Direct seeding versus seedling planting: survival, biomass, growth, and cost up to 6 years for four tropical seasonal tree species

Seedling planting (SP) and direct seeding (DS) are the most used methods of tropical tree propagation. We compared the performance of SP and DS plants of four seasonal tropical species over 6 years, considering survival, growth, above and belowground biomass, and the costs of planting and maintenance. We planted 48 pairs of SP and DS plants of Amburana cearensis, Astronium fraxinifolium, Copaifera langsdorffii, and Tabebuia aurea spaced 2 x 1 m. To evaluate biomass allocation, we dug up 5 individuals of each species after 12 and 30 months. We measured survival and height at the time of planting, and at 12, 30, and 68 months. We modeled differences in survival, biomass allocation, and height over time. We calculated costs per surviving tree and the cost-effectiveness (survival x height increment/cost). Survival was high (average 85%) and it did not differ between planting method for three species; while Astronium showed higher survival via DS (94 vs. 73% SP). Only Amburana presented a higher total biomass in SP than in DS (1.066 vs. 310 g). SP plants of Copaifera and Tabebuia grew taller (1.72 vs. 1.16 m, 1.80 vs. 0.85 m, respectively) than the DS plants. Total cost per surviving tree for DS trees was two times lower than for SP (US$ 1.33 vs. 2.57). Three species were more cost-effective via DS. The higher effectiveness of DS can be explained by the high survival and establishment rate of DS plants, dismissing the need for the several steps related to planting seedlings.

Automated summary

Seedling planting (SP) and direct seeding (DS) are the most commonly used methods for tropical tree propagation. A comparison study of four seasonal tropical species showed that DS plants had higher survival rates and cost-effectiveness, while eliminating the need for multiple steps in planting seedlings.