Canopy development in tropical tree plantations: a comparison of species mixtures and monocultures

Background

The establishment of plantation monocultures has dominated much of the intensive forest management practiced in the humid tropics of the Americas, with most forestry research and practice concentrating on a small number of non-indigenous species. Growing interest exists in modifying these practices both by creating mixed-species plantations and by making greater use of native tree species.

Research goals & methods

This study measures the early development of monocultures and mixtures of Cedrela odorata, Cordia alliodora, and Hyeronima alchorneoides to determine what interspecific differences in structural characteristics lead to good ecological combining ability in fast-growing tropical tree species. High-density plantations were established in the humid Atlantic lowlands of Costa Rica. Height growth was rapid for all three species. In mixtures, a partially stratified canopy developed with the tallest Cordia forming an upper canopy stratum above Cedrela and Hyeronima. Compared to their growth in monoculture, Cordia was taller and Hyeronima was shorter in mixture. In contrast, Cedrela was smaller in mixture than in monoculture, likely due to insectivory.

Conclusions & takeaways

Cordia and Hyeronima were determined to be compatible in mixture due to the formation of a stratified canopy. The taller Cordia had an open canopy structure allowing sufficient light to reach the dense evergreen crowns of the shorter-statured Hyeronima. Similar combinations of characteristics are likely to lead to compatibility in other sets of tree species.