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Some Quantitative Relationships between Leaf Area Index and Canopy Nitrogen Content and Distribution
XINYOU YIN, EGBERT A. LANTINGA, AD H. C. M. SCHAPENDONK and XUHUA ZHONG
Annals of Botany
Vol. 91, No. 7 (June 2003), pp. 893-903
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/42796327
Page Count: 11
You can always find the topics here!Topics: Nitrogen, Vegetation canopies, Leaf area index, Photosynthesis, Simulations, Leaf area, Leaves, Datasets, Wheat, Modeling
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In a previous study (Yin et al. 2000. Annals of Botany 85: 579-585), a generic logarithmic equation for leaf area index (L) in relation to canopy nitrogen content (N) was developed: L = (1/ktn) ln (1 + ktn N/nb). The equation has two parameters: the minimum leaf nitrogen required to support photosynthesis (nb), and the leaf nitrogen extinction coefficient (ktn). Relative to nb, there is less information in the literature regarding the variation of ktn. We therefore derived an equation to theoretically estimate the value of ktn. The predicted profile of leaf nitrogen in a canopy using this theoretically estimated value of ktn is slightly more uniform than the profile predicted by the optimum nitrogen distribution that maximizes canopy photosynthesis. Relative to the optimum profile, the predicted profile is somewhat closer to the observed one. Based on the L-N logarithmic equation and the theoretical ktn value, we further quantified early leaf area development of a canopy in relation to nitrogen using simulation analysis. In general, there are two types of relations between L and N, which hold for canopies at different developmental phases. For a fully developed canopy where the lowest leaves are senescing due to nitrogen shortage, the relationship between L and N is described well by the logarithmic model above. For a young, unclosed canopy (i.e. L < 1.0), the relation between L and N is nearly linear. This linearity is virtually the special case of the logarithmic model when applied to a young canopy where its total nitrogen content approaches zero and the amount of nitrogen in its lowest leaves is well above nb. The expected patterns of the L-N relationship are discussed for the phase of transition from young to fully developed canopies.
Annals of Botany © 2003 Oxford University Press