Return of forest structure and diversity in tropical restoration plantings

Stepping-stone restoration plantings can reconcile conservation goals and local land-use needs in highly fragmented ecosystems. We explored how initial planting composition influences recruiting plant species density, diversity, abundance, and forest structure in a 13-year-old restoration experiment in Los Tuxtlas, Veracruz, Mexico. Treatments included eight fenced plantings with animal-dispersed species, eight plantings with wind-dispersed species, eight unplanted plots to favor natural succession, and eight plots in the primary forest as reference sites. We predicted that by attracting more seed dispersers, animal-dispersed plantings would most closely resemble the primary forest. A census of trees taller than 2 m showed that while wind-dispersed plantings had more recruits, the animal-dispersed plantings most closely resembled the primary forest in pioneer abundance, species density and abundance of biotically dispersed and abiotically dispersed plants, individual tree basal area (in square meters per hectare), and vertical structure. The wind-dispersed plantings more closely approximated the forest in non-pioneer abundance and community composition. However, restoration treatments were more similar to each other than to the primary forest and did not differ in plant diversity. Animal-dispersed and wind-dispersed plantings did not differ in non-pioneer species density and matched the primary forest in total plot basal area. Higher abundance of trees in wind-plantings is explained by lower establishment limitations, seed legacy effects, and rapid reproduction of a few planted species. As the experiment continues, we expect treatment effects on seed dispersers will more strongly influence the recruiting plant community, leading the animal-dispersed plantings to more closely resemble the primary forest in diversity and forest structure.