Testing Applied Nucleation as a Strategy to Facilitate Tropical Forest Recovery

Background

This study considers applied nucleation, or the intensive planting of small patches of a mixture of successional species, as a degraded tropical forest restoration strategy. This approach catalyzes the natural regeneration of the surrounding matrix and larger landscape and could provide a less expensive alternative to the more common, and expensive, plantation-style approach. This study claims to be the first to directly compare tree recruitment beneath these two restoration approaches.

Research Goals & Methods

50 x 50 m plots of abandoned pastureland in Costa Rica's premontane forest zone were assigned with a similar mix of species (T. amazonia, V. guatemalensis, I. edulis, and E. poeppigiana) and spacing in a complete plantation-like covering or in small 4x4,8x8, or 12x12 m patches. After 2.5 years, the vegetation was sampled using a stratified sampling procedure, and sampling continued over the next 4 years. “Resprouts” were not counted, and distinctions were made between wind and animal dispersed species.

Conclusions & Takeaways

The results show that canopy cover was highest in plantaions, then in island plots, and lowest in control plots (95%, 73%, 36%). The number of animal-dispersed seedlings and overall recruits was higher in the island treatments than in controls, and did not differ from plantations. Larger (12x12m) had greater overall density than smaller (4x4m) island plots. Even though only 20% of the area in island plots was planted, there was a similar amount of species abundance established after 4 years as compared to the plantation-style plots. In summary, applied nucleation is a promising restoration strategy that can accelerate forest recovery to a similar degree as plantation-style restoration and is more economical and therefore restoration practitioners should consider the methodology as an alternative to large-scale plantings.