How does a tree grow in diameter and what factors contribute to its growth?

A tree grows in diameter through a process called secondary growth, which occurs in the vascular cambium layer of the tree trunk. The vascular cambium produces new cells that add layers of wood to the tree's trunk, increasing its diameter over time. Factors that contribute to a tree's growth include sunlight, water, nutrients in the soil, and genetic factors. These elements help the tree produce the necessary energy and materials for growth.