Effect of microhabitat on seed fate and seedling performance in two rodent-dispersed tree species in rain forest in French Guiana
1997
Forget, P.M.
The establishment probabilities, short-term survival, growth rates and biomass allocation patterns of seedlings in two large-seeded tree species, Carapa procera (Meliaceae) and Vouacapoua americana (Caesalpiniaceae), were studied in contrasting microhabitats at Paracou, French Guiana. Seeds (100 per habitat per species) were buried to simulate rodent caches into gap and understorey microhabitats (n = 20 of each) surrounding mature parent trees. The experiment was replicated in Carapa procera (in early March and May) to investigate the effect of temporal variation in seed dispersal on the establishment process. Surviving seeds and sprouting seedlings were repeatedly censused during 2 years after establishment, and the causes of mortality determined. Growth and biomass parameters were calculated for surviving seedlings after 2.5 years. A greater proportion of seeds and germinating seedlings were dug up but less seedlings suffered from damping-off in C. procera than in V. americana. For both species, short-term survival of seedlings was lower in the understorey where predation by mammals and damping-off occurred more frequently than in gaps. Damping off killed more Carapa procera seedlings when buried in March than in May, whereas mammal predation caused more deaths in May planted seeds. Although survival and growth were enhanced in gaps for both species, seeds and seedlings were much more intolerant to the understorey microhabitat in Carapa procera (almost 100% mortality in shaded habitat) than in Vouacapoua americana. Seedling biomass allocation was consistent with previous data for large-seeded species but differed markedly between the two study species.
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