التفاصيل البيبلوغرافية
| العنوان: |
Canopy developmemt in tropical tree plantations: a comparison of species mixtures and monocultures |
| المؤلفون: |
Ewel, J. J., Kelty, M. J., Menalled, F. D. |
| المصدر: |
Forest Ecology & Management; 5/12/1998, Vol. 104 Issue 1-3, p249, 0p |
| مصطلحات موضوعية: |
AGROFORESTRY |
| مستخلص: |
In this study, the early development of monocultures and mixtures ofCedrela, odorata, Cordia alliodora, and Hyeronima alchorneoides was measured to determine what interspecific differences in structural characteristics lead to good ecological combining ability in fast-growing tropical tree species. Plantations were established at high density (2897 trees/ha) on fertile alluvial soil in the humid Atlantic lowlands of Costa Rica. The three species are native to the region and were selected to represent a range of crown structure, leaf morphology,and phenology. Height growth was rapid for all three species, with dominant heights (mean height of tallest 20% of trees) of monoculturesreaching 7--8 m at age 2.0 yr, and 14--15 m at age 4.0 yr. At age 2.0 yr, monocultures had nearly reached their maximum leaf area index (LAI), with Hyeronima forming a denser canopy (LAI of 4.5) than the other two species (LAI's of 2.5). In mixtures, a partially stratified canopy developed with the tallest Cordia forming an upper canopy stratum above Cedrela and Hyeronima. Mixtures reached an LAI of 3.9 by age3.0 yr, approaching the level of the Hyeronima monoculture. Comparedto their growth in monoculture, Cordia was taller and Hyeronima was shorter in mixture, but both species developed larger mean crown sizeand breast-height diameters in mixture. In contrast, Cedrela was smaller in all dimensions in mixture than in monoculture. The poor growth of Cedrela in mixture likely resulted from the early onset of interspecific competition coupled with damage from attacks of the shootborer Hypsipyla grandella. Cedrela seedlings recovered their rapid growth in monoculture after early insect attacks, but were suppressed in mixtures by the competition from surrounding trees of Cordia and Hyeronima which are not susceptible to the shootborer. The compatibility of Cordia and Hyeronima was related to the formation of a stratified canopy in mixture. Cordia has more rapid seedling height growth than Hyeroni [ABSTRACT FROM AUTHOR] |
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