GLOBALLY, RHODODENDRONS are pro-moted as ornamentals because of their striking colours. They are planted along the roads in tourist places because of their aesthetic value. The plant has a huge presence in Sikkim. For the past 10 years, the state has witnessed a huge influx of tourists and was voted by the Lonely Planet as one of best places to visit in the world in 2014. We were born and brought up in Sikkim Himalaya, and have also resea-rched in depth on the Rhododendron plants. Through our observations, we have been able to unravel the many linkages and interactions between the Rhododendron plants and other life forms in the forests.
The upper reaches of the Sikkim Him-alaya are home to many beautiful flowering plants. Rhododendron of the Ericaceae family is the dominant flowering plant of this region. Of the 86 species found in India, Sikkim Himalaya hosts about 38 species of Rhododendrons, and they are found at a height of 1,700-5,500 m. Along the ele-vation, these species differ in its life forms. For example, in the mid-temperate forests they occur as tall trees, whereas in the sub-alpine region, which covers the area just below the tree line, these species are found as shrubs. In the higher alpine region, above the tree line, these species occur in the form of thickets and scrubs.
Ecological linkages
Rhododendron forests are a very important habitat for the survival of fauna and flora of high altitudes. Their branching structure creates a fascinating understory for Hima-layan ungulates such as Musk deer, which can be often seen feeding on the petals of Rhododendron campanulatum. It also sup-ports other important life forms such as Himalayan Monal and Blood Pheasants.
Apart from animals, there are many insects and birds that depend on Rhodod-endrons for their food. Flies are the smallest insects and important visitors of Rhodod-endron flowers. They visit Rhododendron flowers for nectar and pollen, which serves as a source of carbohydrates and proteins.
After several observations, we realised that Rhododendrons also enable spaces that serve as popular destinations for honey-moon for several species. Big, spacious florets of Rhododendron provide a good place for flies to mate. This, in turn, attracts predacious insects such as wasps that take advantage of the activities of flies and prey on them. They also stay on these flowers to perform their nuptial act. However, they inadvertently pollinate the flowers as the species produce profuse pollen, which are held in a string, and sticks to the body of these insects.
Species such as R thomsonii and R hodgsonii attract an array of birds such as Sunbirds, Warblers and Laughingthrush, which can be seen hovering around the Rhododendron flowers during the flowering season. Apart from obligate nectar feeders, some species such as Sunbirds use them as facultative feedees, and go for both nectar and the insects. Tits and Laughingthrush can be seen tearing the petals apart to reach out to these insects.
It is interesting to observe wide vari-ations in the nesting times—some birds nest during the peak flowering period, when the resource availability is very high, some nest just at the onset of the flowering season, while others prefer the period when the flowers get wilted.
The Musk deer (above) can be often seen feeding on the petals of Rhododendrons. The plant also supports important bird species such as the Blood Pheasants (right)
Occasionally, during elevation walks we have often witnessed a flurry of activity among the birds. After a careful obser-vation, we realised that weasels, one of the active small carnivores of high altitudes, were raiding nests devouring eggs and nestlings. We often saw large birds of prey flying low over the Rhododendron canopy, perhaps shadowing these marauders of nests, and other small beings such as Pika. However, Pikas often fall prey to these birds. It is a pleasure to watch the Pikas collect the fallen petals of Rhododendron and scurrying to the burrows on noticing us. They stock the petals in their burrows for the harsh winter.
Cultural courseSikkim is the first Indian state to develop an eco-tourism policy with the help of Japanese and American experts. The state capitalises on the flowering season of Rhododendrons by organising cultural events which further enhances its tourist edge. Singhba Rhodod-endron Sanctuary and Barsey Rhodod-endron Sanctuary located in north and west Sikkim come alive during the Rhodod-endron festivals. The forests appear like a red blanket of flowers as the tourist season overlaps with the flowering timing of this one plant genus. Tourism raises substantial revenues for the state government to main-tain these sanctuaries.
Local communities too benefit from the presence of Rhododendrons plants. Home stays have sprung up, where people serve a local brew called Chang. Rhodod-endrons have high ethnic uses as well. Rhododendron anthopogon locally called sunpatey is used as a natural incense by the Buddhist community. The Rhododendron aroboreum, locally known as lali guran, is commonly used to prepare wine. Its rich ethnic and economic value therefore high-lights the strong cultural services that this genus provides to the people of Sikkim.
The blooming of Rhododendron arbo-reum in Himalayan foothills signals the onset of spring. We have personally experi-enced shifts in the flowering timings of Rhododendron over the years. Many studies have highlighted the sensitivity of these plants, attributing the flowering phenology to an increase in temperature. Any shift in its flowering timing can affect the services that it provides to other life forms in the forests and to the people. Importantly, the intera-ctions it shares with its pollinators can get decoupled, which could further affect the entire ecosystem.
Apart from the cultural and aesthetic services that emerge from the Rhodod-endron forests, the plants are well entwined in interacting with a range of fauna and play the role of a keystone species of the Hima-layan region. Scientific studies on the func-tioning of the Rhododendron ecosystem could perhaps help mitigate the effects of future warming.
