PARENT SESSION
Poster Session #39: Light Relations.
Wednesday, August 7. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Role of leaf area, intercepted radiation, and foliar nitrogen in controlling productivity of loblolly pine.

Narahari, Nikhil^*,1, Teskey, Robert¹, Will, Rodney¹, ¹ University of Georgia, Athens, GA

ABSTRACT- The relative importance of leaf area index (LAI), intercepted photosynthetically active radiation (IPAR), and canopy nitrogen content in controlling the productivity of loblolly pine stands (Pinus taeda L.) was examined in a replicated study in the upper Coastal Plain and Piedmont of east central Georgia. Established in 1998, five study sites each consisting of six stands of varying densities from 740 to 4400 stems per hectare provided the opportunity to study stands with vastly different leaf areas and growth rates without introducing the confounding effects of age. LAI was calculated using leaf litter traps, IPAR was measured with a ceptometer and corrected to a constant sun angle, and foliar nitrogen was measured by needle collection and analysis for nitrogen concentration. IPAR increased with stand density, however the increase was not linear with increasing stand density. At the period of peak LAI, convergence in IPAR of the higher density stands was observed. Average sun angle-corrected IPAR was 27% and 77% for the least dense and most dense stands respectively. Average foliar nitrogen concentration was 13 mg g^-1 and was not significantly affected by stand density. In these same-aged stands, all measured parameters were related to growth with a combination of LAI and IPAR serving as the chief controlling factor to productivity across stand densities.

KEY WORDS: leaf area index, foliar nitrogen, intercepted radiation, pinus taeda