Introduction
Large community gatherings often take place under shade of trees, sheltered from the elements. Over time, the historical, archaeological, or cultural heritage of the site grows, with the trees themselves becoming symbolic representations of their legacy (Wani et al., Reference Wani, Sahoo and Gupta2020; Sharma et al., Reference Sharma, Pandey and Sharma2021; Saxena and Coggins, Reference Saxena, Coggins, Saxena and Coggins2022). The origins or existence of these heritage sites are typically determined based on written records, folklore, or traditional knowledge, without scientific validation (Smith, Reference Smith2006; Tripathi et al., Reference Tripathi, Kotlia, Tiwari, Pokharia, Agrawal, Kumar and Long2021). These heritage trees and sites illustrate environmental modifications for cultural reasons during the early Anthropocene (Lewis and Maslin, Reference Lewis and Maslin2015). In the context of South Asia, this era may date back several millennia.
Heritage trees in high-latitude sites like Europe and Japan have been dated using dendrochronological techniques because they are of species with annual growth rings (Haneca et al., Reference Haneca, Čufar and Beeckman2009; Miyahara et al., Reference Miyahara, Paixão, dos Santos, Pagin-Cláudio, da Silva, Bertoleti and de Lima2022). However, in the Indian subcontinent, the heritage trees are primarily broadleaf species without annual growth rings, such as Ficus religiosa or Peepal, Ficus benghalensis, Banyan, Bargad or Vat, Mangifera indica or Mango or Aam, Azadirachta indica or Neem, and Tamarindus indica or Tamarind or Imli (Bar-Ness, Reference Bar-Ness2013; Dey et al., Reference Dey, Shyam, Chakraborty and De2022). Large community gatherings in the subcontinent often take place under large Banyans (Bash, Reference Bash2002). Despite their deep-rooted cultural significance, there remains a considerable lack of scientifically validated ages of heritage trees, especially in south and southeast Asia. Addressing this gap would not only confirm the ages of these trees, but also support more effective conservation efforts.
Radiocarbon dating has been instrumental in determining the age of ancient trees worldwide. For example, an oak in Aspromonte, Italy, was discovered to be 934 ± 65 years old (Piovesan et al., Reference Piovesan, Baliva, Calcagnile, D’Elia, Dorado-Liñán, Palli, Siclari and Quarta2020). The Grootboom baobab in Namibia was found to be 2429 ± 14 calibrated years Before Present, where ‘Present’ is set to 1950 CE (years BP) old, the oldest known living angiosperm (Patrut et al., Reference Patrut, Woodborne, Patrut, Rakosy, Lowy, Hall and Von Reden2018). In India, two baobabs were dated to ca. 800 years BP, the oldest baobabs outside Africa (Patrut et al., Reference Patrut, Garg, Woodborne, Patrut, Rakosy, Ratiu and Lowy2020). These studies relied on high-precision calibration of the radiocarbon time scale, refined over the years to date ancient organic materials (Stuiver and Pearson, Reference Stuiver and Pearson1986; Hajdas et al., Reference Hajdas, Ascough, Garnett, Fallon, Pearson, Quarta, Spalding, Yamaguchi and Yoneda2021; Reimer, Reference Reimer2022). At buried archaeological sites, layered excavations provide organic samples for radiocarbon dating, as well as pottery or masonry for TL/OSL dating (Panzeri et al., Reference Panzeri, Caroselli, Galli, Lugli, Martini and Sibilia2019; Shumilov et al., Reference Shumilov, Kasatkina, Krapiec, Chochorowski and Szychowska-Krapiec2020; Pukelytė et al., Reference Pukelytė, Baltrūnas and Karmaza2022; Kumar and Golani, Reference Kumar and Golani2023). However, dating becomes more challenging at continuously occupied sites without significant burial (e.g., Boretto et al., Reference Boretto, Cioccale, Gordillo, Carignano and Recalde2024), where site-associated trees are the only option to estimate minimum age (Jordan et al., Reference Jordan, Haddon-Reece and Bayliss2014).
Genus Ficus of the Moraceae or Mulberry family covers the tropics and subtropics, containing over 1000 species of vines, shrubs, epiphytes, hemiphytes, and trees (Berg, Reference Berg1989; Raturi et al., Reference Raturi, Chauhan, Gupta and Vijendra2001; Lansky and Paavilainen, Reference Lansky and Paavilainen2010). Amid the Moraceae family, the Ficus, especially F. benghalensis and F. religiosa, are considered to have the longest lifespans (Brown, Reference Brown2020; Chakraborty et al., Reference Chakraborty, Mahajan, Bisht and Sharma2022; Batalova and Krutovsky, Reference Batalova and Krutovsky2023). Among the Ficus species, Banyans are renowned for their hanging roots descending from horizontal branches, anchoring into the ground, and becoming secondary trunks (Bash, Reference Bash2002). Over time, a single banyan tree can create a network of interconnected trunks of unparalleled complexity covering thousands of square meters (Bar-Ness, Reference Bar-Ness2010). In the subtropical humid biome of the central Ganga plains, ancient trees often rot internally while remaining intact externally (Jha, Reference Jha2020). In the largest specimens of Banyan, the primary trunk might have rotted away, with secondary trunks maintaining the canopy. The identification of the oldest or primary Banyan trunk is further complicated due to the complex non-radial system of interconnected trunks.
Indian banyans are often historic trees linked to ancient and mythological events, and the largest trees in the world by canopy coverage (CC) area. The largest Indian Banyan measured by CC is Thimmamma Marrimanu, Andhra Pradesh, spreading ∼19,108 m2, followed by Kabir Vad in Gujarat (17,520 m2), the Banyan at Majhi, Uttar Pradesh (∼16,770 m2), and the Banyan in the A.J.C. Bose Indian Botanical Garden, Howrah, West Bengal (∼16,531 m2) (Bar-Ness, Reference Bar-Ness2010).
An Indian banyan with CC 4069 m2 in the Siddhwari sacred grove, Upper Ganga Ramsar site, was radiocarbon dated by Patrut et al. (Reference Patrut, Garg, Patrut, Woodborne, Rakosy and Ratiu2023), with a minimum age of 346 ± 40 years BP. This Banyan was sampled following the protocol for baobabs in Patrut et al. (Reference Patrut, Mayne, Von Reden, Lowy, van Pelt, McNichol, Roberts and Margineanu2010), at a height of 3.70 m and trunk diameter 0.95 m, without reaching the oldest part of the trunk (i.e., the pith). Moustafa (Reference Moustafa, Kahramanoglu, Kafkas, Küden and Çömlekçioğlu2020) dated Indian banyans at four sites in Egypt by counting rings and measuring branch circumferences, assuming the visible rings were annual without dendrochronological corroboration or standardization. The Old Trees list (Brown, Reference Brown, Dean, Meko and Swetnam1996) notes many trees dated by dendrochronology or radiocarbon, but the only Ficus mentioned is the Bodhi Tree, which is a F. religiosa in Sri Lanka, dated solely by historical records (Brown, Reference Brown2020). Apart from the Ficus, the only dated Mulberry tree to our knowledge is the one from southern Italy, at 647 ± 66 years BP by Palli et al. (Reference Palli, Baliva, Biondi, Calcagnile, Cerbino, D’Elia and Muleo2023), among a group of parent fruit trees.
To address the challenges posed by the unique biological and cultural characteristics of heritage trees in the Indian subcontinent, it is essential to develop or identify alternative dating methodologies. This effort would not only enrich understanding of these cultural landmarks, but also contribute to the preservation of human heritage. Realizing the above research gap, our study focuses on two key research problems: (1) investigation of analytical dating methods to provide precise age estimates for complex heritage trees and associated cultural sites, such as the Indian banyan tree in Munger, Bihar; and (2) improving biological and cultural understanding of heritage trees with precise historical timelines to support conservation efforts of South Asia’s continuously occupied historical sites.
Study Area
The central Ganga plains, presently covering the Indian states of eastern Uttar Pradesh and Bihar, have a long record of high population densities and prosperous civilizations. The modern state of Bihar, named after the numerous extant Buddhist centers called Viharas, historically had two main power foci: Magadh, near the Ganga channel, with its capital at Pāṭaliputra (the present city of Patna), and Mithila, in the Terai region towards the north (Dyson, Reference Dyson2018). The Magadh region has been home to dynasties that periodically ruled most of the subcontinent, as the fertile lands supported large populations and, consequently, large armies.
Transition periods between the stable dynasties were marked by conflicts for this rich land. These struggles were most prominent during the late medieval period in India, starting with the decline of Buddhism in its original region (Bakshi and Chaturvedi, Reference Bakshi and Chaturvedi2007). The beginning of this period is marked in 1200 CE by the destruction of the Viharas, including the famed universities of Nalanda and Vikramshila, by the armies of Bakhtiyar Khilji under Qutb-ud-Din, of the Ghulam dynasty. The declining Sena dynasty rulers fell facing the same army in 1203, ∼320 km downstream on the Ganga in Gaud (Jūzjānī, Reference Jūzjānī1881; Sarkar, Reference Sarkar1927). During this period, the region witnessed constant dynastic turmoil. The Ghulam dynasty, followed by the Khiljis, and later the Lodis and the Mughals, all engaged in battles against multiple local rulers to secure this fertile and strategic region, which ended in the establishment of stable Mughal rule in the region in 1556 (Choudhury and Chandra, Reference Choudhury and Chandra1960; Bakshi and Chaturvedi, Reference Bakshi and Chaturvedi2007; Prasad, Reference Prasad2021).
Approximately 140 km downstream from the capital Patna towards Gaud, the modern city of Munger encompasses a few rocky hills surrounded on three sides by the river Ganga. Munger, earlier Monghyr, has a fort and many other old hilltop buildings said to be from before 1200 CE, but with little written documentation to underpin this (Fig. 1c). On a hill 2 km NE from the fort, inside the Indian Tobacco Company (ITC) campus established in 1901, lies a heritage building with late Mughal (1748–1858) architecture with British modifications, named the ‘Burra Bungalow’, meaning the large house (Choudhury and Chandra, Reference Choudhury and Chandra1960; Dadlani, Reference Dadlani2018).
(a) The area of the Central Ganga plains marked on a map of South Asia. (b) Map of Central Ganga plains with referred historical sites marked. (c) Location of the Banyan Tree at ITC campus in Munger, Bihar.
In front of the bungalow stands a giant banyan tree with multiple trunks and a canopy spanning over 2,500 m2. According to local lore, this banyan served as a gathering place where the local populace met with their rulers before and during the early colonial period, suggesting it may have been deliberately planted on the hilltop for this purpose. Since establishment of the ITC campus, and likely even earlier, the site has been maintained as a curated garden. This maintenance has prevented new secondary trunks from taking root and expanding the canopy for at least the past 125 years. Based on the canopy size rankings established by Bar-Ness (Reference Bar-Ness2010), the Munger Banyan is ranked approximately fourteenth in the world. However, given that its spread has been controlled for over a century, its natural, unrestricted size would likely have been significantly larger.
Materials and Methods
Field sample collection
This study focused on dating the Banyan tree and evaluating the site for its historical and ecological significance, contributing to ongoing research on heritage-tree preservation. Tree-ring core samples were collected using a Haglöf increment borer, following standard dendrochronological techniques (Fritts, Reference Fritts1976). The central composite trunk (Fig. 2a) consists of a primary trunk surrounded by multiple branching limbs and one or more secondary trunks. All are entirely covered in prop roots, making it impossible to distinguish them visually. Only one secondary trunk was partially exposed and was sampled at the chest height of ∼1 m as TB-MUN-01, leading to a core of length ∼45 cm (Fig. 2b). The lowest accessible point of the ostensibly oldest branch coming off the primary trunk at ∼2 m height was cored as TB-MUN-02, producing a ∼22.5-cm-long core (Fig. 2c). The sampling procedure, including coring height, was driven by the aim of accessing the oldest wood at pith (following Fritts et al., Reference Fritts, Smith, Budelsky and Cardis1965). The primary trunk and secondary trunks closest to the primary were not accessible without significantly harming the tree.
Heritage Banyan tree at ITC campus, Munger, Bihar, India. (a) Central composite trunk; the yellow mark denotes the sampled secondary trunk and branch. (b) Secondary trunk sampled as TB- MUN-01. (c) Oldest apparent branch sampled as TB-MUN-02.
Sample processing and wood anatomical observations
After tree-ring core extraction, the cores were mounted on a wooden frame and stabilized with minimal glue. To avoid potential contamination during radiocarbon dating, the samples were not polished before pith sampling was completed. This was to prevent the dust of silicon carbide and various organic resins, the usual abrasive materials in sandpapers, from settling in wood surface pores and contaminating samples, especially for AMS radiocarbon measurements. Instead, the upper surface of each core was carefully cut with a fine knife to expose the wood cells for viewing under a microscope. The innermost rings were examined closely to locate the pith, which serves as the starting point for the tree’s chronological record (Fritts, Reference Fritts1976). Since the pith represents the oldest wood formation, we collected the dating samples from the pith area, avoiding the lower part in contact with the glue. After subsampling of the pith, samples were polished carefully to analyze the ring structure.
Standard dendrochronological methods rely on consistent ring-width patterns across multiple radii and trees to establish reliable chronologies. This is achieved using various dendrochronological techniques, including skeleton plotting (Stokes and Smiley, Reference Stokes and Smiley1968), ring-width plots (Rinn, Reference Rinn, Balder, Strauch and Backhaus2003), and statistical validation through the dating quality check Program COFECHA (Holmes, Reference Holmes1983). In the case of the Munger banyan (Fig. 3), the comparisons were primarily between multiple radii within the primary trunk and major secondary trunks, not assuming perfect synchrony but expecting detectable pattern matches if annual rings were present and climate-responsive. The lack of clear matches raised questions about the regularity of annual ring formation in this species, rather than simply reflecting expected differences in growth rates.
Scans of samples TB-MUN-01 (01a–01c) and TB-MUN-02 (02a–02c) after polishing. a = bark; b = middle; c = close to pith.
The wood in the pith area of a tree represents the first cell walls produced in the juvenile trunk of the young tree (Fritts, Reference Fritts1976). Secondary trunks in Banyans, such as the one sampled as TB-MUN-01, start as a thin prop root growing vertically down from a branch, connect to the ground, and start thickening (Colin et al., Reference Colin, Sanjines, Fortin, Bontemps and Nicolini2012); that thin prop root is represented in the pith.
Alpha cellulose, which is a primary component in plant cell walls, is deposited in cells when they start forming, the thick cell wall providing rigidity and a major component of properly functioning xylem vessels (Taylor, Reference Taylor2008). Among different forms of cellulose, alpha-cellulose is chosen for stable-isotopic and radiocarbon analyses because its original carbon isotope composition is not altered through time, and it is resistant to decay, so it is a reliable wood component for isotopic analysis at time scales relevant to the Holocene epoch (Ren et al., Reference Ren, Schubert, Lukens and Xu2023).
Considering the above, in both samples, the separated pith wood was isolated and processed for alpha-cellulose extraction (following Bose et al., Reference Bose, Chakraborty, Borgaonkar, Sengupta and Ramesh2014; modifying Leavitt and Danzer, Reference Leavitt and Danzer1993, and Loader et al., Reference Loader, Switsur and Field1995). This process involves treatment with an 80°C solution of NaClO2 in the presence of HCl to remove lignin, followed by the removal of hemicellulose via NaOH, and ending with neutralization, yielding pure alpha cellulose. This sequence aimed to remove lignin, hemicellulose, and potential contaminants while preserving the most stable fraction of the wood without significant carbon or oxygen isotopic exchanges due to the use of acetic acid.
Radiocarbon dating and calibration
Radiocarbon dating is a widely used method for determining the age of organic material. The age reflects the time when the cells die and become part of the plant structure, so that the organic materials inside the cell stop exchanging carbon with the atmosphere. The cellulose samples extracted above were pre-processed, following Dunbar et al. (Reference Dunbar, Cook, Naysmith, Tripney and Xu2016), to remove modern carbon contaminants from the samples. The samples were then powdered and dried in an oven for complete removal of moisture and subsequent graphitized using an ‘Automated Graphitization Equipment 3’ (Ionplus AG, Switzerland) coupled with a ‘Vario Isotope Select’ Elemental Analyzer and ‘Isoprime precisION’ IRMS from Elementar Analysensysteme GmbH, Germany, in the Radiochronology and Isotopic Characterization Laboratory of the Birbal Sahni Institute of Paleoscience, Lucknow, India, following Agnihotri et al. (Reference Agnihotri, Gahlaud, Patel, Sharma, Kumar and Chopra2020). Afterwards, these graphite targets were analyzed using the AMS radiocarbon dating at Isotoptech Zrt. Facility at Debrecen.
Conventional radiocarbon ages were calibrated using the IntCal20 calibration curve. Initial calibration was performed using the online software Calib v8.20, and final calibrated ages and associated uncertainties were obtained using OxCal v4.4. Calibrated ages reported in the manuscript and in Table 1 represent median probability ages derived from the full calibrated probability distributions. Age uncertainties are expressed as highest posterior density (HPD) ranges calculated using OxCal. All calibrated ages are therefore probabilistic estimates rather than single-point determinations.
Radiocarbon ages of the Munger Banyan; present work.
The calibration (Fig. 4) suggests that the dating of these samples might be less accurate than from the Americas or Europe due to limitations in the calibration data. For TB-MUN-01, the calibrated date range is 1493–1670 CE, with a 90.1% probability, and with 5.3% probability for this date lying between 1780 and 1798. The calibrated date range for TB-MUN-02 is 1280–1329 with 45% probability, and 1338–1396 with 50.5% probability. The radiocarbon dating results and calibrated ages are expressed in years BP. For discussions in this article, we will use the median assigned year.
Recalibration of Radiocarbon ages using OxCal version 4.4, with IntCal20. (a) TB-MUN-01 276 ± 36 and (b) TB-MUN-02 652 ± 37 BP, shown (in red) with 1σ range within the probability distribution plotted on the vertical axis. The x-axis shows the calibrated date range, expressed in calendar years CE. The y-axis shows the radiocarbon age, represented in years BP. The blue line shows the probability distribution of the calibrated radiocarbon date. The shading indicates the uncertainty range, while the darker blue areas likely represent regions of higher probability. The gray histograms represent the probability distribution of the calibrated date for the sample. The width and height of the histogram bars indicate the range of dates for the samples. The red warning note suggests the date may extend out of range (as shown in the red-shaded area) and fall outside the range where the calibration curve is well constrained.
Results and Discussion
Interpretation of the radiocarbon ages of Munger Banyan
The sampled prop root (TB-MUN-01) of the Munger Banyan reached the ground around 1585 ± 36 CE. The sampled branch (TB-MUN-02) originated as a thin shoot around 1342 ± 37 CE. Typically, a Banyan’s primary branch develops alongside the main trunk within the first year, while secondary and tertiary branches may emerge within the first decade or later, depending on the species and environmental conditions. Branches or prop roots begin as thin shoots, gradually thickening over time (Colin et al., Reference Colin, Sanjines, Fortin, Bontemps and Nicolini2012). If the primary trunk were available for dating, or TB-MUN-02 is not a primary branch as assumed during sampling, this Banyan would likely be significantly older. Compared to the only other radiocarbon-dated Banyan in the world by Patrut et al. (Reference Patrut, Garg, Patrut, Woodborne, Rakosy and Ratiu2023), the minimum age of Munger Banyan is at least two hundred years older.
The Munger Banyan tree likely took root toward the end of the early medieval period for the Subcontinent (550-1200 CE) or at a minimum during early phases of the late medieval period (1200–1526 CE) (Sircar, Reference Sircar1971; Chandra, Reference Chandra2007). As the architecture of the Heritage building nearby, the Burra Bungalow, ranges from late Mughal to early British periods (1700–1800 CE) in the Subcontinent (Choudhury and Chandra, Reference Choudhury and Chandra1960; Koch, Reference Koch1991), the Munger Banyan seemingly predates it significantly, which might imply that the tree is a remnant of an older natural forest. Over time, it may have functioned as a gathering spot for official or cultural activities, and the building was built to host local rulers when they attended meetings at an already-established heritage gathering site.
Limitations and opportunities in radiocarbon dating for tree-age chronology
For the Munger Banyan, the radiocarbon ages represent the age of the tree’s internal wood (the pith), which marks the point when the cellulose in the shoot or root ceased carbon exchange with the atmosphere. Notably, the age difference between the two samples (TB-MUN-01 and TB-MUN-02) underscores the challenges of dating trees with ancient lineages and complex structures (Stuiver and Suess, Reference Stuiver and Suess1966; Pearson et al., Reference Pearson, Leavitt, Kromer, Solanki and Usoskin2022).
The difference between the relatively small analytical uncertainties of the measured radiocarbon ages (±36–37 years; Fig. 4) and the broader calibrated calendar-age ranges mainly reflects characteristics of the radiocarbon calibration curve, rather than uncertainties related to tree-growth processes. In particular, intervals of reduced slope or plateaus in the IntCal20 calibration curve can lead to broad calibrated age ranges even when radiocarbon measurements are analytically precise (Stuiver and Pearson, Reference Stuiver and Pearson1986; Reimer, Reference Reimer2020; Hajdas et al., Reference Hajdas, Ascough, Garnett, Fallon, Pearson, Quarta, Spalding, Yamaguchi and Yoneda2021). Consequently, calibrated radiocarbon ages should be regarded as probabilistic estimates derived from probability density distributions, rather than exact calendar-year determinations (Pearson et al., Reference Pearson, Leavitt, Kromer, Solanki and Usoskin2022).
Radiocarbon dating of non-ring-bearing trees such as Ficus benghalensis is additionally constrained by sampling limitations related to complex multi-trunk architectures. In large banyan trees, decay of the primary trunk, restricted access to the oldest wood, and conservation considerations may require sampling from secondary trunks or major branches. Such samples provide minimum age estimates for the individual tree, rather than definitive establishment ages (A. Patrut et al., Reference Patrut, Mayne, Von Reden, Lowy, van Pelt, McNichol, Roberts and Margineanu2010; R.T. Patrut et al., Reference Patrut, Garg, Patrut, Woodborne, Rakosy and Ratiu2023). Further uncertainty may arise from the geographical distribution of calibration data underlying IntCal20, which is dominated by records from the Northern Hemisphere middle latitudes, with limited direct input from the Indian subcontinent (Reimer, Reference Reimer2020). While IntCal20 represents the best available global calibration dataset, this uneven spatial coverage may contribute additional uncertainty when applying calibrated ages to tropical South Asian contexts. Taken together, these considerations highlight the need for cautious interpretation of radiocarbon-derived ages of heritage trees and emphasize the value of continued methodological refinement, including careful sampling strategies, probabilistic age modeling, and future development of regionally informed calibration datasets to improve chronological resolution in such studies (Hajdas et al., Reference Hajdas, Ascough, Garnett, Fallon, Pearson, Quarta, Spalding, Yamaguchi and Yoneda2021; Pearson et al., Reference Pearson, Leavitt, Kromer, Solanki and Usoskin2022).
Tree growth occurs annually, and the pith represents the first year of woody tissue formation. Our samples represent less than a year of growth, yet the radiocarbon error exceeds 35 years. This indicates that radiocarbon uncertainties in tree samples arise primarily from calibration effects rather than from biological growth processes, which occur on a seasonal-to-annual scale rather than a decadal scale. Therefore, the small radiocarbon error bars and broader date ranges are more related to radiometric calibration than to actual tree growth. In sediment samples, errors of a century or more can arise from compaction and mixing, but these issues do not affect living trees.
Radiocarbon dating provides a reliable framework for establishing temporal sequences (Reimer, Reference Reimer2020) despite certain limitations, including the influence of excess anthropogenic radiocarbon in the atmosphere, commonly known as the bomb effect, and rising input of 14C-depleted CO2 in the atmosphere from fossil-fuel combustion over time, known as the Suess effect (Hua and Barbetti, Reference Hua and Barbetti2004; Guilderson et al., Reference Guilderson, Reimer and Brown2005; Hajdas et al., Reference Hajdas, Ascough, Garnett, Fallon, Pearson, Quarta, Spalding, Yamaguchi and Yoneda2021). Certain intervals, particularly the three-century 1⁴C plateau immediately preceding 1950 CE, exhibit reduced temporal resolution due to minimal changes in calibrated ages despite measurable variations in 1⁴C activity (Biondi et al., Reference Biondi, Santos, Rodríguez and Sosa2023; Manning, Reference Manning2024). Improved chronological resolution under such conditions can be achieved using wiggle-matching techniques (Hogg et al., Reference Hogg, Turney, Palmer, Cook and Buckley2013; Biondi et al., Reference Biondi, Santos, Rodríguez and Sosa2023). We are currently advancing the application of wiggle-matching approaches and are working toward obtaining additional radiocarbon dates from the Munger Banyan samples for this purpose. A significant source of error in the calibration might arise from the fact that IntCal20 lacks any data from the Subcontinent south of the Himalayas, as per the IntCal20 website (https://intchron.org).
Importance of the Munger Banyan to heritage conservation
The Munger Banyan tree is very well-maintained and conserved as part of an ornate garden inside the ITC campus. In fact, out of all such trees we have seen since the beginning of our endeavor of dating heritage trees and their associated sites, this tree is the least threatened one and has the most access for sampling. All other well-conserved trees we have noted are either inside temples or inside reserve forests; in the former case, sampling access is limited due to the deity status of the trees. A larger number of such trees near or inside urban areas are, however, only conserved by the forest department records and the religious feelings of people around them.
Conclusions and Future Prospects
This research introduced a more precise and scientifically rigorous approach to dating ancient banyan trees, moving beyond historical records and local narratives. By determining that the Munger Banyan is ca. 700 years old, we have identified it as the oldest accurately dated Ficus benghalensis known to date. Radiocarbon dating of this banyan provides a chronological framework for future research to connect its growth period with historical and climatic events, offering valuable insights into the region’s natural history. The study also identified limitations, including restrictions on the number of samples and environmental influences, highlighting the need to refine dating techniques across different regions and species. This approach offers valuable insights into the intersection of natural and human histories during the Anthropocene.
The preservation of these heritage trees not only supports scientific research but also underscores their cultural and ecological importance in India and the subcontinent. By integrating dendrochronology, radiocarbon dating, and historical ecology, this study enhances our understanding of the region’s natural history while emphasizing the need to conserve these living monuments for future generations.
Acknowledgments
The authors express their sincere gratitude to Prof. Mahesh G. Thakkar, Director, Birbal Sahni Institute of Palaeosciences (BSIP), for his insightful comments and valuable guidance. Sanjay Kumar Singh Gahlaud, Dr. Srinivas Bikkina, and Late Dr. Rajesh Agnihotri of the Radiocarbon Dating Facility at BSIP have our gratitude for their help in the dating process. Drs. Binita Pharityal, Scientist F; Anupam Sharma, Scientist G, and Vandana Prasad, former Director, BSIP, are thanked for their constant encouragement of this research. The authors thank the Bihar Forest Department, especially the Research Training and Public Relations Division, Patna, for their continuous support in formulating the project and processing the funding. During sampling, the support of the District Forest Officer, Munger, and all his staff, as well as the ITC, was invaluable. This work was funded by the Environment, Forest, and Climate Change Department, Government of Bihar. BSIP/RDCC/Publication no. 47 /2024-25.
Funding
Environment, Forest and Climate Change Department, Government of Bihar, India, grant to Trina Bose.
Competing interests
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Author Contribution declaration
Trina Bose: conceptualization, sample/data collection, data curation, data analysis, interpretation, MS writing; Mayank Shekhar: data curation, data analysis, interpretation, MS writing; Akhilesh K. Yadava: data curation, interpretation, MS writing; Avanish Mishra: sample/data collection, data curation, data analysis; Arya Pandey: sample/data collection, data analysis; Anurag Kumar: data analysis.
