Transplanting naturally regenerated tree seedlings for tropical forest restoration: a case study of Calophyllum brasiliense and Vochysia guatemalensis in Mexico

Plant species produce far more seedlings than those surviving to adulthood. It would seem reasonable to take advantage of that excess production, by relocating seedlings to desired restoration sites. There is, however, little information available on this issue. In the present study, we collected naturally regenerated seedlings of two native species, Calophyllum brasiliense (bari) and Vochysia guatemalensis (corpo), in old-growth forest patches, and transplanted them for the enrichment of a secondary tropical forest in Veracruz, Mexico. For transplanted C. brasiliense seedlings, overall survival was 32% after 20 months, and for V. guatemalensis seedlings it was 66% after 26 months. The mean height (+/- standard error) of all C. brasiliense and V. guatemalensis seedlings that survived until the end of the study, was 33 +/- 2 cm (from initially 12.9 +/- 0.2 cm) and 52 +/- 5 cm (from 4.6 +/- 0.1 cm), respectively. We applied a cost-benefit model to assess the trade-off between initial-investment costs and the resulting survival of transplanting naturally regenerated seedlings in the current study, in comparison with direct seeding (with and without the protection of seeds and emerged seedlings) reported in a previous study for the same area and species. For C. brasiliense, the success of transplanting naturally regenerated seedlings was always inferior to direct seeding without protection, whereas for V. guatemalensis it was always superior. Comparing the transplantation of naturally regenerated seedlings with direct seeding with protection, the best propagation strategy depended on the (monetary) value that a treelet is expected to be worth after 2 years.

Automated summary

Plant species produce more seedlings than those who survive to adulthood. Relocating seedlings to desired restoration sites could be a reasonable approach to utilize their excess production. However, there is limited information available on this issue. This study transplanted naturally regenerated seedlings of two native species, Calophyllum brasiliense and Vochysia guatemalensis, to enrich a secondary tropical forest in Veracruz, Mexico. Survival rates and growth trajectories of the transplanted seedlings were compared with direct seeding methods used in previous studies. The results showed that the success of transplanting naturally regenerated seedlings depended on the species and the monetary value of the treelets after 2 years.