China News Service, Beijing, June 6 (Reporter Sun Zifa) The Institute of Qinghai-Tibet Plateau of the Chinese Academy of Sciences (Institute of Qinghai-Tibet Plateau, Chinese Academy of Sciences) announced on the 6th that researcher Wang Tao from the Ecosystem Function and Global Change Team of the Institute, together with Peking University and Xishuangbanna, Chinese Academy of Sciences Tropical Botanical Gardens, etc., the latest research released a high-definition panorama of the alpine treeline in the Himalayas, showing that the average altitude of the Himalayan treeline is 3,633 meters, and the treeline height in the eastern region is nearly 800 meters higher than that in the west.
This important research paper on the ecology of the Qinghai-Tibet Plateau was recently published online in the international professional academic journal "Nature-Ecology and Evolution".
The study also predicts that by the end of this century, the tree line in the eastern, central and western Himalayas is expected to climb by 140 meters, 45 meters and 6 meters, respectively, thus providing a direct scientific basis for the conservation and management of high-altitude biodiversity in China.
Treeline panorama of the Himalayas.
Photo courtesy of Institute of Qinghai-Tibet Plateau, Chinese Academy of Sciences
Wang Xiaoyi, the first author of the paper and a postdoctoral fellow at the Institute of Qinghai-Tibet Plateau of the Chinese Academy of Sciences, said that the alpine treeline, as the highest altitude limit of tree distribution, is generally considered to be an indicator and record carrier of rapid climate warming in high-altitude areas.
The Himalayas have the highest treeline in the world, which is an ideal place to test and develop the theory of alpine treeline distribution.
However, the current academic community still lacks a systematic understanding of the distribution and formation mechanism of alpine treelines.
To this end, a cooperative team led by the Qinghai-Tibet Plateau Institute of the Chinese Academy of Sciences has developed a large-scale remote sensing automatic extraction of alpine tree lines by combining field monitoring data, 700,000 sub-meter-level visual interpretation samples, and 30-meter resolution satellite remote sensing data. Method, the panorama shows the distribution map of the alpine treeline of the Himalayas stretching 2400 kilometers.
This study found that the average altitude of the Himalayan tree line is 3633 meters, and the tree line height in the eastern region is nearly 800 meters higher than that in the west; Treelines are distributed below this isotherm.
The study revealed that human activity is the key driving force for the deviation of the treeline distribution in the central Himalayas from the global treeline isotherm, while drought and human activities are the main factors for the deviation of the treeline in the western part of the world.
Researcher Wang Tao, the corresponding author of the paper, pointed out that 200 years ago, Alexander von Humboldt, known as the "father of modern geography", pioneered the study of alpine tree lines, first proposed the climate-driven theory of alpine vegetation distribution, and pioneered "isothermal". The concept of "line" opened the prelude to the search for a universal explanation for the distribution of alpine vegetation; German plant ecologist Kristin Kohler found that the global alpine treeline distribution converges to a consistent temperature threshold, revealing that the location of alpine treeline is located in the growth The isotherm with an annual mean temperature of 6.4°C.
However, accumulating ground-based observations suggest that not all alpine treeline locations coincide with this global treeline isotherm.
Scientists have proposed a package of derived hypotheses including carbon starvation, growth restriction, disturbance, freezing stress and resource limitation. The theory of treeline distribution in alpine mountains, which originated in the 19th century, is causing intense debate and extensive discussion in the academic community.
He said that this study proposes that drought and human activities are the driving mechanisms that cause the distribution of Himalayan tree lines to be high in the east and low in the west. The results provide a new theory for accurately understanding the asynchronous changes in the Himalayan tree lines under the background of global warming. The hypothesis brings new research ideas and paradigms to the field of alpine treeline research, and develops and enriches the classic theory of alpine treeline distribution pioneered by Humboldt.
Wang Tao said that based on the above analysis of the treeline driving mechanism, combined with the prediction of future climate by the Earth System Model, this study predicts that by the end of this century, the treeline in the eastern Himalayas is expected to climb 140 meters, while the treeline in the central and western regions will change. Relatively small, climbing only 45 meters and 6 meters; the eastern tree line climb will cause the natural habitat of alpine endemic species to be compressed by 20%-70%, which will increase the risk of high altitude endemic species loss.
The research team also suggested that China needs to re-examine the existing strategies for alpine biodiversity conservation, and urgently needs to include alpine endemic species into the priority protection scope, such as the establishment of ecological corridors to prevent the loss of high-altitude biodiversity.
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