ABSTRACT
Concentration .............................................................. 177 7.5 Results.......................................................................... 178 7.6 Summary...................................................................... 181 Acknowledgments................................................................. 183 References............................................................................. 184
7.1 INTRODUCTION
Photosynthesis and the incorporation of photosynthate into plant biomass (net primary productivity, NPP) varies
spatially and through time at individual locations as a response to climate. In particular, the amount and seasonal distribution of precipitation and the length and warmth of the growing season are the primary determinants of biomass production in natural ecosystems and also for agroecosystems. Over the past century regional meteorological measurements have shown that global climate is changing (Easterling et al., 1997). Some of this change has been the result of rising atmospheric concentration of CO2 from fossil fuel burning and land-use change (Folland et al., 2001). As CO2 concentrations in the air continue to rise, additional solar radiation is trapped in the atmosphere and warms the planet. Over the next century, CO2 concentrations will continue to rise and additional changes in climate are expected.
