Development of the Monsi-Saeki Theory on Canopy Structure and Function

Functional Significance of Shade‐Induced Leaf Senescence in Dense Canopies: An Experimental Test Using Transgenic Tobacco

“…Thus, at low N availability, plants were predicted to drop their leaves before they reach zero carbon balance. Models further derived that the optimal N distribution over the foliage should parallel the vertical light gradient in a canopy, which indeed has been frequently observed in natural stands of vegetation (Hirose 2005). This is because high leaf N contents and associated photosynthetic capacity can result in greater benefits in terms of carbon gain in leaves receiving high light than in shaded leaves (Field 1983).…”

“…Vegetative SAG plants achieved a lower calculated daily carbon gain than competing WT plants because the former retained leaves with a negative carbon gain in the shaded, lower part of the canopy. Sensitivity analyses showed that the carbon gain of SAG plants would increase if these lower leaves were shed and the N reallocated from these The efficient use of resources for photosynthesis, the process driving plant growth, is considered important for plant fitness (Mooney and Gulmon 1979;Hirose 2005). Plants in dense herbaceous vegetation compete with their neighbors for available light and other resources; in particular, nitrogen often limits plant growth in such communities (Chapin 1980).…”

“…In the past, numerous theoretical models have been developed to approach the question of optimal strategies for the maximization of carbon gain and fitness in dense stands (reviews in Grindlay 1997;Anten 2005;Hirose 2005). Monsi and Saeki (1953) derived that the LAI is optimal if the lowest leaves in the canopy receive an amount of light equal to their light compensation point, at which point these leaves should be dropped.…”

“…Real values of LAI were always found to be larger and real N distributions less steep than predicted ones (see reviews in Anten 2005;Hirose 2005). In all these studies, optimal characteristics were defined as those resulting in maximum whole-stand photosynthesis.…”

Spatio-temporal variations in photosynthesis

“…k is a constant related to leaf inclination and is also important for characterizing the leaf canopy as is briefly explained below. For historical overviews of the research field before and after the Monsi-Saeki theory, see Monsi et al (1973) and Hirose (2005).…”