Designing a Grassland Estate, Cultivating Biodiversity

In 1997, Thomas Woltz of Nelson Byrd Woltz Landscape Architects (NBW) began working with Seven Ponds Farm in Virginia to restore bio-diversity and natural heritage to this 60 ha cattle farm. Over the past 16 years, Woltz and his team, along with constant collaboration and communication with the land-owner, have turned what was once overgrazed pasture land into a model for restoration of biodiversity and ecological services. We at Ecological Restoration interviewed Thomas Woltz to gain his perspective on the restoration of this agrarian landscape to a functioning grassland/meadow and forest complex in the foothills of the Blue Ridge Mountains.

Seven Ponds Farm is privately owned and the owners of the property deeply value nature and the restoration of biodiversity and ecological services for overall health of the landscape and their family. From the beginning, the goal of this landscape transformation was to maximize native biodiversity while restoring a degraded agricultural landscape. Although previous owners used the land for farming income, the new owner is dedicated to Virginia natural heritage and biodiversity. Additionally, Woltz and the property owners wished to use design to reveal the ecological narratives of the landscape. What is most unique about the design are the additional goals of producing knowledge through restoration experimentation and emphasizing the critical importance of ongoing monitoring in the designed landscape.

Figure 1.

This previously incised stream was subject to nutrient and sediment overload. The construction of small stone spillways created multiple small ponds and facilitated the regrading of the stream while also providing walking paths for access throughout the property.

In the beginning, restoration of the farm faced several major landscape issues. First, the farm was heavily grazed by cattle for close to 75 years. This grazing pressure led to limited biodiversity in the open fields, severe erosion of the two distinct watersheds on the property, and prevalence of invasive plant species. Additionally, overabundance of white-tailed deer in the area caused the degradation of ground vegetation and sapling trees in the woodlands of the property, decreasing biodiversity even further. As restoration progressed, other issues appeared, particularly the pressure of invasive plant species on the meadow restorations and the pressures of surrounding suburban development.

In order to deal with the eroded waterways and incised streams, Woltz and his team designed small pools at the headwaters of the streams to slow water flow (with the added benefit of providing habitat for amphibians) (Figure 1). They used filtration strips and shrub plantings to stabilize the stream banks. They have also planted native tree species across the property, within highly designed gardens as well as woodlands. Since the beginning of the project, they have planted nearly 10,000 native trees as part of a large reforestation effort, using black fabric mats and plastic tubes to increase early establishment rates by suppressing competing plants and inhibiting deer herbivory. In other areas, large expanses of grasslands have been established where there were once grazing pastures. Constant management of invasive plant species has occurred over the last 16 years by the farm staff using both mechanical and chemical methods of control. Finally, in late 2012, a 2.7 m high deer fence was built surrounding the entire property to reduce the effects of overgrazing by white-tailed deer.

It is in the grassland meadows where NBW has incorporated the science of restoration most clearly. The grasslands cover over 12 ha of rolling hills within the property and have winding paths throughout (Figure 2). The paths are laid out in long, gracious curves topographically, allowing visitors to immerse themselves in this big powerful landscape. Woltz feels the paths really allow people to closely experience the meadow (which can reach 2 m high by the end of the growing season), feeling the surrounding landscape. Visitors experience the local changes in diversity as they walk through a topographic and temporal gradient. As guests walk downhill they experience wetter meadows. The temporal gradient is represented by the burn regime of the restorations. Some fields are three years since the last burn, while others were...