What is the Himalayan tree line? What is its use?

Image source: Beijing Daily

The alpine treeline, as the highest altitude boundary of tree distribution, is generally considered to be an indicator and record carrier of rapid climate warming in high-altitude areas.

Himalayas

The highest tree line in the world

Also 200 years ago

Known as the "Father of Modern Geography"

Alexander von Humboldt

One of the three major mountain ranges visited

It can be said to be testing and development

An ideal place for alpine treeline theory

Image source: Baidu Encyclopedia

However, we still lack a systematic understanding of the distribution and formation mechanism of the alpine treeline in the Himalayas. To this end, Wang Tao, a researcher from the Ecosystem Function and Global Change Team of the Institute of Tibetan Plateau Research, Chinese Academy of Sciences, and other researchers from Peking University and Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, combined field monitoring data, 700,000 sub-meter-level visual interpretation sample points, and 30-meter resolution satellite remote sensing data to develop a large-scale remote sensing automatic extraction method for alpine treelines, presenting a panoramic view of the alpine treeline distribution map of the Himalayas stretching 2,400 kilometers.

Panorama of the Himalayas treeline

Image source: Institute of Tibetan Plateau Research, Chinese Academy of Sciences

The study shows that the average altitude of the Himalaya treeline is 3,633 meters, and the treeline in the eastern region is about 800 meters higher than that in the western region. Most of the treeline locations in the eastern Himalaya roughly coincide with the treeline isotherm, while nearly 93% of the treeline in the central and western regions is below this isotherm. Combining multiple factors such as climate (drought, radiation damage, low temperature frost damage, etc.), human and natural interference (fires, earthquakes, etc.), the study revealed that human activities are the key driving force that causes the treeline distribution in the central Himalayas to deviate from the global treeline isotherm, while drought and human activities are the main factors that cause the treeline in the west to deviate. It is proposed that drought and human activities are the key mechanisms that cause the Himalaya treeline distribution to be high in the east and low in the west.

The research results provide a new hypothesis for accurately understanding the asynchronous changes in the Himalayan tree line under the background of global warming, bring new research ideas and paradigms to the field of alpine tree line research, and develop and enrich the alpine tree line distribution theory pioneered by Humboldt.

Future changes in the Himalayan alpine treeline and their impact on habitats of endemic species

Image source: Institute of Tibetan Plateau Research, Chinese Academy of Sciences

Based on the above analysis of the treeline driving mechanism and combined with the Earth system model's projections of future climate, this study predicts that by the end of this century, the treeline in the eastern Himalayas is expected to rise by 140 meters, while the treeline in the central and western regions will change relatively little, rising only 45 meters and 6 meters; the rise of the treeline in the east will cause the natural habitats of high-altitude endemic species to compress by 20% to 70%, increasing the risk of loss of high-altitude endemic species.

The research team suggested that my country needs to re-examine its existing alpine biodiversity conservation strategies and urgently include alpine-specific species in the priority protection scope. For example, ecological corridors should be established to prevent the loss of high-altitude biodiversity. This study provides a direct scientific basis for the conservation and management of high-altitude biodiversity in my country.

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Source: Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Xinhuanet

Producer: Ma Yujuan Editor: Wu Nan

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