Design & Inspiration Today • How to Green Your Arboretum

How Green is Your Arboretum

The incessant hum of Loop 610 traffic permeates the western edge of the Houston Arboretum & Nature Center, like waves crashing on a beach. Just 75 feet from the state's busiest freeway, rabbits scamper through the underbrush, purple beautyberries cling to the drooping canes of bright green plants and a dry, woodsy scent hangs in the air.

Today, piles of dead brush still sit beside some of the trails, and the ragged tops of dead trees waiting to be removed are visible through the woods. The non-profit organization that operates the arboretum has watched quietly while parks in other parts of the city have been dramatically reinvented. Now, they say, it's their turn.

"We're the silent giant," said executive director Deborah Markey.

The arboretum has launched a $40 million campaign to make the wildest area of Memorial Park as wild as it can be. The project will take several years. In the meantime, construction inside the preserve may look anything but natural to some people.

The arboretum's master plan calls for major improvements including a hike-and-bike trail along the northwest perimeter; an expanded network of nature trails; the conversion of the current visitors' center into an education facility with a world-class 'nature playscape'; a separate bus entry; and a new visitors center with a cafe and more parking.

The land itself will also get a makeover.

The arboretum lost 60 percent of its tree canopy to the double whammy of Hurricane Ike in 2008 and the drought of 2011. Long before these natural disasters, trouble was taking root within its ecosystems, where slivers of prairie and post oak savannah blend into woodlands, wetlands and riparian areas. Landscape architect Steven Spears of Design Workshop, the plan's lead consultant, classifies much of the lush growth that appears natural as a "woodland uprising" caused by a century of surrounding human activity.

"We're not letting nature just be nature," Spears said.

Eons ago, cycles of fire would have cleared out much of the underbrush and encouraged more wildflowers and grasses as well as more resilient trees to grow, he said.

Across Woodway Drive, other forested areas of the park have the same issue. The recent use of herbicides to open up the savannah near Crestwood Drive has drawn the ire of neighbors.

People don't like change, Markey said. "They just see a removal process. They don't really understand that what you're doing is removing invasives that so you can replace the natives."

Pimples and dimples

In 1951, the city carved 265 acres from Memorial Park to create the arboretum, which has always been bounded on the south by Buffalo Bayou and to the east by Union Pacific railroad tracks. When Woodway and the 610 West Loop were built, the preserve quickly lost 110 acres to roads and rights-of-way. The highway infrastructure also plugged a bayou tributary that ran through a deep ravine.

Restoring the landscape while expanding programming posed "a complicated problem that needed a comprehensive solution," Spears said.

His collaborators include Reed-Hilderbrand landscape architects, ecologists from the Lady Bird Johnson Wildflower Center, transportation planners from Walter P. Moore, cultural planners from SWCA environmental consultants, Texas A&M University forester W. Todd Watson and park operations experts from ETM Associates.

"The restoration will be based very much on science, not just something pretty that's going to be put back," Markey said. "The whole idea of the master plan is to restore the landscape in a way that's more meaningful."

One page of the plan contains four maps illustrating the arboretum's drainage patterns, micro-topography, soil types and tree loss. Spears and his team stacked them to understand why, exactly, so many trees died.

The micro-topography map - a close-up of the land's grading - provided a surprising clue, revealing a phenomenon Spears calls "pimples and dimples." These slight undulations of 12 to 18 inches in the land may have been formed by wind, similar to dunes on a beach. The convex pimples have sandier, better draining soil. The concave dimples have hard clay soil.

Construction could begin by May 2016 on new roads, trails and other infrastructure funded with $5 million of Uptown Tax Increment Reinvestment Zone (TIRZ) money.

The arboretum has raised $19 million of the remaining $35 million for three additional phases of work.

"It sounds like chump change compared to the Memorial Park master plan," Markey said, "but $40 million is a lot for a $2.2 million organization to raise."

Better facilities, trails

The arboretum organization was founded in 1967 to help educate city school children. Markey said that role is more important than ever. "There's going to be another drought," she said. "There's going to be another hurricane. We have to prepare the landscape for that time to come."

A decade ago, the arboretum's annual budget was $738,000. Income from programs and classes is up more than 400 percent, to $460,000 a year. To serve about 250,000 people who now visit the arboretum each year, the staff has ballooned from 8 to 24 people. They share the aging nature center building with a cacophony of school children on weekdays and during the summer. Renovating that building will allow the arboretum to double its youth programs, Markey said.

Spears expects families to flock to the new nature playscape on weekends. His firm is designing a series of four super-sensory discovery gardens where kids will be encouraged to "really get their fingers dirty."

Because better facilities and trails will inevitably bring bigger adult crowds as well, the plan calls for 270 new parking spaces.

Markey said they'll be designed "in a beautiful way," around a large new storm water retention pond. That area and the new visitors center designed by Lake|Flato Architects will sit near the arboretum's northern edge.

"Right now, you drive through the largest natural area," Spears said. "We want to get visitors out of the car early."

Markey hopes to have the new facilities and major portions of the restored landscape open by 2018. Phases 3 and 4 will address areas closer to the bayou.

"The southern half is the most intact ecosystem," Spears said. "We don't want to disturb too much of that. It survived."

Professional birder and Chronicle nature writer Gary Clark, who teaches workshops at the Houston Arboretum & Nature Center several times a year, believes the number of birds at the arboretum has declined recently. Storm, drought damage and the proliferation of non-native plants are factors, he said.

The arboretum could potentially host about 300 species of birds, Clark said, because Houston sits within a major flyway used by many species that migrate between North America and the tropics.

"Houston is a very rich area for birds because it's a bayou city," Clark said. "The arboretum participates in that wider ecology."

Restoring some of the arboretum's more open, original landscape could encourage more birds to visit. "The nature of the woods is, birds stay out of sight," Clark said. "But if you can return the post oak savannah, nature will take care of the rest."

A thicker tree barrier will be planted along the western perimeter to help mitigate freeway noise, most of which comes from the adjacent overpasses. A sound wall wouldn't be high enough to have any effect there, Spears said. "We're pinched on both sides," he said. "It's not like the Union Pacific track is some quiet little gem. But it's not as constant as the freeway."

New trails will be concentrated on the arboretum's east side, where it's generally quieter. Markey hopes to see more wildflowers and blooming trees in the spring and shrubs full of berries in the fall.

But Spears envisions creatures even more ephemeral -fireflies - returning to the landscape, blinking as they float above prairie grasses at night in early summer.