How sunlight benefits trees
Sunlight is the common unifying factor in all of life on the planet. Humans receive energy from the nutrients they take in via eating. However, plants do essentially the same thing by using photosynthesis or absorbing sunlight. In order to understand what light actually does for tree’s its first necessary to understand what happens in the absence of sunlight. In many cases the tree’s leaves will not grow to adulthood. This means the tree will not be able to store the maximum amount of energy necessary for the cold months of the year. Oftentimes the leaves themselves will actually turn unattractive colors as well such as a dirty yellow. This signifies a lack of nutrition, and sometimes is matched with the leaves becoming brittle or easily damaged. In other cases a lack of sunlight will show up in the form of less varied leaves as well. This means the tree is lacking in different types of nutrients and so fewer types of leaves can be grown.
Sunlight is what allows trees to create chlorophyll which is essentially sugar to aid in the strength, health, and growth of the tree. This is why proper pruning techniques make such a huge difference to lifespan, and health of your tree.