The world’s oldest area of alpine plants has been discovered in China.
The oldest Alpine plant region on Earth, located in the Hengduan Mountains in southwest China, is more than 30 million years old, according to scientists. American and Chinese researchers say that the alpine flora of the Hengduan Mountains has existed continuously for much longer than any other alpine flora on Earth.
Plant diversity in the region today can be traced back to newly formed mountain ranges 30 million years ago and later, according to plant DNA analysis.
When the Indian tectonic plate crashed into Asia about 40 million years ago, the impact on biodiversity was like a “jet fuel overflow” due to new weather conditions. According to the scientists, the Alpine community of the mountain includes special communities adapted to stressful environmental conditions, including past climate changes.
“Our historical reconstructions indicate that alpine flora appeared in the Hengduan Mountain region at the beginning of the Oligocene,” said Professor Xiang Yaowu of the Chinese Academy of Sciences. “This is much earlier than the supposed origin of other existing Alpine floras.”
The scientists focused on plants growing above the tree line, called the alpine zone, in the Hengduan Mountains. It was found that this relatively small area is home to a third of all plant species in China. In the Hengduan Mountains, you can see coniferous forests, rapid glacial streams, rocky valleys and meadows teeming with wildflowers.
The team wanted to find out how the plants are distributed in the alpine regions of the Hengduan Mountains, the Himalayas, and the Qinghai-Tibetan Plateau, and how they got there. The researchers used DNA and fossilized samples to build family trees from 18 groups of flowering species and calculate how long ago their common ancestor lived.
The DNA of the different plant species present in this region can help determine how closely related the plants are to each other and how they evolved. Scientists note that the formation of a community rich in diverse plant species was caused by “ancient mountain building” and is highly dependent on geology and climate.
Many of the plants first originated in the Hengduan Mountains, but the collision of the Indian tectonic plate with Asia 40-50 million years ago slowly created new mountains, including the Himalayas. As a result, new habitats formed on the slopes of the mountains and in the valleys below and the region began to experience more intense monsoons. Perhaps this was because the mountains changed the prevailing winds, creating new weather patterns.
As the landscape became more turbulent over time, the now isolated plant populations diverged into their separate species, resulting in the biological diversity of today.
The researchers say that figuring out how species evolve and spread, and why some places are richer than others, is key to understanding and protecting the world around us. Mountain ecosystems tend to be very sensitive to things like global warming, because the organisms that live there depend on a narrow range of altitude and temperature.
“Understanding how historical environmental changes affected Alpine plants 20 million years ago can help us predict how today’s climate change will affect their descendants,” said study author Dr. Rick Rea.