The short-term effects of fertilization on loblolly pine photosynthesis and biomassThis article is part of a larger document. View the larger document here.
The physiological processes in loblolly pine leading to enhanced growth in response to fertilization have not been clearly established. We tracked net photosynthesis (Pn), height, basal diameter, and volume changes in loblolly pine seedlings in response to fertilization during the entire 2004 growing season. Pn measurements were conducted prior to fertilization and after fertilization in early May. The seedlings that received fertilization showed an increase in Pn rates above the controls for most of the growing season. Also, the fertilized seedlings had height, basal diameter, and volume increases of 10, 13, and 34 percent over the unfertilized seedlings. We conclude that fertilization led to an initial increase in Pn rates, which helped create extra photoassimilate to be used in building larger leaf areas, which in turn led to more above ground biomass.