The research focused on plantations established in 2016 under Jan Van Yojna, a private-land social forestry scheme launched by the Government of Jharkhand in which beneficiaries plant timber and fruit trees on plots of 0.5 to 50 acres, with the state covering 75 percent of establishment and maintenance costs for the first three years. By December 2020 the scheme had created 172.77 acres of new plantation cover across Ranchi district, holding 15,849 trees. Yet despite its policy significance, no published quantitative evaluation of the scheme’s carbon storage performance had existed until now.

The team, led by Md Shahzad Ahmad of Ranchi University, selected two sites from 26 active plantations in Ranchi district. The first, at BUDMU, was a 2.2-acre polyculture of 652 trees spanning seven species: four timber species, teak (Tectona grandis), gamhar (Gmelina arborea), mahogany (Swietenia macrophylla) and shisham (Dalbergia sissoo), alongside three fruit trees, mango, amla and guava. The second, at ANGADA, was a 2.0-acre monoculture of 500 teak trees. Both sites sat on the shallow, red-brown lateritic soils of the Ranchi plateau and had been managed under the standard JVY protocol, with the beneficiaries maintaining complete year-wise tree counts and maintenance records from 2016 to 2020.

The methodology combined several established carbon-accounting techniques. Every tree at both sites was individually enumerated and measured for girth at breast height, from which diameter was derived, and heights were recorded with a clinometer. Tree volumes were estimated using species-specific regression equations published by the Forest Survey of India, converted to green weight with species-specific wood densities, and then to dry weight using oven-dry ratios. The carbon content of stem, branch and leaf tissues was determined by the modified Walkley-Black wet oxidation titration, run in triplicate with a coefficient of variation below five percent. Root carbon was estimated as 26 percent of the above-ground total, following allometric proportions documented for tropical trees. Finally, total carbon was converted to carbon dioxide equivalents using the IPCC Tier-1 stoichiometric factor of 44/12, or 3.667.

The results were unambiguous at the site level. The BUDMU polyculture stored 15.32 tonnes of carbon, equivalent to 56.19 tonnes of CO2, or 17.21 tonnes of carbon per hectare. The ANGADA monoculture stored 5.92 tonnes of carbon, or 21.71 tonnes of CO2, at 7.31 tonnes per hectare. Normalised by area, the polyculture’s advantage was 2.35-fold, slightly lower than the whole-site ratio of 2.59 because BUDMU also carried a higher stem density, 732 trees per hectare against 618. Per-tree carbon dioxide equivalent at BUDMU was 86.17 kilograms, nearly double the 43.42 kilograms at ANGADA, despite the polyculture holding only 30 percent more individual trees.

Perhaps the most ecologically revealing finding was that a single species drove most of the polyculture’s advantage. Gmelina arborea, a fast-growing pioneer with low wood density and heavy stem allocation, accounted for 58.80 percent of the BUDMU site’s carbon total, or 33.04 tonnes of CO2. Teak contributed 18.44 percent and shisham 10.92 percent, with the remaining four species collectively adding 11.85 percent. Intriguingly, when the researchers compared teak trees across the two sites, individual teak trees in the mixed stand were marginally heavier in carbon, 12.28 kilograms per tree against 11.84 kilograms at the monoculture. The authors suggest, cautiously, that this is consistent with a facilitative inter-specific effect, possibly involving reduced intraspecific competition or nitrogen enrichment from the leguminous Dalbergia sissoo, though the study did not directly test this hypothesis.

Component-wise analysis showed that stems dominated carbon storage in most species, following the pattern stem, root, branch, leaf. At BUDMU overall, 69.91 percent of carbon sat in stems, 20.63 percent in roots, 9.03 percent in branches and just 0.40 percent in leaves. Notable exceptions emerged in mahogany and amla, which allocated more carbon to branches than to stems, a pattern the authors attribute to the high architectural branching characteristic of these species at this young growth stage.

The team then translated the ecological measurements into economic terms under three price scenarios. Using Voluntary Carbon Market pricing of five dollars per tonne of CO2 at the conservative end and fifteen dollars per tonne for certified nature-based-solution projects at the premium end, the BUDMU site’s sequestered carbon carried a hypothetical value of 280.93 to 842.79 dollars, while ANGADA’s ranged from 108.56 to 325.68 dollars. Under India’s Green Credit Programme rate of 650 rupees per tonne, the combined domestic potential was 50,634 rupees. The authors stress repeatedly that these figures are hypothetical and illustrative: neither site has undergone additionality assessment, third-party verification or registration with any carbon standard, and the revised Green Credit Programme framework issues forestry-linked credits only after a post-plantation monitoring period and makes them non-tradable outside limited circumstances.

The study is equally candid about its limitations, which the authors argue should shape how the findings are used. With one plantation sampled per management type, plantation type and site are completely confounded, meaning the observed difference could reflect species composition, underlying site quality, planting density or management history, and the design cannot statistically separate these contributions. The two sites were also purposively selected as the best-surviving examples from a scheme that experienced substantial attrition: only 26 of 78 original beneficiaries in Ranchi district remained active by 2020, with roughly 18 percent plant survival scheme-wide, and only four active sites retained 400 or more surviving trees. Sensitivity analyses varying the root-to-shoot proportion between 20 and 30 percent and the carbon factor by ten percent produced an indicative uncertainty envelope of roughly eight to twelve percent around the headline figures, applied symmetrically at both sites.

Even so, the findings carry real weight for policy. India’s updated Nationally Determined Contribution commits the country to creating an additional carbon sink of 2.5 to 3.0 billion tonnes of CO2 equivalent through forest and tree cover by 2030, and Jharkhand suffers among the highest rates of forest degradation in the country. The authors suggest, as a hypothesis for further testing rather than a formal recommendation, that plantation designs combining a fast-growing carbon sink like Gmelina arborea with nitrogen-fixing timber trees and fruit species could optimise carbon, livelihood and biodiversity outcomes simultaneously, since the fruit trees provide interim household income during the timber rotation. They recommend a replicated, multi-site carbon-monitoring programme across a stratified sample of active JVY sites before such a design becomes departmental guidance, and they note that any carbon-finance engagement would need to aggregate many smallholder plots into a single project to make monitoring and verification costs proportionate to the modest credit volumes each individual plot generates. If those hurdles can be cleared, the BUDMU and ANGADA comparison suggests that the species mix written into a planting plan may matter as much as the act of planting itself.

Subject of Research: Comparative carbon storage and green economy valuation of polyculture versus monoculture plantations under a social forestry scheme in Jharkhand, India

Article Title: Comparative biomass carbon storage, CO2 mitigation potential and green economy valuation of polyculture and monoculture plantations under the Jan Van Yojna social forestry scheme in semi-humid tropical Jharkhand India

Article References: Ahmad, M. S., Singh, U. S., & Naaz, N. (2026). Comparative biomass carbon storage, CO2 mitigation potential and green economy valuation of polyculture and monoculture plantations under the Jan Van Yojna social forestry scheme in semi-humid tropical Jharkhand India. Discover Forests, 2(1), Article 79. https://doi.org/10.1007/s44415-026-00142-4

Image Credits: AI Generated

DOI: 10.1007/s44415-026-00142-4

Keywords: carbon sequestration, social forestry, polyculture, monoculture, Tectona grandis, Gmelina arborea, Jharkhand, Jan Van Yojna, carbon credits, Green Credit Programme, IPCC Tier-1, tropical plantations

The research, led by scientists at the ICFRE-Institute of Forest Productivity in Ranchi, began with an ambitious field campaign spanning four consecutive fruiting seasons between 2021 and 2024. Survey teams crisscrossed four agro-climatic zones, from the Eastern Plateau and Hills through the Lower and Middle Gangetic Plains to the Eastern Himalaya, searching natural forests, forest fringes and farm boundaries for exceptional individuals. Using standard phenotypic selection criteria employed in tree breeding worldwide, they identified 434 Candidate Plus Trees, or CPTs, selecting trees that towered over their neighbors in height, girth and clear bole length while remaining free of pests, diseases and mechanical damage. The resulting collection revealed striking phenotypic variation: tree heights ranged from just 4.6 meters to an impressive 32.67 meters, while girth at breast height spanned from 24.4 centimeters to a remarkable 347.5 centimeters, reflecting a mixture of juvenile and mature individuals across the landscape.

Geography shaped the harvest of selections in revealing ways. The Eastern Plateau and Hills zone, which holds the bulk of the region forest cover, yielded 331 of the 434 candidate trees, while the Eastern Himalayan region contributed 57 and the Lower Gangetic Plain 37. The Middle Gangetic Plain in Bihar, where forest cover stands at only 7.84 percent according to the India State of Forest Report 2021, produced just nine selections, a sobering reminder of how habitat loss narrows the genetic options available to breeders and conservationists. Interestingly, the few trees found in the Middle Gangetic Plain showed comparatively high mean values for both height and girth, which the researchers attribute to the nutrient-rich alluvial soils of the Gangetic floodplain, a hint that environment and genetics interact closely in shaping the species growth performance.

To peer beneath the bark and into the DNA, the team genotyped a representative subsample of 279 candidate trees using twelve polymorphic simple sequence repeat markers, or SSRs, developed through genome skimming at the ICFRE-Institute of Forest Genetics and Tree Breeding in Coimbatore. These codominant microsatellite markers, valued for their high polymorphism and reproducibility, detected 58 alleles across the sampled trees, with three to seven alleles per locus and an average of 4.83. The markers proved highly informative: mean expected gene diversity reached 0.695 and the polymorphism information content averaged 0.643, with eight of the twelve loci exceeding the 0.60 PIC threshold that breeders consider strongly discriminating. These figures confirm that Eastern India harbors substantial hidden genetic variability in White Teak, comparable to the allelic richness reported for other tropical hardwoods such as Dipterocarpus condorensis, Toona ciliata, Grevillea robusta and various Eucalyptus species.

One of the study most intriguing findings, however, was a paradox. Observed heterozygosity averaged just 0.10, far below the expected heterozygosity, signaling a pronounced deficit of heterozygotes and pointing to intense localized inbreeding. The researchers offer several converging explanations. Fragmented landscapes disrupt random mating and force biparental inbreeding, elevating local homozygosity even in naturally outcrossing species. The Wahlund effect, in which genetically structured subpopulations are pooled into a single regional sample, artificially inflates expected diversity relative to observed diversity. The deliberate selection of elite candidate trees may also capture co-ancestral family lines with lower heterozygosity, and null alleles arising from primer-site mutations, a known artifact of SSR genotyping in non-model trees, likely inflated homozygous scorings. The sparse distribution of Gmelina in natural stands, which hinders random mating, may compound all of these effects.

Bayesian clustering analysis using the STRUCTURE software delivered the study headline discovery: the species in Eastern India is organized into two major genetic lineages. Of the 279 genotyped trees, 135 were assigned to lineage one, 108 to lineage two, and 36 were classified as admixed. The lineages map neatly onto geography. Trees from the Eastern Himalayan region overwhelmingly belong to lineage one, while trees from the southern Eastern Plateau and Hills and the Lower Gangetic Plain cluster predominantly in lineage two. Pairwise genetic distances reinforce this picture, with the Eastern Himalaya and Middle Gangetic Plain emerging as the most genetically distinct pair, while the Eastern Plateau and Hills and the Lower Gangetic Plain show the highest genetic similarity. Similar bimodal geographic clustering has been documented in Toona ciliata and Eucalyptus pellita, suggesting that discrete subpopulations tied to distinct geographic origins may be a recurring theme among widely distributed tropical trees.

Analysis of Molecular Variance added crucial nuance to this structure. A striking 92 percent of the total genetic variation resides within populations rather than among them, a pattern typical of outcrossing, long-lived perennial species that maintain high intra-population diversity. Genetic differentiation between populations, measured by the fixation index FST, was a moderate 0.077, and the estimated gene flow of nearly three migrants per generation indicates ongoing genetic exchange across the studied zones. In other words, Eastern India White Teak is weakly but detectably structured: pollen-mediated gene flow has historically homogenized much of the variation, yet two deep lineages persist, each carrying regional genetic identity, including private alleles found only in the Eastern Plateau and Hills and the Eastern Himalayan populations. For breeders, this is precisely the kind of architecture worth exploiting, since crossing genotypes from both lineages could maximize diversity and potentially unlock heterosis, the hybrid vigor that boosts growth and productivity.

The molecular work was only half the mission. To convert discovery into a durable breeding resource, the team established three progeny trial-cum-germplasm banks in Jharkhand, at Chandwa in Latehar, Ukrimari in Khunti and Harhad in Hazaribagh, using seed collected from 83 of the selected candidate trees. Seeds were soaked, de-pulped, scarified and germinated in sand beds before the seedlings were transplanted into randomized block designs with three to five replications. Early measurements after one year already show site-driven differences: mean tree height reached 226.64 centimeters at Harhad but only 89.37 centimeters at Chandwa, with collar diameters ranging accordingly. The researchers caution that the trials are still juvenile and that definitive statistical conclusions must wait for multi-year data, but the distribution of genotypes across the trials mirrors the diversity captured in the broader sampling, confirming their role as a living core collection.

These progeny trials are more than repositories. They constitute the structured pedigrees and phenotypic datasets on which advanced-generation breeding depends, and as they mature they could support genome-wide association studies linking molecular markers to economically critical traits such as growth rate and wood quality. Over the long term, the trials can be converted into seedling seed orchards, supplying genetically improved seed for plantation forestry, agroforestry and farm forestry across the region, while simultaneously serving as the base population for a second cycle of improvement. In a warming and deforested landscape, such ex situ gene banks that conserve common, rare and private alleles alike are increasingly viewed as essential insurance for the adaptive potential of commercially and ecologically important trees.

The broader significance of the study extends beyond a single species. White Teak sequesters carbon on degraded lands, enriches livestock fodder with protein-rich leaves, yields bioactive compounds used in traditional medicine and supports livelihoods from carving workshops to pulp mills, with rotation cycles as short as four to five years for pulpwood and around ten for timber. By documenting where the species genetic wealth lies, and by warning that the heterozygote deficit signals real inbreeding pressure in fragmented stands, the research gives forest managers in Eastern India a scientific compass for conservation decisions. Preserving trees from both genetic lineages, especially the genetically unique Himalayan and plateau populations, will be critical to maintaining the evolutionary flexibility of a species that millions of farmers and foresters depend upon. What began as a survey of 434 exceptional trees may ultimately grow into one of the region most consequential investments in sustainable forestry.

Subject of Research: Genetic diversity and population structure of Gmelina arborea in Eastern India for tree breeding and conservation

Article Title: Genetic diversity, population structure and germplasm assemblage of Gmelina arborea in Eastern India for sustainable breeding and conservation

Article References: Kumar, A., Gowda, M. G. M., Kumar, R. R., Kumari, A., & Pandey, R. K. (2026). Genetic diversity, population structure and germplasm assemblage of Gmelina arborea in Eastern India for sustainable breeding and conservation. Discover Plants, 3(1), Article 438. https://doi.org/10.1007/s44372-026-00920-6

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00920-6

Keywords: Gmelina arborea, White Teak, genetic diversity, SSR markers, population structure, candidate plus trees, progeny trials, tree breeding, Eastern India, conservation, agroforestry, germplasm