Comparative growth performance of eight tropical tree species on sites of varying altitudinal gradients in Lantapan
S. Koffa; D. Garrity; M. Ngugi
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International Centre for Research in Agroforestry
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Abstract: Introduced on sits of varying altitudes, the growth response of 21-month-old plots of Acacia mangium, Albizia lebbekoides, Eucalyptus robusta, Rucalyptus torilliana, Gmelina arborea, Paraserianthes falcataria, Pterocarpus indicus and Swientenia macrophylla was investigated and determined. At each site and across sites, species differed significantly in height and diameter growth. These differences were an indication of genotype x environment interaction which was reflective of magnitude of species-site specificity. Altitude influenced species performance significantly through its effect on the nutrient availability and temperature of experimental sites. The quantities of Calcium, Magnesium, Phosphors and Potassium decreased with increased altitude, and percent Nitrogen, organic carbon and organic matter increased with increased altitude.
Temperatures decreased with increased altitude. As far as the rate of growth on the various sites, the tested species were Generally classified as fast and slow growers. The relatively fast-growing species were Acacia mangium, Albizia lebbekoides. Eucalyptus robusta, Eucalyptus torilliana, Gmelina
arborea and Paraserianthes falcatria. Pterocarpus indicus and Swientenia macrophlla had grown relatively slowly. Quite apart from the differences in growth per unit of time between the fast and slow growing species, slow-growers performed poorly at higher altitudes where fast-growers performed much better. However, some slow-growers had showed a strong potential to grow at higher altitudes. Eucalyptus robusta, A. mangium and Albizia lebbekoides had demonstrated the ability to thrive and grow equally well on sites at higher and lower altitudes.