Establishing and monitoring permanent forest plots illuminates the ecological processes that determine forest composition and structure at local scales (Zuleta et al., 2017). These plots can provide detailed information on demographic processes at the species level, and relate demography to ecological conditions. Demographic processes, through shaping local forests at many sites over an extensive area, may predict broad-scale patterns of species dominance and distribution (Duque et al., 2017).
A permanent, continuous 100-ha forest plot was established in 1989, where all Lecythidaceae (Brazil nut relatives) were identified, measured and tagged. We have recensused the plot, including finding and remeasuring all tagged individuals, recording mortality, and identifying, measuring, and tagging new recruits into the 10cm dbh size class. I use this long-term, fundamental data to ask how and why demographic rates differ across Lecythidaceae species in a mature Amazonian forest. Additionally, I investigate factors contributing to Lecythidaceae hyperdominance by addressing the following questions: 1) Do Lecythidaceae hyperdominant species demonstrate higher per capita recruitment, relative growth rate, or lower per capita mortality than non-hyperdominant species? 2) Do Lecythidaceae hyperdominant species demonstrate a weaker maximum growth-mortality trade-off than non-hyperdominant species?
Results/Conclusions
Thirty-nine species of Lecythidaceae occur in the plot, eight of which are Amazonian hyperdominants. Species abundances range from 1 to 1787 individuals. Sixteen species are locally common (≥ 1 individual/ha), and 23 are locally rare. Average growth rates are very slow, at 0.13cm per year. Relative growth rate (RGR) is correlated with maximum adult size; understory species have significantly lower RGR than canopy and emergent species (p <.05). Average per capita mortality is 0.21; understory species have the highest per capita mortality (0.25), and canopy species the lowest (0.19). While per capita mortality increases with maximum growth in non-hyperdominant species, it decreases in hyperdominant species, suggesting a decreased maximum growth-mortality trade-off. There are a total of 930 recruits in the plot – average per capita recruitment is 0.082. Locally common hyperdominants have higher per capita recruitment than locally common non-hyperdominants (p <.05).
Lecythidaceae is an ecologically, economically, and culturally important clade throughout the Amazon, and contains an outsized number of hyperdominant species. Hyperdominants demonstrate higher plot-level per capita recruitment, and may be less prone to ecological trade-offs than non-hyperdominants. Long-term forest plot data is integral to determine how forest demographics are changing as a consequence of global change, and how this may alter patterns of species dominance.