A maple tree could be studied in many fields of science. What aspects of a maple tree might be studied in chemistry?

Chemical reactions, kinetics, organic chemistry

Explanation:

You might study the chemical reaction, learn about the differences between products and reactants, about delta H and exothermic and endothermic reactions. You may also study Kinetics by studying the rates of reactions with certain chemicals in a maple's enzymatic processes.

Another thing that you might learn about is organic chemistry. The glucose molecules, carbohydrates, lipids, nucleic acids, all have a structure based on the Carbon atom. You can learn about the specific structures of some chemicals that are involved in photosynthesis and simple hydrocarbons that are involved in photosynthetic/bio-synthetic pathways.

There's probably a lot more - but these are the most basic things I could think of.