Competitive effects of a dominant palm on sapling performance in a Neotropical rainforest

Eradication of herbivores, due to human disturbances, produces a demographic outburst of highly competitive prey species, which in turn reduces plant species diversity. This happens at Los Tuxtlas tropical rainforest, Mexico, where a population outburst of the understory palm Astrocaryum mexicanum is ostensibly excluding tree species, but how this is occurring is still unknown. We used a neighborhood approach to explore the effects of palm shading and palm crowding on the survival and growth (RGR) of saplings of six common tree species. Sixteen to 32 saplings (1.5-2.5 m height) per species were used as focal individuals of circular neighborhoods (4 m radius), which included palms ≥ 1cm stem length potentially competing for light or soil resources. Shading was estimated using hemispherical photographs. Overall, survivorship was high combining all species (93.8%/yr). In most species shading produced a displacement of the crown, which increased with specific leaf area of species. In three ...