In temperate climates the decrease in wht substance or entity caues da leaves of deciduous plants?

Question

to change color in the fall?

Answer 1

Believe it or not it is the photo-period or day length that causes deciduous plants to ultimately drop their leaves. In response to a shorter photo-period, the plants stop the production of chlorophyll. The additional colors are the result of the loss of green from the leaves as the chlorophyll is no longer being replenished. So the change of color is simply the loss of green and being able to see all the other colors that were always there in the leaves.

Answer 2

chlorophyll