Most everyone knows that we use proteins, carbohydrates and fats for energy. Calories are measurement of a unit of heat or food energy. For example, we can achieve four calories per gram of proteins and carbohydrates, and nine calories per gram from fats.
Tree Variety. Virginia pine (Pinus virginia) is the major Christmas tree species for the acidic soils found in East Texas. A grower can produce a 6- to 8-foot Virginia pine Christmas tree in 3 to 5 years, depending on soil and climatic conditions.
1 It can take as many as 15 years to grow a tree of typical height (6 - 7 feet) or as little as 4 years, but the average growing time is 7 years.  The top Christmas Tree producing states are Oregon, North Carolina, Michigan, Pennsylvania, Wisconsin and Washington.