Trees
Benefits of Trees
In addition to beautifying the region, trees and other vegetation absorb pollution, curb the heat island effect, control stormwater runoff, and save energy costs.

A recent study by American Forests calculated the economic value of some of these services. Existing trees in the region remove an estimated 83 million pounds of air pollutants each year. This annual air pollution removal is valued at $208 million, reflecting the price that society would have paid for externalization, such as health care costs, if the trees did not exist. Area trees also control 2.4 billion cubic feet of stormwater when it rains. This calculates into a one-time $1.33 billion savings on construction of stormwater management systems. Shade from trees reduces air conditioning costs an average of $72 annually for a detached, single-family home, according to the research. This adds up to citywide household savings of $26 million each year.

Tree Loss
The study found a 16 percent decline of the urban canopy in the Houston area over the last three decades. In 1972, more than one million acres in the region had 50 percent or greater tree cover. That figure dropped by 150,000 acres in 1999. Conversely, acreage with less than 20 percent tree cover increased by 13 percent, or 200,000 acres, in the same time period.

Tree Protection
Cities in the Gulf Coast Region have varying policies that protect certain trees. The City of Houston Tree and Shrub Ordinance requires city permission before trees larger than 1.5 inches in diameter located in public rights of ways can be removed; this includes trees in esplanades and the areas between sidewalks and the street. In 2003, the ordinance, which previously protected trees on commercial prop-erty was expanded to protect trees on private property. Some also suggest that trees be considered in all public works, transportation, and development decisions. Tree planting and protection are inexpensive, non-invasive methods for air pollution reduction and stormwater management. Several groups are working to add these strategies to the State Implementation Plan to reduce ground-level ozone (see Air Pollution).

Recent Progress
Blue Ribbon Tree Committee
In March of 2001, Houston Mayor Lee P. Brown convened a special committee to review the city's tree planting and protection ordinances and address larger tree issues. In the fall of 2002, co-chairs of the Blue Ribbon Tree Committee, representing developers, beautification groups, and environmental organizations, submitted their 25-page report. The committee's recommendations resulted in a significantly stronger city ordinance.

Houston Green continued
The Texas Forest Service has received federal funds to further analyze the region's existing tree resources and their role in reducing air pollution and the urban heat island effect. The project will build on the work of Houston Green, a coalition of regional government, business, and nonprofit organizations that released a report in December 2000 that estimates the economic value of the tree canopy in the Houston-Gulf Coast region. The final product of this further research will be computer software that local tree organizations can use to determine the effects of existing tree cover, select priority planting sites, and help with planning and management activities. A 1998 study by the Food and Drug Administration found pesticide residues in 35 percent of the food tested. Although exact health effects are difficult to determine, scientists have linked pesticides to many types of cancer, and to nervous system disorders, genetic mutations, and immune system dysfunction.

What You Can Do
Plant trees
Trees for Houston, a local nonprofit organiza-tion, sells trees to plant in parks, esplanades, and along street rights-of-way. Call (713) 840-8733 to learn more. Annually, to celebrate Arbor Day, the Parks and Recreation Department gives out free tree seedlings. Call (713) 845-1000 for more information.

Report tree ordinance violators
Ctizens can report potential violations of the Tree and Shrub Ordinance by calling TreeScape at (713) 942-7275. Watch for trees in danger as well. Trees with ribbons tied around them may be about to get the axe.

Register an old tree
The Harris County Tree Registry, established in 1992, recognizes the largest trees of each native genus and species in Harris County. If you would like to nominate a tree, contact the Park People at (713) 942-PARK. A volunteer forester will measure it; qualifying trees will receive a certificate and be listed in the next edition of the registry.