Researchers have numbered and fitted each individual wild plant with a GPS tracker so its condition can be monitored, and data－including height, tree crown diameter and diameter at chest height－have been collected steadily over the years.

"Statistics show that about 70 percent of the artificially cultivated saplings have survived," said Zhang Tianbi, a researcher at the botanical garden. On Aug 10, a Qiaojia five-needled pine that was cultivated off-site at the garden bore nuts for the first time.

Plant cultivation and seed storage are two of the main methods of this form of off-site conservation, because it's a simple, economical way of conserving certain plants and animals in selected areas outside of their natural habitats.

The Kunming Institute of Botany is currently storing the seeds of more than 10,000 plant species, the highest number among all countries in Asia.

Researchers from the institute have also developed plant tissue culture techniques (used to develop thousands of genetically identical plants from a single parent) for in vitro propagation and conservation. They have successfully propagated 42 plant species with extremely small populations via these techniques.

"Species that have survived for thousands of millennia, and were once widespread across the Northern Hemisphere but survive today only in China are a special part of the shared natural heritage of humanity. In such instances, the attention that the PSESP program brings to these species is especially important," wrote Peter Crane, an evolutionary biologist and plant paleontologist from the Yale School of the Environment in the United States, in an email exchange with China Daily.

"The program underpins China's role as the global guarantor of the long-term future of plant species that were here long before people came to dominate this planet. Reflecting on these ancient species should engender a degree of humility while encouraging us to think more carefully about calibrating our impacts on the natural world," he added.