Climate change altering rhododendron bloom time: report

Rhododendron arboreum is the first of the rhododendron species to flower in the Himalayas.  

The blooming of rhododendrons heralds the onset of spring in the Himalayas, but thanks to climate change they are now flowering early in the winter itself, research shows.

A study by a group of scientists of the G.B. Pant Institute of Himalayan Environment and Development, Almora, has generated evidences of changes in flowering phenology of Rhododendron arboreum flower in Uttarakhand.

Real-time field observations from 2009-11 showed peak flowering during early February to mid-March while earlier the full bloom was noticed from March to May, when the spring season sets in.

“The present field observations over three years revealed considerably higher frequency (47-75 per cent trees) of bloom during February-March, which provides a strong basis to prove other observational reports of advancement in flowering events of target species from spring to winter,” said Dr. Ranbeer S. Rawal who led the research.

In his report he said that generalised additive model (GAM) using real-time field observations and herbarium records (1893-2003) predicted 88-97 days early flowering over the last 100 years.

Rhododendron arboreum is a small evergreen tree and is known for the captivating beauty of its deep red or pale pink flowers.

Throughout the region, the species commands a high socio-cultural reverence and has been designated as the state tree of Uttarakhand.

With the blooming of the rhododendrons, locals in the Garhwal Himalayas celebrate ‘Phool Sankranti’, a festival of flowers.

For the research, the scientists identified four sites with abundance of the species in Uttarakhand’s Kumaon region.

To correlate the change in flowering pattern with change in climate, they analysed long-term temperature data of the region for the preceding 41 years (1971-2011) which showed a significant increase in mean maximum temperature.

GAM using long-term temperature data, real-time field observations and herbarium records depicted annual mean maximum temperature responsible for shifts in flowering dates of the species, said the report.

The study provides an important insight of species response to climate change in the Indian central Himalaya and highlights the need for further research on the subject to improve our understanding of the effects of climate change on species and consequently on ecology of the region, Dr. Rawal said.

Phenological responses of plants, particularly the early flowering ones, are considered among the prominent biological indicators of climate change.

The report said more rapid advancement of flowering in different species in recent decades has been reported from other parts of the globe too.

“Such advancement is most often attributed to corresponding increase in temperature,” it said.

“While the estimates of change need to be treated as most conservative, the trends definitely warrant attention as an indicator of climate change impacts on flowering phenology of prominent regional species, and the likely consequences for ecosystem processes,” said the scientists.

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Printable version | May 6, 2021 6:38:24 PM | https://www.thehindu.com/sci-tech/energy-and-environment/climate-change-altering-rhododendron-bloom-time-report/article6166035.ece

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