URBAN CANOPY
Experts say trees could be the remedy for many of the city’s problems
Talk to someone who is passionate about trees and they will likely tell you that having lots of trees in the city will ward off a host of urban ills.
“Our community trees are essential to all of our health and all of our well-being,” said Bryan Suhr, founder of the nonprofit Think Trees New Mexico, which held its annual conference Jan. 19-20 to provide education and training for professionals who grow and care for trees.
The benefits of an urban canopy go well beyond the cooling relief of the shade they provide in our brown desert environment. Suhr said studies have shown urban trees can help slow storm runoff and reduce erosion, absorb carbon from the air, reduce dust pollution, even encourage customers to linger longer in shopping plazas.
The presence of trees encourages people to spend more time outside in their neighborhoods, Suhr said, bringing health benefits and helping to reduce street crime.
“I really believe trees are an inexpensive solution to a lot of the problems socially in our cities,” said Andrew Lisignoli, who shares Suhr’s passion for trees.
Lisignoli is sales manager at Trees of Corrales, a nearly 100-acre farm on the north side of Corrales that grows and sells around 20,000 trees annually to independent garden centers and landscapers in New Mexico, Arizona, West Texas and Utah.
But New Mexico’s dry climate, vast temperature swings, harsh sunlight and strong winds make it a challenging environment for trees. A study published in 2012 in the journal Urban Forestry & Urban Greening said Albuquerque lost 2.7 percent of its total tree canopy between 2006 and 2009.
“In the summertime if you were to drive from the airport to any hotel you would see dead trees on the horizon. Those dead trees don’t paint a welcome picture for industry to move to Albuquerque or businesses to come,” Suhr said.
He praised Rio Rancho for starting a program in 2011 to train “tree stewards,” volunteers who monitor and help care for trees in local parks. The program, part of Keep Rio Rancho Beautiful, a division of the Parks, Recreation and Community Services Department, currently has 47 volunteers. Albuquerque doesn’t have such a program.
Albuquerque City Forester Joran Viers said trees in city parks benefit from irrigation installed to maintain the grass. But, he said, commercial developers often don’t consider how much space a tree needs to thrive when designing commercial spaces. There has also been a
trend to remove turf and xeriscape with rocks to reduce water consumption. Viers supports efforts to conserve water but if not done correctly, it can be damaging to tree health.
“The reality is, trees are big plants and they need a lot of water,” said Viers.
Viers said the most common mistake is to put down permeable fabric and gravel and to place irrigation drip emitters at the tree base. The gravel absorbs heat, increasing the tree’s need for water. However, the fine roots that absorb water needed to feed the tree are at the edge of its canopy not at the base, Viers said.
“The result is a heat stressed tree and progressive die-back of branches,” said Viers. The process may take a few years and property owners may not realize what caused the problem.
He recommends replacing gravel and fabric with chipped wood that doesn’t convert sunlight into heat and when watered will decay, contributing organic matter into the soil. Local chipped wood suppliers include Pete’s Landscaping at 5200 Modesto NE and Soilutions at 9008 Bates Road SE, in the South Valley.
“Research shows this helps stimulate tree growth, like a natural forest floor,” Viers said.
Watering routines differ depending on soil type, he said. Less frequent and deeper watering is best. He recommends watering enough to wet the soil up to a depth of 18 inches to 24 inches around the edge of the tree canopy.
“You may have to run your drip systems for a few hours every other week instead of daily for a few minutes,” Viers said.
Instead of guessing, he suggests watering for a set period, then digging down until you reach dry soil and measuring the depth.
Don’t plant trees too deeply, he warned. The base roots should flare out just above the ground level. He recommended putting a layer of compost just beneath the wood chips but on top of the soil. Amending the soil around the tree roots below the surface, makes it harder for the roots and water to spread to surrounding earth.
“You basically create a potted plant,” Viers said.
While Albuquerque’s environment is tough on trees, there are several types that do well when planted correctly in an optimum location and properly watered.
Viers and Lisignoli mentioned Chinese pistache, honey locust, hybrid varieties of elm, red Texas oak and bur oak and hackberry. They said cottonwoods do best in valley soil near the Rio Grande. Stone fruit trees like cherries, which are popular around town, are prone to drought stress. The city of Albuquerque website cabq. gov also has a list of trees appropriate for planting in Albuquerque and the surrounding area.