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Crown structure, light availability, and stand dynamics in forest plantations in Costa Rica: A comparison of species mixtures and monocultures
Abstract
By studying crown structure, leaf area index (LAI), and light interception during the first 3.5 years of development, I assessed the patterns of above-ground space partitioning and stand dynamics in monocultures and mixtures of three tree species (Cedrela odorata, Cordia alliodora, and Hyeronima alchorneoides). Plantations were established in the tropical rain forest of Costa Rica. To understand species differences during the period of free growth, I measured leaf distribution, crown shape, and biomass allocation strategies of each species at age one year. To compare stands dynamics among monocultures and mixtures I obtained the size, crown shape, and relative position of plants at regular time intervals between age 1.5 and 3.5 years. Stand-level measurements of LAI, and canopy light transmission complemented these individual-tree measurements. Before the onset of competition, there was a statistically significant multivariate difference in crown architecture among the three species. The mean dry biomass (grams/tree)was 990.0 in Cedrela, 665.3 in Cordia, and 1281.4 in Hyeronima. Proportionally Cedrela allocated more biomass into roots than the other two species. Biomass allocation within crowns was correlated with specific above-ground architecture. Differences in stand composition caused major modification in several morphological traits. On average, the performance of Cordia and Hyeronima individuals growing in mixtures exceeded that observed in monocultures. Cedrela showed an opposite trend with larger trees in monocultures than in mixtures showing the effect of suppression in mixtures. At age 2.0 years monocultures had almost reached their maximum LAI values. Approximate LAI values were 4.5 for Hyeronima and 2.0 for the other two monocultures. LAI of the mixtures increased from 2.0 at age 1.5 years to 4.0 at age 3.5. At the end of this study a two-stratum canopy had developed in mixed-species stands with the shade-intolerant Cordia above both the gap-dependent Hyeronima and the suppressed Cerela. Thus, Cordia and Hyeronima showed compatible height growth and crown structural characteristics in mixtures. The growth patterns of mixed stands suggests that both inter-specific competition with neighboring trees and infections by shoot-boring larvae of a lepidopteran species are responsible for the suppression of Cedrela.
Subject Area
Forestry|Ecology|Botany
Recommended Citation
Menalled, Fabian Daniel, "Crown structure, light availability, and stand dynamics in forest plantations in Costa Rica: A comparison of species mixtures and monocultures" (1996). Doctoral Dissertations Available from Proquest. AAI9639001.
https://scholarworks.umass.edu/dissertations/AAI9639001