The type of tree that produces the most oxygen is the mature oak tree. While various tree species contribute to oxygen production, oaks are particularly effective due to their large size and extensive leaf surface area. They can absorb carbon dioxide and release substantial amounts of oxygen through photosynthesis, especially during their growing season. As keystone species in ecosystems, oak trees also support diverse wildlife, providing habitat and food. Although individual trees' productivity can vary based on species, age, and environmental conditions, mature oaks are among the top contributors to oxygen generation in forests.