I grew up in a house between two huge walnut trees. Those old trees fed, shaded and entertained us. Many evenings were spent cracking walnuts, our fingers turning black. Summer days, we enjoyed climbing, creating rope swings and building forts in our tall, sturdy trees. Fortunately, the developer who built our neighborhood preserved much of the existing walnut orchard when he built the homes. I have vivid memories of the thick, rough trunks, the strong branches, the perfect perches and the smell of roasting walnuts.

As Arbor Day approaches, we are reminded of the crucial role trees play in our city and in our world — they are nature’s remarkable gift to us.

Here are 12 ways that trees keep our environment beautiful and healthy:

1. Trees combat the greenhouse effect
Burning fossil fuels and destroying tropical rainforests have created excess greenhouse gases. Heat from the sun, reflected back from the earth, is trapped in this thickening layer of gases, causing global temperatures to rise. Carbon dioxide (CO2) is a major greenhouse gas. Trees absorb CO2 and release oxygen back into the air. In one year, an acre of mature trees absorbs the amount of CO2 produced when you drive your car 26,000 miles and can provide enough oxygen for 18 people.

2. Trees clean the air
Trees absorb odors and air pollution and filter particulates out of the air by trapping them on their leaves and bark.

3. Trees cool streets and cities
Average temperatures in Los Angeles have risen 6 degrees Fahrenheit in the last 50 years as tree coverage has declined and the number of heat-absorbing roads and buildings has increased.
Trees can cool cities by up to 10 degrees Fahrenheit, by shading homes and streets, breaking up urban “heat islands” and releasing water vapor into the air through their leaves.

4. Trees save water
Shade from trees slows water evaporation from thirsty yards. Most newly planted trees need only fifteen gallons of water a week.

5. Trees help prevent water pollution
Trees reduce runoff by breaking rainfall, allowing water to flow down the trunk and into the earth below the tree. This prevents stormwater from carrying pollutants to the ocean and replenishes underground aquifers.

6. Trees help prevent soil erosion
On hillsides or stream slopes, trees slow runoff and hold soil in place.

7. Trees shield children from ultraviolet rays

Skin cancer is the most common form of cancer in the United States. Trees reduce UV-B exposure by about 50 percent, thus providing protection to children on school campuses and playgrounds, where children spend hours outdoors.

8. Trees provide food
Fruit trees can yield up to 15-20 bushels of fruit per year and can be planted on most urban lots. Aside from fruit for humans, trees provide food for birds and wildlife.

9. Trees heal
Studies have shown that patients with views of trees out their windows heal more quickly and with fewer complications. Children with ADHD show fewer symptoms when they have access to nature.

10. Trees block things
Trees can mask concrete walls or parking lots, and unsightly views. They muffle sound from nearby streets and freeways. Trees absorb dust and wind and reduce glare.

11. Trees increase property values
The beauty of a well-planted property and its surrounding street and neighborhood can raise property values by as much as 15 percent.

12. Trees increase business traffic
Studies show that the more trees and landscaping a business district has, the more business will flow in. A tree-lined street will slow traffic, so drivers have time to look at the storefronts.

The city of Ventura has been designated a Tree City USA, and we continually strive to improve the health of our urban forest — 35,000 city trees in parks and along public streets. You may have noticed one of our most recent additions, slow-release watering bags on newly planted street trees. This gives thirsty young trees the water they need and saves time for our busy urban forestry staff. We are also requiring that the landscaping in parking lots include plenty of canopy trees, for purposes of shade, aesthetics and water and air quality.

Help us celebrate Arbor Day this year by planting a tree in your yard. Recommended species for Ventura are listed on our website, www.cityofventura.net, under Urban Forestry. The city will also be celebrating Arbor Day by planting 22 new trees at Citrus Glen Elementary School on Friday, April 26, at 9 a.m.