Variation in Seed Harvest Potential of Carapa guianensis Aublet in the Brazilian Amazon: A Multi-Year, Multi-Region Study of Determinants of Mast Seeding and Seed Quantity

This work augments research on masting for the economically important tropical tree Carapa guianensis Aublet, specifically on whether determinants of mast years vary regionally, spatially, and due to longer term ENSO climate patterns. Longer term measurements (an 11-year period in Acre and Roraima
4 years and 8 months in Amapá) from three regions of the Brazilian Amazon allowed for the analysis of whether climate cues were regionally consistent for this species. We used generalized linear mixed models, to determine which factors were significant in predicting whether trees would produce in a given year and to model the seed production quantity. We found a positive effect of increasing the diameter at breast height (dbh) on the quantity and likelihood of seed production. Our results also suggested that ecosystems and climate cues may jointly affect seed production. In flooded forests, increases in dry season rainfall had a negative impact on the likelihood of seed production whilst none of the precipitation variables investigated influenced the quantity of seeds produced. In drier terra firme forests in Acre with extended dry seasons, increases in dry season precipitation had significant and positive impacts on both the likelihood and the quantity of seed production. Our results illustrate the importance of considering plant habitat and climate to better understand individual and regional differences in seed production and their responses to inter-annual climate variation.