How do trees with red leaves allow photosynthesis to ocurr?

Question

How do trees with red leaves allow photosynthesis to ocurr?

Answer 1

Red leaves are caused by just an extra set of pigments (anthocyanins) in addition to the normal green chlorophyll.  

Anthocyanins are the water-soluble pigments responsible for red and blue in flowers, and the stuff that gets extracted from red cabbage for the common demonstration of pH.

In plants, besides their role in pollinator attraction, anthocyanins can serve as antioxidants and as "sunscreen" for the leaves, helping prevent damage from UV and blue wavelengths of light in high light situations ("photoinhibition".

Answer 2

Very strong colours mask the green of chlorophyll, but photosynthesis still takes place (red, brown and even blue seaweeds photosynthesise).