Direct Seeding to Restore Tropical Mature-Forest Species in Areas of Slash-and-Burn Agriculture

After tropical lands have been abandoned from anthropogenic pressures, often forest structure and some species recover naturally. Studies suggest, however, that mature-forest species are frequently slow to establish and an active management strategy may be necessary. We tested direct seeding of mature-forest species as a restoration strategy in sites previously used for slash-and-burn agriculture in semi-evergreen, seasonal forest in the Yucatan peninsula, Mexico, and evaluated when in the successional process this strategy had the highest success rate. We planted three mature-forest species (Brosimum alicastrum, Enterolobium cyclocarpum, and Manilkara zapota) in three forest ages: recently abandoned (< 5 years), young successional forest (8-15 years), and reference forest (> 50 years). Overall, an average of 5-41% of planted seeds germinated, and 3-35% were present through the seedling stage. Only M. zapota had higher germination in the reference forest than in the other forest ages, whereas the other two species had similar percentage germination in all successional stages. Of the seeds that germinated in the 8-15 years sites and the reference forest, 58-95% of the seedlings survived through the end of the study, whereas survival in recently abandoned sites was less than 50% in most cases. Seedling height was generally similar across forest age categories. Our results suggest that direct seeding these mature-forest species after the first few years of natural succession could be a successful strategy to accelerate and guarantee their establishment.