Houston’s newest heroes are ‘super trees’
Not too far out along the Bayport Berm, the maw of earth-moving machinery gives way to the chirping of songbirds. Deer and bobcat have left tracks in the mud. Coyotes have dropped furry scat. Hawks soar overhead.
The Port of Houston built the berm, a 2.6mile-long, 20-foot-high ridge that curves from about Texas 146 to Galveston Bay, to buffer the communities of Seabrook and Jardin del Mar and preserve nearby natural areas from the sights and sounds of its busy Bayport Container Terminal. A massive land development is now under construction on the terminal side. But wildlife sights and sounds appear to be increasing, too.
It isn’t so obvious yet, but volunteers have planted about 2,500 native tree saplings on the berm since July. And that number will double by the end of March, says Deborah January-Bevers,
the president and CEO of Houston Wilderness, a nonprofit founded in 2002 to support and coordinate the work of many partners who want to preserve and promote the 10 diverse ecoregions that lie within the Houston metro region’s 13 counties.
The berm sits along the Great Texas Coastal Birding Trail, an important stop for migrating and overwintering birds. Before heavy industry arrived, the whole area was a wildlife paradise. Patches of it still are. Armand Bayou Nature Center is nearby, and other surprisingly lush pockets of undisturbed marshland and woods lie between the berm and Galveston Bay.
One of the grants supporting berm-planting effort incorporates an avian count, and the number of species seen so far has been promising. Loggerhead shrikes, raptor-minded songbirds on the species watch list, are among the birds that have been sighted.
January-Bevers has been astonished by how quickly wildlife has responded. “I hate to be clichéd,” she says, “but build it, and they will come.”
Eagle Scouts, corporate groups and other volunteers are not planting just any native trees. They are installing 12 species of regional “super trees” that provide multiple ecosystem services, a phrase that’s as much about humans as wildlife habitat.
You will be hearing more about super trees. Houston Wilderness and its partners have identified and ranked 14 native species based on their ability to absorb air pollution, stormwater and volatile organic compound emissions (air-quality issues caused by, say, the disruption of soils) as well as to sequester carbon emissions and increase wildlife habitat.
Live oaks are the heaviest lifters, able to sequester 268 pounds of carbon emissions and absorb more than 2,600 gallons of flood water and 2 pounds of greenhouse gases by the time they are 10 years old. The top 12 super tree list also includes, in descending ranking, box elder, laurel oak, red maple, river birch, American elm, slipper elm, tulip tree, American sycamore, green ash, loblolly pine and white ash.
January-Bevers also is happy to see most of the berm’s newly planted trees establishing themselves with little care. The berm was built with heavy clay soil dredged from Galveston Bay, “but trees figure it out,” she says. In a section with modest irrigation, 10 of the 42, 3-year-old specimens installed during a planting day in July — the worst possible time — have died.
But the survivors are already working. Even if the trees are just 8-10 feet tall, birds use them for perching, nesting and food. The trees start sequestering carbons right away, and the older they get, the more they will sequester.
Pioneering efforts
The port spent $4 million to build the berm and begin planting native trees, shrubs and grasses several years ago. Efforts accelerated last year after Houston Wilderness organized its $600,000 Port of Houston Tree Planting Program with the port, the Houston Health Department, Trees for Houston, Buffalo Bayou Partnership and the land restoration company RES.
Unlike the conservancies driving public-private efforts to improve city parks and trails, Houston Wilderness does not operate or maintain the land it helps to steward. For years, it has been more policy-focused than hands on, organizing large initiatives, such as the Gulf Coast Regional Conservation Plan, and packaging collaborative grants for what January-Bevers calls “pioneering projects.”
The recent creation of oysteries in Galveston Bay and a monarch butterfly flyway, that’s now statewide, were pioneering, she explains. The port planting is another, aiming to bring 1 million new super trees to a 30-mile chain of land that encompasses the riparian habitats of Lower Buffalo Bayou, Lower Brays Bayou and 25 miles of the Houston Ship Channel.
“People didn’t even know if there would be enough land,” January-Bevers says. Before anyone began planting, the group did a comprehensive inventory of existing native trees and shrubs. Now, Houston Wilderness staff are out there digging in the soil alongside armies of volunteers.
The scale of the entire port planting project matters if the city of Houston is to reach an even bigger milestone put out there last February within its wide-ranging, 184-page Resilient Houston plan: 4.6 million new super trees in the ground by 2030, which equates to two trees for each of the city’s 2.3 million people.
The complex plan delivered a framework for addressing Houston’s susceptibility to a multitude of shocks and stresses, with 18 “high level targets” that range from job development, the economy and transportation to equitable neighborhoods and emergency alert systems, but the environment figures into many of them.
“We have a lot to do in a short amount of time,” says Marissa Aho, the city’s chief resilience officer, “and trees solve multiple things.” Along with green infrastructure, stormwater management and other environmental goals, her laundry list considers quality of life, beautification and health disparities.
Mass plantings of super trees with large canopies are top of mind right now because she has just released the results of a 2020 heat mapping campaign that suggests where they should be a priority. Volunteers measured heat and humidity in the morning, afternoon and evening on Aug. 7 in 32 zones across 320 square miles; the largest community heat-mapping campaign in history. Temperatures varied by as much as 10 degrees in the morning and 17 degrees in the afternoon across Harris County.
The Gulfton area was the hottest of the hottest spots, which fell generally southwest and north of downtown. “It might be obvious already, but now we have data,” Aho says.
Super trees will be an important tool for mitigating urban heat islands. And they need to come ASAP. According to Resilient Houston, the city could see more than 74 days (10.5 weeks) per year with a heat index of more than 105 degrees by 2050. (It’s currently 10 days.)
Changing after Harvey
Scientists know trees communicate through their root systems and canopies. Imagine the inaudible chatter as they become more plentiful in the region, thanks to a major paradigm shift that has gained steam since the wake-up call of Hurricane Harvey.
Land-hungry subdivision developers may have been partly to blame for the storm’s destructive floods, but now, many routinely seek ways to use nature to their advantage, rather than trying to control it. And green infrastructure is a selling point. JanuaryBevers cites the 11,400-acre Bridgeland in Cypress, Houston’s top-selling master-planned community, as just one shining example.
She is especially keen on super trees, though, because tree-planting initiatives dovetail with two of the three priorities of another big-picture vision, the Gulf-Houston Regional Conservation Plan her organization facilitated.
If one of those ambitions is realized, half of the public and private land across eight counties will utilize nature-based stabilization techniques such as lowimpact development, living shorelines and bioswales by 2050. “That could be green stormwater infrastructure or large-scale tree planting,” January-Bevers says.
She likes to brag on the Shell campus at Dairy Ashford and Interstate 10. “They reuse rainwater, have something akin to lowimpact development areas and have aerated ponds with native trees. They’ve converted what wasn’t buildings and sidewalks, and they encourage their 6,000 employees to walk out there to exercise and reduce stress,” she says.
Another conservation plan goal “puts Houston in the global equation,” she says, noting that 95 percent of the region’s soil has been tilled, releasing harmful carbons. “Our carbon sequestration is about half what it could be,” she says. The plan aims for a 0.4 percent annual increase in carbon offsets — which, again, makes super trees superheroes.
While not directly related to trees, the plan’s other (and first) goal would certainly provide more space for them: It calls for doubling the amount of protected and preserved land in the region by 2040, from 12.3 to 24 percent.
“Protected and preserved” covers all kinds of what JanuaryBevers calls “additive” projects, from golf course conversions such as Exploration Green to the Harris County Flood Control District’s $2.5 billion detention plans to the development of master planned communities. “The development community is often left out of that equation, but more and more of them are working to add as much protected land as they can because they know now that’s how their subdivisions don’t flood,” she says.
Is it realistic to think such lofty goals can be achieved? “With maybe the exception of a concrete dam, there’s almost nothing nature based, infrastructure wise, that doesn’t fit into one of these three goals, which is why they’re timely and why they work so well,” JanuaryBevers says.
Having a goal allows stakeholders to prioritize and plan, she adds. “Different organizations are picking up on and using our data at a regional scale. That’s important to us because it’s the kind of thing that’s going to help us achieve our goals.”
Houston Wilderness, the city of Houston, Harris County, the Texas Department of Transportation and major landscape architects formed a strategy group in November to reach the 4.6 million native trees goal. They are now compiling the first-ever regional, large-scale tree planting manual to help anyone who wants to pitch in, from private developers to individuals.
About 210,000 native trees were planted last year. That number needs to double to meet the 2030 goal. “It will require a collaborative effort to target large-scale native tree species plantings, including the super trees, all around Greater Houston — along waterways and the lengthy Houston Ship Channel, in public rights-of-way, corporate and residential green spaces, and in heat-sensitive areas,” January-Bevers says.
But she also takes it down to the micro level. The only designated super tree that’s not readily available is the slippery elm, which she says is “literally impossible” to buy commercially in Texas right now because landscape architects and developers previously did not request it from tree farmers.
January-Bevers won’t be deterred. She is babying 30 small slippery elm seedlings in her backyard. The berm planting will be done by the time they are strong enough to put out there in the world, but other projects will be fertile ground.