The trees we don’t count: How Assam’s disappearing homestead forests are becoming a climate crisis

BHRIGU KUMAR KALITA

There was a forest behind our home, though we rarely called it a forest. To us, it was simply the bamboo grove and some plants where morning light filtered through trembling leaves, where birds announced the arrival of dawn, and where the wind carried the fragranceof wildflowers. Narrow paths disappeared beneath fallen leaves, leading to ponds, gardens, and forgotten places filled with moss. We gathered fallen branches, listened to the rain, and watched fireflies glow among the trees. It was not a distant wilderness but a familiar part of our everyday life – a living presence that protected, surrounded, and quietly shaped our childhood.

Long before climate change became a scientific vocabulary, Assamese households had their own ways of understanding the relationship between a home and its surrounding landscape. The ancient traditional verses of Dakar bason like –

-describe an ideal bari (backyard) not simply a pice of land with a house on it, but as an organised living space where crops, animals, trees, water, sunlight and shade had their place. Behind these lines lies something more than an old description of rural life, where different elements were arranged not independently but in relation to one another.

We rarely call these places forests, but perhaps that is precisely the problem. Across Assam, trees have long stood within and around human settlements – mango, jackfruit, neem, areca, bamboo and many others – forming what modern ecological research increasingly recognised as homegarden agroforestry systems. A 2024 study of 192 homegardens in the Brahmaputra valley, for instance, documented 101 tree species, where 39.58% of gardens had more than 10 vegetable varieties, 68% had at least one bamboo variety, 76% had at least one banana variety, and 20% contained ponds.

A 2014 peer-reviewed study of Upper Assam home-gardens surveyed home-gardens ranging from about 535 to 4013 m², with an average size of 1724.9 m³. Researchers recorded 156 tree species among 323 plant species, 106 herbs, and 61 shrub species in home-gardens. These trees are not merely decorative objects placed around buildings. Their canopies intercept sunlight, provide shade, and release water through evapotranspiration, helping regulate local thermal his is not merely anAssam-specific issue; it reflects a wider national blind spot concerning  Trees Outside Forest (TOF).

The Indian state of Forest Report 2023 estimates that TOF covers approximately 30.70 million hectares, accounting for 37.11% of India’s total forest and tree cover. The country’s total growing stock is estimated at around 6430 million cubic meters, of which nearly 1951 million cubic meters lie outside recorded forest areas. Studies project that India’sTOF systems could sequester approximately 3.4 gigatons of CO₂ by 2040, contributing significantly to the country’s climate commitments.

What this trees actually provide?

The bamboo clump behind the house, the jackfruit shading the courtyard, the mango, areca-nut and banana plants along the boundary-these “invisible forests” are far more than domestic decoration. Globally, trees outside forests (TOF) and homegarden agroforestry systems are now recognised as major carbon sinks, storing anywhere from 15 to over 150 Mg C/hain biomass and soils, with meta-analyses showing agroforestry soils holding ~19% more carbon than treeless croplands.

In cities, they function as distributed cooling infrastructure: European modelling shows that reaching 30% tree canopy can lower urban temperatures by ~0.4°C on average (up to several degrees locally) and cut heat-related deaths by about 40%, while Guwahati-specific work already records ~5°C cooler surfaces under existing canopy even as the city’s green cover shrinks from 23.8% to 21.3%.

At the same time, homestead trees stabilise soils, improve infiltration, reduce runoff and erosion, and support rich agrobiodiversity-Assam’s Brahmaputra Valley homegardens alone host over 100 tree species, including endangered and culturally vital plants, while providing fruit, bamboo, fodder and medicinal resources to ~85% of rural households. In other words, every jackfruit, bamboo clump and mango tree we remove is not just a lost shade patch; it is a small but real piece of climate, water, food and cultural infrastructure quietly erased from the landscape.

Homegardens are also an important source of household income, not merely ecological spaces. A 2025 assesment across Assam’s five agro climatic zones found that produce from homegardens contributes approximately 43% of total househol income. For rural families, this diversity can reduce dependence on a single source of income while providing food and useful household resources. In cities also terrace gardening also get popular now.

Concrete replaces climate infrastructure: the thermal cost

As Assam’s homestead forests vanish, they are being replaced not by neutral space but by heat-amplifying concrete. In Guwahati, a 2024 microclimate study documented a 10.06% decline in canopy cover alongside a 13.46% increase in built-up area and 3.85% loss of open spaces, with land surface temperature rising as vegetation shrank (NDVI–LST correlation: −0.468 to −0.224).

Field measurements showed car-roof temperatures of 26.32°C without canopy versus 21.17°C under high canopy—a 5.15°C cooling effect from trees alone. The city’s area-weighted land surface temperature rose by ~1°C between 2020–2025, while green cover fell from 23.8% to 21.3% and built-up area expanded from 71.7% to 74.8%, pushing wards like 6 and 23 from “moderate” to “critical” heat-stressed categories.

Guwahati is not unique: globally, meta-analyses of 128 studies estimate urban trees reduce air temperature by 0.5–5.8°C and surface temperature by 2–12°C, while a 2026 Nature Communications study of 8,919 cities found existing canopy mitigates 41–49% of maximum potential urban heat-island effects. When homestead trees give way to concrete courtyards, paved roads and multi-storey buildings, Assam is not just losing shade—it is dismantling distributed cooling infrastructure that global science confirms can lower temperatures by several degrees and reduce heat stress for millions.

In rural Assam, a single ancestral homegarden with 60+ mature trees is now divided among brothers building separate homes—each retaining only 10–12 trees while clearing the rest for concrete foundations, parking, and expanded rooms. Across thousands of such fragmentations, 5–10% of homestead tree cover vanishes per generation, not from logging but from inheritance-driven subdivision.

Climate connections: cooling, carbon and health co-benefits

Assam’s homestead trees function as distributed climate infrastructure, delivering measurable cooling, carbon storage and health benefits. Global meta-analyses show urban vegetation can reduce particulate matter by 16.5–26.7%, NOₓ by 13.9–36.2% and SO₂ by 20.5–47.8%, while systematic reviews link greater tree canopy (more than grassland) to improved psychological wellbeing, cardiovascular health and lower cortisol levels.

In carbon terms, home-garden agroforestry systems store 40–80 Mg C/ha globally, with bamboo-based home-gardens in Barak Valley sequestering 1.20–1.46 Mg C/ha/year and contributing 84.6% of total carbon via soil pools. Scaling conservatively, Assam’s ~6.4 million home-gardens could store 25–51 million tonnes of carbon (equivalent to 94–188 million tonnes CO₂)-a massive, uncounted pool that rivals the 174 million tonnes CO₂ released from the state’s 2021–2023 forest loss.

Meanwhile, reaching 30% canopy cover in cities could cut heat-related deaths by ~40%, and in Guwahati, high canopy already provides ~5°C surface cooling.Car roofs without canopy reached about 26.32°C, compared with 21.17°C under high canopy coverage in the observations reported by the study. Afternoon air temperatures and mean radiant temperatures were lower by up to 4.9°C and 5.48°C, respectively, at stations with greater canopy cover. When homestead trees vanish, Assam loses not just shade but a multi-functional climate shield that global science confirms can cool cities, sequester carbon and improve human health simultaneously.

Are we measuring the wrong trees?

When we talk about forests, we measure forest cover, protected areas and reserved forests— essential metrics that answer one question: How much forest do we have? But they miss another: How much tree cover are people losing from where they live?

Globally, this blind spot is increasingly recognised. An 11-country comparative study found that trees outside forests accounted for more than 10% of national above-ground tree biomass in six countries, with Bangladesh reaching a striking 73%—demonstrating that a nation’s trees do not necessarily live inside forests. Africa’s FAO Open DEAL assessment identified ~7 billion trees outside forests across the continent, while a 2026 Nature Communications analysis of 8,919 urban areas estimated that existing tree cover already mitigates 41–49% of maximum potential urban heat-island effects, cooling land surfaces by an average of 2.13°C compared to built-up areas.

Yet these trees remain fragmented across institutions and poorly represented in national statistics. In Assam, the gap is stark: 101 tree species persist in just 192 Brahmaputra Valley homegardens, while Guwahati’s canopy has shrunk by 10.06% alongside a 13.46% increase in built-up area.

The question is no longer whether we can map mature trees inside settlements, bamboo groves, pond-side vegetation and village road canopy-satellite imagery and GIS make this increasingly possible. The question is whether we are counting them as part of the landscape that matters, or continuing to measure only the forests we protect while the trees we live with vanish unnoticed.

From conservation to tree-sensitive development

The answer does not have to be “stop building.” Assam’s towns and villages will continue to develop-families need larger houses, better roads, drainage and schools. The more useful question is: Can development happen without unnecessarily destroying mature vegetation?

Scientific evidence suggests this is not only possible but essential. A 2026 global synthesis of 1,590 agroforestry studies found that trees improve water regulation by +71%, soil organic carbon by +20%, and erosion control by +6% compared to treeless alternatives-but crucially cautioned that evidence strength varies by function and context, meaning local measurement matters.

In Guwahati, where canopy has declined by 10.06% alongside a 13.46% increase in built-up area, a house can sometimes be designed around an existing jackfruit rather than removing it; a village road can retain mature shade trees where engineering permits; a municipality can measure canopy alongside built-up area in ward-level planning. The distinction between a young ornamental sapling and a 30-year-old mango tree is not sentimental-it is ecological.

Global studies show that every additional 1 metre of tree height correlates with ~0.16°C lower land-surface temperature, meaning mature homestead trees provide cooling that saplings cannot immediately replicate. In Bangladesh, 419 plant species were recorded across just 402 homegardens, with 82% of species occurring in 50 or fewer gardens-demonstrating that biodiversity is distributed across many small private landscapes, not concentrated in protected reserves.

When these trees vanish for concrete courtyards or widened roads, we lose not just shade but decades of accumulated ecological function. Tree-sensitive development does not mean halting progress; it means recognising that a mature areca-nut grove, bamboo clump or pond-side jackfruit are community ecological asset worth mapping, measuring and designing around before they disappear irreversibly.

The tree we forgot to count: a call for reassessment

Return to the old mango tree. Perhaps it has stood beside a house for forty years. Children once climbed it. A family once waited for its fruit to ripen. Birds still arrive before sunrise. Its roots occupy a small piece of soil that has not yet been covered by concrete. On a satellite image, it may appear as one small patch of green.

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On a forest map, it may not appear at all. Yet multiply that tree by thousands of homes, villages, roadsides, ponds and courtyards across Assam, and the ecological picture begins to change. Our grandparents knew this intuitively. The Dakar Bachan instructed: “Bamboo to the north, jackfruit on the edges, mango in the centre-only then do we understand the work of a homestead.”

The proverb warned: There will be people only if there are trees.” These were not poetic flourishes; they were ecological design principles encoded in oral tradition.

Today, science confirms what tradition long held: trees outside forests mitigate 41–49% of urban heat-island effects, store 40–80 Mg C/ha in agroforestry systems, and support 101 species in just 192 Brahmaputra Valley homegardens.Yet these trees vanish from maps, statistics, and policy.

The recommendation is clear: Assam needs a homestead vegetation census-mapping mature trees, bamboo groves, pond-side vegetation and orchard patches alongside official forest cover. Municipalities should measure canopy percentage alongside built-up area in ward-level planning.

Developers should distinguish between a sapling and a 40-year-old jackfruit whose cooling, carbon and biodiversity functions have accumulated over decades. Perhaps the question is no longer simply how many forests Assam has left. Perhaps we should also ask: How many trees remain where people live?

Because some of Assam’s most important green spaces may never have been labelled forests at all-and if we do not count them now, we will not know what we have lost until the shade is gone, the birds have moved on, and the concrete has hardened beyond repair.

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