Not Enough Trees

Source: la.curbed.com

Los Angeles is 21% covered by tree canopy, according to the Million Trees LA initiative, a fact confirmed by a recent study from the Woods Hole Research Center. This doesn't even compare to the national average of 27% and is even less impressive considering the region's temperate climate and decentralized pattern of urbanization.

When thinking about the impact trees have on urban and global sustainability, consider a few of the highlights from TreePeople's "Top 22 Benefits of Trees."

• Trees absorb odors and pollutant gases and filter particulates out of the air by trapping them on their leaves and bark.
• In one year an acre of mature trees can provide enough oxygen for 18 people.
• Trees cool the city by up to 10°F, by shading our homes and streets, breaking up urban “heat islands” and releasing water vapor into the air through their leaves.
• Three trees placed strategically around a single-family home can cut summer air conditioning needs by up to 50 percent.
• Shade from trees slows water evaporation from thirsty lawns. Most newly planted trees need only fifteen gallons of water a week.
• Trees reduce runoff by breaking rainfall thus allowing the water to flow down the trunk and into the earth below the tree, which prevents stormwater from carrying pollutants to the ocean.
• Tree prevent soil erosion by slowing runoff and holding soil in place.
• Trees reduce UV-B exposure by about 50 percent
• An apple tree can yield up to 15-20 bushels of fruit per year and can be planted on the tiniest urban lot.