Rediscovering Nature in the Suburbs of Western Plano

by Andrew Duggan, Mesa Design Group

The Arbor Hills Nature Preserve is unique because the park was designed as a 125-acre wildlife preserve in the midst of Urban Sprawl in Northern Texas. The preserve was designed to reflect the farming heritage of the surrounding area which is why the bathrooms, seen in the foreground, were built in the style of a grain silo. Behind Cedar Elms, Hackberry's and Bur Oaks in the background are the small and large pavilions. From the large pavilion, where the main trail extends north and west, visitors have a full view of the preserve.

The City of Plano initially conceived the property to be developed into a typical, suburban recreation park, complete with ball fields and tennis courts. Upon initial site reconnaissance, however, the planning team discovered a site that could become more of an asset for the community and add a unique facility to the city's collection of parks. The property sits in the transition zone between the Blackland Prairie region and the Whiterock Escarpment, home to a variety in animal and plant habitat. An inventory of existing species revealed that a remnant "Blackland Prairie" plants were reclaiming the old farmstead and begging for attention. Site diversity also included the Indian Creek Tributary and over 80 feet of natural topography change. The opportunity presented itself for a park based on preservation and educational discovery. The end result: the Arbor Hills Nature Preserve.

The city embraced the suggestions of MESA Design Group to develop the Nature Preserve concept and contracted them to lead a team for master planning the park and completion of Phase I construction drawings. The grand opening of Phase I was appropriately marked by the ceremonial throwing of a "seed ball" (clay mixed with seeds which are gradually dispersed through rain) over the hillside overlook.

The entry drive and parking lot are organized in a curling arc, similar to the form of a tornado swirling across the prairie, and acts as a symbol of man's interference with nature. From the moment the visitor enters the parking area, the presence of a large two-stage bio-filter denotes a removal from the normal suburban conditions. The bio-filter is the culmination of the path of the "twister" and reminds visitors of man's impact on the environment. Constructed with stone steps and gravel bottom, the landmark entry feature allows toxins to settle out in the detention area before being released back to the groundwater. The significance of this is made evident by the proximity to the remnant farm cistern that still remains in the plaza area.

All high-impact features of the master plan (i.e. heavy site disturbance such as grading, paving, etc.) are placed on areas of the property that were previously disturbed by the farming practices of former land owners. Parking areas were designed with no curbs, allowing for a visually seamless edge with the prairie. Only the interpretive trail ventures down the hillside into the undisturbed areas of the site. Such attention to preservation and interpretation is carried out through all areas of the park.

A grouping of pavilions beckons visitors from the parking area. Sitting on the upper edge of the hillside, the pavilion site was chosen for its full view over the preserve and across to the neighboring hill. One of the trail bridges across the creek is visible from the overlook. The forms recall the agricultural heritage of the region and the feeling is one of complete removal from the suburban surroundings. Designed by Larson & Pedigo Architects of Dallas, the structures are named after native tree species and are constructed of Leuders Limestone and steel. Leuders was chosen for its durability and resemblance to the Austin Chalk stone existing on site. The three structures are open to the public, but may also be rented individually or together, providing facilities for various groups within the community. The pavilions are lit by incandescent rafter lights that throw light up toward the high ceilings. The effect is a warm glow reflected down and out of the structure, similar to the nighttime view of a farmhouse out on the prairie when viewed from afar. Nearby is the restroom facility. Formed in the image of an old granary, the unique building is distinctive and can be seen from the road. The imagery of these structures makes one proud to be Texan.

Integrated into the education programming is the diversity of plant and animal habitat in the preserve. Five distinct ecological zones are present: Prairie, Riparian, Edge, Woodland, and Wetland. The true Blackland Prairie regions are some of the most fertile soils in the world, but represent one of the rarest landscapes in Texas. Intensely farmed in the past, the blackland prairie zone at Arbor Hills was the most disturbed. Eventually, a system of controlled burning will help to reestablish the native grasses and wildflowers on top of the hill, all of which will grow especially tall due to the rich soil.

The upland prairie on the far side of Indian Creek Tributary is home to numerous wildflowers and is quite attractive to butterflies. Animals noted on site include red foxes and red-tail hawks. The preserve provides a stop-over for some 300 to 500 species of birds which pass through Texas during winter migration. Uncommon in the suburbs, a woodland habitat introduces visitors to mature trees that follow the creek and climb the far hillside. A short side trail encounters a shallow creek branch and invites visitors to sit and listen to the water moving among the boulders. Geologic formations resembling geodes in the creek will eventually be called out on trail maps and interpretive signage. From open hilltop prairie to enclosed lowland forests, Arbor Hills Nature Preserve brings visitors up close and personal with the native Texas landscape.

The hike & bike trail meanders from the pavilion plaza past the playground and down the hillside, encountering each of the distinct ecological zones in the park. Three crossings of the Indian Creek Tributary required bridges. There was significant difficulty in the design of these bridges due to the fact that the flow was in constant flux caused by ongoing land development upstream. An existing waterfall actually moved 100 yards over the course of construction. The abutments were designed by the Landscape Architects with stone cladding to deter erosion. One design constraint noted during the construction document phase was for the trail to be completely accessible by emergency and security vehicles. This required a realignment to provide proper turning radius and special engineering on the bridges. The trail itself is 10-feet wide, over two miles long, slopes some 70 feet down the hillside, and is entirely ADA and AASHTO compliant. A local mountain bike club donated time and materials to construct a single-track trail entirely separate from the interpretive trail system. Future additions to the educational trail will include trail spurs in each ecological zone, specifically designed for interaction with plants or wildlife.

The construction phase of the project was carefully monitored by the Landscape Architects over the year and a half of construction. Extensive site cleanup and restoration was necessary in areas that were heavily impacted by dumping. Special care was taken in staking the trail in the field for both tree preservation and grading issues. Many of the large trees that could not be worked around on the trail alignment were actually transplanted by the city to other locations in the preserve. The City of Plano invested in the concept of preservation and even adopted creative maintenance techniques, including a mowing schedule for the grasses in wildflower areas. In fact, the only maintained "turf" areas are the shoulders to the trails, entry drive, and parking area.

Future phases of Arbor Hills will include other elements outlined in the master plan. Near the top of the list is implementation of the extensive interpretive graphics package prepared by Secker Brink Graphic Design. The innovative trail markers and sign panels highlight the diversity in plant and animal species present within the park. The signage program will have direct connections with educational activities being run at the day camp and promote the ongoing theme of "discovery." An interactive sundial, expansion of the playground, wildlife viewing blinds, and intensive native planting establishment are also planned.

Arbor Hills Nature Preserve was awarded a Texas Chapter ASLA award for the master plan in 1997. Phase I opened in September 1998. The project provides the citizens of Plano with an innovative nature park that promotes the rediscovery of nature from practically their own backyards. lasn