Brilliant green leaves of summer filled with chlorophyll that uses the sun and nutrients from the tree through the warm months. As the earth turns and the days grow shorter the fluid in the leaves becomes restricted by the cooling temperatures and the chlorophyll decreases.
Modern landscaping in the city leans toward evergreen because the autumn leaves do fall to the ground creating a mess. Rural and natural areas have the space needed for trees that drop their leaves. The cycle replenishes the soil providing nutrients necessary for the Spring.