Article citationsMore>>

I. Cowan, “Regulation of Water Use in Relation to Carbon Gain in Higher Plants,” In: O. L. Lange, P. S. Nobel, C. B. Osmond and H. Ziegler, Eds., Physiological Plant Ecology II. Water Relations and Carbon Assimilation, Encyclopaedia of Plant Physiology Vol. 12B, Springer, Berlin, 1981, pp. 589-614.

has been cited by the following article:

• TITLE: Simulations of Seasonal and Latitudinal Variations in Leaf Inclination Angle Distribution: Implications for Remote Sensing

  AUTHORS: Karl F. Huemmrich

  KEYWORDS: Leaf Angles; NDVI; fAPAR; Canopy Reflectance Models; Canopy Structure

  JOURNAL NAME: Advances in Remote Sensing, Vol.2 No.2, June 11, 2013

  ABSTRACT: The leaf inclination angle distribution (LAD) is an important characteristic of vegetation canopy structure affecting light interception within the canopy. However, LADs are difficult and time consuming to measure. To examine possible global patterns of LAD and their implications in remote sensing, a model was developed to predict leaf angles within canopies. Canopies were simulated using the SAIL radiative transfer model combined with a simple photosynthesis model. This model calculated leaf inclination angles for horizontal layers of leaves within the canopy by choosing the leaf inclination angle that maximized production over a day in each layer. LADs were calculated for five latitude bands for spring and summer solar declinations. Three distinct LAD types emerged: tropical, boreal, and an intermediate temperate distribution. In tropical LAD, the upper layers have a leaf angle around 35° with the lower layers having horizontal inclination angles. While the boreal LAD has vertical leaf inclination angles throughout the canopy. The latitude bands where each LAD type occurred changed with the seasons. The different LADs affected the fraction of absorbed photosynthetically active radiation (fAPAR) and Normalized Difference Vegetation Index (NDVI) with similar relationships between fAPAR and leaf area index (LAI), but different relationships between NDVI and LAI for the different LAD types. These differences resulted in significantly different relationships between NDVI and fAPAR for each LAD type. Since leaf inclination angles affect light interception, variations in LAD also affect the estimation of leaf area based on transmittance of light or lidar returns.