Himalayan medicinal plants under threat due to climate change

Image shows woody stem of Rubus ellipticus with fruiting
  • Medicinal plants in the Himalayas are under threat due to climate change.
  • The findings call for reorienting conservation strategies.
  • The new research provides insights to policy makers to identify suitable sites for future conservation.

Medicinal plants in the Himalayas are under threat due to climate change, which calls for reviewing current conservation strategies, including protected parks in the mountain ranges, new research shows.

The findings from two new research papers come even as the latest Intergovernmental Panel on Climate Change (IPCC)’s Sixth Assessment Report warns of the impact of climate change on natural and human systems.

A study in Sikkim from Bhim Rao Ambedkar college, Delhi University, analysed the potential habitat distribution of 163 medicinal plant species in both the current and future climates scenarios in 2050 and 2070. It used the ‘maximum species distribution modelling’ technique that combines observations of species occurrences, with environmental information, to project future distribution of species.

The analysis of Sikkim, part of the Eastern Himalayas biodiversity hotspot, reports that the majority of the medicinal plant species are found in the tropical and subtropical regions in the Sikkim Himalayas, at 300 metres to 2000 metres heights. Most of these are likely to shift upwards and northwards in future climate scenarios.

Current species-rich areas are likely to shift by 200 m and 400 m in 2050 and 2070, respectively, the study published in Ecological Informatics reports. More alarmingly, some 13-16% of medicinal plant species in the region are likely to lose their habitats by 2050 and 2070. The results highlight that species that are restricted to specific areas and have a narrow height distribution “are the most vulnerable species and likely to go extinct due to climate change in the Himalayas,” the study cautions.

The study by researcher Manish Kumar from Bhim Rao Ambedkar college also attempted to identify the most suitable areas for conservation and test the effectiveness of the existing Protected Area (PA) network in conserving medicinal plant species in current and future climate scenarios.

Image shows wildflowers in high-altitude meadow in Sikkim, India
Wildflowers in spring in Sikkim. High altitudes have a significant effect on the phenology, or life cycles, of plants, often influencing their size, seasonal growth and flowering, and even the kind of pollinators they attract. Photo by Pradeep Kumbhashi/Wikimedia Commons

It shows that only five out of the eight protected areas in Sikkim Himalayas are effective in the conservation of medicinal plant species in current and future climates. “The boundaries of existing PAs need to be expanded in order to accommodate the upward shifts in the spatial distribution of species, especially in the case of those PAs that are located in the lower elevations or tropical regions,” the study recommends.

“These PAs happen to occupy the most suitable habitats of medicinal plants in Sikkim,” Kumar explained to Mongabay India. “The main problem with the design of existing PAs is that they are ‘static’ in nature, and once their boundaries are defined in the official notification, they remain as such,” he says.

“The need of the hour is to make them ‘dynamic’, that is, systematically and periodically assess them and realign their boundaries as and when the need arises,” such as due to effects of climate change or changes in land cover, he says. The research also indicates that the most suitable habitats are in the 860 m to 2937 m height, which could serve as highly suitable habitats for medicinal plant species in Sikkim Himalaya. Conservation actions could focus on these areas to mitigate the effect of climate change.

“Perhaps it would be best suited if conservation actions and protected areas are designed in and around the middle elevations in the Himalayas as these are the areas that would likely emerge as the zones that would harbour maximum medicinal plants in future,” Kumar adds.

“We do need to redefine the boundaries of existing protected areas for more effective conservation,” says Kumar.

Read more: In Arunachal’s Sessa Orchid Sanctuary communities collaborate with forest officials to conserve orchids

Meanwhile, a second modelling study for the periods 2041-2060 and 2061-2080, focused on an endangered medicinal plant Picrorhiza kurroa (Royle ex Benth) in the Uttarakhand part of the Himalayas. The plant, locally known as kutki or kadu, is among the several globally significant medicinal plants in the Himalayas, which are highly sensitive to climate change and are under threat, due to their narrow distribution range and small population size. The study, conducted by a team of researchers from Dehradun-based institutes, aimed to identify the most critical environmental variables affecting P. kurroa distribution, and predict current and future suitable habitats for P. kurroa under various climate scenarios.

It found that “overall, there is a decrease in the habitat of P. kurroa under climate change scenarios.” The highly suitable areas for P. kurroa in Uttarakhand were found to be primarily in Chamoli, Bageshwar, and Pithoragarh districts. Some locations in Rudraprayag and Tehri districts were also highly suitable for P. kurroa., Uttarkashi district has good potential for its growth.

“Overexploitation and unscientific extraction of endangered medicinal plants are a threat to its survival,” says Saurabh Purohit, from the Indian Institute of Remote Sensing, Dehradun and one of the study authors.

Image shows flowering of four different plants in the Himalayas
(Clockwise from top left) Rhododendron arboreum, Hypericum patulum, Angelica archangelica and Berberis aristata, are some of the medicinal plants found in the Himalayas. Photos by Manish Kumar.

Future conservation and nature-based solutions

Scientists are recommending a mix of conservation strategies to counter the predicted losses and redesign conservation strategies. The authors of the two studies say their research provides insights to policymakers to decision-makers to identify suitable sites in the wild for conservation.

The Dehradun scientists suggest a three-pronged approach to protect P. kurroa: first, predict potential suitable habitats for P. kurroa under different climate change scenarios; next track and monitor natural or anthropogenic factors that worsen the habitat decline, and strengthen research on the ecological characteristics and habitat of P. kurroa.

“It’s high time that we start to assess our conservation actions, conservation policies, and conservation designs from a scientific perspective,” says Kumar. “We need to incorporate the effects of climate change in our policy framework, especially given the fact that the Himalayas are warming three times more than the global average.”

K. S. Kanwal, a scientist at the G.B. Pant National Institute of Himalayan Environment, Dehradun, specialising in environmental impact assessments on biodiversity and ecology, says that there is an urgent need to strengthen in-situ and ex-situ conservation measures to reverse the loss of threatened medicinal plants. He also suggests the conservation of endangered medicinal plants in PAs, and designating some areas as ‘new’ medicinal plant conservation areas (MPCA).

The Himalayan ecosystems are highly vulnerable to adverse impacts of climate change, but there is limited work on assessing the impacts of climate change on medicinal herbs in the region, he says. Some recent studies have shown that climate change is affecting the distribution range and diversity of Himalayan medicinal plants; and influencing their phenology or flowering and vegetative growth period, which ultimately affects their productivity. Changes in temperature impact the secondary metabolites of medicinal plants.

Strict implementation of local and international laws can improve the situation, says Purohit.

Also, increasing cultivation of endangered medicinal plants can save them from extinction in the wild, adds Purohit. “It would meet the ever-growing demand of medicinal plants in local and international markets and would lessen the burden on wild medicinal plants.”

During the COVID-19 period the demand for medicinal herbs has increased up to three to four times, which increased the pressure on the collection of the already depleting medicinal plants in the wild, says Kanwal. “One of the major reasons for the depletion is unsustainable and overharvesting of medicinal plants from the Himalayan region,” he adds.

Image shows a village overlooking a valley in Sikkim
Rapid urbanisation and consequent fragmentation of habitats and natural forests have grown exponentially in Sikkim, decreasing the space for its rich biodiversity to flourish. Photo by Goyaldevender/Wikimedia Commons.

Kanwal suggests habitat mapping of endangered plants; ex-situ conservation in herbal gardens, implementing sustainable harvesting protocols, long-term monitoring and documentation of endangered medicinal plants among measures to reverse the decline. Kanwal suggests a slew of possible nature-based solutions to conserve threatened and rare medicinal plants of the Himalayan region, such as promotion of cluster-based cultivation of endangered medicinal plants; growing them to restore degraded or abandoned lands;  and setting up model nurseries, genetic resource centres, and germplasm repositories for providing elite quality planting materials to the farmers.

Possible solutions for sustainable production of Himalayan medicinal herbs suggested by Kanwal include training Himalayan communities in medicinal plants production, processing, and marketing; promoting medicinal plant conservation education among the youth.

Areas of high exploitation and high threats should be set aside for in-situ conservation programs, says Kumar. Examples include the People and Plants Initiative of the World Wildlife Fund in the Dolpo region of Nepal, which could successfully conserve medicinal plants through the use of indigenous knowledge and traditions. “Approaches like this not only meet conservation targets but also ensures sustainable livelihoods and economic benefits to the local tribal populations,” says Kumar.

Purohit points out that nature-based solutions such as the traditional concept of ‘sacred groves’ and revitalising indigenous traditional knowledge can conserve the endangered medicinal plants could help mitigate the adverse impacts of climate change. “Policies should be made exclusively for alpine meadows regarding the restricted access of the people,” he says.

Read more: Sikkim’s urban sacred groves mitigate double the carbon compared to a natural rural forest

Banner image: Fruiting shrub of Rubus ellipticus, or the Himalayan yellow raspberry, native to China, Nepal, the Indian subcontinent, and the Philippines. Photo by Manish Kumar.

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