Indigenous knowledge has great scientific value as it can be instrumental in efforts towards scientific raw data and also conservation. Such is the case of indigenous knowledge of Himalayan medicinal plants, which can be rooted in a culture’s heritage. This can be severely affected by climate change, with most biodiversity occurring up to an altitude of 2,000 m mainly due to rainfall and sunlight. An increase in rainfall and warming due to climate change could greatly affect plant biodiversity in the region.
Studies on Himalayan Medicinal Plants
Between 1979 and 2006, 264 studies that focused on the biodiversity, ethnobotany and ethnomedicine of Himalayan medicinal plants and also aromatic plants in the Nepal Himalayas were carried out. These studies were utilized by Kunwar & Bussmann (2008) in their study of the undocumented richness and biodiversity of Himalayan medicinal plants in Nepal as marked by indigenous practices.
Prior to these studies, about 21 to 28 per cent of Himalayan medicinal plants with ethnomedicinal value were reported in Nepal. The studies revealed that as much as 55 per cent of the Himalayan medicinal plants in the region had ethnomedicinal value. These findings point towards a huge amount of traditional knowledge about important Himalayan medicinal plants that had yet not been documented such that they could prove ethnomedically useful to modern medical research. The study by Kunwar & Bussmann also found that this abundance of Himalayan medicinal plants decreased with an increase in altitude whose relative percentage of useful plants increased with an increase in altitude.
This increase in proportion can be chiefly attributed to an increase in preference to herbal remedies in areas at a high altitude combined with a lack of availability of alternative choices along with constricting poverty. The wide use and conservation of indigenous remedies with Himalayan medicinal plants in this regard can greatly improve the lives of people living in great poverty. In a separate study by Joshi, Satyal & Setzer (2016) the roles played by aromatic plants among tribal populations living in the Himalayas in providing food and medicine were studied. Their study summarizes the aromatic medicinal plants, 116 species in all, and their use by 26 families living in the Himalayas. Himalayan medicinal plants turn out to be greatly useful for local populations, making a case for the pursuance of protecting the biodiversity of Himalayan medicinal plants.
Plant Biodiversity and Use in the Himalayas
There is incredible biodiversity of plant life in the Himalayas in the Himalaya Centre of Plant Diversity, which is a narrow band in the Himalayan region of great plant biodiversity located near the southern borders of the Himalayas. The defining factor that influences this plant biodiversity are the Monsoon rains, a seasonal characteristic in which up to 10,000 mm of rainfall can occur during the summer season.
According to the distribution of altitudinal zones, there are tropical lowland rainforests and alpine meadows at higher altitudes. Estimates suggest that there could be up to 6,000 species of Himalayan plants in Nepal alone. Of these at least 1,957 plant species are restricted to the Himalayan range. In the Himalayas in India, it is estimated that there are greater than 8,000 species of vascular plants, out of which about 1,748 species are said to be Himalayan medicinal plants (Joshi, Satyal & Setzer, 2016).
Higher plants in the Himalayas have played a unique and key role among tribal communities in the Himalayas through their history to the present day. Tribal communities in the Himalayas depend upon these plants for nutrition and medicinal needs. The use of Himalayan medicinal plants is very common, and many plants that grow wild or are cultivated have been used to cure afflictions throughout the history of these communities. In present times the use of Himalayan medicinal plants has increased, and are not being used just as herbal medicines, but are also being commercially utilized by the cosmetic industry as natural ingredients.
The historical usage of Himalayan medicinal plants dates very long back indeed, and written records of Himalayan plants being used as medicine occur in the Rigveda texts from around 6,500 years ago, which was followed by the Atharveveda and the Ayurveda. In terms of recorded historical accounts of Himalayan medicinal plants in Nepal, the oldest one is Saushrut Nighantu, written in 878 AD. The text records the usage of 278 medicinal plants in the Nepalese territory. A prominent later text is the encyclopaedic text Nepali Nighantu, published in 1969 by the Royal Nepal Academy, which contained a collection of traditional knowledge of 750 Himalayan medicinal plants. Nepal presently reports a total of 1,012 plants that have human applicability, out of which 554 are Himalayan medicinal plants (Kunwar & Bussmann, 2008).
Out of the world’s total population, about 60 per cent rely on traditional medicine. For India the percentage is about 70 per cent and for Nepal its 80 per cent (Shinwari et al., undated). Plants provide the bulk of the raw materials for the preparation of these traditional remedies. Asia is one of the places in the world where medicinal plants are used the most, and other than the Ayurveda utilized by Vedic civilizations, other disciplines that utilize medicinal plants include Amchi, Unani, Siddha, and the Chinese disciplines of traditional medicine along with many others.
The biodiversity of Himalayan medicinal plants was found by Kunwar & Bussmann to increase with an ascent of up to 2,000 m, after which it proceeds to decline. The most highly coveted Himalayan medicinal plants can be found in the tropical and alpine zones. The distribution of Himalayan medicinal plants at these high altitudes are regulated by both ecophysiological and by external environmental factors. That plant biodiversity is most prosperous at between 1,000 to 2,000 m in altitude could be attributed to the optimum amount of energy and rainfall received in this region.
Joshi, Satyal & Setzer’s (2016) study identified several genus of plant species in the Himalayas. Among them are the genus Artemisia, the genus Cinnamomum, the genus Cymbopogon, the genus Juniperous, the genus Nepeta, the genus Origanum and the genus Valeriana. There is however a great dearth of information both of the biological activities of the essential oils of plants and the ethnobotanical uses of all the plant species. Threats also arise in the Himalayas due to unsustainable harvesting, increasing environmental degradation, invasive species, and climate change. With most biodiversity occurring up to an altitude of 2,000 m mainly due to rainfall and sunlight, an increase in rainfall and warming due to climate change could greatly affect plant biodiversity as rainfall along with sunlight are principal components of determining species biodiversity. Conservation thus presents significant challenges that could be greatly exacerbated if climate change has adverse effects on species biodiversity.