Habitat description
Open communities on dry, nutrient poor soils, the Sandplain Grassland and Heathland communities that make up this habitat type typically occur on glacial outwash. Key indicators of these communities are a dominant presence of warm-season grasses (Sandplain Grassland) and heath shrub species like low blueberry, sheep laurel and teaberry (Sandplain Heathlands). Although clear examples of these communities may be separated into either grassland or heathland based upon a dominance of grass-like plants or heath shrubs, these community types often grade into each other. Therefore, many of these sites occur as a continuum of the two community types. Trees (typically oak) may occur within Grassland/Heathland communities, but always at a very low percent cover.
These are disturbance dependent communities historically associated with fire occurring on the landscape with regular frequency. High integrity examples of these communities are now quite rare and represent critical conservation resources; not only for the persistence of the communities themselves, but for the large and diverse suite of highly specialized and often imperiled plants and animals that are directly dependent upon them.
Associated habitat types
This habitat typically occurs within a broader matrix of Barrens (Open woodlands, ridgetop, and shrubland) or Woodland habitats. However, due to the fragmentation of modern landscapes, these communities can also now occur as standalone features. Ridgetop Heathlands (S2) are included in the Barrens habitat type.
Characteristic communities and species
More information on the specific natural communities within this habitat type is available from the following fact sheets:
- Sandplain Grassland (S1)
- Sandplain Grassland Inland Variant (S2)
- Sandplain Heathland (S1)
- Sandplain Heathland Inland Variant (S2)
Sandplain Grasslands and Heathlands support some of the richest suites of specialized and imperiled species in Massachusetts. For example, the few remaining large occurrences of Sandplain Grassland communities in the state are the primary habitat of state-listed grasshopper sparrow, upland sandpiper and vesper sparrow, and Heathland communities support over two dozen species state-listed moths and butterflies. Sandplain Grassland and Heathland communities also support a disproportionally high percentage of the Commonwealth’s bee fauna.
Ecological processes
Nutrient-poor, dry soils are a driver for the presence and persistence of this habitat type. These harsh conditions favor the establishment of warm-season grasses and heaths, naturally limiting generalist species that would otherwise quickly overwhelm the community. Periodic fire or other disturbance is also needed to prevent the accumulation of organic material and soil enrichment, and a shift in vegetation. Natural disturbance processes to maintain the open structure of this habitat may include, fire, salt spray, storms, wind, and/or growing season frost.
Threats
Changes to the modern landscape, such as fire suppression, habitat fragmentation, and off-road vehicles are threats to this habitat type. The frequency of natural disturbances is unlikely to be sufficient to maintain high-quality Sandplain Grassland and Heathland habitat. Therefore, a lack of management (especially prescribed fire) as well as inappropriate management (such as mowing regimes that conflict with the persistence of target species) can be considered major threats. It remains unclear how climate change will affect this habitat that is maintained by dry, harsh conditions.
Restoration & management recommendations
Before undertaking a project, it is important to establish clear goals that are compatible with site conditions. Factors to consider include identifying the resources required for restoration and long-term maintenance, and securing community, stakeholder, and institutional support. For more information, please see: Habitat Management Priorities and Planning.
It is important to restore and manage both large and small remaining patches of this habitat type as small sites situated around and between large sites facilitate the movement of species (and genetics) and support the long-term persistence of obligate species across the landscape. Small patches of these communities are often remnants of much larger occurrences of important historic sites, and therefore have the potential to support rare obligates seldom found elsewhere.
Established Sandplain Grassland and Heathland communities require regular disturbance (see Ecological Processes above). In the modern absence of adequate natural disturbance processes, active management must now be employed to maintain the habitat. Thoughtful mechanical disturbance has become an important tool in maintaining the structure of these communities, though mechanical disturbance in the absence of periodic fire does little to address the build-up of organic materials and nutrients, or the persistence of fire-dependent plants. Prescribed fire, mowing, soil scarification and herbicide are the primary tools for managing these communities.
- Prescribed fire: Whenever possible, prescribed fire should be the primary tool for the management of established Sandplain Grassland and Heathland communities. Ideally, each unit within an established Sandplain Grassland community should be burned approximately every 2-4 years, and Heathland communities every 5-8 years, in the absence of natural disturbance factors such as wind, salt, or frost. In most cases, an entire site should not be burned in a single year, but instead at least half of the site (and in some cases more) should be left unburned for at least one growing season to provide refugia for specialized obligate species. Fire is important to the suite of plant species in these communities not only to maintain structural integrity and remove thatch, but also to stimulate germination and increase flowering, fruiting, and seed release for many rare plants.
Whether to use growing-season burns or dormant-season burns is dependent upon any time-of-year restrictions for sensitive species as well as the specific objectives of the burn. A reduction in generalist vegetation can be achieved with growing season burns; dormant season burns are useful for reducing thatch and other unwanted fuels. In most cases, it is rare to have the ability to manage a site with prescribed fire alone. Therefore, a comprehensive and adaptive plan that also includes mowing and possibly herbicide should be adopted. - Mowing in Sandplain Grassland: Mowing can be an important management tool for reducing woody vegetation; especially in Sandplain Grassland communities. Mowing should be employed in ways that do not cause adverse long-term impacts on populations of target species, however, rotational growing season mowing that leaves a significant portion of the available habitat intact during a given growing season, may be necessary in some cases to achieve community composition objectives. Short-term impacts may be necessary for the long-term persistence of the population at a site; these impacts can be acceptable if adequate temporal refugia and appropriate return intervals are established. If the species in question are state-listed, a habitat management plan approved under the Massachusetts Endangered Species Act is required.
As important a tool as mowing is for maintaining the Sandplain Grassland community to achieve structural and some compositional objectives, mowing alone cannot address the critical threat of accumulation of organic material and nutrients that can lead to a shift towards cool-season grasses and other generalist vegetation. When prescribed fire is an option, mowing should be viewed as a supplement to prescribed fire. Periodic prescribed fire will always be important for removing thatch that leads to soil enrichment. - Mowing in Sandplain Heathland: Mowing can be an important tool in controlling pioneering woody vegetation above low heaths. Growing season mowing can injure (and ultimately reduce) competing woody species, but the potential impact to target heath species recommends dormant-season mowing of undesirable woody vegetation as an effective way of lowering the height of this vegetation, making it available for efficient herbicide treatment the following growing season. Where competing vegetation is growing interspersed with desired heath species, mowing blades can be set above the level of the heath layer. As with prescribed fire, maintaining temporary undisturbed refugia to offset the disturbance of mowing is important.
- Invasive Plant Control: The thoughtful use of herbicide can be a critical tool in managing Sandplain Grassland and Heathland communities. Specialty herbicides that do not impact grassy plants can be especially useful in controlling unwanted invasive plants and woody vegetation in Sandplain Grasslands. More targeted applications of generalist herbicides can be important for controlling woody vegetation, clonal forbs and invasive species in both Sandplain Grassland and Heathland situations. Mowing/cutting woody vegetation prior to herbicide application, and then applying the herbicide to the resprout, will achieve very targeted control of otherwise tall woody vegetation.
- Soil exposure: Areas of bare mineral soil within these communities are critically important in supporting specialized invertebrates, especially a wide variety of bee species. Scarification can be very beneficial in Sandplain Grassland communities as both invertebrate habitat and to engage the latent seed bank. Shallow scarification can also be very beneficial in Heathland settings, but most heath species are sensitive to deeper scarification, and therefore care should be taken.
Ecologically compromised Sandplain Grassland and Heathland communities often require more involved restoration activities to return them to a state of integrity and function. Understanding the feasibility of a restoration project in relationship to your capacity to carry out a long-term restoration project is essential when deciding whether to take on a project. Fortunately, Heathland communities are incredibly resilient, and typically respond robustly to restoration activities. Sandplain Grassland communities are generally more difficult to restore when degraded, but their obligate species also respond quickly and favorably to restoration actions. Some restoration considerations are listed below:
- Most degraded Heathlands have simply been overwhelmed by vegetative succession (e.g., over-topping by canopy trees), and in this state, can be relatively easy to restore by removing enough of the tree canopy to allow light to reach the heath below. In some cases, chemical control may be required to reduce resprouting of tree stumps. Most heaths are clonal and consist of extremely large underground root networks, so even if above-ground heath appears sparse, the root network will often vigorously sprout once canopy trees are removed.
- Degraded Sandplain Grassland communities can be found in a diverse set of conditions brought about by a diverse list of stressors. The persistence of obligate species (especially little bluestem) is an important factor in deciding the feasibility of Sandplain Grassland restoration. In general, woody vegetation can be easier to overcome during restoration than cool-season grasses and clonal forbs. However, herbicide use can be effective in overcoming all generalists in a restoration project.
- Community structure does not need to be “pure” across a site; interstitial emergent trees (oak, red cedar, and pitch pine) and aggregations of shrubs (e.g., scrub oak or hazelnut) can add important diversity. In general, Sandplain Grasslands can function well with sparse emergent trees (savanna-like), and Heathlands can function with an even higher rate of retention (up to open woodland). Tree retention should be avoided in the core of grassland bird areas, and generalist tree and species not associated with fire and xeric environments should be avoided.
- Seeding may be desirable during initial Sandplain Grassland restoration efforts. Generally, only little bluestem (Schizachyrium scoparium) should be the initial species seeded to a site because most other Sandplain Grassland obligate species will persist in the seed bank for decades and may already be poised to recolonize a site once the soil is disturbed during restoration activities. In Massachusetts, warm season-grass species other than little bluestem are generally not encouraged for seeding because they can quickly grow dominant and overwhelm the community. Any seed brought into a project should always be from a local ecotype, and should be clean of unwanted species.
Examples
- Frances Crane WMA, Falmouth
- Westover Airforce Base, Chicopee
- Southwick WMA, Southwick
- Leyden WMA, Leyden
- Barre Heathland: Ware River Watershed, Barre
Additional resources
- Coming soon