The majestic Himalayas are not just home to the world’s tallest mountains but also recognised as a global biodiversity hotspot. The region, characterised by its high altitude and varied ecosystems, is home to a unique array of plant and animal species, including many that are endemic. The region is also on the front lines of climate change. Like the rest of the planet, temperatures here are shifting, impacting the delicate balance of life. Researchers are now turning to unlikely allies in their quest to understand these changes: lichens.
A lichen is a composite organism. It emerges from algae or cyanobacteria living among the filaments (hyphae) of the fungi in a mutually beneficial symbiotic relationship. Lichens are also incredibly sensitive to their environment. A recent study, including researchers from North Eastern Hill University, Shillong, Meghalaya, Space Applications Centre-ISRO, Ahmedabad, CSIR-National Botanical Research Institute, Lucknow, and others, has used this property of the lichens to signal shifts in the Himalayan climate.
Did You Know? Lichens can tolerate extreme cold, strong winds, and high levels of UV radiation, making them ideally suited for the harsh conditions found at high altitudes in the Himalayas. Lichens also play a role in breaking down rocks and contributing to soil formation, making them essential players in the ecosystem, even if they grow very slowly. |
The researchers embarked on a journey across the Indian Himalayan Region, from the western ranges of Jammu and Kashmir to the eastern reaches of Arunachal Pradesh. They collected data on over 1475 lichen species, spanning an elevation gradient from 1000 to 4500 meters. This vast area experiences dramatic changes in temperature, rainfall, and sunlight as you ascend the mountains. The team analysed the diversity of these lichen communities and, crucially, their functional traits. Functional traits are specific characteristics of an organism that help it survive and thrive. For lichen, these could be its growth form, the type of algae it partners with, or how it attaches to a surface.
The team found that lichen diversity isn't evenly distributed across the mountains. It peaks in the mid-elevational zones, specifically between 2000 and 2500 meters, and then declines at higher elevations. This hump-shaped pattern is a common observation in nature and is often linked to the idea of the mid-domain effect, where different species might overlap in their preferred habitats.
More importantly, the researchers found a strong connection between these functional traits and the elevation. This means that as the environment changes with altitude, becoming colder, drier, and experiencing more wind and UV radiation, different lichen traits become more or less common. For example, lichens with certain growth forms or those that can tolerate drier conditions become more prevalent at higher, harsher altitudes. The study also revealed a significant difference in lichen communities between the western and eastern Himalayas, suggesting that variations in temperature and rainfall between these regions play an essential role in shaping which lichens can survive.
The finding indicates that by studying how these functional traits change, researchers can get a clearer picture of how the microclimate is changing. The team used statistical methods, including a method called Non-metric Multidimensional Scaling (NMDS), to visualise these complex relationships and confirm that elevation is a significant factor influencing lichen distribution and their traits.
This research recognises that lichens are not just passive inhabitants of their environment but actively respond to it through their traits. While earlier studies have looked at how lichen species shift with climate, this study emphasises the importance of their functional traits as a more direct indicator. More studies are needed that directly link lichen biodiversity with specific microclimatic conditions over time, but the current findings provide a strong foundation for this future research.
In a world grappling with the impacts of climate change, having reliable bio-indicators is incredibly valuable. Lichens, being so sensitive, can act as early warning systems. By monitoring changes in lichen communities and their functional traits, scientists can better understand the pace and nature of climate change in sensitive mountain ecosystems like the Himalayas. This information is vital for conservation efforts, helping us protect not only these unique lichen species but also the broader ecosystems they are a part of.
This article was written with the help of generative AI and edited by an editor at Research Matters.