Ecology of Aglaia mackiana (Meliaceae) seedlings in a New Guinea rain forest

The large seeds of Aglaia mackiana (Meliaceae) germinate and produce vigoro us seedlings under closed canopies or in large gaps. To assess seedling eco logy after germination, we measured growth, herbivore damage, and survivors hip of seedlings over one year. The sample included shaded seedlings From d ispersed seeds, undispersed seeds under parent trees, and seedlings transpl anted to gaps. We quantified the light environment using hemispherical cano py photographs taken above seedlings at the beginning and end of the one-ye ar study. Seedlings transplanted to gaps grew faster and had more leaves, larger tota l leaf surface area, longer secondary roots, and greater root mass than sha ded seedlings. Seedlings in gaps did not differ from shaded seedlings in su rvivorship or amount of herbivore- and pathogen-caused leaf damage. The canopy photographs taken one year apart suggest there is a rough equili brium in dosed canopies with slight changes occurring around an average lig ht level. Sites with < 0.06 ISF (a unitless, relative measure of canopy ope nness or reflected sunlight) tended to remain the same with minor fluctuati ons toward brighter or darker. Sites with canopy openness > 0.06 ISF tended to close; few gaps grew larger. Seedlings under parent trees and seedlings away from parent trees had simil ar amounts of leaf damage and virtually identical survivorship after 18 mon ths, but seedlings under parent trees had slower growth rates and smaller t otal leaf surface areas. Dispersal did not strongly benefit seeds via escap ing high levels of mortality or competition around the parent.