To accelerate the restoration of vegetation across the large areas affected by landslides in the upper reaches of the Matai’an River, the Hualien Branch of the Forestry and Nature Conservation Agency (FANCA Hualien), together with National Ilan University, used drones to overcome the challenges of steep terrain and locations inaccessible on foot. The third vegetation restoration operation was completed from September 5 to 7. For the first time, five new planting materials developed by the National Ilan University team were introduced, with a total of 67 delivery points completed, covering an area of 20.1 hectares. Including the previous two operations, the total delivery area has now reached 40.2 hectares. The aim of this project is to gradually restore vegetation to the bare slopes. The landslide areas in the upper reaches of the Matai’an River are steep and remote. Traditionally, afforestation is done manually, but this results in difficulties with transporting seedlings and materials, as well as posing considerable risks to personnel traversing unstable terrain. The FANCA Hualien collaborated with National Ilan University to integrate forest regeneration, planting material research and development, and drone flight technology in this project. Seeds, seedlings, and planting materials were delivered to the landslide slopes by aerial drop, with the goal of exploring safer and more suitable methods for the restoration of large-scale landslide areas. The highlight of this mission was the first-ever on-site introduction of five types of planting materials developed specifically for seed germination, seedling protection, and drone delivery. Among them, the “wet seed pellets” encapsulate the seeds of Formosan alder and Roxburgh sumac, encased in gel pellets to increase moisture supply and provide a protective coating. The “planting capsules” encapsulate Formosan alder seeds and planting materials in water-soluble capsules. The capsules will gradually dissolve after landing and coming into contact with water, thereby creating suitable conditions for seed germination. Another breakthrough is the “planting seedling pack,” the contents of which include pre-germinated Formosan alder seedlings, growing medium, and seeds in a water-soluble netting pack. Drones are then used for precise aerial drops to the planned locations. This allows landslide restoration to shift beyond the past practice of “seed sowing” to attempting the direct delivery of seedlings. The team also developed “tapioca soil balls,” which are micro-granules suitable for application by standard agri-drones, as well as “seed balls” that incorporate and apply a coating to various plant seeds such as Formosan alder, Formosa ash, and silvergrass with a water-retaining growing medium. By using different plant species and coating methods, they can test which combination is better suited to the unique environment of the Matai’an River landslide area. The FANCA Hualien pointed out that the first two drone-based replanting and restoration operations were completed on December 10-11 last year and January 30-31 this year. When the National Ilan University team conducted an on-site investigation in April this year, they found seedlings of Formosan alder and Formosa ash at multiple drop points, as well as coppice shoots of plants such as wild sugarcane, dense-flowered false-nettle, and Formosan eupatorium, indicating that some vegetation had begun to grow on the exposed slopes. However, drone seeding is not a case of “afforestation by simply scattering seeds.” The FANCA Hualien noted that the restoration of vegetation in landslide areas is a long-term task. Whether plants can successfully germinate, survive, and gradually form a stable vegetation bed is influenced by many factors, such as rainfall, slope stability, soil conditions, and seed germination rates. The FANCA Hualien will continue to collaborate with National Ilan University to track the germination, growth, and survival of the five new planting materials through on-site sample plot surveys and drone imaging. Restoration effects of different slope environments and materials will be compared, with material configuration and application strategies continuously adjusted based on the monitoring results, so that vegetation restoration can move forward from simply “being sown” to “being able to grow and survive.” According to the FANCA Hualien, as plant root systems and surface vegetation are gradually established, it is expected to lower the direct impact of rainwater on exposed slopes and reduce the runoff of soil and sand downstream, serving as an auxiliary measure to reduce the risk of river siltation and sediment blockage. In the future, the FANCA Hualien will continue to accumulate experience in the application of drones in the restoration of large-scale landslide areas, using technology to access mountainous areas that are difficult to reach on foot, thus laying the foundation for the long-term restoration of the forest ecosystem in the upper reaches of the Matai’an River. Link to images of the aerial drops: https://drive.google.com/drive/folders/1Sc5-BD8QLrOSaxgr3kcSdVTZOxeAp2Ly
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