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Climate change will significantly alter habitats for key tree species essential for livelihoods and medicinal use, a new study reveals.
Non-timber forest produce from India’s tropical dry deciduous forests, such as bael (wood apple) and bahera, is expected to thrive, while species like chironji, mahua and amla (Indian gooseberry) will be negatively impacted, the study indicates.
The research considers climate scenarios from the Representative Concentration Pathways (RCP) 2.6 and 8.5. According to the Intergovernmental Panel on Climate Change, RCP 2.6 assumes carbon emissions begin declining by 2020, whereas RCP 8.5 predicts a temperature increase of 3.3 to 5.7 degrees Celsius if current trends continue.
The study, titled How can dry tropical forests respond to climate change? Predictions for key Non-Timber Forest Product species show different trends in India published in the journal Springer, analyses the climate suitability of various species. It projects an increase in suitable habitats for bael (A marmelos) and bahera (Terminalia bellirica), while chironji (Buchanania lanzan), mahua (Madhuca longifolia) and amla (Phyllanthus emblica) are expected to see declines.
Bael and bahera are anticipated to show resilience to future climate changes, with minimal impacts. In contrast, chironji, mahua, and amla, which are sensitive to high temperatures and rainfall variations, are likely to decline.
The study reveals that by 2070, under the RCP 8.5 scenario, highly suitable habitats for bael will shift to the south Deccan plateau, eastern plateau, east coast, upper and lower Gangetic plains, and Punjab plains. However, these species will retreat from current habitats in the Siwalik hills, Western Ghats of Kerala, and northeastern India due to increased monsoon precipitation and higher altitudes creating favourable conditions.
For bahera, climate suitability is projected to increase in the Western Ghats, Central Highlands, south Deccan plateau, eastern plateau and east coast. Currently, bahera is found in the Western Ghats, Central Highlands and Siwalik hills, with moderate presence in the Upper Gangetic plains, Central Highlands, eastern plateau and Chhota Nagpur plateau. It shows low suitability in central and southern states like Karnataka, Telangana, Kerala, Andhra Pradesh, Tamil Nadu, Maharashtra, Bihar, West Bengal and northeastern India. Both bael and bahera are drought-tolerant and can thrive in poor or dry soils.
Conversely, with the expected global temperature rise by 2100, the increased intensity and frequency of rains in India will severely impact the mahua tree, shrinking its habitats. Currently, mahua is concentrated in the Western Ghats, Central Highlands and south Deccan Peninsula.
Amla is primarily found in the Siwalik hills, Western Ghats, Assam hills, and Brahmaputra valley. The study predicts a decrease in suitable habitats for amla in these regions. Chironji is currently located in the Western Ghats, Central Highlands and Siwalik hills. For chironji and amla, excessive heat and changes in annual rainfall under RCP 8.5 will reduce suitable habitats.
“The model predictions were validated by the presence of fossil pollen records of all target species in the habitats specified by past projections, indicating the species' presence since ~6000 years before present. These past projections indicated that the target species were widely distributed in the past, suggesting that the warm, humid climate in India at the time contributed to their broadest distribution,” stated Jyoti Srivastava, a scientist at the Birbal Sahni Institute of Palaeosciences, Lucknow.
“By demonstrating a strong agreement between the paleo proxy data and past projections of the target species made using Species Distribution Models, this combined technique serves as an efficient tool for validating these predictive models," she added.
In addition to habitat disruption, climate change, invasive species, overexploitation and pollution are significant threats to global biodiversity. The study's findings can guide conservation and restoration plans to mitigate the impacts of climate change on NTFP species. The authors also urged the government to implement policies involving native peoples to protect major NTFP species.
“Additionally, in order to develop sustainable solutions for management and conservation of the entire tropical and sub-tropical forest ecosystem we require more such studies in future as it is still unknown how the Indian forests will react to upcoming changes in climatic regimes,” said Srivastava.