Infodoc : Sciences, Techniques et Culture

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. 2 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. 3 Surviving seeds and sprouting seedlings were repeatedly censused during 2 years after establishment, and the causes of mortality determined. Growth and biomass parameters [...]

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. 2 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. 3 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. 4 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 occured more frequently than in gaps. 5 Damping off killed more Carapa procera seedlings when buried in Match than in May. whercas mammal predation caused more deaths in May planted seeds. 6 Although survival and growth were enhanced in gaps for both species, seeds and seedlings were much more intolérant to the understorey microhabitat in Carapa procera (almost 100% mortality in shaded habitat) than in Vouacapoua amricana. 7 Seedling biomass allocation was consistent with previous data for large-seeded species but differed markedly between the two study species. (Résumé Scannérisé)