The Journal of Environmental Management published a 15‑year chronosequence study across 75 riparian sites in Brazil’s Amazonia‑Cerrado transition, all previously cleared for cattle pasture. The sites were restored using five different approaches: broadcast‑seeding (45 sites), hole‑seeding (11), row‑seeding (10), seedling planting (4) and natural regeneration (5).
By the 15‑year mark, row‑seeded sites had accumulated a mean aboveground biomass of 155.2 tonnes per hectare—roughly double the 80.6 tonnes of broadcast‑seeded areas and 73.8 tonnes of hole‑seeded plots, and far ahead of seedling planting (67.8 tonnes) and natural regeneration (97.1 tonnes).
The advantage of row‑seeding lies in the precision of grain drills that bury seeds at a depth suited to long‑lived pioneers such as Enterolobium timbouva. These trees, with substantial seed reserves, thrive underground, avoiding surface predators and drought, and dominate sites older than a decade. Broadcast‑seeded sites, by contrast, favor the short‑lived Tachigali vulgaris, whose populations wane after 10‑20 years.
Soil carbon stocks, however, told a different story. Ranging from 11.4 to 73.5 tonnes per hectare across all sites, the soil’s organic carbon was driven almost entirely by local edaphic factors—cation exchange capacity, base saturation and moisture—rather than restoration method or site age.
Economically, row‑seeding proved the cheapest of the direct‑seeding techniques, costing about $2,442 per hectare, close to the $2,451 of broadcast‑seeding and lower than hole‑seeding's $3,246. With a cost of $7.91 per tonne of CO₂ sequestered, it beats broadcast at $15.30 and hole at $22.10, and sits well below the roughly $29 per tonne reported for mixed‑species plantings elsewhere in Brazil.
These findings suggest that adopting row‑seeding could dramatically increase carbon capture while cutting reforestation costs, offering policymakers a clear, evidence‑based pathway for scaling up tropical restoration efforts.