Photosynthetically active radiation (PAR) diminishes substantially with passage through the canopy o

As in the sea, sunlight changes as it shines through vegetation on land. A mature temperate or boreal forest can reduce the total quantity of light reaching the forest floor to about 1% to 2% of the amount shining on the forest canopy. However, forests also change the quality of sunlight. Within the range of photosynthetically active radiation, leaves absorb mainly blue and red light and transmit mostly green light with a wavelength of about 550 nm. As in the deep sea, the organisms on the forest floor live in a kind of twilight.