chapter  15
16 Pages

Satellite-Based Modeling of Gross Primary Production of Terrestrial Ecosystems �������������������������������������������������������������������������������������������������������

ByXiangming Xiao, Huimin Yan, Joshua Kalfas, Qingyuan Zhang

Plant photosynthesis occurs within the chloroplasts of plant leaves and is composed of two distinct processes: (1) light absorption, that is, chlorophyll absorbs photosynthetically active radiation (PAR, mostly visible spectrum) from sunlight; and (2) carbon fixation, that is, the absorbed energy is then used to combine water and CO2 to produce sugar (Figure 15.1). Plant photosynthesis is well understood at the chloroplast and leaf levels through direct measurements by instruments (Taiz and Zeiger 2002). However, there is no direct instrument-based measurement of plant photosynthesis at

CONTENTS

15.1 Introduction ........................................................................................................................ 367 15.2 Leaf Area Index, APARcanopy, and FPARcanopy ........................................................ 369

15.2.1 Global Production Efciency Model ................................................................... 370 15.2.2 MODIS Daily Photosynthesis Model .................................................................. 371

15.3 Chlorophyll, Light Absorption by Chlorophyll, and FPARchl ..................................... 371 15.4 Detailed Description of the Vegetation Photosynthesis Model .................................. 372

15.4.1 Model Input Data ................................................................................................... 372 15.4.1.1 Satellite Data ............................................................................................ 372 15.4.1.2 Climate Data ............................................................................................ 373

15.4.2 Estimation of Vegetation Photosynthesis Model Parameters ........................... 373 15.4.2.1 Light Absorption by Chlorophyll ......................................................... 373 15.4.2.2 Effect of Temperature on Gross Primary Production ........................ 374 15.4.2.3 Effect of Water on Gross Primary Production .................................... 374 15.4.2.4 Effect of Leaf Age and Phenology on Gross Primary Production ................................................................................ 374 15.4.2.5 Maximum LUE ........................................................................................ 375

15.4.3 Model Evaluation ................................................................................................... 376 15.5 Case Study Estimating Gross Primary Production of C4 Maize Cropland

Using the Vegetation Photosynthesis Model ................................................................. 376 15.6 Summary ............................................................................................................................. 378 Acknowledgments ...................................................................................................................... 379 References ..................................................................................................................................... 379

the canopy and landscape scales, and how to scale up photosynthesis from individual leaves to the canopy and landscape is still a challenging and hotly debated topic. At the canopy and landscape scales, photosynthesis is often termed gross primary production (GPP).