Production Efficiency and Radiation Use Efficiency of Four Tree Species Receiving Irrigation and Fertilization

Author： Allen Christopher B. Will Rodney E. Jacobson Marshall A.

Publisher： Society of American Foresters

ISSN： 0015-749X

Source： Forest Science, Vol.51, Iss.6, 2005-12, pp. : 556-569

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Abstract

To determine the effect of resource availability on efficiency of stemwood production, we calculated radiation use efficiency (Ε_stem = stem production/photosynthetically active radiation [PAR] interception) and production efficiency (PE_stem = stem production/leaf area index [LAI]) from measurements of LAI, intercepted photosynthetically active radiation (IPAR), and stem production on stands of Pinus taeda, Pinus elliottii, Liquidambar styraciflua, and Platanus occidentalis during the sixth growing season. Treatments were control, irrigation only, and irrigation plus 57, 85, or 114 kg N ha⁻¹ y⁻¹. Compared to the control, irrigation plus 85 kg N ha⁻¹ increased stem production: 8.7–15.0 Mg ha⁻¹ y⁻¹ (loblolly), 6.0–10.7 Mg ha⁻¹ y⁻¹ (slash), 1.2–12.8 Mg ha⁻¹ y⁻¹ (sweetgum), and 0.5–9.6 Mg ha⁻¹ y⁻¹ (sycamore). Annual PAR capture and LAI were correlated with stem production (r² = 0.80, r² = 0.66, respectively, average of 4 species). Fertilization and irrigation increased Ε_stem and PE_stem for sycamore, whereas only fertilization increased efficiencies for sweetgum. Irrigation increased PE_stem for the pines. Foliar [N], often a surrogate for photosynthetic efficiency, was positively correlated with both efficiency variables for the hardwoods (r² from 0.65 to 0.79). For the pines, canopy size was the primary growth determinant. FOR. SCI. 51(6):556–569.