Himalayan Conifers Outstore Broadleaved Forests in Carbon Along Elevation Gradients

Deep in the mountains of northern India, an answer to one of climate science’s most practical questions is hiding in plain sight among the trees. A sweeping synthesis of more than two decades of research across the Indian North-Western Himalayas has revealed that coniferous forests, dominated by species such as deodar, blue pine and fir, store on average about 51 percent more biomass carbon per hectare than their broadleaved counterparts. The finding, published in Environmental and Sustainability Indicators, offers the most comprehensive regional picture yet of how carbon is distributed across one of the world’s most ecologically complex mountain systems, and it arrives at a moment when governments are scrambling to identify which landscapes can deliver the greatest climate mitigation returns.

The research team, led by scientists from the Indian Council of Forestry Research and Education network, compiled data from 112 peer-reviewed studies published between 2000 and 2022, covering the three Himalayan states of Jammu and Kashmir, Himachal Pradesh and Uttarakhand. The initial search retrieved 231 records, which the authors filtered through successive rounds of title, abstract and full-text screening. Studies of mixed conifer-broadleaf forests were excluded because the fifteen available datasets were too few to support robust comparison, leaving a clean division between the two major forest categories. The final database spans a geographical area of nearly 230,000 square kilometres, stretching from subtropical foothills to subalpine timberlines above 4,000 metres.

Methodological harmonisation was central to the exercise. Because individual studies reported biomass in tonnes, megagrams or quintals per hectare, the team standardised everything to megagrams per hectare. Where belowground biomass or carbon concentrations were missing, they applied Intergovernmental Panel on Climate Change default factors, assuming roots equal 30 percent of aboveground biomass and that carbon constitutes 47 percent of total biomass. The authors acknowledge that uniform conversion factors introduce uncertainty, since root-to-shoot ratios and carbon content vary with species, stand age and environment, but they argue that IPCC defaults provide a transparent and widely accepted basis for regional-scale comparison when species-specific coefficients are unavailable.

The headline result is striking in its consistency. Across all three states and nearly all altitudinal bands, conifer forests accumulated more biomass carbon than broadleaved forests. The gap was widest in Uttarakhand, where conifers held roughly 81 percent more carbon, and in Jammu and Kashmir, where the difference approached 68 percent. In Himachal Pradesh the margin narrowed to about 30 percent. The pattern reflects fundamental differences in tree biology: conifers such as Cedrus deodara, Pinus wallichiana and Abies pindrow are slow-growing, long-lived species with dense wood, allowing them to accumulate and retain carbon over centuries, whereas many broadleaved species grow faster but turn over biomass more quickly.

Among broadleaved forests, the tallest carbon champions were the moist sal-bearing forests of Uttarakhand, where mean total biomass reached 415.62 megagrams per hectare, and the oak and mixed coniferous forests of Himachal Pradesh, which peaked at 466.48 megagrams per hectare. Chir pine stands consistently anchored the lower end of the range, a consequence of the species’ lower wood density and its light-demanding habit, which produces open stands with wider spacing and fewer stems per hectare. In Jammu and Kashmir, subtropical dry evergreen forests recorded the highest broadleaved biomass at 184.90 megagrams per hectare, while moist temperate deciduous forests fell to just 97.81, their seasonal leaf fall and faster turnover hampering net carbon accumulation.

Conifer figures told an even more dramatic story. Uttarakhand’s moist deodar and blue pine forests averaged 626.10 megagrams of total biomass per hectare, the highest value in the entire synthesis, while dry deodar and subalpine fir forests reached 511.01. At the other extreme, the Neoza pine and dry temperate forests of Himachal Pradesh averaged only 90.22 megagrams, illustrating how sharply cold, arid conditions constrain productivity even among otherwise high-performing conifers. Biomass carbon followed the same trajectory, with temperate conifer groups in the Himalayan Moist Temperate category routinely storing between 171 and 228 megagrams of carbon per hectare.

Altitude emerged as a powerful but context-dependent driver. Broadleaved forests in Uttarakhand peaked in biomass and carbon between 2,000 and 3,000 metres, reaching 481.84 megagrams of biomass per hectare, before declining sharply above 3,000 metres where shorter growing seasons and colder temperatures limit growth. In Himachal Pradesh, broadleaved carbon peaked lower, between 1,000 and 2,000 metres. Conifers showed their own quirks: Uttarakhand’s conifer carbon peaked at 2,000 to 3,000 metres, while Himachal Pradesh recorded its highest conifer values, an extraordinary 701.05 megagrams of carbon per hectare, in the lowest elevation band. The authors caution that some of these anomalies may reflect uneven sampling rather than genuine ecological minima.

The state-level contrasts are equally revealing. Broadleaved forests achieved their highest mean total biomass in Uttarakhand at 417.88 megagrams per hectare, followed by Himachal Pradesh at 275.54 and Jammu and Kashmir at 238.62. For conifers the ranking inverted: Jammu and Kashmir led with 397.95 megagrams per hectare, ahead of Uttarakhand and Himachal Pradesh. The explanation lies in geography and climate. Jammu and Kashmir’s high, continental and relatively dry terrain favours conifer dominance, while its restricted subtropical zone limits broadleaved forest extent. Himachal Pradesh, spanning elevations from 350 to over 6,000 metres with well-distributed rainfall, hosts the greatest diversity of forest types in the region, seven broadleaved and eight coniferous categories.

Why do temperate conifers outperform? The synthesis points to a convergence of mechanisms. Slow growth and long lifespan mean carbon stays locked in trunks for decades or centuries. Dense wood packs more carbon into every cubic metre. Cooler temperatures at higher elevations suppress microbial activity and decomposition, extending the residence time of organic matter in both biomass and soil. Comparable patterns have been documented in boreal and temperate forests of northern Europe and Siberia, where conifer dominance produces some of the highest carbon densities on Earth. The authors also note that conifers’ extensive root systems, well adapted to cold, high-altitude environments, contribute substantial belowground storage that broadleaved systems do not always match.

The practical implications are considerable. The Indian Himalayan Region holds an estimated 5.4 billion tonnes of carbon and sequesters roughly 65 million tonnes annually, making it a cornerstone of India’s climate commitments. The new regional baseline allows policymakers to move beyond generic national averages and design site-specific management strategies. The authors argue that temperate conifer systems in mid-to-high altitude zones should be treated as priority areas for carbon conservation, while emphasising that both forest categories play distinct roles in the carbon cycle and that conserving them together is essential. They also flag the study’s limitations: literature-based syntheses carry risks of publication bias and heterogeneity, and future work should integrate soil organic carbon more systematically and validate estimates with remote sensing. Still, as mountain forests worldwide face warming temperatures, shifting precipitation and intensifying disturbance, knowing precisely where the carbon lives, and which trees guard it best, has never mattered more.

Subject of Research: Biomass and carbon storage variation in broadleaved and coniferous Himalayan forests along altitudinal gradients

Article Title: Variation in biomass and carbon storage in broadleaved and coniferous forests along altitudinal gradation and forest type

Article References: Panwar, P., Sharma, P., Bhardwaj, D., Kumar, K., Apshahana, K., Premkumar, K., Shahina, N., Abha Manohar, K., Sarkar, B. C., Singh, M., Shukla, G., Chakravarty, S., & Verma, M. R. (2026). Variation in biomass and carbon storage in broadleaved and coniferous forests along altitudinal gradation and forest type. Environmental and Sustainability Indicators, 32, Article 101553. https://doi.org/10.1016/j.indic.2026.101553

Image Credits: AI Generated

DOI: 10.1016/j.indic.2026.101553

Keywords: carbon storage, forest biomass, Himalayas, conifers, broadleaved forests, altitude, carbon sequestration, climate change mitigation, meta-analysis, Uttarakhand, Himachal Pradesh, Jammu and Kashmir