Radiation interception and growth of planted and coppice stands of four fast-growing tropical trees.
Abstract
To test whether coppice regrowth of short-rotation tropical trees had a higher growth per unit of intercepted radiation than the original planted stands, above-ground biomass and leaf area were measured, and light interception calculated, in a 2-yr experiment on the island of Maui, Hawaii. Biomass and intercepted radiation were larger in coppiced than in planted stands of Eucalyptus camaldulensis from 3 to 12 months, and equal in Acacia auriculiformis throughout. For Gliricidia sepium, biomass and radiation interception were larger in coppiced than in planted stands from 3 to 9 months, but the coppiced stands stagnated and so biomass in planted stands exceeded coppice biomass from 12 to 18 months. Biomass of Leucaena diversifolia was larger in planted than in coppiced stands from 9 to 18 months, whereas intercepted radiation was somewhat less in planted than in coppiced stands from 3 to 12 months. Radiation conversion ratio, ε, in coppiced stands was ≤ε in planted stands. ε was lower in coppiced than in planted stands of G. sepium and L. diversifolia, but similar for the other two species. Conversion ratios for solar radiation ranged from 0.76 to 1.06 g/MJ for planted stands and from 0.37 to 0.87 g/MJ for coppiced stands receiving irrigation or rainfall in excess of 300 mm over a 3-month period. When stands did not receive supplemental irrigation or rainfall exceeding 300 mm over 3 months, radiation conversion ratios were positively correlated with rainfall in planted stands of all species except Leucaena diversifolia, but were not correlated in coppiced stands.