Editing IPCC:AR6/WGII/Chapter-5 (section)

==== 5.7.4.1 Medicinal plants ====

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Research is limited on the effects of climate change on the distribution, productivity or availability of medicinal plants ( [[#Applequist--2020|Applequist et al., 2020]] ), but some are facing threats due to climate change ( [[#Phanxay--2015|Phanxay et al., 2015]] ; [[#Chirwa--2017|Chirwa et al., 2017]] ; [[#Chitale--2018|Chitale et al., 2018]] ). Climate change is projected to impact some medicinal plant species through changes in temperature, precipitation, pests and pathogens; unsustainable harvest of high-value species will significantly exacerbate these impacts ( ''medium evidence'' , ''high agreement'' ) ( [[#Applequist--2020|Applequist et al., 2020]] ). Table 5.9 highlights that climate change impacts on medicinal plant species will vary greatly by species. Medicinal plants that grow in arid environments are also highly susceptible to climate-induced change ( [[#Applequist--2020|Applequist et al., 2020]] ). Arctic medicinal species may also be particularly at risk due to climate change ( [[#Cavaliere--2009|Cavaliere, 2009]] ).

'''Table 5.9 |''' Observed and predicted impacts of climate change on selected medicinal plant species.

{| class="wikitable"
|-
! Region

! Species

! Observed and projected impacts of climate change

! Assessment of evidence and level of agreement

|-
| Egypt, Sub-Saharan Africa, Spain, Central Himalaya, China, Nepal

| General assessment of medicinal plants

| Habitat suitability and/or range distribution will shift or may be lost ( [[#Munt--2016|Munt et al., 2016]] ; [[#Yan--2017|Yan et al., 2017]] ; [[#Brunette--2018|Brunette et al., 2018]] ; [[#Chitale--2018|Chitale et al., 2018]] ; [[#Zhao--2018|Zhao et al., 2018]] ; [[#Applequist--2020|Applequist et al., 2020]] ), including in high-elevation meadows which are home to some of the most threatened plant populations and contain a high number of and higher proportion of species used as medicine compared with lower-elevation habitats ( [[#Salick--2009|Salick et al., 2009]] ; [[#Brandt--2013|Brandt et al., 2013]] ).

| ''Medium confidence''

|-
| Hindukush Himalaya

| ''Gynostemmapentaphyllum''

| The elevated CO 2 and temperature can increase biomass, but the health-promoting properties such as total antioxidants, phenols and flavonoids are expected to decrease ( [[#Chang--2016|Chang et al., 2016]] ).

| ''Medium confidence''

|-
| Arctic

| Golden root ( ''R'' ''hodiola rosea)''

| Population decline has been associated with drying of stream beds and alpine meadows, which are predicted to become more severe under climate change

( [[#Cavaliere--2009|Cavaliere, 2009]] ; [[#Brinkman--2016|Brinkman et al., 2016]] ).

| ''Medium confidence''

|-
| North America

| American ginseng ( ''P'' ''anax quinquefolius'' )

| Modelling of the combined impact of climate change (warming) and harvesting pressure indicates a nonlinear increase in extinction risk ( [[#Souther--2014|Souther and McGraw, 2014]] ).

| ''Medium confidence''

|-
| Asia

| ''Gentiana rigescens''

| A model evaluating future climate impacts shows a westward range shift and major loss of highly suitable habitats. Modelling also shows a potential decline in quality (chemical concentration of iridoid glycoside, which is highest in highly suitable habitats) due to climate change ( [[#Shen--2021|Shen et al., 2021]] ).

| ''Medium confidence''

|-
| Africa

| ''Alstoniaboonei''

| Modelling indicates that the range for this species remains relatively stable, with a possible modest expansion at the northern and southern margins of the range ( [[#Asase--2019|Asase and Peterson, 2019]] ).

| ''Medium confidence''

|-
| Asia

| ''Homonoia riparia''

| Modelling of future climate scenarios in Yunnan Province, China projects that habitat suitability improves ( [[#Yi--2016|Yi et al., 2016]] ). Modelling of future climate scenarios across the whole species range in China shows that both the suitable area and suitability of the habitat increase ( [[#Yi--2018|Yi et al., 2018]] ).

| ''Medium confidence''

|-
| Asia

| ''Notopterygiumincisum''

| Modelling for future climate change shows areas of suitable habitat will significantly decrease; however, the area of marginally suitable habitat will remain relatively stable ( [[#Zhao--2020|Zhao et al., 2020]] ).

| ''Medium confidence''

|-
| Himalayas

| Himalayan yew ''Taxus wallichiana''

| Modelling shows projected shrink in climatic niche of the species by 28% (RCP4.5) and 31% (RCP8.5), highlighting the vulnerability to climate change impacts ( [[#Rathore--2019|Rathore et al., 2019]] ).

| ''Medium confidence''

|-
| Iran

| ''Daphne mucronata''

| Modelling of future climate change projects disappearance of the species below 2000 m, significant change in distribution between 2000 and 3000 m and no change above 3000 m ( [[#Abolmaali--2018|Abolmaali et al., 2018]] ).

| ''Medium confidence''

|-
| Central America

| Pericón or Mexican Mint Marigold

''Tagetes lucida''

| Models predict range to contract somewhat and shift northward ( [[#Kurpis--2019|Kurpis et al., 2019]] ).

| ''Medium confidence''

|-
| Africa

| Rooibos tea ''Aspalathus linearis''

| Modelling of future climate scenarios shows substantial range contraction of both wild and cultivated tea, with range shifts southeastwards and upslope ( [[#Lotter--2014|Lotter and Maitre, 2014]] ).

| ''Medium confidence''

|-
| Himalayas

| ''Lilium polyphyllum''

| Habitats of this species will shrink by 38–81% under future climate scenarios and shift towards the southeast region in Western Himalaya, India ( [[#Dhyani--2021|Dhyani et al., 2021]] ).

| ''Medium confidence''

|-
| Iran

| ''Fritillaria imperialis''

| Modelling shows 18% and 16.5% of the habitats may be lost due to climate change by 2070 under RCP4.5 and RCP8.5, respectively. Further, it is observed that, under the current climatic conditions, the suitable habitat may become unsuitable in the future, resulting in local extinction ( [[#Naghipour%20Borj--2019|Naghipour Borj et al., 2019]] ).

| ''Medium confidence''

|-
| Himalayas/ China

| Snow lotus ( ''Saussurea spp'' ''.'' )

| Climate change is a significant threat to this species ( [[#Law--2005|Law and Salick, 2005]] ). Laboratory and field trials show considerable plasticity and a wide thermal range for germination, which may help compensate for range reductions under climate change ( [[#Peng--2019|Peng et al., 2019]] ).

| ''Medium confidence''

|-
| North Africa

| Atlas cedar ''Cedrus atlantica''

| Modelling shows a significant and rapid contraction of distribution range, upward elevational range shift, increased fragmentation, and possible disappearance in many North African localities ( [[#Bouahmed--2019|Bouahmed et al., 2019]] ).

| ''Medium confidence''

|-
| Asia/South Korea

| ''Paeonia obovata''

| Modelling of climate change scenarios shows significant loss of suitable habitat and possible disappearance of ''P. obovatain'' in South Korea after 2080 ( [[#Jeon--2020|Jeon et al., 2020]] ).

| ''Medium confidence''

|-
| Iran

| ''Salvia hydrangea''

| A projected loss of habitat in the southeast of the range will not be compensated by the northward or upward elevational range migration (Ardestani and Ghahfarrokhi, 2021).

| ''Medium confidence''

|-
| Patagonian, Argentina

| ''Valeriana carnosa''

| Modelling for future climate scenarios projects a 22% loss of the suitable habitat ( [[#Nagahama--2020|Nagahama and Bonino, 2020]] ).

| ''Medium confidence''

|-
| Western Ghats, India

| Kokum

''Garcinia indica''

| Predictions of climate change impact on habitat suitability indicate drastic reduction in the suitability by over 10% under RCP8.5 for the years 2050 and 2070 ( [[#Pramanik--2018|Pramanik et al., 2018]] ).

| ''Medium confidence''

|-
| Himalaya

| ''Ophiocordyceps sinensis''

| A decline of the species is largely due to over harvesting, but ecological modelling indicates that climate warming is also contributing to this decline ( [[#Hopping--2018|Hopping et al., 2018]] ).

| ''High confidence''

|-
| Pacific islands

| Noni ( ''Morindacitrifoli'' ), naupaka ( ''Scaevola spp'' .), kukui ( ''Aleurites moluccana'' ) and milo ( ''Thespesia populnea'' )

| May be less susceptible to climate change as they are fast growing, have high reproduction rates, grow at sea level (and are often salt-tolerant) and have significant room for range shifts ( [[#Cavaliere--2009|Cavaliere, 2009]] ).

| ''Low confidence''

|}

Changes in range distribution will interact with detailed local knowledge and Indigenous knowledge needed to harvest and use medicinal plants. Northward range shifts, for example, may mean certain plants still exist, but not where they have traditionally been important as medicine, and possibly moving suitable ranges outside of areas where plants species have sufficient protection ( [[#Kaky--2017|Kaky and Gilbert, 2017]] ). Climate-induced phenological changes are already observed as a threat to some species ( [[#Gaira--2014|Gaira et al., 2014]] ; [[#Maikhuri--2018|Maikhuri et al., 2018]] ). Other major climate-induced impacts on medicinal plants will be via the phytochemical content and pharmacological properties of medical plants ( [[#Gairola--2010|Gairola et al., 2010]] ; [[#Das--2016a|Das et al., 2016a]] ). Experimental trials have shown that drought stresses increase phytochemical content, either by decreasing biomass or increasing metabolites production ( ''high confidence'' ) ( [[#Selmar--2013|Selmar and Kleinwachter, 2013]] ; [[#Al-Gabbiesh--2015|Al-Gabbiesh et al., 2015]] ).

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