Growth analysis of some Agathis species.
Seedlings of Agathis macrophylla and A. robusta ssp. nesophila were grown in a tropical glasshouse near Oxford, England, in either full daylight or partial shade (12% daylight). Both species had similar values of relative growth rate (RGR) and unit leaf rate (NAR) (net assimilation rate). Shading reduced the RGR by about 30% and NAR by about 40% compared to full light, the values in light and shade being n.s.d. In full light, the NAR of the tree seedlings was only 20-33% of that of sunflower (Helianthus annuus) in the same glasshouse, a difference similar to that reported for other woody plants. Results suggest that enrichment planting of Agathis spp. will succeed in fairly small canopy gaps.