The effect of leaf litter on early seedling establishment in a tropical forest

Investigated how different litter depths affected establishment of tree species in the semideciduous tropical forest of Barro Colorado Island, Panama, using Aspidospermum cruenta, Ceiba pentandra, Cordia alliodora, Gustavia superba, Luehea seemannii and Ochroma pyrimidale. The establishment environment for seedlings, with respect to litter, is highly variable at scales of 1-20m. Presence of litter affected five species, but the nature and the magnitude of the effect were species-specific. The smaller seeded shade-intolerant species had fewer seedlings establishing under leaf litter than on bare ground. The species ranged from strongly negatively affected (Luehea) to moderately negatively affected (Cordia, Ochroma) to affected only by extreme amounts of litter (Ceiba). The presence of litter influenced Gustavia, one of the larger seeded shade-tolerant species, but did not affect Aspidospermum, the other larger seeded species. Gustavia had more seedlings establishing under litter in the sun, but presence of litter had no effect in the shade. Litter caused reversals in the relative ranking of species success, eg Gusatavia preferentially established under relatively deep litter depths in the sun where Luehea could not establish. -from Authors