Assessing UAV direct-seeding for tropical forest restoration: carbon sequestration potential and cost efficiency

The high cost, labor intensity, and infrastructure needs of manual tree planting limit the scale of global forest restoration. UAV-assisted direct seeding is a promising alternative, but comparative empirical data are scarce.

This study assesses UAV-assisted direct seeding as a cost-effective alternative to manual planting for tropical forest restoration by comparing early-stage above-ground biomass (AGB) accumulation, species diversity, and cost-effectiveness.

Over a 2.5-year period in the Amazon biome, we measured seedling growth and species diversity in UAV-direct-seeded sites. These measurements were compared to a benchmark from manual planting projects using descriptive metrics and statistical testing. Cost-effectiveness was analyzed across three adaptive management scenarios requiring one, two, or three seeding rounds.

A descriptive comparison showed the median AGB of direct-seeded sites was nearly double that of a benchmark from manually planted projects at 1.5 years, increasing to over threefold at 2.5 years. However, outcomes across the sites were highly variable; estimated species richness (Chao1) ranged from 3 to 29, with natural regeneration comprising the majority of species at the youngest site. In a single-round scenario, direct seeding was 2- to 9-times more cost-effective (based on cost per kg AGB), but this advantage was lost when three rounds were required.

UAV-assisted direct seeding is a viable method for achieving key ecological outcomes, including rapid biomass accumulation and species diversity, in early-stage tropical forest restoration. However, its success and cost-efficiency are highly dependent on site conditions permitting establishment in a single seeding round. Implications for Practice: This study provides evidence that, in suitable contexts, UAV direct seeding can more than double the area restored for the same cost as manual planting. This makes it a powerful addition to the practitioner's toolkit, especially for large or inaccessible areas where manual planting is logistically prohibitive. However, realizing this efficiency requires a holistic ecological approach, encompassing site assessment, species selection, and seeding density, to ensure high establishment success in a single intervention. By dramatically improving the cost-per-hectare, this technology can significantly increase the scale and impact of restoration programs. https://doi.org/10.32942/X2N041 Forest Management, Life Sciences, Other Forestry and Forest Sciences large scale reforestation, carbon credits, ecological restoration, CO2, carbon sequestration, carbon capture Published: 2025-02-14 20:50 Last Updated: 2025-07-08 03:49 CC-BY Attribution-NonCommercial 4.0 International Conflict of interest statement: Some authors are affiliated with a private sector company specializing in direct seeding for tropical reforestation. However, this affiliation did not influence the study’s design, analysis, or interpretation. No conflicts of interest exist regarding the publication of this work. Data and Code Availability Statement: Open data/code are not available. They will be made available after peer-review. Language: English