The National Arbor Day Foundation has released maps with revised “hardiness zones.” These zones can be used for determining which plants can be grown in certain parts of the United States. For example, a Norway spruce grows well in zones 3 through 7, but would not grow well in much of the South. These maps reflect the realities of changing climate: most of the nation is warmer now than at the time the previous map was published by the USDA, which was in 1990.
USA 2006 Hardiness Zones:
USA 1990 Hardiness Zones:
USA Hardiness Zone Changes:
The pink and red areas are in warmer zones than in 1990.
Here’s what the Arbor Day site has to say about the benefits of trees:
Trees counteract global warming in multiple ways. Atmospheric carbon dioxide is the leading contributor to global warming, and as trees grow they remove CO2 from the atmosphere, storing the carbon and releasing oxygen. A single tree can remove more than a ton of CO2 over its lifetime. Also, shade provided by trees reduces summer air conditioning needs. According to the USDA, the cooling effect of a healthy tree is equal to 10 room-size air-conditioners operating 20 hours a day. Trees reduce the “heat-island” effect in urban areas, where summer temperatures are generally warmer than the surrounding countryside. According to the U.S. Forest Service, 50 million strategically placed shade trees could eliminate the need for seven 100-megawatt power plants. Additionally, trees around homes and in cities slow cold winter winds, reducing the need for winter heating. This relief on fuel consumption for heating and cooling helps reduce CO2 emissions from burning fossil fuels.
Grace and Peace