Direct Seeding of Late-Successional Trees to Restore Tropical Montane Forest

background

This study measures seed germination, seedling establishment, survival, growth and foliar nutrient content of five late-successional tree species which were directly seeded into three different habitats representing different stages of succession in tropical montane Costa Rica.The study also compares the costs of direct seeding with locally collected seeds with planting nursery-raised seedlings.

Research Goals & Methods

Seeds of the five tree species were planted in four replicate blocks containing three habitat types: recently abandoned pasture; young successional forest (8-10 years); and 3-year-old mixed-species tree plantations (fast-growing N-fixers).

Conclusions & Takeaways

Germination was found to vary greatly among species but not with the habitat; however, seedling survivorship was found to be significantly higher in the tree plantations. Seedling height, total overall biomass, and foliar P, N, S, Mn and Cu content were also highest among seedlings in the plantations. In particular, Garcinia intermedia had a significantly higher overall rate of germination and survival than the other four species in year one. With regard to costs, they found that planting seedlings as opposed to direct seeding was 10 to 30 times as expensive. The cost of direct seeding in pastures was 2 to 4 times more expensive than planting in either the forests or plantations.The authors posit that differences between growth and survival among the habitats are related to differing levels of nutrient availability.