RECRUITMENT PATTERN OF VOUACAPOUA-AMERICANA (CAESALPINIACEAE), A RODENT-DISPERSED TREE SPECIES IN FRENCH-GUIANA

The recruitment pattern of Vouacapoua americana (Caesalpiniaceae) and the relationship between growth and survival of recruits were analyzed from 1984 to 1991 on two 2500 m2 plots, one with and one without free soil drainage. Most seeds and seedlings below two adult trees in the plots died within 6 to 8 months of establishment. Virtually all seedlings still alive several months after fruiting arose from seeds that were buried by scatterhoarding rodents. Because rodents do not disperse seeds a great distance and Vouacapoua seedlings survive well in the shaded understory, offspring recruitment was more dense near adults than further away. A significantly lower proportion of newly established seedlings died on freely drained soil than where drainage was blocked; mortality was due to ''damping-off' from fungal attack. First-year survival of seedlings from scatterhoarded seeds and growth rates for understory seedlings from 1984 to 1986 were higher on freely drained soil than on blocked soil. Long-term offspring survival was similar on both plots, while height increment was significantly greater on the freely drained plots than on the poorly drained soil. There was a significant negative relationship between the initial seedling density and proportion of survival on both plots within 6-8 months of establishment. However, there was no evidence of long-term compensatory mortality; the greater the initial density, the greater the final density of recruits surviving through years. The Vouacapoua recruitment pattern appears typical of a partially repelled syndrome with recruits growing both near adults and further away. High Vouacapoua tree density on soil with good drainage, as reported in the literature, is likely to result from better environmental conditions for early seedling survival and long-term growth of recruits.