The paths through our woods now have a thick, crunchy carpet that, when dry, announces my strides to my furry fellow-mammals who also tread there. But, if I remain still long enough, it announces their strides to me. Fair enough.
This fall, it seems that the yellow leaves are holding on longer than the red leaves. These red leaves on trees along the path shown above are long-gone now:
As I understand it, the yellow leaf color is caused primarily by the natural loss of a chemical (chlorophyll), while the red is caused primarily by the energetic production of a new chemical (anthocyanin). But, why would a tree go to the trouble of producing a new chemical before it shuts down many operations for the winter?
A little (probably inadequate) online research indicates that there are two popular scientific theories that suggest it is a matter of self-protection, but in defense against different dangers. One theory suggests that red leaves help trees absorb damaging sunlight during their transition; that is, red is a “sunscreen.” The other theory suggests that red leaves keep away harmful insects, especially aphids. Some scientists think that both theories may be correct.
(Images taken in Brooklin, Maine, on October 20 [carpet] and 9 [branches], 2021.)