Contents
XVII
23.6 Conclusions: Gobal Scale Maps of Observed
and Predicted Amax ............................... 503
Appendix: References for Global Measurements
of Amax ......................................... 506
References ...................................... 508
24
Remote Sensing of Terrestrial Photosynthesis
C. B. Field, J. A. Gamon, and 1. Pefiuelas
24.1 Remote Sensing, from the Leaf of the Globe ....... .
24.1.1 A Range of Approaches ......................... .
24.2 Models: from Radiance to CO 2 Exchange .......... .
24.3 Remote Sensing of Photosynthetic Capacity ........ .
24.3.1 Absorbed Radiation ............................. .
24.3.2 Photosynthetic Pigments ......................... .
24.3.3 Other Compounds .............................. .
24.4 Remote Sensing of Physiological Status ............ .
24.4.1 Fluorescence ................................... .
24.4.2 Xanthophyll Pigments ........................... .
24.4.3 Canopy Temperature ............................ .
24.5 Remote Sensing of Environmental Factors .......... .
24.6 Conclusions .................................... .
References ..................................... .
25
Are C 4 Pathway Plants Threatened
511
511
512
512
513
513
518
519
520
520
521
523
523
524
524
by Global Climatic Change? ....................... 529
S. Henderson, P. Hattersley, S. von Caemmerer,
and C. B. Osmond
25.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 529
25.2 Low Atmospheric CO2 Concentrations and Evolution
of C 4 Pathway Photosynthesis ..................... 530
25.3 Physiological Flexibility in C 4 Plants
Under High CO 2 Concentrations ................... 532
25.3.1 Coordination of Metabolism ...................... 532
25.3.2 Leakage of CO2 from the Bundle Sheath. . . . . . . . . . .. 534
25.3.3 Translocation of Carbohydrate ..................... 537
25.3.4 Water Use Efficiency ............................. 537
25.3.5 Nitrogen Use Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . .. 537
25.4 Growth and Competition Between C 4 and C 3 Plants
Under Elevated CO 2 •••••••••••••••••••••••••••••• 538
25.5 Present Distributions and Diversity of C 4 Plants ..... 539
25.6 Future Distributions of C 4 Plants .................. 543
25.7 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 544
References ...................................... 546