ABSTRACT
A successful tree species produces enough good seed to replace parents, gets them to potentially useful sites, and equips them physiologically to germinate under circumstances probably suitable for establishment. Then comes the "moment of truth" when, through the act of germination, an individual seed commits itself to environment. In addition to the "dormancy problem," temperature response may vary with the way seed are exposed to temperature over time. Seed are known to respond to light via the red–far-red-mediated photo-conversion of phytochrome, and seedlings appear after disturbances which create forest gaps or larger openings. Consider the temperature regime of a seed lying on a soil surface or partly covered by surface materials. Under natural conditions, most forest tree seed germinate; seed of only a few genera are capable of germinating through much litter. Reducing heat loss implies higher surface temperature, and the associated higher water vapour pressure can sometimes lead to greater water vapour loss."
