Veera Sekaran of NUS's Regenerative Agritech Centre, who designed CDL's microforest, says these projects need a minimum of 150 to 200 square meters to cool their surroundings effectively and support meaningful biodiversity. A microforest needs enough room for its vegetation to function together as habitat.

Research indicates that forests covering more than 10 hectares can cool their surroundings by 1 degree Celsius within 330 meters of their perimeter. That reach is much greater than the 1 to 2 meters measured beyond the edge of the City Square Mall microforest.

The temperature figures describe different effects. The reduction of up to 5 degrees Celsius at City Square Mall was measured inside the microforest against surrounding roadside areas at midday. The 1 degree Celsius figure for larger forests describes cooling extending into their surroundings.

Singapore's microforests can bring shade, vegetation and wildlife into tightly developed places. Larger secondary forests supply those benefits over much wider areas. Their loss therefore involves a change in the reach and scale of environmental services, even while smaller green spaces are being created.

The central planning challenge is how to combine urban planting with the retention of established forest. Microforests offer useful additions to the city, while extensive woodland carries ecological functions built over decades of regeneration.

Choosing Plants for More Than Appearance

Sekaran has urged Singapore to reduce its reliance on imported ornamental plants and make greater use of native vegetation adapted to local conditions. His concern is that much urban greening still favors decorative appearance over the needs of wildlife and the demands of a hotter climate.

Ornamental plants can struggle as Singapore's heat increases. They may attract pests and diseases and require frequent maintenance, including pruning, grass cutting and fertiliser application. Native species are adapted to local conditions and extreme heat, support richer biodiversity and require relatively little intervention once established.

Sekaran is applying that approach while developing a masterplan for the 150-hectare NUS campus. He wants indigenous species and spontaneous regeneration to replace more of its manicured landscapes. Spontaneous regeneration means allowing vegetation to grow naturally, rather than shaping every patch through repeated planting and trimming.

Examples include the critically endangered rambai tree, Baccaurea motleyana, and the tongkat ali tree, Eurycome longifolio. Such plants can survive better in urban conditions while providing food for local wildlife and medicinal value for people.

The Building and Construction Authority's (BCA) Green Mark certification scheme already awards points for using Southeast Asian species and creating wild landscapes. Sekaran argues that native plants should receive more weight in the assessment.

BCA maintains that Green Mark takes a comprehensive approach, balancing several measures. The practical challenge also extends to plant supply: local nurseries often struggle to obtain native species compared with imported ornamentals. Changing the landscape therefore requires suitable plants to be available as well as a willingness to use them.

The Gaps in Forest Protection

Singapore has no comprehensive Environmental Impact Assessment (EIA) law requiring systematic evaluation of ecological consequences before development approval. An EIA examines how a proposed project could affect its surroundings, including habitats and wildlife, before decisions are made.

Tools exist to assess which secondary forest plots should be conserved or developed. Environmental advocates have nevertheless called for stronger legal frameworks to formalize protection processes. Their concern is that valuable habitat can remain exposed to development despite its ecological role.

Singapore also has not adopted biodiversity offset mechanisms. In countries that use them, developers clearing forest may be required to compensate by protecting or restoring ecological areas elsewhere. The intention is to account for the habitat lost when construction proceeds.

Without such mechanisms, forest loss in Singapore is rarely compensated on an equivalent basis in ecological function or timing. An established forest already contains mature vegetation and developed relationships among species. Restoration and new planting require time to grow and recover those functions.

The One Million Trees programme largely focuses on peripheral parts of the island rather than replacing particular habitats lost within the urban core. Its planting target sits alongside decisions about individual forest sites, each with its own wildlife, location and role in the surrounding landscape.

The absence of stronger legal requirements leaves conservation decisions exposed to immediate economic pressures. Calls for ecologists to take a greater role in certification and planning also reflect concern that engineers alone should not determine how nature fits into Singapore's construction industry.

Learning to Accept Wilder Greenery

Singapore's Garden City model encouraged appreciation for tidy parks and manicured landscapes. Acceptance of spontaneous, less controlled vegetation has been more limited, even as the City in Nature ambition calls for richer habitats.

Building owners can resist naturalistic planting because it may bring wildlife close to residents and other urban users who feel uncomfortable with such encounters. The question of what to plant is therefore also a question of what kind of nature people are willing to live beside.

The COVID-19 pandemic brought a change in some attitudes. Maintenance crews could not reach certain sites during lockdown periods, allowing large areas of greenery to grow wild. Sekaran described how residents responded to that change:

During Covid, more people began to sit in nature and appreciate that spontaneous greenery was not so bad. We started to move away from the manicured landscapes we had been used to under the 'garden city' model.

CDL's microforest project has also involved residents through the iNaturalist platform. Citizen science participation recorded 65 observations across 46 species, giving people a direct role in noticing and documenting the life around the planting.

An adjacent Eco-Train, a repurposed subway carriage with air conditioning, was designed to teach children about forest ecosystems. It has attracted 70,000 visitors since March 2025. Together, the carriage and citizen observations connect the small forest with public learning.

These activities aim to build recognition of nature's value beyond appearance or immediate usefulness. A less manicured patch can become somewhere to observe wildlife and understand how living things share an urban space.

The Cost of Planting and the Cost of Losing Forest

Establishing CDL's microforest cost approximately S$69,000 (US$54,000). Much of the expense came from the compressed timeline of two months, which required mature trees to be planted alongside saplings.

Operational costs fall sharply compared with traditional landscaping. Native species can remove the need for constant pruning, pesticide application and irrigation. The project therefore illustrates a difference between the initial expense of creating a forest planting and the continuing expense of maintaining ornamental grounds.

Secondary forests already supply services that would otherwise need to be replaced or managed in other ways. They absorb and store carbon, help clean the air, manage water and retain stormwater. These functions contribute to the city's daily environmental needs alongside their role as wildlife habitat.

As climate change intensifies rainfall patterns, Singapore increasingly relies on green areas to collect water and direct it toward retention ponds that act as urban wetlands. Vegetation and land able to hold water form part of that system.

Replacing forest functions with engineered solutions carries costs that often exceed the immediate profits from development. The financial comparison therefore extends beyond the value of a cleared site or the expense of planting new trees. It includes the continuing work that an existing ecosystem performs.

Housing demand creates another powerful pressure. Singapore has limited land and a growing population, leaving the government to balance conservation with accommodation. Clearing secondary forest for public housing meets citizen needs through development that has democratic support.

The competing uses are both tangible: homes and infrastructure on one side, established habitat and environmental services on the other. Decisions about forest land determine how those needs are distributed across the island.

What Singapore's Green Choices Add Up To

Singapore's greening achievements and its forest losses are unfolding together. Approximately 47 percent of its spaces have been greened since the 1960s, while secondary forests covering 18 to 20 percent of the island remain vulnerable to development. Land that could be developed under current masterplans totals up to 7,331 hectares over the coming decade.

The City Square Mall microforest offers measurable benefits: cooler conditions within the planting, birds detected through acoustic monitoring and greater species richness than nearby grass. Its limited cooling reach outside the forest also shows why the size and location of green areas matter.

Native planting, lower maintenance requirements and greater public acceptance of wild vegetation could make urban greenery more useful to wildlife and residents. Legal protection, ecological assessment and the treatment of habitat losses shape what happens to the larger forests that already exist.

The million-tree target gives Singapore a clear planting deadline of 2030. The broader challenge is to retain the functions of established forests while providing homes, workplaces and infrastructure on a small island. Success depends on the quality and extent of nature that survives, as well as the number of trees added.

What to Know

• Singapore aims to plant one million additional trees by 2030 while secondary forests are cleared for housing, industry and infrastructure.
• Secondary forests cover 18 to 20 percent of the island. Up to 7,331 hectares could be developed under current masterplans over the coming decade.
• CDL's City Square Mall microforest began at 260 square meters in March 2025 and doubled in size within a year.
• NUS researchers measured temperatures inside the microforest up to 5 degrees Celsius below surrounding roadside areas at midday, with cooling extending 1 to 2 meters beyond its edge.
• Monitoring detected 31 bird species, while environmental DNA sampling suggested approximately 70 percent greater species richness than nearby grass patches.
• Sekaran advocates more native planting, less reliance on ornamental species and greater acceptance of naturally regenerating landscapes.
• Singapore lacks a comprehensive EIA law and has not adopted biodiversity offset mechanisms.
• Established forests provide carbon storage, air purification, water management and wildlife habitat alongside the city's newer planting projects.