MYCOTROPHIC STRATEGY OF 13 COMMON NEOTROPICAL TREES AND SHRUBS

We conducted a greenhouse experiment using common Puerto Rican trees and shrubs that span the spectrum of neotropic life histories. Our working hypothesis was that species had a higher colonisation rate of arbuscular mycorrhizal fungi (AMF) as they established further and further after a disturbance (quantified as increasing seed size). Results suggested that (1) Cecropia schreberiana and Schefflera morototoni were weakly-facultative mycorrhizal, (2) Casearia arborea, Inga laurina and Guarea guidonia were strongly-facultative mycorrhizal and (3) Piper glabrescens, Tabebuia heterophylla, Palicourea riparia, Buchenaria capitata and Dacryodes excelsa were obligately mycorrhizal with (4) Psychotria berteriana, Prestoea montana and Manilkara bidentata also obligate but at a reduced level. In general, these species were adapted to low inorganic phosphorus, colonised well with AMF and agreed with our working hypothesis; however, three shrub species (Piper, Palicourea, Psychotria) did not. Finally, we also found that shade tolerance of the test species corresponded with the AMF results better than their wood density or drought tolerance.