Restoring abandoned pasture land with native tree species in Costa Rica: An ecophysiological approach to species selection

This study was designed to characterize the growth and light requirements of six native tree species (Pseudosamanea guachapele (Fabaceae), Tabebuia impetiginosa (Bignoniaceae), Ceiba pentandra (Bombacaceae) Bombacopsis quinatum (Bombacaceae), Dalbergia retusa (Fabaceae), and Tabebuia rosea (Bignoniaceae) in the field under contrasting light environments and grass competition. Understanding their early establishment requirements could be used in selecting proper light and competition regimen for the success of restoring pastures after abandonment. Field studies were conducted in the pastures of the Santa Ana Conservation Center in Costa Rica. Two grass competition regimes were selected, one dominated by Hyparrhenia rufa (Tall-grass) and another dominated by Cynodon mlenfluensis (Short-grass). Three light treatments were created (100%, 37% and 2% light) using either neutral shade cloth (37% and 2%) or no shade cloth (100%). Growth characteristics, biomass partitioning and light response curves of the seedlings were measured. Overall, P. guachapele had the best performance in competing with the grasses followed by D. retusa. T. impetiginosa, and T. rosea, which had similar results regardless of the grass. C. pentandra did not do well under tall grass. The 2% light treatment greatly reduced seedling performance for all species and 37% had no effect except for D. retusa.  We recommend planting P. guachapele as an initial step in reforesting pastures. Once they are established and shade produced by the tree reduces grass cover, T. rosea, T. impetiginosa and C. pentandra can be planted.