A. malaccensis is widely distributed in Bangladesh, Bhutan, India, Indonesia, Malaysia, Myanmar, Nepal, Philippines, Singapore, and Thailand (Oldfield et al., 1998). It is now listed as critically endangered by the IUCN in all those countries (IUCN, 2024). A. malaccensis produces a highly valuable fragrant resin that impregnates the heartwood (agarwood) in response to fungal and other microbial infections (Chhipa and Kaushik, 2017).

The wood has been traded globally for centuries and is deeply rooted in some religions’ spiritual culture. Beyond its cultural and religious uses, it is also traditionally used for health problems, such as skin problems, thyroid problems, and joint pain (Grosvenor et al., 1995). The versatile uses of agarwood have led to a global increase in demand, endangering the natural populations of A. malaccensis. Overharvesting and unsustainable harvesting techniques are the main problems causing the decline of wild populations. In the past, collectors harvested agarwood from the forest by cutting dozens of Aquilaria trees because they could not accurately identify which trees contained resin and were ready to be harvested (Irnayuli et al., 2011).

Regarding production, Indonesia, Malaysia, and Thailand are the largest exporting countries in South Asia. From 2000 to 2023, these countries exported 2.448,5, 2.158,5, and 1.827,6 metric tons of agarwood chips, respectively. In the case of Indonesia and Malaysia, practically all material is collected from the wild (99,6%). Thailand and Malaysia are the biggest exporters of essential oil products, with around 4,2 and 1.5 metric tons from 2000 to 2023. On the other hand, around 57% of Thailand’s oil production comes from plantation agarwood of three species, whereas only 19% is produced in Malaysia (Thompson et al., 2022).

It is estimated that more than 60 million trees have been planted (IUCN, 2024) and resin induction techniques have been developed to meet high market demand and maintain the sustainability of wild plant habitats (Thompson et al., 2022). In contrast, the trees are found in low densities (up to 2/ha) in the wild, and only a small percentage of all non-cultivated trees–between 1% and 10% – produce agarwood with valuable resin (Thompson et al., 2022). Artificial methods for inducing infection have been developed to produce the resin using highly virulent fungi like Fusarium spp. This method has successfully increased the relative share in exports of products from cultivation compared to wild-harvested products (Thompson et al., 2022). However, the increase in the ratio does not necessarily prevent a decline in wild populations. Illegal harvesting still occurs in almost all producing countries because the agarwood harvested from wild Aquilaria is generally considered higher quality than cultivated Aquilaria (Kanazawa, 2017; Tamuli et al., 2005).

Another strategy to address overexploitation is logging restrictions and prohibitions for the species. Wild Aquilaria logging is illegal in several countries, with only Indonesia and Malaysia still allowing it under quotas and controls. China, Malaysia, Nepal, and Indonesia use assisted natural regeneration to rebuild wild populations. Only oil and live plants are subject to export licenses in India, while raw materials are unavailable (Thompson et al., 2022).

Although the survival and habitat of A. malaccensis seem to be impacted by climate change, it depends mainly on annual average rainfall, soil pH, and yearly average temperature. Changes in temperature, rainfall, and precipitation associated with climate change will affect the survival of this species. Tropical plants are predicted to face the most significant risk from climate warming as they experience temperatures closer to their upper germination limits (Sentinella et al., 2020). This is supported by evidence that recent droughts in parts of Southeast Asia (e.g., Thailand and Myanmar) have resulted in high agarwood tree mortality in some plantations (Thompson et al., 2022). Moreover, pests and diseases also threaten the life of this species. In several cultivation sites in India, most plantations face high mortality rates due to dry soil, moist weather, and high temperatures (Bhattacharjee et al., 2024). Furthermore, sap-suckers, leaf defoliators, and wood borers (insects from the orders Coleoptera and Lepidoptera), and several diseases are known to damage leaves, stems, and roots, especially in young plants (Samsuddin et al., 2019). Overharvesting and unsustainable harvesting are the main problems with this species’ availability in nature. Changes in temperature and rainfall correlated with climate change can also change the distribution and population, accelerating the decline of the wild population (Table 2).

B. sacra trees and other species produce an aromatic resin known as frankincense, widely used in religious rituals, perfumes, and as an ingredient in traditional medicines. Frankincense has a known medical and religious history dating back nearly 5,000 years (DeCarlo et al., 2023). This resin has been used to treat wounds, skin infections, inflammatory diseases, dementia, and other ailments, in medicine systems including Ayurvedic and TCM. Its widespread use over thousands of years makes it one of the oldest globally traded commodities (DeCarlo et al., 2020; Khalifa et al., 2023).

B. sacra is native to the arid regions of Oman, Yemen, Ethiopia, Somalia, and Kenya (Hamdiah et al., 2022; Eshete et al., 2012; DeCarlo et al., 2023). Harsh climatic conditions, including high temperatures and low rainfall, are the characteristics of these areas. Climate change poses an additional threat to this species, as rising temperatures and changes in precipitation patterns may affect its growth and resin production (Mwijuke, 2024; DeCarlo et al., 2020; Eshete et al., 2012; Gonzalez, 2020). Climate models predict increased temperatures and decreased precipitation in the growing regions of B. sacra and Boswellia papyrifera (Rajpoot et al., 2020; Gidey et al., 2020). This may lead to habitat loss and reduced species viability. Other factors influencing the decline of tree populations include fires, animal grasing, changes in land use, insect attacks, and improper harvesting (DeCarlo et al., 2020). In Ethiopia, the world’s largest exporter of frankincense, the Boswellia tree is predicted to become almost extinct within the next 3 decades (Johnson et al., 2022; DeCarlo et al., 2020).

Trade in frankincense has increased significantly in recent decades due to high demand in global markets. However, this increased demand has led to overexploitation, threatening the sustainability of the species (Gonzalez, 2020). In impoverished regions of Somali, cutting down and collecting is a primary and crucial source of income for the deprived populated areas (DeCarlo et al., 2020). The problem is aggravated by the fact that Boswellia trees have a limited growing range at high altitudes with specific climates and growing conditions in the arid regions of the Middle East (Gonzalez, 2020). These factors make the survival of frankincense even more difficult.

B. sacra produces a significant number of seeds, but the viability of these seeds varies greatly depending on the health of the parent trees and environmental stressors, and germination rates under natural conditions are very low, typically between 1% and 10% (Hamdiah et al., 2022; Al-Harrasi et al., 2019). This low rate is attributed to various factors, including issues with genetic diversity, environmental conditions, and seed viability. Attempts to improve germination rates have been made using a variety of methods. For example, seed sorting by flotation can help remove non-viable seeds, and specific growing conditions such as optimal moisture, temperature, and light are critical to improving germination success. Some studies have shown that controlled pollination and selective breeding can achieve higher germination rates, sometimes reaching 40%–60% under ideal conditions, but more research is needed. DeCarlo and co-authors (DeCarlo et al., 2020) highlights the discrepancy between production and trade volumes. This indicates that current harvesting practices are unsustainable, and that overharvesting reduces resin quality and quantity. B. sacra and related species face multiple threats from overexploitation, climate change, habitat loss, and biotic determinants. It is crucial to implement sustainable harvesting practices, protect its habitat, and involve local communities in conservation efforts (Table 3).

Saffron is known for its high price and complex technological process of growing and processing. C. sativus, from which saffron is obtained, depends on human propagation (El Merzougui et al., 2024; Busconi et al., 2018). According to some sources, its wild forms were found only on the islands of Crete and Santorini in 2,000–1,800 BC, that is, 3,800–4,000 years ago (Nemati et al., 2019). Since then, the species has propagated vegetatively only with human participation (Busconi et al., 2018). Traditionally, C. sativus is grown in large quantities in Iran, India, Morocco, the United States, Spain, and Greece. However, Crocus is also cultivated in other European countries, although in smaller volumes (Kothari et al., 2021; Mehmeti et al., 2024).

Saffron is considered one of the most ancient products in the world–it is mentioned in Egyptian papyri, the works of Homer and Hippocrates, and even in the Bible, along with olives and figs (Hofmann and Ratsch, 2005). It is the most expensive spice in the world; its price can range, depending on quality, from USD 5 to 11,000 per 1 kg (Mehmeti et al., 2024). Saffron has a variety of uses, from cooking (Butnariu et al., 2022) to traditional medicine, for its anti-cancer (Bhandari, 2015) and neuroprotective properties (Bian et al., 2020; Abdian et al., 2024). Saffron is described in several World Pharmacopoeias (Mykhailenko et al., 2022; Mykhailenko et al., 2020a), but it remains a poorly recognised and appreciated medicinal plant in mainstream medicine. Demand for the spice is steadily growing, while recently, there has been a significant decrease in harvest volumes due to geographical and climatic conditions (Pirasteh-Anosheh et al., 2023; Razmavaran et al., 2024). Farmers have repeatedly experienced significant climate impacts on shifting planting and harvest dates, as well as reducing harvest volumes and the quality of plant materials (Sam, 2024).

The annual global production of saffron is estimated to be around 300 tons, with the main producers being Iran (90%–93% of global production), India, Greece, Morocco, and Spain (Busconi et al., 2018; Fernández et al., 2011). During 2023–2024, Iran saw a sharp decline in saffron production linked to several causes: climate change (average temperature increase of almost 2.8°C in October and November 2022 compared to 2021), poor agricultural practices, lack of rainfall (down 52% in the last winter of 2023 and during flowering), drought in certain areas (like Gonabad, Mah-Velat and Khaf), unusually cold winters and warm weather during saffron flowering (SunLand Saffron, 2024). In most regions, saffron production in Iran has decreased by more than 60% in the last 50 years. According to the Khorasan Razavi Agricultural Organization, Iranian farms have produced an average of 350–370 tons of saffron in recent years, while only 140 tons of saffron were produced in 2023 (SunLand Saffron, 2024).

Similar changes have occurred in Kashmir (India), the second-largest saffron-producing region and a traditional growing area since the 5th century BC (Desk, 2024; Bukhari, 2020; Saraf et al., 2018). Due to distinct climate changes, drought conditions in the region have meant that saffron yields have halved over the past 2 decades. There has been a decline in production in Kashmir since 1999 due to decreased rainfall, delayed flowering, and impact on crop yields (Husaini, 2014); productivity reduced in 1999–2003 from 3.12 to 1.57 kg/ha. In a report on the harvest in November 2023, Indian media outlet News18 reported that the region now produces an average of 2.34 tons of saffron per year, or less than a quarter of its production over 6 years ago. In February 2024, Agriculture and Farmers Welfare Minister Arjun Munda said that saffron production in Kashmir decreased by 67.5% between 2010 and 2023, but from 2022–2023, saffron production increased marginally by 4% (Aamir, 2024). In 1930, Spain was the world’s largest saffron producer, harvesting 120 tons of saffron grown on 13,000 ha of land annually (SunLand Saffron and Herbs, 2022). By the 1970s, annual production had dropped to 70 tons. Today, about 140 ha, the vast majority of them in Castilla-La Mancha, are devoted to C. sativus. Total production for 2022 was approximately 450 kg. Today, Iran produces between 200 and 250 tons of saffron per year, and Greece produces about 2.5 tons (Sam, 2024).

Currently, there is no stable production of saffron in European countries since the corm is susceptible to fungi and very sensitive to temperature changes. In recent years, 200 producers whose saffron origin status is protected have seen their crops affected by the climate emergency. Saffron cultivation is highly dependent on specific climatic conditions. Unpredictable weather patterns, such as temperature fluctuations and irregular rainfall, can impact on saffron yields, posing a challenge for consistent production (Table 4).

Ginseng root in commerce is obtained from diverse species of Panax (Araliaceae), including P. ginseng C.A.Mey. (Korean or Chinese ginseng). P. quinquefolius as well as Eleutherococcus senticosus (Rupr. & Maxim.) Maxim. (Siberian ginseng, Araliaceae). In terms of sustainability, there is a similarity in its use and pharmacological profile to the Asian species of Panax. American ginseng and Asian ginseng may increase energy levels, lower blood sugar and cholesterol levels, relieve stress, promote relaxation, treat diabetes, and control sexual dysfunction in men (Brinckmann and Huang, 2018).

Despite the widespread and stable cultivation of P. quinquefolius in Canada (60%), the United States (30%), and China (7%) (Shen et al., 2019; Xiao, 2000), interest in American ginseng wild-harvested raw materials from North America (United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont, and Missouri) and Canada still exists. Vandalism and illegal harvesting of raw materials in forests continue despite the existing status of the species as being endangered nationally [Vulnerable (G3)] and laws for its protection and conservation, especially in Ontario and Quebec (Government of Canada, 2015). American ginseng is now considered an endangered species in 16 United States states, and in another 10 states of the United States, P. quinquefolius is listed on Appendix II of CITES (Convention on International Trade in Endangered Species CITES, 2024), which restricts trade in whole roots and root slices.

The uncontrolled digging of wild roots for export is due to the high price of raw materials on the black market based on its popularity in traditional Chinese medicine (White, 2000). Another threat is the logging of mesic hardwood forests since the species requires rich soil in a moist, generally shaded setting. Ginseng is physiologically adapted to low light levels and can experience early leaf senescence or depressed growth with moderate-high light levels (USFWS, 2005), which can be an issue with increased forest fragmentation.

Sales of wild and cultivated ginseng exceed USD 25 million each year in North America, with wild ginseng seen as the more desirable type. Data from the U.S. Fish and Wildlife Service indicate that thousands of pounds of wild ginseng roots are exported annually. For instance, in 2019, over 80,000 pounds of wild ginseng were exported from the United States. Since the process of plant cultivation faces various problems, the increased interest in wild forms of the species is due to environmental changes that reduce the cultivation area and the quality of the product itself. Therefore, for the introduction and cultivation of plants, it is necessary to identify the maximum similarity of the new ecological distribution of P. quinquefolius and predict its response to future climate change. Various simulations of American ginseng responding to a 1°C increase in maximum growing season temperature over the next 70 years showed that the risk of local extinction for average population size (n = 140) was 65%, which far exceeds the additive effect of the two factors (risk of extinction = 8 and 6% for deforestation and climate change respectively) (Souther and McGraw, 2014). Among the main external factors of plant mortality are the effects of warming and illegal harvesting, leading to the loss of natural habitat, such as deforestation (Souther, 2011; Souther and McGraw, 2014; Souther et al., 2012). Internal reasons for decreased yields of American ginseng include slower plant growth, reduced fertility, and disease susceptibility.

Additionally, factors affecting plant populations also include predatory wild animals eating young plants, which affects the growth and survival of ginseng, as well as the influence of invasive species competing for habitat (McGraw et al., 2013). However, the key and most dangerous influence is human activity (Case et al., 2007), which, on the one hand, leads to unsustainable harvesting methods or urbanisation of the territory, which leads to habitat destruction, and on the other hand, indirectly affects the intensity of climate change and its impact on a species. Changes in temperature and precipitation patterns due to climate change could affect the distribution and health of ginseng populations (Canada. Environment and Climate Change Canada, 2018). Increasing temperatures and changes in precipitation lead to habitat loss and increased vulnerability to pests and diseases. Regional studies indicate that North-eastern U.S. forests may face increased temperatures and altered precipitation, potentially stressing ginseng habitats (McGraw et al., 2013) (Table 5).

P. microphyllus (or jaborandi) is widely distributed in the northern region of Brazil (Sawaya et al., 2011) and is one of the most important commercial products of the native Brazilian flora. The genus Pilocarpus is the only natural and economically viable source of pilocarpine currently known (De Abreu et al., 2005). Four (of 17) species, including P. microphyllus (also P. alatus, P. carajensis, and P. sulcatus) have been listed as threatened in Brazil due to a lack of sustainable management (Abreu et al., 2007). Pilocarpine, an important imidazole alkaloid, is extracted from the leaves of jaborandi, and is a sympathomimetic agonist in ophthalmology, where it is used as a miotic, in open-angle glaucoma, and to contract the pupil after the use of atropine (Sneader, 2005). Pilocarpine is also a powerful stimulant of salivation and perspiration (Budavari, 1989). In 1994, pilocarpine was approved by the North American Food and Drug Administration (FDA) for the treatment of post-radiation xerostomia (dry mouth) in patients with head and neck cancer (Gornitsky et al., 2004; Sidhu, 2014). Scientific studies have reported that the pilocarpine content in jaborandi varies in response to abiotic determinants and seasonally (Avancini et al., 2003; Monteiro et al., 2023). Plants of jaborandi in the forest seem to accumulate more pilocarpine in the leaves, with mean values ranging from 400 to 500 mg/g (Sousa, 1991).

The German pharmaceutical company “Merck” has held a decade’s monopoly on the purchase of jaborandi leaves and the production of pilocarpine in Brazil, most importantly in Maranhão, which produces around 95% of all national production (IBGE 1975–1998) (Pinheiro, 1997). These approximately 2,300 ha have partially replaced the extraction process of wild populations. The main destinations of pilocarpine for international trade are Germany and the USA, with around 70% and 17% of Brazilian exports, respectively (CNI, 2014). In Germany, the “Boehringer-Ingelheim” company has a virtual monopoly on the distribution of pilocarpine (CNI, 2014). The price paid by pharmaceutical industries prompted the widespread participation of local people in collecting the leaves of bushes growing in the forests. As a consequence of this intense gathering, jaborandi was included in the Brazilian list of endangered species with a status vulnerable A2cd (Pinheiro, 1997; Pinheiro, 2002).

This shrub is native but not endemic to northern and northeastern Brazil, occurring more specifically in eastern Pará, northwestern Maranhão, and northern Piaui and to some areas in French Guiana and Suriname (Pirani and Groppo, 2014). This region is characterised by annual precipitation between 2,000–2,400 mm, while the average annual temperature varies from 23°C to 26°C (Moreira et al., 2021), which offers the species the maturation of its fruits and flowers and, subsequently, good growth. The natural habitat is open sunny forest habitats, river basins with sandy soils, and rocky outcrops of pre-Amazonian forests (Skorupa, 2000). The main threat to this species’ habitat is anthropogenic activity, such as Amazon deforestation for agriculture and mining. Being a hermaphrodite, cross-pollination is the norm. Unfortunately, no information is available regarding this species’ reproductive method (Sandhu et al., 2006). Recent studies indicate that this species has high levels of genetic diversity and an effective population size sufficient to reduce the probability of extinction due to inbreeding depression (Monteiro et al., 2022).

The investments and technological advances advocated to increase productivity and leaf yields indicate that pilocarpine has long been a profitable business for the pharmaceutical industry, as well as supporting the development of agriculture and other forms of harvesting raw materials among local people (Pinheiro et al., 2006). The development of technologies that allowed for the cultivation of jaborandi in small regions could serve as a method for reducing pressure on natural populations (Caldeira et al., 2017). Propagation of these species is usually carried out by producing seedlings from recently collected seeds, allowing germination to reach up to 96% (de Meneses et al., 2007), with peak fruiting and seed dispersal occurring from May to July under natural conditions (Muniz, 2008; Rocha et al., 2014). Conservation programs and management plans have been established for this species in the Carajás National Reserve (Pará, Brazil) (Monteiro et al., 2022). Sustainable management in natural areas and cultivation are potential avenues for plant conservation. The development of a germplasm bank and rescue accessions are solutions that can be utilised to preserve genetic material for breeding, involving the reintroduction of thousands of plants in areas designated for conservation and sustainable uses. To accomplish this, a series of multidisciplinary studies will be required, including ones on genotype selection, propagation, maximising biomass and pilocarpine production, and identifying nutritional requirements and environmental variables that will boost pilocarpine yield (Caldeira et al., 2017) (Table 6).

R. rosea, commonly known as rose root, is a perennial species known for its adaptogenic properties for stress and fatigue, which make it popular in traditional medicine and modern supplements, especially in Russia, Scandinavia, and China (Aiken et al., 2007; Booker et al., 2016). However, unlike C. sativus and P. quinquefolius, in addition to the significant exploitation of the species, another problem is climate change, which leads to the migration of plant populations to colder zones of the Alps (You et al., 2018b). The global market for R. rosea is estimated at tens of millions of dollars per year (360ResearchReports, 2022). The species is collected from wild populations and cultivated sources, but the collection of wild plants predominates due to the perceived higher potency of wild accessions. Overharvesting of wild populations, especially in Russia, Mongolia, and China, has led to significant declines in natural populations. Sustainable harvesting methods are not widely adopted, leading to the risk of local extinction and genetic depletion.

R. rosea usually grows in cold, moist, and well-drained environments such as the Arctic, North America, Canada, and mountainous areas of Europe and Asia (Small and Catling, 1999; Brown et al., 2002; Hung et al., 2011), which are especially vulnerable to temperature shifts caused by climate change. Recent studies have shown that Rhodiola is sensitive to changes in temperature and rainfall patterns (You et al., 2018b). Climate change poses a threat by altering environmental conditions and potentially reducing suitable habitats. In regions such as the Altai Mountains and the Tibetan Plateau, rising temperatures and changing rainfall patterns are expected to affect the distribution and abundance of R. rosea (Kubentayev et al., 2021; Klanderud, 2005). These changes could alter its geographic range, potentially reducing its available habitat.

Biotic determinants affecting the specie' abundance include slow growth rates, special habitat requirements, and limited seed dispersal, which contribute to its vulnerability. However, habitat loss due to forced migration is the main threat to the species, caused by both natural and anthropogenic determinants. Over the last decade, the populations have decreased significantly, and the species has the status of “endangered” and is listed in Appendix II (CITES). In addition, R. rosea also has Global G5 Secure status (from 2015) in Canada and the U.S. (NatureServe Explorer, 2023b). Promoting the cultivation of R. rosea as an alternative to wild collection can help meet market demand while conserving wild populations. Research into effective cultivation methods continues and has shown promising results in reducing pressure on natural habitats (Table 7).

W. salutaris (known as pepper-bark tree, referring to the peppery taste of the bark and leaves) is an endangered species highly valued in South African traditional medicine (Williams et al., 2013; Van den Bosch et al., 2023). The bark of the tree is used to treat a multitude of ailments, including coughs, fever, colds, headaches, inflammation, bladder infections, abdominal pains, skin irritations, ulcers, and sores (Maroyi, 2013; Van Wyk and Gericke, 2000; Van Wyk et al., 2009). Leaves and root bark are also used but to a much lesser extent. The plant material is traded commercially at traditional medicine “muthi” markets, resulting in unsustainable harvesting of wild populations (Williams et al., 2013; Burrows et al., 2018). The leaves and bark both contain drimane sesquiterpenoids (Mashimbye et al., 1999), such as polygodial and isopolygodial, warburganal, salutarisolide, mukaadial, and muzigadial (Rabe and van Staden, 2000).

W. salutaris is capable of regenerating vegetatively by suckering, but a loss of sexual reproduction will result in decreased genetic diversity in a population, negatively affecting long-term persistence (Botha et al., 2004; Johnson et al., 1995). Clusters of trees studied in KwaZulu-Natal were reported to be generally all clones, with no seedlings found (Scott-Shaw, 2001). Flowers are bisexual but it is unknown whether this species is self-compatible and able to undergo successful self-pollination (Van den Bosch et al., 2023). Outcrossing populations should, in principle, have increased genetic diversity and therefore a greater ability to adapt. W. salutaris is challenging to propagate from seed owing to a paucity of viable seeds owing to high predation levels, insect infestations, and loss of viability during storage of the recalcitrant, desiccation-sensitive seeds (Symmonds and Crouch, 2000). High phenolic content has impeded tissue culture, but an in vitro technique is available (Kowalski and van Staden, 2001). Shoot-tip cuttings have proven successful in cultivation projects (Symmonds and Crouch, 2000).

The population size of W. salutaris has been approximated at between 4,638 and 4,566 plants, with the largest recorded subpopulation within the South African range consisting of 952 plants (Harvey-Brown et al., 2022). There are potentially larger subpopulations as yet unrecorded, but these are not likely to have more than 5,000 mature individuals. Conservation of W. salutaris was initiated by the company HL&H (now known as Mondi Forests), with the establishment of a living gene bank of about 1,000 trees (Van Wyk, 2011). A significant number of trees was propagated by this organisation for distribution in 1996 when W. salutaris was selected as “Tree of the Year” in South Africa. In the Kruger National Park, thousands of cultivated saplings have been distributed to traditional healers, decreasing the rate of decline in the population and improving the species’ status from endangered to vulnerable but declining (Harvey-Brown et al., 2022).

Another conservation initiative is to promote the use of leaves as a substitute for the bark material, as two of the most bioactive ingredients, polygodial and warburganal, have been detected in both leaf and bark extracts (Drewes et al., 2001). Traditional healers occasionally use leaves in treating particular complaints, but if this could be encouraged on a larger scale, more sustainable harvesting levels could be achieved from wild as well as cultivated populations (Botha et al., 2004). However, Leonard and Viljoen (Leonard and Viljoen, 2015) cautioned that the shorter shelf-life of leaves compared to that of bark may be a concern for traditional healers.

The most significant threat to W. salutaris is the overharvesting of bark and roots for traditional medicinal use (Veeman et al., 2014). The tree can tolerate some harvesting by producing coppice shoots and regrowing stripped bark, but excessive harvesting can cause the death of the tree (Harvey-Brown et al., 2022). Overuse of the bark has resulted in the species being listed as extinct in the wild in Zimbabwe (Maroyi, 2008) and locally in some regions of KwaZulu-Natal, South Africa (Harvey-Brown et al., 2022). The mean thickness of bark sold in the Johannesburg markets decreased significantly from 1994 to 2001, indicating that bark from smaller trees was increasingly harvested as larger, more mature trees became unavailable (Williams et al., 2007). Other factors that influence tree growth include agricultural activities, the use of trees as building material, road construction (Harvey-Brown et al., 2022; Veeman et al., 2014; Cunningham, 1993), fires (Senkoro et al., 2020), grazing by herbivores, termite infestation, and damage caused by fungal diseases (Harvey-Brown et al., 2022).

Information on the environmental requirements and precise distribution of W. salutaris is scanty. The distribution of W. salutaris is dispersed and fragmented at present, possibly as a result of biogeographical and climatic influences, but its ecological requirements are largely unknown (Senkoro et al., 2024). In an earlier study, it was suggested that the species is sensitive to lower temperatures and has a reasonable tolerance to drought and precipitation levels, with an affinity for more moist areas (Senkoro, 2021).

Climate projections have predicted an increase in intensity of rainfall over the eastern parts of southern Africa, but that rainfall would be less frequent (Kusangaya et al., 2014). In the Kruger National Park, changes in the intensity and timing of certain environmental conditions, including droughts and floods, were proposed by Kitajima and Fenner (Kitajima et al., 2000) to be detrimental to the establishment of W. salutaris seedlings. However, using climatic model predictions, it was reported that for the next 80 years, the distribution of W. salutaris is not likely to decline because of factors related to climate change (Senkoro et al., 2024). This study did not take into account the effect of climate change on species interacting with W. salutaris, including humans, pollinators, and parasites. Although climate change may not pose the greatest threat to the sustainability of W. salutaris, cultivation and reintroduction alone are not likely to enhance the conservation of the species if the threat of overexploitation of bark for medicinal use, as well as the impact of wildfires, charcoal production, and land use transformation, are not addressed. In summary, an integrated management strategy for W. salutaris is essential to ensure its sustainability. This involves increasing cultivation and redistribution efforts as well as successfully managing protected areas (Table 8).