Targeting no-maintenance tropical forest restoration by seeding a whole successional species composition

Résumé fourni par la source

Tropical forest restoration faces a significant bottleneck from invasive exotic grasses, whose control is costly through frequent weeding and carries environmental and human risks with herbicide use. This study investigated a no-maintenance direct seeding approach utilizing a whole successional species composition to overcome this bottleneck. We implemented four successional stages (<1-year, 1-4-year, 4-10-year, >10-year) in a factorial design across three experimental blocks, each with five plots. We tested broadcast vs. row seeding and simple vs. enriched compositions, evaluating ground cover, stem density, and species richness at multiple intervals over 64 months, with no post-planting weeding performed. Results showed rapid and constant ground cover with a rapid shift in successional stage dominance. The broadcast seeding with simple composition treatment proved most effective, achieving the highest coverages of seeded species in each successional stage, the lowest exotic grass cover, and the highest stem density for the 4-10-year and >10-year stages. Key species like Crotalaria spectabilis (<1-y), Senna alata (1-4-y), Senegalia polyphylla, Piptadenia gonoacantha, and Guazuma ulmifolia (4-10-y) demonstrated high success. The 1-4-year and 4-10-year stages effectively shaded out exotic grasses and positively influenced the establishment of later successional trees. Although successful, exotic grasses still posed a challenge, suggesting the potential need for integrated management. Future efforts should focus on improving seed technology and seeding densities for species that attract seed dispersers. This comprehensive direct seeding strategy is a promising practice for achieving high-quality secondary forests with reduced maintenance needs.

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