Traditional ladders keep farmers high up in canopy

Beneath the sprawling canopy of centuries-old pear trees in Shichuan town, Lanzhou, orchard work takes place high above the ground, within trees that can reach more than 10 meters in height.

Farmers here rely on a traditional wooden scaling ladder system known as tianbashi, a practice passed down through generations and recognized as a provincial-level intangible cultural heritage in Gansu.

Rather than a single tool, tianbashi represents a complete system of high-altitude farming knowledge used to access, manage and care for some of the world's oldest pear trees.

The system is closely tied to an elevated cultivation model known locally as gaotian, or "fields in the sky", in which branches are lifted and supported by wooden frames, forming a layered orchard structure above the ground.

"In other places, farmers plant on the ground, but here they plant in the sky," said Li Xiaoli, a staff member of the orchard's protection center.

"Mechanized operations can lead to soil compaction and surface hardening over time. In contrast, the tianbashi system places far less pressure on the ground. As farmers work above the soil using wooden ladders, the impact on the orchard floor is minimal, helping preserve soil structure and ecological stability," Li said. "It also offers greater flexibility, allowing workers to move through dense canopies and reach branches more precisely than machinery."

According to the Food and Agriculture Organization, this reflects a long-evolved traditional knowledge system in which seasonal ecological practices are embedded in every stage of orchard management.

Using tianbashi, farmers carry out key seasonal tasks including pruning, flower management, pollination, fruit thinning, harvesting and ecological pest control, all guided by agricultural calendars shaped by flowering cycles and tree growth patterns.

For local farmers, tianbashi is more than a working method — it is inherited memory. Techniques such as high-altitude pruning, bark treatment and seasonal canopy care are learned through generations rather than formal training.

"These old pear trees are like our ancestors," said 63-year-old farmer Wei Zhouyu. "We must care for them using traditional methods."

Among these tasks, flower management is especially important. During blooming season, farmers perform flower thinning by gently shaking branches from elevated positions. The practice reduces excessive blossoms so nutrients concentrate in fewer fruits, improving size and quality, while also dislodging insects and eggs.

Equally important is pollination. Because main varieties such as the Dongguo and Ruan'er pears depend on cross-pollination, farmers plant compatible trees like Sumu and Changba pears throughout the orchard. Climbing the wooden ladders, they manually transfer pollen between varieties to ensure stable yields and high fruit quality.

Wei also practices winter bark scraping, a traditional technique that removes old bark, helps eliminate overwintering pests and improves tree health. "Removing the old bark helps the tree breathe more easily," he said.

Wei manages 16 ancient pear trees, including some over 400 years old.

The work remains demanding. Pruning, pollination and harvesting all require long hours in the canopy, and many young people are reluctant to take over. "It's hard and sometimes dangerous," Wei said.

To address this, local authorities have incorporated tianbashi into heritage protection programs and training systems to encourage knowledge transfer. The orchard's protection center has also established a nursery with more than 2,000 saplings for restoration, while experts train farmers in green pest control and scientific orchard management.

The FAO said that the Shichuan system demonstrates how traditional agricultural knowledge continues to function as a living system rather than a relic of the past.