Why do leaves fall. Is it because of the cold weather or is it because the equinox and time associated with the sun being out during day and night. I live in texas , my wife states that the cold weather tells the tree to start loosing leaves , but i think it's because of the day night ratio and the equinox. Which is right guys? Please help Patrick
Patrick it has to do with the ratio of red and infrared light. at the beginning of autumn in the northern hemisphere these ratios start to get out of kilter and so begin the process of turning the leaves and having them drop. pierrot
Not all decidious trees loose there leaves at the same time, or at the same rate. Some begin turning colors in late summer and drop early (Maple), and others like Alder hold their leaf into December with little change in color. A sudden early cold spell could trigger some leaf drop, but as peirrot pointed out it's mainly due to light level changes.
There are also lots of tropical trees which are dry-season deciduous; they lose their leaves in response to drought and then come back into leaf when the rain starts again
