Restoring Bamboo-Deciduous Forest to a burnt site at Pong Yaeng Nork

Early in 2024, wildfire swept through a bamboo-deciduous forest at Pong Yaeng Nork, Mae Rim, within Doi Suthep-Pui National Park, destroying much of the existing vegetation. At the request of the park authority, Chiang Mai University's Forest Restoration Research Unit (FORRU-CMU) launched an ambitious project to restore the forest. The project is funded by the Plant Genetic Conservation Project under the Royal Initiative of HRH Princess Maha Chakri Sirindhorn.

The project aims to not only re-establish the native forest to enhance biodiversity, but also to test species suitability to this harsh lowland site and their response to various fertilizer treatments. The project planted 8.4 rai of land, with a total of 3,500 trees in the rainy season of 2024. The site has also become an outdoor classroom for local schools, engaging students in hands-on conservation efforts through the Young Forest Restorers (YFR) program.Local school children planting a tree to restore bamboo-deciduous forest at Pong Yaeng Nork in June 2024A mix of 33 native tree species were carefully selected to accelerate forest recovery. The first 10 were planted in replicated experimental plots to test fertilizer effects, while the remaining 23 species were planted as a buffer zone around the experimental plots. Species were chosen based on FORRU's previous data from testing species on bamboo-deciduous forest sites.

Fertilizer Experiment

To test the effects of 4 fertilizer doses on tree growth, the project includes four replicated treatment groups:

• Control (50g of organic fertilizer per tree) - this is our usual treatment
• 100g per tree
• 150g per tree
• 200g per tree

Each treatment was applied at planting time and three times throughout the 1st rainy season. The treatments will be repeated in the 2nd rainy season.

Testing carefully measured doses of fertilizer - applying too much is a waste of money. This study found that 50 gm is probably enough per tree.

Drone & Ground-Based Monitoring

Aerial surveys were performed with a drone to gauge pre-existing tree cover. This helps with project planning and provides a baseline, against which to assess subsequent recovery. Furthermore, trained volunteers and students recorded tree height, root collar diameter and survival rates during ground surveys.

This is what we've done so far:

• May 10, 2024 – Initial site survey and aerial mapping using drones.
• June 13 & 26, 2024 – Setup of fertilizer experiment plots.
• June 29 & July 13, 2024 – Tree planting events with students, park rangers, and volunteers.
• July 19, 2024 – Baseline tree monitoring to track survival and growth.
• July - November 2024 – Regular maintenance, including weeding and fertilizer application.
• November 23, 2024 – End of the first rainy season monitoring.

Early Results

• High Survival Rate – After the first rainy season, 93% of trees survived, with six species showing over 75% survival, indicating strong site suitability. Top performers were Erythrina stricta and Balakata baccata.
• Minimal Fertilizer Effect – surprisingly higher fertilizer doses did not significantly improve performance, suggesting our original protocol of apply 50g per tree each time is already sufficient.

Baseline monitoring tree heights, root collar diameter, crown width and health status. Note the ring of fertilizer applied around the base of the tree.

Why This Project Matters

• Restoring a Critical Ecosystem – Bamboo-deciduous forests support unique biodiversity and play a vital role in watershed protection.
• Engaging Local Communities – The project fosters environmental stewardship by involving students, volunteers, and national park rangers.
• Advancing Science – By testing tree species and fertilizer treatments, we gain valuable insights to improve future reforestation efforts.
• We will need volunteers to help with maintenance and monitoring during the 2nd rainy season, so please keep an eye on our Facebook for notices of volunteer events.