Habitat description
Ephemeral upland habitats consisting of varying amounts of shrubs, grasses, flowering plants, and small trees (generally less than 10 feet tall). Occasional mature trees may also be present particularly in abandoned pastures. They form on sites formerly cleared for agriculture or other purposes and include utility corridors. Cultural Shrublands would ultimately revert to forest in the absence of continued human disturbances (e.g., grass mowing, brush hogging, or burning). The presence of Cultural Shrubland habitat on the landscape varies in time and space depending on the type and extent of human disturbance that created or maintains them or the length of time that has passed since agricultural activity was abandoned in the old field. It is an ephemeral habitat that will occur only as long as it is maintained or it will eventually become forested.
Associated habitat types
Cultural Shrublands are similar in plant structure, but not composition to some natural communities that also consist of a grasses, flowering plants, and shrubs with few or no trees (see list below). These natural communities differ from Cultural Shrublands because they occur in situations where soils, moisture, slopes, temperature ranges, other physical conditions and ecological processes contribute to the plant species composition and structure often promoting and maintaining it. Early stages of Young Forest habitat, like Cultural Shrublands, can also develop under a variety of physical conditions and consist of grasses, flowering plants, shrubs, and young trees as they develop.
More information on natural communities (Swain 2020) with similar characteristics is available from the following fact sheets:
- Scrub Oak Shrubland (S2)
- Sandplain Heathland (S1)
- Sandplain Heathland – Inland Variant (S2)
- Ridgetop Heathland (S2)
- Maritime Juniper Woodland/Shrubland (S3)
Characteristic communities and species
Cultural Shrublands are typically composed of clumps of common native shrubs such as blackberry, raspberry, and blueberry also establish after agricultural activity has been abandoned. Additional native shrub species can include azalea, elderberry, leatherleaf, sweet fern, sassafras, low rose, new jersey tea, pasture rose, dogwood, or meadowsweet. Grasses and flowering plants that include non-native cool season grasses along with common native flowering plants such as horseflyweed, butterfly milkweed, common milkweed, joe-pye weed, boneset, primrose, goldenrods, and asters are often present. Native warm season grasses can also colonize over time in agricultural fields that have been abandoned. Scattered clumps of tree species may include aspen, birches, cherries, maples, or willows. Numerous types of invasive plants often establish in Cultural Shrublands, most commonly black swallowwort, bedstraw, oriental bittersweet, multiflora rose, autumn olive, and buckthorn.
Cultural Shrublands offer foraging and nesting sites for nectaring insects, nesting and basking habitat for reptiles, and breeding sites for songbirds, including many declining shrubland birds. In addition, they serve as habitat for many animals during all or part of their annual or life cycles. Among vertebrate wildlife species in New England, 13% (3 of 13) of amphibians, 62% (16 of 26) of reptiles, 37% (79 of 214) of birds, and 72% (46 of 64) of mammals use shrub/old-field habitats (DeGraff and Yamasaki 2001). Some vertebrate species demonstrate preferred use of shrub/old-field sites, including reptiles like the Eastern Ratsnake, Eastern Hog-nosed Snake, and Spotted Turtle; birds such as the Willow Flycatcher, Blue-winged Warbler, and Song Sparrow; and mammals like White-footed Mouses and Ermine. Black Bear, Bobcat, and Moose use shrubland habitat seasonally for foraging.
Cultural Shrublands occur in association with other habitat types based on the landscape setting and land use history within which they exist. Because they are usually present on active or abandoned farmlands, they can be directly adjacent to existing hay fields or other crop fields, or Cultural Grasslands being managed as habitat. Cultural Shrublands may also be associated with Successional Forest stands that have developed on abandoned agricultural fields or Young Forest created through habitat or forest management. They are often in a setting that includes adjacent forest habitat.
Ecological processes
Creation and maintenance of Cultural Shrubland habitat occurs through human activities such as grass mowing, brush hogging, or prescribed burning and not natural ecological processes such as those that create and maintain natural communities with similar plant structure. Once Cultural Shrublands are created, succession, or change in plant species over time, is the primary ecological process that alters the habitat in the absence of continued human activity. Through the sequential process of succession, the combination of grasses, flowering plants, shrub, and young trees changes over time. Shrubs and trees that establish in the fields will eventually shade the grasses and flowering plants and the fields will become dominated by them. Typically within fifteen to twenty years, the abandoned agricultural field will consist primarily of young tree species with a minor shrub component and after thirty years will be a forest stand. Active management is required to maintain Cultural Shrubland habitat that consists of patchily distributed grasses, flowering plants, shrubs, and young trees.
Threats
- Climate Change: Predicted changes in precipitation patterns, summer temperatures, and drought may alter the composition and rate at which the plant community changes over time, but management can maintain vegetative structure consisting of patchily distributed grass and flowering plants along with clumps of shrubs and young trees that are favored by those animal species that utilize Cultural Shrublands.
- Residential and Commercial Development: Development of abandoned farms consisting of agricultural fields which could serve as Cultural Shrubland negatively impacts potentially valuable habitat patches and fragments a landscape that could offer opportunity for colonization and dispersal of species that utilize them.
- Agriculture: Converting abandoned agricultural fields back to active farming will likely result in a decrease in wildlife habitat, including Cultural Shrublands, as it is unlikely that land already devoted to residential, commercial, or industrial development will be converted to farms.
- Energy Production and Mining: Sand and gravel extraction results in conversion of shrublands to often unsuitable habitat. Once extraction is completed, these areas become prime sites for residential or commercial development, leading to permanent loss of habitats. Abandoned agricultural fields are often chosen for installation of solar arrays resulting in a loss of the opportunity to manage them as Cultural Shrubland habitat. Utility corridors that are not managed to control invasive plant species or where plants are mowed and cut during breeding season offer reduced benefit of serving as Cultural Shrubland habitat consisting of beneficial native grasses, flowering plants, shrubs, and young trees.
- Human Intrusions and Disturbance: Recreational use for trails and other activities can increase the interaction between large-bodied snakes, like Eastern Ratsnake and North American Racers, and people, leading to mortality and collection of these species. They can also be disruptive to bird breeding activity.
- Natural System Modifications: Former agricultural land use with the addition of lime and fertilizers or pasturing animals has caused changes in soil chemistry favoring non-native cool season grasses and non-native flowering plants.
- Invasive Species: Invasive species are recognized as one of the greatest threats to natural plant communities and can alter ecological relationships or soil chemistry. Particularly problematic in regenerating areas such as Cultural Shrublands are the shrub species of Multiflora Rose, Glossy Buckthorn (Frangula alnus), Common Buckthorn (Rhamnus cathartica), and Autumn Olive (Elaeagnus umbellata).
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.
Establish and maintain Cultural Shrubland patches that are a minimum of 0.5 acre to approximately 5 or 10 acres or more. Cultural Shrubland habitat should consist of native grasses and flowering plants interspersed with approximately 50% cover of native shrubs and/or small hardwood trees with fewer softwood trees and patches of bare ground. The size of the existing or potential habitat can be an important factor in management decisions regarding this habitat type and the species it is likely to support:
- Small Cultural Shrublands Cultural Shrublands of less than 3 acres can provide enough habitat for nectaring insects, snakes, turtles, or small mammals. Sites of this size situated around and between large sites facilitate the movement of species (and genetics) between sites and support the long-term persistence of species across the landscape, providing refugia and redundancy.
- Medium sized patches of Cultural Shrubland between 3 and 5 acres can provide adequate nesting or foraging habitat for ground dwelling birds and small mammals in addition to supporting nectaring insects, snakes, and turtles. Most obligates associated with these communities are not area sensitive, and therefore can persist on relatively moderately sized patches contributing to local biodiversity.
- Larger Cultural Shrublands, exceeding 5 acres, will support multiple nesting pairs of obligate bird species and provide foraging habitat for larger mammals along with the benefits to other species.
It is important to maintain and manage Cultural Shrublands through periodic grass mowing, brush hogging, and/or prescribed burning or the vegetation will change and no longer offer characteristics preferred by those species that use them. Invasive species control will also likely be required. Foraging, nesting, or roosting sites for insects, amphibians, turtles, birds, or bats can be enhanced in Cultural Shrubland by providing preferred features.
Management practices can include:
- Invasive Plant Control: The thoughtful use of herbicide can be a critical tool in managing Cultural Shrublands. Specialty herbicides that do not impact grasses or flowering plants can be especially useful in controlling unwanted invasive shrubs. More targeted applications of generalist herbicides are 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.
- Mowing/Mulching: Grass Mowing will maintain areas of the shrubland that consist of grasses and flowering plants and should generally occur after the first fall frost to preserve nectar and pollen sources for insects. Mowing/Mulching clumps of shrubs and young trees before stems are 3 inches in diameter or are too large for available equipment to handle is best conducted every 3 – 5 years.
- Tree Cutting: Clumps of small diameter trees hardwood trees that establish within the Cultural Shrubland can be cut by and stacked into brush piles and/or burned. If a large number of young trees have begun to establish throughout the shrubland, they should be removed as they will shade out desirable flowering plants and shrubs. Often trees colonize along the edges of fields and should be eliminated to maintain the size of the habitat. In addition, an ecotone, transition between plant communities, can be established between Cultural Shrubland and Upland Forest habitats by removing approximately 50% of the canopy trees in the forest up to 100 feet from the field edge. This will encourage germination of flowering plants and densely growing shrubs and young trees that offers nectaring opportunities, foraging, cover, and perching sites at or near ground level.
- Prescribed Fire: As an alternative to Field Mowing or Brush Mowing, prescribed fire can be used as a management tool for establishing and maintaining Cultural Shrublands. Ideally, each unit within an established Cultural Shrubland should be burned approximately every 4-8 years. The entire site can be burned in a single year. 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. An additional benefit of fire is soil exposure which provides ground nesting bee habitat and germination sites for plants in Cultural Shrublands.
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 herbicide use should be adopted. - Open Burning: An additional option for removing vegetation in Cultural Shrublands to achieve the benefits of fire would be to conduct open burning. Brush, cane, and tree prunings are acceptable materials to burn. Burning piles of these materials in the Cultural Shrubland will create patches of exposed soil which provides ground nesting bee habitat and germination sites for plants. Open burning is allowed from mid-winter to early spring across most of Massachusetts with permits issued by local fire departments.
- Habitat Structures: Habitat management practices such as exposing soil, retaining or creating snags and roost trees, installing nest boxes or nesting platforms, constructing brush piles, or placing drumming logs result provide nesting or roosting opportunities, and cover. These enhance habitat for bees, amphibians, turtles, birds, and bats and can be provided in a variety of upland habitat types including Upland Forest, Young Forest, Cultural Shrubland, Cultural Grassland, or Sandplain Grassland, and wetland, or aquatic habitats such as Forested Swamps, Marshes, Wet Meadows, Ponds, or Gently Sloping Streams.