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Interrelationships among light, photosynthesis and nitrogen in the crown of mature Pinus contorta ssp. latifolia

Posted date: May 29, 2015
Publication Year: 
1999
Authors: Schoettle, Anna W.; Smith, W. K.
Publication Series: 
Scientific Journal (JRNL)
Source: Tree Physiology. 19: 13-22.

Abstract

Scaling leaf-level measurements to estimate carbon gain of entire leaf crowns or canopies requires an understanding of the distribution of photosynthetic capacity and corresponding light microenvironments within a crown. We have compared changes in the photosynthetic light response and nitrogen (N) content (per unit leaf area) of Pinus contorta Dougl. ssp. latifolia Engelm. (lodgepole pine) leaves in relation to their age and light microenvironment. The vertical gradient in integrated daily photosynthetic photon flux density (PPFD) from the upper to the lower crown of lodgepole pine was similar in magnitude to the horizontal gradient in daily PPFD along shoots from young to old leaves. The relationship between light-saturated net photosynthesis (Amax) and daily PPFD was significant for both young and old leaves. However, old leaves had a lower Amax than young leaves in a similar daily irradiance regime. For leaves of all ages from throughout the crown, Amax was linearly related to the estimated daily net carbon gain that leaves could achieve in their natural PPFD environment (estimated Aday) (r2 = 0.84, P

Citation

Schoettle, A. W.; Smith, W. K. 1999. Interrelationships among light, photosynthesis and nitrogen in the crown of mature Pinus contorta ssp. latifolia. Tree Physiology. 19: 13-22.