By late February, the soil is beginning to thaw across the Heartland. Triggering metabolic activity in the roots of plants, the thaw advances slowly over the coming weeks. Lawns begin to green up by early March, followed by low deciduous shrubs and small trees as the month progresses. Since it takes awhile for this metabolic renewal to spread through plants, most larger trees do not begin to leaf out until April, with some species well ahead of others. Locusts and black walnuts are among the last trees to produce new shoots and leaves.
This progressive change in our landscape is absolutely vital to almost all species of life on earth; only deep marine organisms, able to feed on sulfides from hot smokers and volcanic vents, are independent of the solar food chain. The greening of plants, a reflection of chlorophyll production, initiates photosynthesis, whereby plants convert solar energy to starch and sugars. By doing so, they nourish their own growth and provide food for a vast array of herbivorous and omnivorous animals, from insects to elephants; in turn, these creatures are prey for carnivorous plants and animals and, eventually, all groups provide sustenance for bacteria, fungi and scavengers. Green is the color of life on Earth.
