Habitat description
Cultural shrublands are 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. Cultural shrublands occur on sites formerly cleared for agriculture or other purposes, including utility corridors. Cultural shrublands would ultimately revert to forest in the absence of continued human disturbances (e.g., mowing, brush hogging, or burning). Cultural shrublands exist across Massachusetts in various states since the time of abandonment.
Characteristic natural communities
As cultural shrublands typically develop on former agricultural lands or other clearings such as utility corridors, they are not associated with or included within specific Massachusetts natural communities. Vegetation generally consists of clumps of native and exotic shrubs such as blackberry, blueberry, and multiflora rose, a mix of grasses and flowering herbs, and scattered clumps of trees such as cherries, birches, and willows. Vegetation composition and structure can vary considerably among sites.
Characteristic plants and animals
Cultural shrublands offer foraging and nesting sites for many pollinators, 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 including post-fledging forest nesting birds. Some vertebrates 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 mice and ermine. Black bear, bobcat, and moose use shrubland habitat seasonally for foraging.
View a complete list of Species of Greatest Conservation Need associated with this habitat.
Associated habitats
Cultural shrublands occur in a diversity of landscape settings across the state. Because they are often present on active or abandoned farmlands, they can be located directly adjacent to existing hay fields or other crop fields, or cultural grasslands being managed as habitat. Cultural shrublands may also be associated with and ultimately transform into young forest. Cultural shrublands have similar vegetation structure to other habitats in the MassWildlife habitat classification including dry woodlands and barrens, dry grasslands and heathlands, and maritime shrublands, and many open shrub habitat specialists such as prairie warblers will be found across these habitats.
Ecological processes
Creation and maintenance of cultural shrubland habitat is a result of human activities such as grass mowing, brush hogging, as opposed to ecological processes such as ice scouring and beaver flooding 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. Often within 15-20, the abandoned agricultural field will consist primarily of young tree species with a minor shrub component and after thirty years will be forest. Active management is required to maintain cultural shrubland.
Threats
Development of active or abandoned farmland and other sites with cultural shrubland reduces the availability of these potentially important habitat patches across the landscape that offer opportunities for colonization and dispersal of species that utilize them. Invasive species that are particularly problematic in regenerating areas such as cultural shrublands include multiflora rose, glossy buckthorn, common buckthorn, and autumn olive.
Agriculture can be a threat in some cases, as converting abandoned agricultural fields back to active farming can result in a loss of cultural shrubland. Utility corridors that are not managed to control invasive plant species or where plants are mowed and cut during breeding season offer reduced habitat benefits. Inadequately managed recreational use for trails and other activities (human disturbance) can increase the interaction between people and large-bodied snakes, like eastern ratsnake and North American racers, leading to mortality and collection. Such human disturbance can also be disruptive to bird breeding activity.
Predicted changes in precipitation patterns, summer temperatures, and drought caused by climate change may alter the composition and rate at which the plant community changes over time, but management can maintain the patchily distributed grass, flowering plants, shrubs and young trees that are favored by species utilizing cultural shrublands.
Conservation actions
- Proactive habitat protection: Protect cultural shrublands in conjunction with other associated habitats including broad expanses of matrix forest to maintain healthy and resilient landscapes for people and biodiversity conservation. Prioritize sites supporting state-listed animals and plants and other SGCN, as well as other protection priorities identified in BioMap and other conservation planning tools (e.g., municipal open space plans).
- Habitat restoration and management: See recommendations below.
- Law and policy: Regulate and limit the impacts of development and other land use changes. Innovative approaches to incentivizing compatible development, and farm and forest preservation should be considered where applicable.
- Conservation planning: Include important cultural shrublands in conservation planning efforts at multiple spatial scales. (See BioMap as an example.)
- Monitoring and research: Monitor the health and trends of SGCN populations, plant communities, and other wildlife. Monitor the effectiveness of habitat management efforts and conduct targeted research to improve habitat and population management.
- Public outreach: Include information about the role of cultural shrublands and other similar habitats in biodiversity conservation, flood mitigation, water filtering, and climate resiliency as part of broader communication strategies.
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. Because these areas are ephemeral, establishing and conducting a monitoring protocol over time is useful to track changes in vegetation and noteworthy bird and insect species. The information collected from these surveys can help direct management actions. For more information, please see: Habitat Management Priorities and Planning.
Although cultural shrublands of varying native shrub density provide important habitat, ideally habitat should consist of native grasses and flowering plants interspersed with approximately 40-60% cover of native shrubs and/or small hardwood trees with fewer softwood trees and patches of bare ground. In general, landowners interested in establishing or maintaining cultural shrubland should aim for patches that are >0.5 acre to 5-10 acres or more:
- Small cultural shrublands (less than 3 acres) provide habitat for pollinators and other insects, snakes, turtles, or small mammals. Small patches facilitate the movement of species (and genetics) between sites and support the long-term persistence of species across the landscape.
- Medium-sized patches (3-5 acres) provide nesting or foraging habitat for ground and shrub nesting birds and small mammals in addition to supporting many insects, snakes, and turtles.
- Larger cultural shrublands (over 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.
Cultural shrublands require periodic mowing, brush hogging, and/or prescribed burning to persist. Invasive species control will also likely be required. Foraging, nesting, or roosting sites for insects, amphibians, turtles, birds, or bats can be enhanced by providing preferred features.
- 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.
- Selective tree removal: If many young trees have begun to establish throughout the shrubland, they should be removed as they will shade out desirable flowering plants and shrubs. Clumps of small diameter hardwood trees that establish within the cultural shrubland can be cut and stacked into brush piles and/or burned. 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.
- Invasive plant control: Although mowing alone can maintain shrubland vegetation structure, a high abundance of invasive shrubs will significantly degrade habitat quality, and spot control of tree sprouts can reduce required mowing frequency. Therefore, 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 invasive shrubs. 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.
- Prescribed fire: As an alternative to, or in combination with mowing, prescribed fire can be used to establish and maintain cultural shrublands. Ideally, each unit within an established cultural shrubland should be burned approximately every 3-5 years, unless supplementing with occasional mowing. Fire can be important to some plant species in these communities, maintaining structural integrity and removing thatch, while also stimulating germination, flowering, fruiting, and seed release. An additional benefit of fire is soil exposure which provides ground nesting bee habitat and germination sites for some plants. Whether to use growing-season or dormant-season burns depends upon 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. Prescribed fire should only be implemented by qualified and trained personnel under permits obtained by the proper regulating authorities.
- Open burning: An additional option for removing vegetation is occasional open burning. Brush, cane, and tree prunings can be piled and burned to 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 may be appropriate on a site-specific basis in a variety of habitats including upland forest, young forest, grasslands, shrublands, and heathlands.