RE: Fall

Seems that I should have mentioned why (some) leaves turn red in fall: The leaves produce anthocyanins (a reddish stuff). If there are little nitrogen (and other elements) in the ground, the leaves produce more anthocyanins. The trees get (some of) the nutritionts from the leaves when they fall on the ground near the trees and decompose (and perhaps also some of the nutritionts when the leaves are still left on the trees). See link below.

Anthocyanins occur naturally in some plants with red leaves, especially if the photosynthesis isn't so active in those plants. That means they get more of other nutritionts directly from the leaves (perhaps some antioxidants) by use of the anthocyanins.

Red berries and blue berries in the woods also protect the plants they grow on against microbes and plant illnesses (and probably other plants) by their content of antioxidants. Blueberry plants often have some red leaves, especially if they live in the shade of other plants or trees (or the ground make much shade). So anthocyanins is (at least in some degree) a sort of replacement for photosynthesis among several plants.

If you look at trees getting reddish leaves, you see that leaves in cold or windy parts are more reddish. They still contribute with some temperature protection of the more green leaves on the inside parts, so the green leaves still have some photosynthesis.

http://www.sciencedaily.com/releases/2007/10/071025112042.htm