When you couldn’t see the Arboretum for the trees
Decimation at the hands of Ike, drought helped save the trails’ ecosystem
The death of almost half the trees at the Houston Arboretum and Nature Center might have saved the place. Hurricane Ike and the godawful drought two years later combined to decimate the 155-acre canopy. Thousands of trees, drowned in 2008 and then parched in 2010 and 2011, were marked with an “X” to face the chipper. Debbie Markey, the Arboretum’s executive director, told the Chronicle in late 2011, as though in mourning, “It will be a different landscape.”
And even before the natural disasters, the Arboretum hadn’t been the healthy patch of native wilderness that many people believed. A thicket — a combination of invasive plants and out-of-control natives — had swallowed the land. In the unbalanced ecosystem that had emerged over the decades, bushes and vine-covered trees grew where they had no business growing.
“You’d walk down the trails,” Joe James remembers, “but you couldn’t see into the forest. It was just a wall of vegetation. I hate to say monotonous, but my experience was somewhat monotonous.”
James, a landscape architect with Reed Hilderbrand in Cambridge,
Mass., came to the Arboretum in 2012 and 2013 to collaborate on a new master plan with a team including environmental designers and architects from the Lady Bird Johnson Wildflower Center, Design Workshop, Lake Flato and Main Street Design. When James first walked the trails, he said, “It was a graveyard.”
A few weeks ago, I met him there for a hike. It was the first time I’d been back since the summer before Hurricane Harvey. As James and I walked, he showed me details that help tell the story of the Arboretum’s new life. As Markey predicted, it is a different landscape. It’s much more beautiful now.
JARRING AS it was, the death of all those trees encouraged a total reevaluation of these 155 acres, all the way down to the soil and the seeds. James and the team learned that three distinct ecologies intersect here. There’s the forest, of course, which everyone could see, but there’s a prairie and a bayou, too, which almost no one could see, obscured as they were by that overwhelming thicket.
The team started by embracing this biodiversity. The monotony James had encountered on the trails revealed an ecological problem as much as an experiential one.
Because the Arboretum isn’t as flat as it appeared. In fact, like most of the Houston area before development, it has a “microtopography” of “pimples” and “dimples,” he said. Most of the trees that died were in the slightly depressed dimples. Since those dimples always filled with water when it rained, the trees hadn’t grown their roots as deep as those located in the slightly higher pimples and weren’t as resilient when the drought came.
Emily Manderson worked with James on the master plan before becoming the Arboretum’s conservation director in 2014. “We had the choice to replant it with trees,” she said, “or make it a more resilient ecosystem.”
The discussion, James said, was how to transform the Arboretum — how to make it “less a collection of trees and more a collection of ecologies.”
That’s new. Historically, Manderson said, “passive land management” had been the approach. “But we didn’t have the (forces) that kept it in balance, such as fire or buffalo grazing. So it needed a disturbance.”
In this story, that’s where the hydro ax comes in. The 10-ton tractor with teeth chomped invasive trees, including Chinese tallow, and overly aggressive native trees such as yaupon, along with hundreds of sweaty volunteers, who were armed with loppers and chainsaws.
“You can never go back to what was,” Manderson said. “But how do we try to make it resilient as possible?”
You remove what never should have been there. You weed. Now, five years later, there’s a prairie. But that presented a design challenge: It’s easy for visitors to appreciate the postcard grandeur of a forest. How can designers get us to understand the subtleties of a pimple-dimple complex?
Along the new trails that wind east from the new parking area toward the park’s railroad tracks, James and the team devised a boardwalk system to help. Marine-grade fiberglass spans the dimples, allowing water to move freely and native grasses and wildflowers to spring up through, and decomposed granite covers the pimples.
As you take in the sightlines opened up by that hydro ax and all those loppers and chainsaws, you can feel the microtopography in your feet. James said, “There’s this long view that reminds me of what Texas would look like.”
To the west of here is the newly opened Ravine Trail, closed and inaccessible for years, that winds through a riparian zone north of Buffalo Bayou.
The construction of Loop 610 and Woodway Drive long ago changed the landscape’s drainage patterns, and the banks of the bayou’s tributary continued to slough off, the bridges wash out. James and the team worked with a geofluvial morphologist who introduced chunks of limestone and drove the roots of fallen trees into the banks as a kind of ballast to slow the water down and hold it in small pools.
The removal of even more invasives along the trail here has also revealed a few of what James calls “champion” trees, towering old sycamores and sweetgums, which can be appreciated from a terracing boardwalk using that same marine-grade fiberglass.
Together, these moves, just two of many, James said, exemplify the choices they made “partially in the name of ecology and in the name of human experience. We’ve come up with a way that has expanded both.
“They have to go hand in hand to be successful.”
THE LAST time I’d visited, a few months before Harvey, I met Manderson deep inside the Arboretum. She was working on five-acre test plots of cleared understory to see what would grow, now that more light could get in.
Just three years later, I came away with a sense that park is much more alive, brimming with new plants and people. “We’ve seen so many more pollinators and butterflies,” Manderson said. “Birds are coming back. You can’t help being like, ‘Something magical is happening.’ There’s hope here.”
It seems to me that the story of the Arboretum is about recovery. Right before our eyes, as the team removes, acre by acre, what never should have been there, a more complex landscape is emerging — and so is our understanding of what Houston should look like, of the ecologies that our land used to support, and could support once again.
Of course, the Arboretum is not a finished product. Volunteers are working with the conservation team on other restoration projects, divided by Manderson into “management units.” Construction is underway on a new administrative building, designed by Lake Flato, and the nature center will be renovated into classroom spaces designed by Leslie Elkins Architecture. (The firm also designed the new conservation center.) A nature play area is coming soon, and Manderson is working on “long-term vegetation studies.”
“Nature,” she said, “is about change.” That’s clear here, if you take the long view. Which is the more beautiful one, I think. Now, if you decide to walk the Arboretum, you are able to see from the new parking area some snags, which is what people such as Manderson call dead trees that are still standing. In some ways, these are symbols. She said that they wanted to leave them as a “memory,” but also because birds love them as habitat.
And when they fall down, as they will, bugs are going to love them. Houston should learn to love them.
We might always be eager to plant trees, as James said as we said goodbye. But that’s not always what a landscape needs. That seems a kind of wisdom Houston could embrace.